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Why Do Men Hunt?



The role of men in hunter‐gatherer societies has been subject to vigorous debate over the past 15 years. The proposal that men hunt wild game as a form of status signaling or “showing off” to provide reproductive benefits to the hunter challenges the traditional view that men hunt to provision their families. Two broad assumptions underlie the signaling view: (1) hunting is a poor means of obtaining food, and (2) hunted game is a public good shared widely with others and without expectation of future reciprocation. If hunters lack the ability to direct food shares and obtain subsequent benefits contingent on redistribution, then the ubiquitous observations of male hunting and universal pair‐bonding cannot be explained from a perspective that emphasizes kin provisioning and a division of labor. Here we show that there is little empirical support for the view that men hunt for signaling benefits alone. The ethnographic record depicts a more complex relationship between food sharing patterns, subsistence strategies, mating, and the sexual division of labor. We present a framework incorporating trade‐offs between mating and subsistence strategies in an economic bargaining context that contributes to understanding men’s and women’s roles in hunter‐gatherer societies.
2009 by The Wenner-Gren Foundation for Anthropological Research. All rights reserved. 0011-3204/2009/5001-0003$10.00. DOI: 10.1086/595620
Current Anthropology Volume 50, Number 1, 2009 51
Why Do Men Hunt?
A Reevaluation of “Man the Hunter” and the Sexual Division of Labor
by Michael Gurven and Kim Hill
The role of men in hunter-gatherer societies has been subject to vigorous debate over the past 15
years. The proposal that men hunt wild game as a form of status signaling or “showing off” to
provide reproductive benefits to the hunter challenges the traditional view that menhunt to provision
their families. Two broad assumptions underlie the signaling view: (1) hunting is a poor means of
obtaining food, and (2) hunted game is a public good shared widely with others and without
expectation of future reciprocation. If hunters lack the ability to direct food shares and obtain
subsequent benefits contingent on redistribution, then the ubiquitous observations of male hunting
and universal pair-bonding cannot be explained from a perspective that emphasizes kin provisioning
and a division of labor. Here we show that there is little empirical support for the view that men
hunt for signaling benefits alone. The ethnographic record depicts a more complex relationship
between food sharing patterns, subsistence strategies, mating, and the sexual division of labor. We
present a framework incorporating trade-offs between mating and subsistence strategies in an eco-
nomic bargaining context that contributes to understanding men’s and women’s roles in hunter-
gatherer societies.
The traditional perspective of the hunter-gatherer nuclear
family depends on a division of labor where men hunt wild
animals and women gather plant foods (Lovejoy 1981). The
pair-bond is considered a cooperative venture geared toward
joint production of highly dependent offspring, where women
bear and care for offspring in exchange for long-term pro-
visioning (Isaac 1978; Lancaster 1978). According to this view,
“family organization may be attributed to the hunting way
of life” (Washburn and Lancaster 1968, 295), where “males
hunt and females gather, the results are shared and given to
the young, and the habitual sharing between a male, a female,
and their offspring becomes the basis for the human family”
(Washburn and Lancaster 1968, 301). This hunting-based
model for the evolution of the nuclear family and a coop-
erative sexual division of labor has dominated much anthro-
pological thinking over the past 40 years.
Recent proposals have painted a different portrait of the
hunter-gatherer family. The ubiquity of men’s hunting among
Michael Gurven is Associate Professor in the Department of An-
thropology at the University of California, Santa Barbara (Santa
Barbara, California 93106, U.S.A. []). Kim
Hill is a Professor in the School of Human Evolution and Social
Change of the College of Liberal Arts and Sciences at Arizona State
University (SHESC 233, P.O. Box 872402, Tempe, Arizona 85287-
2402, U.S.A.). This paper was submitted 5 II 07 and accepted 16
VII 08.
foragers is uncontested, but the benefits men receive and their
motivations for hunting are the subject of lively debate. The
“show-off” hypothesis (Hawkes 1990, 1991, 1993) initially
proposed that men hunt to gain social attention and mating
benefits by widely sharing game. This hypothesis was refor-
mulated using costly signaling theory (see Bird 1999; Bliege
Bird, Smith, and Bird 2001; Hawkes and Bliege Bird 2002)
and is hereafter referred to as the “signaling model.” This
model proposes that hunting functions mainly to provide an
honest signal of the underlying genotypic or phenotypic qual-
ity of hunters, which later yields a mating advantage or social
deference. Big game hunting is considered an effective means
to signal because of the large audience, as consumers will pay
attention to hunting yields in order to obtain their shares.
Hunting is thus viewed as status or mating competition, not
familial provisioning, and marriage is reinterpreted as a con-
vention of publicly recognized property rights that reduces
competition among men (Hawkes 2004).
Proponents of the signaling model suggest that were men
primarily concerned with familial provisioning, their subsis-
tence patterns would mirror those of women. Therefore, the
sexual division of labor should be most pronounced when
activities effective for signaling differ from those for producing
1. Occasional protests highlight the importance of women’s subsis-
tence tasks (e.g., Dahlberg 1981), diminishing the traditional emphasis
on hunting, but do not deny the centrality of cooperative unions among
men and women.
52 Current Anthropology Volume 50, Number 1, February 2009
the most food. As Bird (1999, 72) states in a recent review,
“the sexual division of labor seems to make more sense as an
outcome of conflicts rather than similarities in reproductive
This view is incongruent with the observation that
subsistence-behavior dimorphism is rare among most mam-
mals where males engage almost entirely in mating effort.
Divisions of labor are common among “cooperative breeder”
species and social insects where individuals collaborate to
achieve genetic contribution.
The extent to which men’s food contributions serve to
provision families or display status is important for inter-
preting archaeological signs of hunting in the fossil record,
understanding the evolution and maintenance of long-term
pair-bonds, and understanding how fundamental human life-
history traits (delayed childhood, long postmenopausal life
spans, and large brains) evolved (Hawkes et al. 1998; Kaplan
et al. 2000).
The first section of this article assesses four key assumptions
of the signaling model: (1) men forage for large-package-size
items even when alternative foraging strategies yield a higher
long-term average food value, (2) high-variance daily acqui-
sition activities cannot effectively provision offspring,(3) food
transfers by hunters are not paid back later in currencies
directly affecting familial welfare, and (4) women prefer gath-
ering over hunting only because of its higher reliability and
The second section explores men’s and women’s foraging
and reproductive decisions by incorporating bargaining the-
ory in economics, recognizing the potential for cooperation
due to shared fitness interests of men and women and for
conflict under changing conditions and disparities in bar-
gaining power. While Washburn’s and Lovejoy’s original de-
piction of the nuclear family was simplistic, we choose not
2. Primatologists have considered similar proposals emphasizing male
coercion and mate guarding rather than provisioning in the evolution
of pair-bonds and monogamous mating systems (Mesnick 1997; van
Schaik and Dunbar 1990). Parental conflict over offspring investment is
part of a general framework of family dynamics in evolutionary biology
(Parker, Royle, and Hartley 2002). Conflict-oriented views are based on
the fundamental differences in the reproductive biology of male and
female mammals, where fitness gains accrue to males primarily through
increased access to mates and to females by increased access to resources
(Trivers 1972). Because most mammals are polygynous, human pair-
bonds are usually compared with those among bird species that exhibit
high levels of biparental care and monogamy. However, recent DNA
fingerprinting has shown that many species of so-called monogamous
birds show significant extrapair copulation, where up to 47% of broods
may be fathered by other males. In a similar reassessment of avian social
systems, it has been argued that monogamy in birds may be common
not because each sex has the greatest success with monogamy butbecause
of limited opportunities for polygyny (see Black 1996).
3. These issues have reached a new audience of archaeologists who
use costly signaling theory to reinterpret the significance of Archaic period
hunting practices in the western United States (e.g., Broughton and Bay-
ham 2003; McGuire and Hildebrandt 2005). These studies benefit from
not having to rely on contemporary forager ethnography, and they cover
broad stretches of time, but they also raise particular concerns (Codding
and Jones 2007).
to abandon the notion of a complementary, advantageous
sexual division of labor. Our graphic model emphasizes that
underprovisioning, mixed mating and parental investment,
and desertions are all possible outcomes in human marriage.
Assessing Empirical Evidence for the
Signaling Model
Mean Productivity of Hunting
Do men opt for activities providing lower mean nutrient re-
turn rates but higher variance than those of women in the
same society? Studies among three foraging populations—the
Ache of Paraguay, the Hadza of Tanzania, and the Hiwi of
Venezuela—sparked this view and provided data for its eval-
In her original article on male show-offs (Hawkes
1991), Hawkes cited a report that Ache men could gain energy
at higher rates by extracting palm products all day rather than
hunting (Hill et al. 1987). That analysis was incorrect due to
laboratory error in assessing edible portions of palm fiber and
failure to measure the time required to find suitable palms
(experiments now show that only one in 35 encountered
palms has exploitable starch). Twenty-seven years of data
show that Ache men obtain a mean 830 cal/h by hunting,
and men typically obtain a total of 1,340 cal/h from all
resources (meat, fruit, larva, honey) during normal foraging
activities (Hill and Kintigh, forthcoming). New experimental
data also show that male or female groups extracting only
palm products (starch and hearts) could obtain 850–1,200
cal/h (mean 1,050 cal/h). Given the sensitivities of these means
to population age structure, sampled season, and sampleerror
in acquisition rates and caloric values, we conclude that the
current male mixed hunting/collecting pattern produces com-
parable calories per unit time as would foraging exclusively
for palm fiber.
Hawkes and colleagues have also argued that Hadza big
game hunters could gain more calories by gathering or hunt-
ing small game, but published data contradict that claim
(Hawkes et al. 1991, 2001). Hadza men acquired 1,500 cal/
h hunting large game and only 375–1,170 cal/h hunting small
game or trapping (Hawkes et al. 1991, 2001). Hadza women
obtained 900 cal/h foraging for roots or berries (Hawkes,
O’Connell, and Blurton Jones 1989). These estimates of gath-
ering efficiency may be inflated because recent laboratory
analyses of edible tubers show caloric densities lower than
those used by the Hawkes team (Schoeninger et al. 2001, table
2). Thus, Hadza large game hunting produces nearly twice
the energetic-gain rate as gathering and up to four times the
rate potentially achieved by targeting small game. Neverthe-
less, men hunting large game diversify their production port-
4. Contemporary hunter-gatherers are neither modern relics nor mir-
rors into the past but instead represent an imperfect but constructive
lens for learning about past adaptations and behavior under a diverse
set of ecological conditions.
Gurven and Hill Why Do Men Hunt? 53
folio by opportunistically hunting small game and by col-
lecting nonmeat foods such as honey (Marlowe 2004b).
Among Hiwi foragers of the Venezuelan savannas, hunting
is also more productive than gathering (Hurtado and Hill
1990). In the late wet season, pregnant and nursing women
obtained 1,300 cal/h, and those with no small children ob-
tained 1,600 cal/h (Hurtado and Hill 1990, tables 6, 8). Men
acquired 2,700 cal/h by hunting, and in other seasons, men
obtained three to five times as many calories per hour by
hunting as females did from gathering.
Such comparisons are only partially relevant because return
rates are expressed in terms of caloric energy. Lipids and
proteins derive primarily from meat, while plant products
consist largely of carbohydrates and micronutrients. Nutri-
tionally, 1 g of carbohydrate and protein each contains 4 cal,
while 1 g of fat contains 9 cal. Protein-lipid resources and
additional animal-source micronutrients are more nutrition-
ally valuable than carbohydrate in most human societies (see
“Why the Sexual Division of Labor?” below).
Men hunt be-
cause meat often has higher marginal nutritional value than
carbohydrate foods given the differences in macronutrients
and overall supply of the two food types.
Risk-Prone Hunters?
Hunting is characterized by significant daily variation in re-
turns, where even the best hunters may return to camp empty-
handed. Societies dependent on large game, such as whalers,
experience tremendous daily variation in meat production
(Alvard and Nolin 2002). Big game hunters like the Hadza
make large game kills only 4% of the time (Hawkes et al.
1991), whereas the !Kung, Ache, and Hiwi, targeting smaller
game, make kills 27%, 50%, and 44% of the time, respectively.
Under most circumstances, hunting returns are less pre-
dictable than those from gathering, but many economic ac-
tivities yielding variable returns can provide a viable liveli-
hood. Individuals simply adapt to such situations so that
production variance does not result in high daily consumption
variance. Food sharing, food storage, and greater diet breadth
are biocultural means of reducing acquisition variance in an-
imal and human foraging societies (Winterhalder 1990). Shar-
ing is a common solution to acquisition variance among for-
agers, and therefore, the number of receiving families and the
proportions given away are both greater for resources char-
acterized by higher acquisition variance (Hames 1990; Kaplan
and Hill 1985). Without sharing, large game hunting may
never have been viable for our hominin ancestors.
While hunting is often a risky method of daily food ac-
quisition, dependence on plants may also involve problems
of temporal variability. Plants are usually seasonal, and for-
5. As in many foraging groups, Ache and Tsimanecommonly complain
of hunger even though carbohydrate-rich foods such as sweet manioc
and plantains are abundant. The hunger refers specifically to the desire
to eat meat.
agers may experience long periods when few edible plants are
Extreme seasonal plant shortages characterize many
Arctic foraging societies at high latitudes (e.g., Balikci 1970).
During these shortages, foragers may depend on hunted game
despite daily variation in their acquisition.
Men in some foraging populations target small to medium-
sized game, and even Hadza hunters often hunt small game
opportunistically (F. W. Marlowe, personal communication).
Small game has been a component of human diets for at least
200,000 years (Stiner 2002), and its acquisition was unlikely
motivated by signaling. Small game hunting is more pre-
dictable than large game hunting, and in documented hunter-
gatherer societies, small game shares are preferentially con-
sumed within the family (Gurven 2004).
Bliege Bird, Smith, and Bird (2001) and Bliege Bird (2007)
show that men in one foraging society regularly opt for high-
variance, low-return foraging when faced with the same al-
ternatives as women and that the sex differences cannot be
explained by macronutrients. Meriam women of the Torres
Strait collect shellfish or hook-and-line small fish. Men em-
ploy techniques to fish for larger prey at a lower gain rate.
The general division of labor where women collect shellfish
while men pursue larger marine resources is typical of marine
foragers, but the suggestion that men obtain less food over
the long run is novel. These findings suggest that research is
needed to determine how often men pursue foraging strategies
that are suboptimal for familial provisioning.
Sharing and Reciprocity
Hunting is argued to be a poor family provisioning strategy
because it is believed that meat transfers to others are not
paid back in some form at a later date (Bird 1999; Blurton
Jones et al. 2000; Hawkes 1993; Hawkes and Bliege Bird2002).
Signaling proponents view shared meat as lost resources be-
cause men supposedly cannot control the distribution of their
hunted game and nothing is returned in exchange. Men’s food
production is therefore discounted such that only the kept
portion contributes to family provisioning.
A recent comprehensive review shows little support for the
notion that hunters do not (or cannot) influence resource
distributions or that meat is unconditionally shared (Gurven
2004). Empirical evidence does not support the assertion that
6. Among the Hiwi, the primary carbohydrate staple, roots, is only
available 4–5 months during the year. Because metal digging tools are
significantly more efficient than traditional wooden ones, it is likely that
the productive carbohydrate season was shorter before the introduction
of metal tools (Hurtado and Hill 1990).
7. Fifteen years ago, there was much debate about whether tropical
foragers could survive without trading with farmers or cultivating swid-
dens, because seasonal shortages in carbohydrate-rich foods are so com-
mon (Headland and Bailey 1991).
54 Current Anthropology Volume 50, Number 1, February 2009
hunted prey are undefendable public goods.
Studies reveal
sharing bias by categories of individual recipients and in the
size of transferred shares. Kin, neighbors, and cooperative
partners often receive more meat than other group members
in quantitative studies, suggesting some control over distri-
bution by acquirers, even when hunters do not butcher or
divide their prey. Indeed, a hunter’s nuclear family obtains
more from his kill than do other families in all sharing studies
except those among Ache during forest treks.
Preferential food sharing with those who reciprocate is re-
ferred to as “contingency” (Gurven 2006; Hill and Kaplan
1993). Receipt of food that is contingent on having given
food is commonly observed in the ethnographic literature on
foragers and has been found in most societies where tested
statistically (Gurven 2004).
The amount of meat given by
one Hiwi family to another was the strongest predictor of
how much meat was returned by that same family over a 4-
month sample period (Gurven et al. 2000b). The statistical
association between amounts shared and received suggests on
average 35%–45% of game and fish shared by men was re-
turned by the recipient family because it was shared (i.e., with
factors such as kinship and proximity controlled). A much
higher percentage of transferred food was actually returned
to donor’s families, considering the additional, independent,
positive effects of kinship and residential proximity on
amount shared (Gurven et al. 2000b).
The amount of meat received was also significantly asso-
ciated with the amount given to each family among the Pilaga
(Gurven 2004), Yanomamo (Hames 2000), Dolgan, and
Nganasan (Ziker and Schnegg 2005). Among the Ache, meat
sharing is highly contingent at reservation settlements
(Gurven, Hill, and Kaplan 2002), and nonmeat foods are
shared contingently in both the forest and reservation when
other confounding factors are controlled. Contingency
trumps kinship on Ache reservations, with shares going pref-
erentially to kin who give them large amounts of food rather
than those who share little (Gurven, Hill, and Kaplan 2001).
Only Ache forest meat sharing shows no relationship between
amounts given and received among nuclear family pairs
(Gurven, Hill, and Kaplan 2002); however, on forest treks,
meat may still be shared in a contingent fashion (Hill 2002).
Informants state that a man must hunt and attempt to kill
something in order for others to give him a share in the band’s
daily production. Teenage boys are warned that if they do not
hunt, they will not be fed. Men failing to hunt or help in
8. It is also inconsistent with the observation that the same resources
are shared differently across societies or in different contexts (e.g., Ache:
Gurven, Hill, and Kaplan 2002; Huaroni: Franzen and Eaves 2007),which
suggests that game can be defended, if necessary.
9. Even nonhuman primates have been observed to engage in con-
tingent reciprocal food exchange (de Waal 1997).
cooperative hunts are generally not invited to participate on
future treks.
Hadza meat sharing has been described as noncontingent
because individuals approach undefendable kills and take por-
tions for themselves. However, Hawkes, O’Connell, and Blur-
ton Jones’s (2001, table 3) recent data reveal that a hunter’s
family receives a larger portion of his kill (29.9 kg/kill) on
average than do other families (13.5 kg/kill) for the largest
animals. Other biases in meat distribution (to close kin, near-
est neighbors, sharing partners, etc.) have not been examined
among the Hadza, but Marlowe (1999) shows that men with
biological children rather than stepchildren produce more
food, suggesting that Hadza men acquire food partially to
feed their families. Hawkes et al. (2001) report no relationship
between the total amount of meat a hunter provides to all
others and the amounts received in return from all others,
but this does not test contingency. The right of a man or his
family to take a portion of the kill may depend on his attempts
to acquire food (and sharing the results) or provide some
useful good or service, as we suggest among the Ache. If so,
obtaining a share of meat among the Hadza may be contingent
on cooperative behavior that benefits hunters who share; in-
deed, part of demand sharing (Peterson 1993) may reflect
debt obligations based on expected repayment. Whatever the
explanation for demand sharing among the Hadza, our rean-
alysis does show significant contingency for meat transfers
among pairs of Hadza hunters (Gurven 2004).
Women’s sharing patterns, a rarely examined feature of
hunter-gatherer life, also contradict the signaling hypothesis.
It is argued that women target items for which they can con-
trol resource package size and rarely acquire more than their
families can eat (Bird 1999, 68). This is not true of the Ache,
Hiwi, and probably the Hadza as well. Women often inten-
tionally collect larger amounts of food than their family can
consume, then widely share outside their nuclear family. Plant
foods come in small increments, and women could stopwork-
ing upon obtaining enough for their families. Ache women
extract palm fiber starch one handful at a time, producing
between 3,000 and 6,000 calories in each extraction session.
Anecdotal reports suggest similar rates for Hadza root and
berry collection and that Hadza women share with unrelated
individuals (Blurton Jones, Hawkes, and O’Connell 1997).
Ache and Hiwi women must therefore acquire large packages
of collected foods intentionally because they gain from food
transfer. Theory suggests that those gains cannot be increased
by number of mates; gains from sharing should be in some
form that affects women’s or offspring’s well-being. Ache and
10. Anthropologists, providing no meat but sharing in kills, feel pres-
sure from the contingency sharing system and offer gifts and services to
groups such as the Ache and Tsimane in exchange for accompanying
them on treks.
11. An independent assessment of pairwise contingency that con-
trolled for the presence of different hunters during distributions shows
a similarly strong positive relationship (W. Allen-Arave, personal
Gurven and Hill Why Do Men Hunt? 55
Hiwi women give away about 55% of all collected food
(Gurven 2006; Kaplan and Hill 1985). Ache women at res-
ervation settlements share an even higher fraction of their
collected resources (76%). As package size increases, Hiwiand
Ache women keep a smaller percentage for their nuclear
It has long been known that men share a greater percentage
of their production than women; however, this may be be-
cause they often bring in large food packages. Analyses among
the Hiwi (Gurven et al. 2000b), Ache on reservation settle-
ments (Gurven et al. 2001), and Ache on forest treks (Gurven,
Hill, and Kaplan 2002) show no sex differences in amounts
shared outside the family for resources obtained by men and
women after controlling for resource size. If women’s sharing
patterns are identical to those of men, and the production of
large packages and subsequent sharing by women is paid back
in a form useful for parental investment, it seems parsimo-
nious to assume the same for men’s sharing.
Many ethnographies report complaints concerning failures
to meet sharing obligations or expectations, particularly in
the context of pairwise exchange (see Gurven 2004). Men
who hunt only as a form of mating effort should not be
concerned with receiving conditional shares from previous
recipients, nor should they complain or become upset when
shares are not returned.
If signaling provides fitness benefits,
and signalers compete for an audience, men should prefer not
to have their shares repaid, but no evidence supports this
Estimates of contingency show that producers receive back
on average at least a third of what they give away to other
families. These estimates are imperfect windows into com-
plicated cooperative exchange relations (Gurven 2006). There
are reasons to expect that cooperation may not result in com-
plete exchange balance in foraging societies. Among hunter-
gatherers, nuclear families are part of larger extended kin
networks that often subsidize each other’s reproduction over
long time periods. Over any short time period, some indi-
viduals always produce more than they and their families
consume. Even if we consider isolated nuclear families as
independent units, each should have a minimal threshold for
acceptable exchange with others that constitutes an “insurance
policy” guaranteeing resources from reciprocators on shortfall
days or periods of debilitation from sickness and injury. In
understanding the exchange of A’s present production for B’s
future production, there will be a set of potential exchanges
(many unequal) where both A and B can benefit above what
might be expected if no exchange occurs. This region is re-
12. Hiwi women kept about 40% of nonhunted resource packages
over 15 kg, while Ache women kept 20% of fruit, 25% of larva, 25% of
palm heart, and 30% of palm starch packages over 2,000 calories.
13. Anecdotal reports suggest this is not the case for most foragers,
just as abundant studies in economics and psychology show that people
in urban and rural settings around the world get upset and seek to
“punish” perceived defectors in dyadic interactions (e.g., Henrich et al.
ferred to as a “bargaining zone,” the oval region in an Edge-
worth box diagram (Gurven 2004; fig. 1). The final exchange
agreement should be influenced by the relative bargaining
power of each party, reflecting expected costs from giving and
benefits from receiving food. Costs and benefits vary with the
amount of existing resources, influence, production ability,
status, or dependent offspring (e.g., Boyd 1990).
Evolutionary models of sharing do not adequately explain
cultural sharing norms or other conventions that support
extensive cooperation among non-kin. Quantitative analyses
repeatedly show that “need” is one of the strongest predictors
of food flows among hunter-gatherers (Gurven 2004), where
families with more children or greater dependency often re-
ceive larger shares. High family need can be permanent due
to low production ability, or it can be temporary when families
pass through a stage of high dependency (fig. 1). Signaling
proponents argue that flows of food to the needy indicate
“tolerated theft,” but evidence of high producers intentionally
producing and distributing shares to the needy (Gurven 2004)
undermine that suggestion. Net resource flows to needy fam-
ilies may make more evolutionary sense considering the co-
operative nature of human social organization and the novel
proposal that altruistic punishment in the context of inter-
group competition may favor “hyper-cooperation” (Bowles
2006; Boyd et al. 2003).
Why Don’t Women Hunt?
The signaling model suggests that women avoid hunting be-
cause it provides low unpredictable payoffs. We have shown
that hunting yields comparable or higher caloric returns and
more favorable nutrient content than collecting in several
societies. The Agta of the Philippines are often cited as evi-
dence that women can hunt as proficiently as men, despite
encumbrances of childcare. In fact, many forager women,
including Ache and Hiwi, participate in hunting activities.
However, women rarely make kills of medium-sized or large
game; instead, they engage in activities that help men hunt
successfully. In contrast, Agta women hunt with bows and
arrows and kill the same prey as do men. The Agta data are
important because they indicate conditions under which
women may actively hunt. However, fewer than 100 Agta
women claimed to have ever hunted from a population of
about 9,000 on Luzon Island (P. B. Griffin and T. Headland,
personal communication). Most women who reported having
hunted were no longer hunting during the ethnographic ob-
servation period, and most late-twentieth-century Agta had
never heard of women hunters (P. B. Griffin and T. Headland,
personal communication). Hunting production data exist for
a sample of only six women hunters (Goodman et al. 1985),
and available data suggest several patterns relevant to women’s
hunting: (1) carbohydrate resources provided low returns and
were rarely encountered; (2) meat was traded for carbohy-
drates at a favorable rate; (3) fertility and ratios of dependent
56 Current Anthropology Volume 50, Number 1, February 2009
Figure 1. Number of dependents by age for Ache and Dobe !Kung (inset)
females based on age-specific fertility and mortality measures for these
populations. Ache women have high fertility over their lifetimes (total
fertility rate p8), and !Kung women have low fertility (total fertility
rate p4). Adapted from Gurven and Walker (2006).
children to adults were low, with high availability of allopar-
ents; (4) women who hunted were often sterile or postre-
productive; (5) all women’s kills resulted from hunting with
dogs; and (6) women’s hunting always took place less than
5 km from camp, allowing rapid return to dependent off-
spring (Estioko-Griffin 1985, 1986; Goodman et al. 1985).
The first three points may explain why African Pygmy women
participate in communal net and bow hunting activities. Dogs
immobilize Agta prey, perhaps explaining why they regularly
dispatch prey without men whereas Hiwi and Ache women
rarely do. No study of Agta women hunters has examined
whether active hunting is related to women’s reproductive
status at the time of hunting, but anecdotes suggest that
women hunted infrequently or not at all when pregnant or
lactating (Estioko-Griffin 1986, 42).
Brown (1970) proposed that women do not hunt because
it is incompatible with childcare demands rather thanbecause
of strength demands or physical constraints such as endurance
14. Women’s involvement in some hunting activities is probably typ-
ical of most foraging groups, but there are still strong sex differences.
Ache women search for game (and call men when they find it), dig out
some burrowing animals, spot monkeys during hunts, and help track
wounded prey. Hiwi women paddle canoes while their husbands stand
and hunt with a bow for aquatic game. Time allocation data on Ache
women suggest that they spend about 10% of their foraging time helping
in hunts (Hill 2002). During 30 years of fieldwork with the Ache, K.H.
has seen women actively attempting to kill prey a couple dozen times
(only once with bow and arrow) and has heard stories of two women
who hunted regularly before fieldwork. However, in a recent Ache sample
of all game killed by 25 families from 1994 to 1999, men killed 4,437
animals, and women killed 3. Women help in hunts but do not often
make kills.
or spatial abilities (see also Hurtado et al. 1992). Keeping
offspring alive is a top priority for forager women, and it
precludes hunting in most environments. Nursing women
adjust gathering rates according to the age of the youngest
child with them at the food patch, and as infant age increases,
collection rates increase substantially (Hurtado et al. 1992).
Mothers obligatorily care for infants because on-demand
lactation occurs frequently throughout the day. Women would
often lose prey were they to interrupt hunting pursuits to
meet immediate childcare demands. Infants cry and fuss for
many reasons, and failure to react to distress calls lowers infant
viability. The situation is quite different for sessile-collected
resources and some small vertebrates, where pursuit can be
interrupted at any time without loss.
Hunting is also dangerous for infants because of long dis-
tances traveled under arduous conditions and dangers in-
herent in rapid burst pursuits. Males experience higher ac-
cident rates than females among Ache foragers (Hill and
Hurtado 1996) and higher death rates from animal attacks
and snakebite among Tsimane (Gurven, Kaplan, and Zelada
Supa 2007). Because maternal loss is more detrimental than
paternal loss (Sear and Mace 2007), women may be more
averse to risk of injury than men.
Finally, successful hunting requires at least 15–20 years of
experience to obtain maximum return rates. Boys who miss
sensitive-period skill development rarely become proficient
hunters (Gurven, Kaplan, and Gutierrez 2006; Kaplan et al.
2000; Walker et al. 2002). The steepest gains in men’s hunting
returns occur during the years when women experience high
fertility and are constrained from hunting. This may explain
Gurven and Hill Why Do Men Hunt? 57
why postreproductive women, free from childcare constraints,
do not hunt in most societies.
Cooperative Pair-Bonds Revisited:
A Bargaining Perspective
Why the Sexual Division of Labor?
Five critical aspects of hunter-gatherer socioecology lead us
to expect a sexual division of labor: (1) long-term dependency
of high-cost offspring, (2) optimal dietary mix of macronu-
trients from mutually exclusive foods, (3) efficient foraging
based on skill-dependent learning, (4) frequent spatiotem-
poral segregation of important resource types, and (5) sex-
differentiated comparative advantage in tasks. These com-
bined conditions are rare in nonhuman vertebrates but
common to human foragers and perhaps suggest why men
alone hunt in 166 of 179 hunter-gatherer societies examined.
Men and women hunt in 13 societies, and in none do women
alone hunt, whereas women are the main gatherers in two-
thirds of these societies (Ember 1978).
To understand the sexual division of labor, we must con-
sider the costs of joint offspring production. The average
female forager can expect to have five children over her life-
time (Hewlett 1991a) that grow and develop slowly and con-
sume more food than they produce until their mid- to late
teens (Kaplan 1994; Kramer 2005). A reproductive-aged
woman often has multiple offspring of various degrees of
dependency (fig. 1). Even at peak adult production, adultpairs
often cannot feed themselves and their children without as-
sistance (Gurven and Walker 2006). Even foragers at the age
of peak food production may experience net food deficits due
to the composite net caloric demand of offspring.
Offspring need is insufficient to cause specialization insub-
sistence activities by sex or age; macronutrient composition
of foods also matters. There is no consensus on the optimal
combination of lipids, proteins, and carbohydrates in the hu-
man diet, but each is necessary for healthy growth, devel-
opment, body maintenance, and reproduction (see Milton
and Demment 1988 and references therein). Protein-lipid re-
sources and animal-source micronutrients are often difficult
to obtain, produce greater biological benefit per unit weight
or energy, and are more valuable than carbohydrate in most
societies. Increased protein and lipid consumption facilitates
improved growth and health in most societies (Carpenter
1994; Larsen 2003) and are critical to brain growth, immune
function development, and female reproductive function
(Murphy and Allen 2003).
The human gut is adapted to a
mixed macronutrient diet (Aiello and Wheeler 1995), and
biochemical evidence suggests that several essential nutrients
15. Experimental manipulation with isocaloric diets shows improve-
ments in health and growth rates among rats fed with higher protein-
lipid diets (reviewed in Hill 1988). Frugivorous primates regularly forage
at lower caloric return rates in order to obtain protein-lipid foods (see
Milton 1999 for review).
(e.g., taurine, 20- and 22-carbon fatty acids) are onlyobtained
from animal tissues and more so in large game (Cordain,
Watkins, and Mann 2001). Finally, plant diets are low in pro-
tein, vitamins B6 and B12, zinc, iron, and long-chain omega-
3 fatty acids, and plants are often high in toxic antinutrients
(Cordain, Watkins, and Mann 2001).
Foragers should therefore acquire complementary plant
carbohydrates, animal protein-lipids, and micronutrients for
optimal health and growth. Specific macronutrients are pack-
aged in different foods, thus many separate food items must
be included in the human omnivore diet (see Harris and Ross
1987 volume). Game, fish, roots, fruits, honey, nuts, insect
larvae, berries, and other forager foods are often difficult to
acquire and require specialized knowledge, contributing to
the long dependency of hunter-gatherer youth (Kaplan et al.
2000). Productivity in gathering, collecting, and fishing ac-
tivities may often be more size-dependent than skills-depen-
dent, and adult-level return rates may be easily attained (Bird
and Bliege Bird 2002, 2005; Tucker and Young 2005). Con-
versely, efficient hunting requires years of practice among
Ache, Hiwi, Tsimane and other hunting groups. Encountering
and killing animals upon pursuit are the two most difficult
components of hunting that require the longest time delays
to reach peak levels (Gurven, Kaplan, and Gutierrez 2006;
Ohtsuka 1989; Walker et al. 2002).
Healthy diets are provided by different foods whose ac-
quisition requires separate skills and additional time invest-
ment in learning and practice for increasing returns. Under
these circumstances, specialization is a likely, if not inevitable,
outcome even if group members are equally capable of per-
forming all tasks. This is essentially economist Gary Becker’s
argument concerning the familial division of labor applied to
hunter-gatherers (Becker 1973, 1974).
Specialization does not imply that men should hunt and
women gather. Without comparative advantage by sex, each
need only coordinate on a particular complementary set of
activities. Without increasing returns to specialization, both
sexes might become generalists and freely alternate between
complementary activities. However, in the section titled“Why
Don’t Women Hunt?” (above), we presented reasons why men
hunt and women gather. Childcare constraints give men a
comparative advantage in hunting activities, amplified by
men’s greater average strength and body size. Signaling ben-
efits from killing large prey may also motivate male hunting,
but in our view, these are not necessary to explain why men
hunt in foraging societies. Instead, signaling payoffs to hunt-
ing may increase the likelihood that men will hunt more and
under conditions that might otherwise favor greater male in-
volvement in gathering.
Marriage, Parental Investment, and Children as Public Goods
The signaling model does not account for human marriage.
A cooperative pair-bond model explains marriage but does
58 Current Anthropology Volume 50, Number 1, February 2009
Figure 2. Isofitness framework underlying a man’s optimal mix
of household contributions and private gains. Isofitness curves
define combinations of household production and leisure that
result in equal fitness gains. The different budget constraints
(straight diagonal lines) are defined by the total number of hours
available that could be spent in either household production (X-
axis) or leisure (Y-axis). The budget-constraint lines intersect the
two axes at the point where all time would be dedicated only to
that activity. Usually a budget is a straight line, although the
budget line might be bowed outwards if public and private ac-
tivities can be performed simultaneously, as when hunting both
feeds children and signals mate quality. Ais the optimal allocation
of a man’s time to household goods and private gain given the
budget constraint of the thin line, but this point lies below the
woman’s minimum acceptable level of household contribution.
Therefore, a man will choose the suboptimal allocation at B. The
thick black budget line illustrates the case where household goods
are more cheaply acquired than with the thin black line. Under
this scenario, the optimal mix includes more household invest-
ment (C).
not presume that males and females contribute equally. Chil-
dren are shared public goods because they represent fitness
outcomes for both parents regardless of the levels of invest-
ment each of them provides. To model optimal parental in-
vestment, we consider partner utility (fitness) functions that
contain shared household (public) and personal (private)
components. The task is to determine optimal timeallocations
for each marital partner and the resulting level of equity in
the distribution of effort and gains. Extreme possibilities in-
clude “symmetrical” marriages, where similar effort and gains
are realized by each partner; “dictatorial” marriages, where
one partner determines allocations by both (Manser and
Brown 1980); and pair-bond dissolution. The existence of
noncontributing “deadbeat dads” does not deny the benefits
from an economy of scale associated with cooperation in
marriage unions; even with low investment by one partner,
a sexual division of labor may still be optimal. Unstable unions
and unequal bargaining power due to different options avail-
able to each partner can lead to dissolved unions and/or a
failure for one or both partners to invest in household pro-
duction and childcare.
The optimal amount of time spent investing in offspring
can be illustrated graphically using indifference curves. Each
partner decides how much of their daily time budget to spend
in each alternative activity. For simplicity, we group all work
activities and label them “household production,” and all ac-
tivities that yield private gain are labeled “leisure.” Work ac-
tivities include direct resource acquisition, food preparation,
camp maintenance, childcare, and activities such as building
social alliances that may benefit the family. Leisure includes
other social visits, relaxation, grooming, pursuing extrapair
relationships, play, sleep, or any other activity that does not
provide utility to other household members.
Each partner attempts to maximize fitness gains from a
marriage union subject to time constraints by choosing an
optimal set of activities (see fig. 2 for details). Concave iso-
fitness curves describe the combinations of public and private
goods that provide the same fitness. These are called indif-
ference curves because decision makers receive equal benefits
from any combination of activities on the same curve. The
shape of indifference curves depends on several key functional
relationships, such as the shape of the fitness gains for (1)
investments of care and food for offspring, (2) investments
in mate acquisition, and (3) investments in status activities
that may provide both private and public benefits.
The indifference curve approach is useful for visualizing
trade-offs and has been used to model women’s optimal time
allocation to childcare versus food production (Hurtado et
al. 2006). When men’s activities have minimal impact onchild
welfare and when mating opportunities are high, indifference
curves are shallow, and expected male parental investment is
low (Blurton Jones et al. 2000; Hurtado and Hill 1992). When
men’s contribution to the diet is high (e.g., Ache, Hiwi),
indifference curves are steep, and greater paternal investment
is expected. Empirical evidence suggests instead that male
impact on offspring is highly variable cross-culturally (Sear
and Mace 2007). However, measuring the effects of paternal
care is methodologically complex because the presence of oth-
ers who contribute aid during father absence obscures the
true fitness impact of paternal contribution (Winking 2006).
Examining time allocation of men or women in isolation
might lead to the erroneous result that both partners should
become generalists. If pair-bonding entails substantial costs,
individuals may hold minimal expectations of the household
contributions that they demand of potential spouses, or
“threat points.” These describe the contribution threshold
below which an individual may abandon the marriage rather
than compensate for lowered partner investment (fig. 2; Man-
ser and Brown 1980). Studies among several tribal societies
suggest that while men value physical attractiveness more,
both partners are concerned that a prospective spouse be
hard-working, generous, and a high producer (Hill and Hur-
Gurven and Hill Why Do Men Hunt? 59
Figure 3. Reaction curves for husbands (dashed curve,H) with respect
to wives (solid curve,W), and vice versa. An initial level of W’s contri-
bution on the X-axis invokes a reaction by Hthat defines H’s contribution
level on the Y-axis, which then invokes an investment response by W
based on her reaction curve. This maps back to the X-axis, where W’s
new contribution level invokes a new response by H, and so on until an
equilibrium is reached. Regardless of initial conditions, aresults in a
stable equilibrium mix of Wand Hcontributing (albeit unequally) to
the household. cresults in Wcontributing everything to the household,
and Hcontributes nothing. If Winitially contributes more than the
equilibrium amount in b, she will eventually contribute everything to the
household, and Hwill contribute nothing. If Winitially contributes less
than the equilibrium, the reverse outcome will hold. Adapted from Chase
tado 1996; Marlowe 2005). Mutual preferences for these traits
make sense if partners seek gains from marriage that are both
productive and reproductive. If women gained little from
marrying men and were instead only gene shopping, wewould
expect more polygyny than observed among foragers and only
brittle pair-bonds.
In the conceptual model, an initial allocation decision is
made by one partner, a reactionary allocation is made by the
other partner, and so on until one of the following outcomes
is reached: (1) both partners arrive at a stable equilibrium of
household contributions (not necessarily equal); (2) the equi-
librium is unstable, and eventually one partner’s contribution
falls below the dissolution threshold; or (3) one partner always
defects, and pair-bonds never form (Chase 1980). These out-
comes are illustrated by the utility response curves in figure
3. The second scenario represents the downward spiral of a
marriage heading for divorce, where lower investment by one
partner results in higher investment by the other. For example,
a man living with his wife’s kin may reduce familial invest-
ment if he has additional mating opportunities, while his wife
and her kin compensate by investing more until finally the
male is deemed expendable. The third scenario should also
result in divorce, unless the contributing partner has no other
options; if the wife from the above example has no kin or
other bargaining chips, she may always have to invest heavily
in the household, regardless of her husband’s investment.
Normally, optimal time allocation for the male partner (Ain
fig. 2) will not match the optimal solution from the female
point of view. Instead, there is a region between the optimal
male and female solutions (i.e., “bargaining zone”;see “Shar-
ing and Reciprocity,” above) that defines a set of time allo-
cations for each sex that is open to “negotiation.”
Individual attractiveness, status, wealth, specialized skills or
abilities, and other bargaining chips vary across men and
within men over their lifetimes. For example, attractive men
by virtue of their “good genes” might invest less in children
while other men compensate with more long-term investment
(Waynforth 2001); indeed, high-status Aka men spend less
time with their children than lower-status men (Hewlett
1992). Ecological features—the cost of obtaining mates given
the number of competitors, payoffs to male coalitions, dif-
ficulty and productivity of foraging, and social currency of
different foods—will affect opportunity costs of men’s time
spent in subsistence tasks that provision family members.
It might seem that marital commitments are highest when
children are young and spouses have high reproductive value.
Due to long child dependency and serial reproduction, high
16. This process of declaring expectations and responding to a part-
ner’s level of commitment may implicitly underlie the logic of matrilocal
residence and bride-service patterns commonly found in forager and
forager-horticultural societies (Collier and Rosaldo 1981). Men must
demonstrate the willingness to work hard and contribute food to the
household under the supervisory gaze of their new spouse and in-laws.
The important point here, as argued in “Sharing and Reciprocity,” isthat
the bargaining outcome need not insure equal levels of contribution by
men and women in marriage but rather need only insure that men and
women gain more from these unions than they would from alternative
60 Current Anthropology Volume 50, Number 1, February 2009
caloric demands of children in foraging environments may
last into parents’ midforties and fifties (see fig. 1), after which
newly married “independent” offspring may require help. In-
suring survival through the high-mortality period of infancy
and childhood (50% for hunter-gatherer populations) is
only one way that fathers contribute to the welfare of their
children. Fathers may improve child welfare in many ways:
through improved growth and nutrition, with foraging skills
and hunting proficiency, by facilitating alliances andproviding
support during conflict, and through protection from vio-
lence. Pair-bond defection during middle age might be more
costly than earlier in life, especially if male mate value de-
creases with his expected productive life span.
Thus, divorce
rates decrease rather than increase with age, and in at least
two societies, men are more likely to engage in extramarital
sex early in their reproductive careers than they are later,
despite their wives’ declining reproductive value (Winking et
al. 2007). Some high-status men may reap gains from defec-
tion when spouse mate value declines, or they may support
two wives, but these are likely to be exceptions rather than
the rule for most men. These insights help explain whysocially
imposed monogamy is the dominant marriage pattern for
hunter-gatherers (Marlowe 2004a).
An implication from this conceptual exercise is that even
if mating effort were a priority for men, the sexual division
of labor need not be more pronounced in societies where
mating effort gives higher payoffs. The sexual division of labor
may not be affected much at all, although paternal contri-
bution to offspring may be lower when payoffs from mating
effort are high. The Hiwi have a more pronounced sexual
division of labor than the Ache (Hurtado et al. 1992), but
Ache men have much greater mating opportunities and higher
divorce rates. Factors other than mating probably explain why
these societies each show sex differences in resource acqui-
sition. Men may engage in activities yielding high nutritional
utility after accounting for economic choices made by women,
and this may be more so if these activities provide social or
mating benefits. Women may also maximize nutrient gain
rate subject to the constraints of lactation and childcare and
adjust their behavior if men provide certain foods. In such a
scenario, men still face decisions about whether to use re-
sources for mating or parenting investment. In either case,
men should acquire foods of highest utility to women and
children, resulting in a division of labor regardless of whether
mating or parenting provided them the highest payoffs.
17. Economists solve the free-rider problem by incorporating inter-
dependency into personal utility functions. At a proximate level, such
interdependency may reflect love, companionship, or “growing old to-
gether.” While we do not deny the importance of these emotions in
regulating commitment levels within relationships, we are more interested
in the evolutionary logic that should lead to the development of these
emotions in the first place.
On average, men contribute about 65% of the calories and
85% of the protein to the forager diet (Kaplan et al. 2000;
Marlowe 2001). The observation that men hunt and women
gather supported the simplistic view of marriage as a coop-
erative enterprise. Greater sophistication suggests that males
may often be motivated by mating and status rather than
offspring investment. Evidence illustrates that humans are
exceptionally cooperative among primates (Henrich and Hen-
rich 2007) and that long-term pair-bonding and extended
kin-group cooperation are common. Despite extensive the-
oretical debate over the past 15 years, the question of why
men hunt can only be settled with empirical observations.
Are the fitness benefits from meat provisioning sufficient to
explain hunting regardless of whether signaling also provides
fitness benefits? If so, then hunting is “explained” by its pro-
visioning effect on close kin. If signaling or mating benefits
alone make hunting the fitness-maximizing activity of males,
then additional benefits might be irrelevant to why men ul-
timately hunt. However, we may find that payoffs from both
provisioning and signaling together explain why men hunt
rather than gather under most circumstances in all foraging
Numerous observations contradict the signaling view of
hunting. Men isolated from a potential audience still hunt
for a living. When foragers disperse, fission into family-based
foraging parties, are lost, or are out on a raiding party, men
still hunt to feed themselves or their families. Women prod
their husbands to hunt, not to gather. If male payoffs to
hunting were mainly in the form of increased mating op-
portunities, would forager wives be so anxious for their hus-
bands to hunt? We have never heard a forager womanpleading
with her husband to spend the day collecting. Instead, Ache,
Hiwi, Tsimane, and Machiguenga women often vigorously
encourage their husbands to hunt.
Men who do not hunt
often have poorer mate choices. Finally, many human pop-
ulations voice strong desires to eat meat when it is absent
from the diet for a few days, and many tribal populations
have specific vocabulary terms for “meat hunger” (Simoons
In addition to nutritional benefits, hunting is a common
route to high status among foragers (Wiessner 1996). Good
hunters display higher reproductive success everywhere the
relationship has been investigated (Smith 2004), but this does
not mean that the status quest is equivalent to mating effort.
Instead, good hunters are chosen as spouses, even in arranged
marriages, because their higher production ability and gen-
erosity gives them leverage in the mating market, and fitness
effects of status likely accrue to wives, children, and close kin.
Forager women show higher average total fertility the more
18. One is reminded of John Marshall’s 1957 film The Hunters where
the !Kung man, Toma, is actively encouraged to hunt by his wife because
her “breasts are lacking milk.”
Gurven and Hill Why Do Men Hunt? 61
Figure 4. Causal pathways mediating the relationship between hunting
success, social status, and biological fitness. The pursuit of social status
from hunting can provide many benefits in addition to in-pair and ex-
trapair mating access, including deference, coalitionary support, aid in
childcare, and social insurance. Overall impacts of hunting ability on
fitness are mediated by increases in fertility, survivorship, and well-being
of self, spouse, children, and probably other kin as well. Adapted from
Gurven and von Rueden (2006).
that men contribute to the diet (Marlowe 2001), and women
produce less when their husbands produce more (Hurtado et
al. 1992). There are multiple pathways by which hunting abil-
ity can increase reproductive success and thus motivate male
economic behavior (fig. 4). Figure 4 illustrates the alternative
routes by which social status striving can produce benefits
typically attributed only to direct provisioning (Gurven and
von Rueden 2006).
The signaling model posits that extrapair mating benefits
due to partner choice for good genes (rather than for pro-
duction ability or willingness to provide resources) explain
the correlation.
However, the view that hunting is motivated
by mating payoffs conflates psychological motivations un-
derlying men’s time budgets and the fitness effects resulting
from men’s subsistence choices. It is unlikely that all male
status display should be motivated by mating payoffs. While
good hunters often have higher mating success, a study among
Tsimane hunters shows that hunting ability, meat sharing,
and social status associate with increased in-pair fertility but
19. A modified version of the signaling model posits that food pro-
visioning within the pair-bond is also a form of mating effort designed
to reap reproductive gains from the current relationship. In this view,
any form of provisioning can be interpreted as a form of mating effort.
bear no relationship to extrapair mating success (Gurven and
von Rueden 2006). Proficient Tsimane hunters are likely to
share meat and are regarded as hard workers—important
qualities to mates and social partners.
Costly signaling of high phenotypic quality could then re-
sult in favorable treatment by many members of the social
group (Hawkes 1990). As described for the Tsimane, suc-
cessful hunters might gain sexual access to more high-quality
females or obtain more valuable allies, and competitors may
be more reluctant to confront them in a variety of arenas.
Such payoffs affect male fitness through mating success, and
some payoffs might also benefit offspring (e.g., father having
more allies and fewer competitors).
The gains from repeated long-term cooperation with valued
partners seem to make the costs of signaling cooperative in-
20. Women’s food sharing might also best be understood as costly
signaling, yet the payoffs to that sharing are clearly not in mating op-
portunities. Women as well as men compete for status (Campbell 2002),
presumably because this benefits their offspring. In modern societies,
wealthy women engage in public philanthropy, and postreproductive
women buy expensive jewelry and other luxury items clearly designed
to signal status but with no payoff that would qualify such purchases as
mating effort.
62 Current Anthropology Volume 50, Number 1, February 2009
tent worthwhile (Frank 1988). Presumably, these repeated in-
teractions involve dyadic and indirect reciprocity. The benefits
of a reputation for generosity are just beginning to be inves-
tigated in foraging societies. Do individuals who eat from
men’s kills give them other food types, make tools for them,
bring them firewood, babysit or feed their children more of-
ten, or care for their families when they are ill? Ache children
of good hunters experience higher survival (Hill and Hurtado
1996) despite receiving no larger portions of father’s game
than other children. Men who share larger percentages oftheir
food obtain more help when sick or injured (Gurven et al.
2000a). Ache children experience higher mortality after pa-
ternal death or the divorce of their parents. The mechanism
of these survival effects is not known, but we suspect that it
is due to preferential treatment and intermittent feeding of
the offspring of good hunters.
The fitness that accrues to hunters is due to the summed
direct and indirect pathways shown in figure 4. The provi-
sioning pathways may favor hunting in most societies, but
commitment to hunting is reinforced by the signaling payoffs
that aid in mating success and coalition building. Hunting
may be ubiquitous among men cross-culturally precisely be-
cause of the multiple pathways by which it affects fitness via
both private and household gains. Both early historical focus
on family provisioning and recent emphasis on mating payoffs
provide only partial explanations for why men hunt. We have
described a model of the sexual division of labor in which
men hunt and women gather because of maternal constraints,
long learning periods for many foraging activities, and male
comparative advantage combined with the goal of providing
a diverse multinutrient diet. Furthermore, men’s hunting pro-
duction is not lost through sharing but is biased toward family
members and channeled to others strategically via contingent
reciprocity, social insurance, “cooperative breeding,” and
costly display. Other models that emphasize political goals,
enhanced group size, and well-being in the context of inter-
group competition deserve careful consideration.
Long-term pair-bonds cannot be explained by the signaling
model alone because it implies that women should be indif-
ferent to marrying good hunters and men should abandon
their wives as their fecundity declines. Men in foraging so-
cieties voice concern for spousal and offspring welfare; they
engage in daily activities that indicate such concern, especially
when spouses are pregnant. Among the Ache, Hiwi and Tsi-
mane, men often take custody of children after maternaldeath
or divorce and provide extensive support. Several scenario-
based experiments conducted with Ache and Hadza men with
21. Ache orphans tell detailed stories of the hunger they experienced
after their father’s death despite the widespread sharing that characterizes
Ache forest life.
dependents show that they prefer to reside in groups with
good hunters who will help provision their families rather
than in groups of poor hunters where status signaling op-
portunities are high (Wood 2006; Wood and Hill 2000). New
physiological data on male-female and male-offspring bond-
ing mechanisms and hormones that promote such bonding
(e.g., oxytocin, vasopressin, dopamine, decreased testoster-
one) may demonstrate that human males were designed by
natural selection to increase cooperative sentiment with fe-
male partners and to help raise highly dependent offspring
(Gray et al. 2004). These mechanisms may set humans apart
from other apes and may provide a window into the social
structure of our hominin ancestors.
Undoubtedly, spousal conflicts arise because of male mat-
ing goals, and these conflicts may modify men’s behavioral
patterns. Rather than continue to argue over monocausal ex-
planations of men’s hunting, new studies should examine how
costs and benefits of male mating and parenting investment
vary with ecological circumstance, partner status, condition
and need of offspring, and availability of substitutable aid. In
addition, they should examine how hunting rather than gath-
ering might best meet male goals given the constraints of
human social living.
Raymond Hames
Department of Anthropology and Geography, University of
Nebraska, Lincoln, Nebraska 68588, U.S.A. (rhames@unl
.edu). 30 X 08
The question addressed by Gurven and Hill is whether big
game hunting is mating or parental effort or a combination
of the two. They bring clarity to an extremely one-sided char-
acterization of male work in foraging societies. They show
that Hawkes’s claim that hunting is mating effort rests on
unsure foundations, and they conclude that male economic
endeavors, including large game hunting, is largely parenting
effort. They present a model of reproductive and parenting
decisions from the vantage of bargaining theory that captures
much of the realism necessary for modeling marital trade-
A surprising dimension of the signaling hypothesis comes
from its claims of generality. O’Connell, one of Hawkes coau-
thors in the development of the “show-off” theory, makes the
following general claim (Bird and O’Connell 2006, 159):
In fact, paternal provisioning is actually not practiced among
the best-documented low-latitude foraging populations, in-
cluding those occupying habitats most similar to the ones
in which early humans evolved.
Gurven and Hill Why Do Men Hunt? 63
This claim was preceded by Hawkes et al.’s (2001, 705) dis-
missal of the relevance of Arctic foragers, where men peri-
odically are the sole providers for their families. Thisnebulous
argument about the Environment of Evolutionary Adapted-
ness (EEA) leads one to ask what is it about the nature of
high-latitude environments that makes such foragers irrele-
vant. African environments were highly unstable and variable
during much of late hominid evolution. Even today we find
African foragers in desert, savannah, and tropical forest en-
vironments. Such claims lead some to suggest that claims
about the EEA as it relates to the physical environment are
”a patently narrow conceptualization of the hominid past”
(Potts 1998, 94). This restriction ignores a large number of
foraging societies that may provide comparative tests of the
show-off hypothesis. In many foraging societies, local bands
disperse into family units for several months a year. Once
dispersed, all male economic activity was devoted to providing
for his family. Exemplars include the Western Shoshone
(Steward 1936, 230–232), the Netsilik (Balikci 1963, 1968),
Copper Eskimo (Damas 1972, 26–28), and the G/wi (Silber-
bauer 1972, 298; 1978, 116). The G/wi are notable because
they are African low-latitude foragers.
A potential collective action problem is considered when
Gurven and Hill reveal that highly productive hunters pro-
duce more than they receive (for the Hiwi, the amount re-
turned is about a third of what is given). In an early version
of this paper, they argue that these hunters simply paya higher
premium and that there is room for bargaining. This is a very
useful conceptualization, but I would add, however, that pay-
ing a higher premium would also make sense if insurance
coverage was greater. Productive hunters may have more chil-
dren; therefore, they need more coverage. This is reasonable
in view of the fact that good hunters have higher reproductive
success (Kaplan and Hill 1985; Smith 2004; Gurven and von
Rueden 2006). It is also clear that part of their payback may
be of a different currency that transforms reciprocal altruism
into trade. As they note, this trade for high hunting produc-
tivity may range from not traveling when a good hunter’s
family member is ill (Kaplan and Hill 1985) to feeding the
family of a good hunter when the hunter is ill (Sugiyama and
Chacon 2000) to greater acceptance of begging from the chil-
dren of good hunters or to enhanced access to mating op-
portunities (Kaplan and Hill 1985).
Another way to evaluate whether hunting is parental in-
vestment or not is to predict that if males do not hunt and
distribute their kills, then the amount of food received by
their families will be affected. For the Hadza, Marlowe (2006,
85) reports that “Hadza say that people who do not share are
bad people and that they will move away from them.” Gurven
and Hill provide numerous examples of this dynamic. Ache
juvenilicide suggests that this interpretation may be correct.
Children who have lost their fathers have a higher probably
of being killed by men who do not want to support children
who lack fathers who can reciprocally support their children.
Hill and Hurtado (1996, 434) note that “Among the Ache,
child homicide also seems common when unrelated individ-
uals are being coerced into providing resources for a child
who does not receive sufficient parental investment (i.e., or-
phans).” Further on, they also note that children who have
secondary fathers are more likely to be spared such a fate.
These secondary fathers, through the Ache ideology of partible
paternity (Beckerman et al. 1998), are recognized partial gen-
itors of children who may have lost a primary father. Pre-
sumably, the continued distributions by secondary to other
families ensure unbegrudged returns to their partible children.
Finally, a critical lacunae in Hawkes et al.’s presentation of
Hadza data is how resources acquired by men are distributed.
A presentation by Wood (Wood and Marlowe 2007) shows
that 45% of large game taken by a hunter is distributed to
his family compared with an average of 18% to other families.
The advantage to their own families is even greater for other
resources. While successful hunters may not fully control dis-
tributions of large game, distributors clearly bias distributions
in the successful hunter’s direction. This demonstrates that
big game hunting is a mixed strategy even for the Hadza.
Tatsuya Kameda and Rose McDermott
Center for Advanced Study in the Behavioral Sciences,
Stanford University, 75 Alta Road, Stanford, California
94305, U.S.A. ( 22 X 08
Gurven and Hill offer a sophisticated argument in the debate
about the functional roles of men’s hunting and their impli-
cations for the sexual division of labor. Drawing on socio-
ecological factors, they combine elements of provisioning and
signaling in their model explaining why men hunt. Their
argument, which situates men’s hunting in the context of a
bargaining game between husbands and wives (Becker 1973,
1974), is an important step toward a more comprehensive
understanding of the cultural variants as well as the universal
features of the sexual division of labor (Marlowe 2000). How-
ever, the ethnographic data reviewed here may not allow pin-
pointed testing of several key issues in the debate surrounding
the motivation for male hunting. There is no doubt that an-
thropological fieldwork provides richly relevant information
on this question. However, such data remain correlational in
nature, which makes it difficult to disentangle the competing
hypotheses concerning signaling versus cooperative pair-
bonding with rigor. We suggest that controlled laboratory
experiments may help fill in this gap.
As behavioral scientists with an interest in computational
algorithms of the human mind (Kameda et al. 2002; Mc-
Dermott, Folwer, and Smirnov 2008), we would like to discuss
a possible experimental design for one of the hypotheses con-
cerning male-offspring bonding mechanisms suggested by
Gurven and Hill’s argument. Given that our minds are highly
attuned to recurrent adaptive problems viaevolutionary (Cos-
mides and Tooby 1994) and/or cultural processes (Boyd and
64 Current Anthropology Volume 50, Number 1, February 2009
Richerson 1985), experimental testing of psychological ar-
chitectures may shed some new light on the debate. Wepursue
this exercise by briefly examining related literature on hor-
mones first and then sketching the design of a new
Endocrinological responses. Hormones may provide key in-
formation on psychological mechanisms related to male-
offspring bonding mechanisms. We have substantive evidence
that testosterone is associated with increased emphasis on
mating as opposed to paternal effort (“challenge hypothesis”;
Archer 2006). Most studies used North American samples,
but researchers have begun to study non-Western populations
(e.g., Gray, Parkin, and Samms-Vaughan 2007). Muller et al.
(2009), for example, tested two neighboring Tanzaniangroups
(Hadza foragers and Datoga pastoralists). These researchers
reported that lower testosterone among fathers than non-
fathers was evident only for Hadza foragers; no such difference
was found for Datoga pastoralists, where strong social norms
against men’s direct interaction with infants apply to fathers
and nonfathers equally. These patterns may suggest that, as
implied by Gurven and Hill’s model, the two subsistence sys-
tems, or the local socioecology of each community, may affect
husbands’ and wives’ bargaining power differentially, leading
to a different equilibrium of paternal care.
Toward more direct tests of the “hunting (also) for family”
hypothesis: a proposal. Although rich and illuminative, these
data remain correlational. To our knowledge, there are three
published studies that have tested the challenge hypothesis
experimentally (Fleming et al. 2002; Gray, Yang, and Pope
2006; Storey et al. 2000). In these experiments, endocrine
measures were taken from fathers and nonfathers twice,before
and after they were exposed to infant-related stimuli (e.g.,
cries). The results were consistent with the challenge hypoth-
esis. Fathers with lower testosterone levels reported higher
sympathy in response to the baby’s cries than fathers with
higher testosterone levels and nonfathers. Concerned fathers
also had higher prolactin levels than the others, a hormone
shown to be relevant to paternal care in animal studies (Zieg-
ler, Washabaugh, and Snowdon 2004).
Both the ethnographic and experimental studies were fo-
cused on “direct paternal care,” including feeding infants,
showing concerns, etc. However, the current debate is on the
specific functional roles of men’s hunting—whether it
emerges within the context of cooperative ventures between
husbands and wives (Isaac 1978) or whether it is better un-
derstood as a costly signal to increase the hunter’s mating
value or social status (Bird 1999; Hawkes and Bliege Bird
2002). The experiment sketched below may provide a more
direct test for the “hunting (also) for family” hypothesis. As
in the previous experiments, fathers and nonfathers would be
exposed to infant-related stimuli. The “subliminal stimulus”
paradigm (Merikle 2000) might be used here, where the
infant-related stimuli are displayed for a period shorter than
perceptual threshold to minimize demand characteristics.
Then, participants would be asked to work on some rather
tedious (cognitive or physical) task whereby monetary incen-
tives are provided contingent on their performance. Our hy-
potheses are as follows. To the extent that men are equipped
with a psychological architecture to facilitate the “hunting
(also) for family” function, (a) fathers, even if not fully aware
of the real reasons (subliminal stimuli) will generally be more
motivated in the task (e.g., longer persistence) than nonfath-
ers, and (b) this tendency will be more pronounced for fathers
with lower testosterone and higher prolactin levels. Of course,
this experiment does not deal with a real hunting situation,
nor would participants necessarily be hunter-gatherers. How-
ever, we believe that along with the ethnographicobservations,
a laboratory experiment such as this will shed some new light
on the debate. As illustrated by the prevalence of family pic-
tures in workplaces, male psychology may be finely tuned to
various infant-related cues, which serve the “hunting (also)
for family” function.
Karen Lupo and Chris Kiahtipes
Department of Anthropology, Washington State University,
Pullman, Washington 99161, U.S.A. (
23 X 08
Understanding how, when, and why the sexual division of
labor emerged is one of the most compelling issues in human
evolution. Gurven and Hill present a novel conceptual model
that tracks the complexity of responsive allocation decisions
between pair-bonds. We agree with Gurven and Hill that
monocausal explanations are unlikely to explain the persis-
tence and range of hunting options pursued by contemporary
hunter-gatherers. Our reading of the signaling theory is that
it provides an explanation for why men sometimes pursue
dangerous, inefficient, or seemingly wasteful prey. Current
versions of signaling theory emphasize the mutual benefits
gained by the signaler and receiver (but see Cronk 2005).
These benefits are weighted by socioecological contexts that
structure the arenas in which signaling may be effective. Hunt-
ing costly prey is but one arena in which men can signal
underlying qualities for gaining mating opportunities, status,
allies, or political leverage (Bliege Bird and Smith 2005). Thus,
the hunting arenas for honest signaling are limited and so-
cioecologically context dependent.
For instance, among central African Bofi and Aka hunters,
men invest their effort in cooperative net hunts and individ-
ualistic hunting techniques. Cooperative net hunts earn low
returns and have highly variable success rates. Men can do
better if they use individualistic hunting techniques, which
earn higher returns and are associated with a higher success
rate. High-status men rely on nets more than any other tech-
nique, spend less direct time with their children, and share
more meat with people outside their kin group than low-
status men (Hewlett 1991b; Lupo and Schmitt 2004, 2005).
Mothers consistently identified these public foraging events
Gurven and Hill Why Do Men Hunt? 65
as opportunities to identify potential future sons-in-law for
their unmarried daughters. Other men rely largely on indi-
vidualistic technologies, spend more time with their children,
and share less meat with people outside their kin group. Sea-
sonal precipitation limits the use of nets, and even men who
are committed net hunters turn to individualistic methods of
capture during the dry season. While it might be argued that
high-status net hunters indirectly invest in their children by
purchasing material items, our observations show that men
often use the money derived from selling meat to purchase
items that are shared with other men, not their families (cig-
arettes, alcohol).
A more compelling question concerns when the current
patterns of the sexual division of labor emerged. The rec-
ognition that current sex-based patterns of task organization
may not represent prehistoric hominins is not new.But recent
research suggests a more complicated evolutionary trajectory
for labor organization than once imagined. Robson’s (Rob-
son, van Schaik, and Hawkes 2006; Robson and Wood 2008)
analyses of life-history parameters for extant and fossil hom-
inins suggest that the features of modern human life history
are derived and did not emerge as an integrated package.
Comparisons among different hominin species suggest dis-
tinct life histories that differed from one another. The paradox
is further complicated by Lower and Middle Pleistocene pa-
leodemographic data showing high levels of mortality for ju-
veniles and the young, with few individuals surviving into old
age (Caspari and Lee 2004; Kennedy 2003). Material evidence
from Lower and Middle Pleistocene archaeological sites does
not show a marked sexual division of labor or subsistence
specialization and implies a high degree of overlap between
males and females in labor organization (Kuhn and Stiner
2006). The earliest evidence for significant meat consumption
and carcass acquisition suggests hominins engaged in high-
risk ventures (O’Connell et al. 2002). Direct evidence for
hunting does not emerge until after 500,000 years ago, and
the focus was on larger-sized and sometimes dangerous an-
imals (Kuhn and Stiner 2006; Schmitt, Churchill, and Hy-
lander 2003). Smaller-sized prey appear as significant com-
ponents of the diet in Africa after 140,000 years and in Eurasia
40,000–50,000 years ago.
Cumulatively, these data suggest that we need to start con-
ceiving of multiple and mutable configurations for the sexual
division of labor among early hominins that may exceed the
range of variability displayed by contemporary hunter-gath-
erers. Because socioecological circumstances influence the
payoffs derived from provisioning and signaling, we can no
longer view the sexual division of labor as a static phenom-
enon. How do these payoffs change when early Homo erectus
populations colonized different parts of the world? How did
these payoffs vary for subsequent in-filling populations? It is
only within this context that we can hope to understand the
different milieus under which big game acquisition emerged
and persisted.
Signaling does not explain all human hunting behavior, but
it might explain inexplicably expensive or costly activities.
Clearly, there are a variety of relationships between males and
females, from complementary arrangements to those that are
asymmetrical in effort (e.g., Quinlan and Quinlan 2007). We
agree with Gurven and Hill that future research should ex-
amine how the costs and benefits of male mating and par-
enting investment vary with ecological and social circum-
stances and how signaling enhances these payoffs.
Sonia Ragir
Department of Sociology and Anthropology, Building 4S/
203, College of Staten Island, City University of New York,
2800 Victory Boulevard, Staten Island, New York 10314,
U.S.A. ( 27 X 08
Gurven and Hill have done an important reevaluation of a
large and valuable literature on foraging societies and the place
of hunting in the evolution of human pair-bonding. This
paper makes an impressive effort to explain not only the
division of labor that results in “man the hunter” and “woman
the gatherer” but also how this division of labor supports
long-term bonds between men and women past the repro-
ductive prime of both sexes. The data are limited to a few
well-studied ethnographic hunter-gatherer groups that no
longer rely on foraging throughout the year. Nevertheless, the
reasoning is sound, and the multiplicity of pathways to long-
term pair-bonds lends credibility to their claims. However,
while the authors mention that out-of-household exchanges
of meat and plant foods generate a cohesive group (men and
women preferred to live in groups with good hunters), neither
they nor the literature cited looks beyond the individual. Food
sharing among same-sex adults is an adaptive strategy that
appears equally important to social cohesion as that of family
provisioning. Cohesive social groups reduce the selective pres-
sure on high-risk members of a group, such as children with-
out a parent, old men and women, and women without hus-
bands, and they are important to the survival of individuals
as well as the group as a whole.
All human social bonds—except perhaps those intense,
short-term, chemically induced bonds between mother and
neonate and between mating male and female—appear to be
based on exchanges of food and services. Perhaps we are
looking at this the wrong way. Bonds between child and
mother are strengthened and maintained through feeding and
physical contact; pair-bonding is established and maintained
through exchanges of food, sex, and coresidence; group co-
hesion is maintained through cooperative hunting and ex-
changes of meat between hunters, exchanges of staple foods
between women, and residential proximity; and last, men’s
intergroup exchanges of meat, exotic goods, and women es-
tablished long-term alliances between individuals and groups
throughout a region. Cohesion in the group—as a result of
exchanges between men, between men and women, and be-
66 Current Anthropology Volume 50, Number 1, February 2009
tween women—increases the survival of the group and all its
members and reduces the impact of skill-based repertories
like hunting on fitness. A group bound through many male-
male and female-female exchanges of food permits the sur-
vival of children of the best and poorest hunters. The modest
reproductive advantage of the better hunters extends till their
death, and there is no evidence that any evolutionary advan-
tage accrues to a third or more distant generation. The emer-
gence of cooperative food acquisition and sharing may be
sufficient to explain the generation of long-term bonds on
every level of human society—between mother and offspring,
mating pairs, kin groups, community members, and even
Food sharing appears to have emerged as groups of men
cooperated to hunt packages of meat too large to be hoarded,
the semidependency of human childhood extended, and
women cooperated in the feeding and parenting of slowly
growing, closely spaced children. Mauss (1990) argued that
social bonds established and maintained through gifts be-
tween individuals created collectivities and hierarchies of col-
lectivities (Mauss 1990, 5):
It is not individuals but collectivities that impose obligations
of exchange and contract upon each other. . . . These total
services and counter-services are committed to in a some-
what voluntary form by presents or gifts, although in the
final analysis they are strictly compulsory, on pain of private
or public welfare.
Perhaps the pertinent social fact is the tension between group-
and pair-bonds, an economic trade-off between the bonds
that bind the group and those that bind mates rather than
that between status signaling and family provisioning. When
cooperative group activity increases in importance, exchanges
between men increase; as the importance of male cooperation
and cohesion lessens, as it does when the Ache are out of the
forest, provisioning of the family and pair-bonds intensify.
The tension between reproductive pairing and group cohe-
sion—a sociopolitical cost/benefit rather than an individual
evolutionary benefit—may result in a more comprehensive
understanding of the variability we encounter in the examples.
Support for the economics of the facts lies in the flow of meat
and plant foods—that is, the relative density and direction of
exchanges within and between communities—and the effect
of changes in flow from those between adult men to those
between men and women. Those male bonds are important
way beyond status or signaling benefits; the alliances create
and maintain the social group. Gifts of food between women
generate a second level of cohesion within the group that
reinforces long standing (kin) ties and binds women marrying
in from other groups. Direct provisioning of offspring by
women is undisputed and a fairly convincing rational for the
division of labor. All these forms of exchange ultimately lead
to a more stable existence that enhances the reproductive
fitness of everyone in the group.
Alejandro Rosas
Konrad Lorenz Institute for Evolution and Cognition
Research, Adolf Lorenz Gasse 2, A-3422 Altenberg, Austria
( 10 X 08
Gurven and Hill deliver a battering criticism of the view that
status and mating benefits alone explain hunting in extant
foragers. Their reevaluation of the hard data used to support
signaling theory—namely, data on the caloric yield of big
game hunting and on its distribution in the group—should
be of major impact, but it is surprising how often they also
point out ways in which the criticized theory simply fits badly
with commonsensical facts. For example, caloric value alone
does not measure nutritional impact; a specific desire for
meat, due to nutrients difficult to replace, can explain will-
ingness to risk hunting failure. If you control for size of re-
sources, there are no differences in amounts shared by men
and women outside the family, and yet nosignaling hypothesis
is proposed for women’s sharing; men get upset when shares
are not returned, but why should they, if they share formating
and status benefits? The signaling theory does not explain
marriage; if marriage’s only function is to curb the dangerous
effects of competition for status, men surely would have de-
vised alternatives (e.g., hierarchies) to the self-imposition of
obligations to wives and children. The publicly recognized
benefit for good hunters is marrying more or better wives,
which includes the burdens of marriage.Women do not com-
plain when their husbands go hunting, but they should if it
leads to status rather than to provisioning. Women should
be indifferent to marrying good hunters if hunting were all
about status, but they are not; men should abandon their
wives as their fertility declines, but few do.
These arguments have the demolishing force of common
sense but are in tension with the taste for hard data that
dominates the debate. And yet there is a sense in which data
are hard only against a background of conceptual assumptions
that belong in the domain of common sense. Gurven and
Hill demand a measure of contingency in sharing that attends
to the particular representations of fair exchange and reci-
procity governing each society. To me, this demand is plain
common sense. Will colleagues in the other camp accept it?
Some of their arguments assume that the debate is also
about the proximate/psychological and not only about the
evolutionary explanation of hunting. Although evolutionary
explanations are normally not concerned with proximate
mechanisms, it is often impossible to analyze human behavior
abstracting fully from the psychological. Norms and similarly
complex sociopsychological structures are here the correct
proximate stance. Bliege Bird and Bird (2008) make a recent
move in this direction. They analyzed Murta foraging data
and concluded that in Murta society, big game hunting is the
publicly recognized behavioral signature for magnanimity
motives. In Murta ideology, these motives are socially required
if men are to climb the social hierarchy and obtain the re-
Gurven and Hill Why Do Men Hunt? 67
productive benefits of marrying more or younger wives. But
then, if competition for status surfaces in male magnanimity
at the sociopsychological level and in a normative ideology
for upholding the group, the signaling hypothesis loses its
teeth. Kirsten Hawkes (2008) urged the Birds to dilute mag-
nanimity motives into “tolerated theft.” Why? Tolerated theft
strips sharing from all apparent generosity and from socio-
normative motivations. However, this way of adjusting claims
about motivations to her preferred evolutionary explanation
ignores independent evidence to what those motivations are.
Claims about motives should also attend to other research
programs that have been producing “hard data” on human
motivation. Recall here experimental economics and also a
sophisticated experimental research program that addressed
an analogous debate: the egoism-altruism debate (Batson
Hard facts aside, some hypotheses are prima facie more
plausible than others. Gurven and Hill make an intelligent
move when they plead for a pluralism of motives: men want
to provision their families but they also want status. If we are
interested in evolutionary explanations of human motives, a
safe move is to assume that natural selection has longtinkered
with the human psyche. The results are probably not neat
and are analogous to kludges or Rube Goldberg machines. If
men evolved paternal investment from an ancestral state sim-
ilar to present male chimp mating behavior, we are likely to
see a mix of status hunger and genuine concern for offspring,
even more so if, as Gurven and Hill point out, status reverts
often into benefits for offspring. Pluralism of motives also
discloses a disregarded possibility: a polymorphism of strat-
egies as the evolutionary outcome. Plausibly, status motivates
(predominantly) some men while provisioning drives others.
Changes in the data analysis practiced so far may well be
required to tap into evidence for polymorphisms.
Proper development of the interaction between the ultimate
and the proximate levels of explanation is a challenge for the
evolutionary anthropology of hunting, sharing, and marriage.
The bargaining model presented by Gurven and Hill could
give readers a wrong idea about purely selfish motivations in
married couples. Although they warn about this in a footnote,
a more explicit picture of the evolution of genuine emotional
concern for spouses and children would be welcome.
We summarize our position: signaling may be important in
some socioecological contexts but is unnecessary to explain
why men hunt. Provisioning alone can often explain why men
hunt and women gather, but additional benefits are common
because of the nature of human sociality. Aside from direct
offspring provisioning, good hunters who share may gain fit-
ness benefits from contingent reciprocity, social insurancepol-
icies, group augmentation, and costly displays. Displays of
generosity enhance a hunter’s reputation, which helps family
members indirectly and provides alliance and mating benefits
for the hunter (fig. 4). A sexual division of labor in which
men hunt and women gather describes specialization based
on comparative advantage of complementary activities pro-
viding a nutrient-rich diet. Spousal interests will not always
converge, and one partner may free ride on the household
contributions of the other. We agree that moving beyond
simple depictions of the sexual division of labor is a priority
for future research. We describe future directions, highlighting
themes brought up by the reviewers: (a) the need for diverse
methodologies, (b) broader implications for male psychology
and behavior, (c) complex sharing arrangements and evolu-
tionary mechanisms, and (d) sexual divisions of labor in our
evolutionary past.
Methodological pluralism. Kameda and McDermott argue
that only experiments can reliably show causality. We agree
that inferences based on observational ethnographic methods
often face problems of self-selection, bias, and endogeneity.
Careful research design and statistical controls can reduce
these problems in multivariate analyses. Experiments are an-
other solution but should be designed to have external (and
if possible, ecological) validity (Gurven and Winking 2008)
for relevance outside the laboratory. By necessity, these will
be quasi experiments in field settings because often partici-
pants will not be random samples but part of an ongoing
study. Experiments employing standardized stimuli or ex-
posure in naturalistic settings can help inform causal rela-
tionships. Two examples illustrate our point. The Wood ex-
periments described in the target article—where participants
presented with standardized scenarios of hunting parties con-
sisting of hunters of varying skill but with a constant number
of reproductive-aged women—showed that Ache and Hadza
hunters preferred to hunt in bands of good hunters. Their
choice is consistent with a desire to eat well rather than to
receive high prestige from being the successful hunter (Wood
2006; Wood and Hill 2000). Only Ache hunters without de-
pendent offspring preferred to join a group of poor hunters,
where they might have opportunities for “showing off.” Mc-
Millan (2001) investigated whether Ache hunters encounter-
ing prey call other hunters within earshot to help with pursuit.
Helpers increase the probability of success and can increase
caloric return rate but can diminish the direct hunting success
of the caller. McMillan’s analysis of calls and responses is most
consistent with the goal of maximizing food production for
the band rather than for individual prestige.
Hames and Kameda and McDermott comment on our
choice of study populations. We focused primarily on the
Hadza, Ache, !Kung, and Hiwi because they are well-studied
hunter-gatherers and were the original groups cited by
Hawkes and colleagues to support the hunting-as-signaling
view. Ethnographic data from many other foraging groups
lend support to our views on sharing and the sexual division
of labor. Hames provides several examples. Our emphasis on
68 Current Anthropology Volume 50, Number 1, February 2009
foragers comes from the belief that our long evolutionary
history of living as hunter-gatherers has shaped our evolved
cognition, emotions, psychological motivations, and decision-
making abilities. The best way to make inferences about
hunter-gatherer behavior and culture is to develop and test
models that predict optimal behavior given variable ecological
conditions and other parameters under a set of constraints
(Winterhalder and Smith 1992). We agree that no single group
represents all foragers and that no definitive statements about
trade-offs between parenting and mating effort should be
made based only on studies of foragers. A goal of behavioral
ecology is to understand how variation in relevant parameters
interacts with our evolved psychology to influence what peo-
ple do. Nonforagers are not irrelevant here; they add addi-
tional empirical grist to test theoretical ideas about men’s
parenting and mating behavior.
Male psychology, behavior, and hormones. Certain predic-
tions follow from the premise that men’s food production
efforts are mainly motivated by a concern for familial welfare.
First, men should pay attention to opportunities for advanc-
ing offspring welfare. In cases where mating and parenting
investment are separable, differential treatment by men of
biological children and stepchildren of current and former
mates permits further evaluation of investment patterns (An-
derson et al. 1999; Anderson, Kaplan, and Lancaster 1999;
Marlowe 1999). Second, men should focus production efforts
in ways complementary to their mates’. The possibilities for
complementary labor allocations among foragers have not
been fully explored or appreciated. This is particularly prob-
lematic because the fitness implications of nutrient comple-
mentarity are not well understood in humans. Nevertheless,
several examples suggest that spousal complementarity is
widespread. Hadza fathers increase their foraging efforts and
diversify their production portfolios when their wives have
young infants and forage less (Marlowe 2003). Ache and Hiwi
women produce less food per day when their spousesproduce
more (Hurtado et al. 1992). Tsimane fathers focus on child-
care during times when mothers are occupied and unavailable
(Winking et al. forthcoming).
Another area of investigation mentioned by Kameda and
McDermott is the physiological underpinnings of parental
sentiment and behavior. This includes analysis of the hor-
mones prolactin and testosterone and the neuropeptides ox-
ytocin and arginine vasopressin. Prolactin promotes weight
gain, lactation, anxiety, and inhibition of reproductive func-
tion in female mammals. In species showing significant pa-
ternal care, such as cotton-top tamarins and common mar-
mosets, a male’s prolactin levels increase in sync with his
mate’s; an expectant father seems physiologically responsive
to his mate’s pregnancy and imminent birth (Ziegler et al.
2006). A similar response is found among humans but not
other nonpaternal species (Storey et al. 2000). Male couvade
pregnancy symptoms are also not uncommon in cultureswith
high levels of partner intimacy and paternal care (Elwood and
Mason 1994). Vasopressin and oxytocin help modulate at-
tachment, support, and pair-bonding behavior in male ro-
dents (Heinrichs and Domes 2008). Studies among humans
are just now being done. For example, humans with a certain
vasopressin receptor subtype (V1aR) associated with monog-
amous behavior in rodents were happier in their marriages
and felt greater affiliation with their partners (Walum et al.
Testosterone has also been examined as an endocrine mod-
ulator of parenting and mating behavior (Muller and Wrang-
ham 2001). Research in several countries shows that married
men and new fathers exhibit lower testosterone levels than
single men or those without small children (Gray et al. 2002,
2006), and this same result is found among Hadza men (Mul-
ler et al. 2009). Men in relationships but with sexual interest
in other women have higher testosterone than those who do
not report outside sexual interests (McIntyre et al. 2006).
It is important to recognize (cf. Kameda and McDermott)
that most of the results from human studies are correlational,
complicating inferences about causality (P. Gray, personal
communication). Many of these studies only focus on prox-
imity to infants. In natural fertility societies, married men are
likely to have small children for several decades, although
men sometimes spend little time in direct proximity to infants
and children (Hewlett 1991a). Much of our argument about
men’s familial contributions implies forms of indirect rather
than direct childcare. It is not obvious how the two might be
related. For example, Lupo and Kiahtipes argue that Aka
Pygmy men seek prestige by net hunting, although Aka men
have been ranked as the “Best Dads in the World” by Father
Direct, a British organization on fatherhood, based on Aka
fathers’ very high level of direct proximity to children. The
only endocrine study that measured paternal attitudes and
actual offspring investment showed no relationship between
these measures and testosterone, vasopressin, and oxytocin
(Gray, Parkin, and Samms-Vaughan 2007). Storey et al. (2000)
did show, however, that men with higher prolactin and lower
testosterone levels were more reactive to infant distress. Future
research should better link endocrine measures and emotions
with behavior using a prospective design in different socio-
ecological contexts.
Sharing and complex social arrangements. We agree with
Rosas that evolutionary explanations assume functional de-
sign and evolved psychological motivation. Ethnographic ob-
servations and experimental evidence are more consistent
with a psychology of contingent reciprocity and group co-
operation than with phenotypic signaling. Sharing patterns
among hunter-gatherers appear to imply more than just the
evolutionary models of kin selection, reciprocal altruism, and
costly signaling (Gurven 2004). Even when contingent reci-
procity has been confirmed, good hunters consistently give
away more than they receive, and family size or “need” is an
important determinant of food transfers (e.g., Gurven 2004;
Allen-Arave, Gurven, and Hill 2008). Similarly, small groups
of interdependent foragers generally share meat more indis-
criminately than those from larger groups of more indepen-
Gurven and Hill Why Do Men Hunt? 69
dent foragers. The full suite of possible evolutionary expla-
nations for such highly cooperative patterns has barely been
explored. We and Hames mention the health insurance pre-
miums good hunters might pay by extensive sharing to help
themselves and their families during periods of sickness and
injury. Investing in a reputation for generosity by sharingmay
be important among foragers with frequent opportunities for
cooperation and where reliable and trustworthy partners are
in short supply (Gurven et al. 2000a; Panchanathan and Boyd
2003; Smith and Bliege Bird 2005). Aspects of cooperative
breeding and between-group competition may also be critical
(Bowles 2006). A variety of social norms and sharing rules
(e.g., favoring hunt participants, in-laws, pregnant women,
coresident non-kin) may spread by cultural group selection
(Gintis et al. 2005). Interdependent groups are highly co-
operative on a daily basis, and we hypothesize that contin-
gency in these groups is usually based on labor contributions
rather than direct tit for tat in food currencies (Gurven, Hill,
and Kaplan 2002; Hill 2002). These and other new evolu-
tionary treatments may help bridge the gap between common
ethnographic anecdotes of “generalized reciprocity,” as sug-
gested by Ragier, and the standard models of evolutionary
Sexual division of labor in hominid evolution. Lupo and
Kiahtipes raise questions about the sexual division of labor
throughout human evolutionary history. Our discussion of
why men hunt assumes a humanlike foraging niche in which
peak production is delayed and juveniles are low producers.
We recognize that the ability to make inferences requires
knowledge about the reliance on hunting, the timing of
growth and development, and the dependency of offspring,
as revealed by the absence or presence of distinct life-history
traits (e.g., childhood, adolescence). But knowledge about
hominin foraging patterns is not as clear as Lupo and Kiah-
tipes describe. For example, recent papers reanalyzing tooth
and percussion markings on bone assemblages from Olduvai
Gorge highlight methodological difficulties (Domı´nguez-
Rodrigo and Barba 2006, 2007); these authors conclude that
early hominids actively hunted and that the “passive scav-
enging hypothesis is clearly rejected by careful taphonomic
analysis of Plio-Pleistocene sites” (189). The portrait of hom-
inid life history is also far from resolved. Data on braingrowth
and tooth eruption patterns in Homo erectus are still some-
what contradictory, but Neanderthals show consistent evi-
dence of a slow, humanlike life history (Ponce de Leo´n et al.
2008) despite the fact that they may not show marked eco-
nomic specialization by sex (Kuhn and Stiner 2006). For these
reasons, we made no claims about the timing of the typical
sexual division of labor. Definitive statements about the tim-
ing of a gendered division of labor await further investigation.
Certainly we agree with Lupo and Kiahtipes that the sexual
division of labor is not now, nor was it ever, static. Examples
of men gathering and women hunting small game in different
societies illustrate the flexibility of economic decision-making
among foragers.
Human divisions of labor must be considered in a larger
evolutionary context. Divergent economic strategies, special-
izations, and complementarities are recurring themes
throughout more recent human history: why did humans ever
domesticate animals? An energy-maximizing forager would
never pay the high costs of producing meat calories by feeding
animals more plant calories than can ever be recovered.Those
meat calories, however, consist of proteins, lipids, and mi-
cronutrients that are highly valued because of their biological
impact. Similarly, honeybees forage for pollen rather than
nectar, and primates often forage for insects rather than fruits.
No one has ever argued that animal husbandry is a costly
signal or a form of mating effort. In groups that practice
slash-and-burn horticulture, men usually clear the trees and
the brush, whereas women are involved in planting, weeding,
and harvesting. In tropical populations of southeast Asia and
New Guinea, men cut palm trees and split them before women
process the sago palm starch. No one has argued that tree
cutting is an honest signal or worthy of prestige. This ar-
rangement is another example of an efficient division of labor
that takes comparative advantage into account. Why men
hunt and women gather may be no different.
—Michael Gurven and Kim Hill
References Cited
Aiello, L., and P. Wheeler. 1995. The expensive-tissue hy-
pothesis: The brain and the digestive system in human and
primate evolution. Current Anthropology 36:199–221.
Allen-Arave, W., M. Gurven, and K. Hill. 2008. Reciprocal
altruism, rather than kin selection, maintains nepotistic
food transfers on an Ache reservation. Evolution and Hu-
man Behavior 29:305–318.
Alvard, M., and D. Nolin. 2002. Rousseau’s whale hunt? Co-
ordination among big game hunters. Current Anthropology
Anderson, K. G., H. Kaplan, D. Lam, and J. Lancaster. 1999.
Paternal care by genetic fathers and stepfathers. II. Reports
by Xhosa high school students. Evolution and Human Be-
havior 20:433–452.
Anderson, K. G., H. Kaplan, and J. Lancaster. 1999. Paternal
care by genetic fathers and stepfathers. I. Reports from
Albuquerque men. Evolution and Human Behavior 20:
Archer, J. 2006. Testosterone and human aggression: An eval-
uation of the challenge hypothesis. Neuroscience and Bio-
behavioral Reviews 30:319–345. [TK/RM]
Balikci, A. 1963. The Netsilik Eskimo. New York: Natural
———. 1968. The Netsilik Eskimo: Adaptive processes. In
Man the hunter, ed. R. B. Lee and I. DeVore, 68–82. Chi-
cago: Aldine. [RH]
———. 1970. The Netsilik Eskimo. New York: Natural History.
70 Current Anthropology Volume 50, Number 1, February 2009
Batson, C. D. 1991. The altruism question: Toward a social-
psychological answer. Hillsdale, NJ: Erlbaum. [AR]
Becker, G. S. 1973. A theory of marriage. I. Journal of Political
Economy 81:813–846.
———. 1974. A theory of marriage. II. Journal of Political
Economy 81:S11–S26.
Beckerman, S., R. Lizzaralde, C. Ballew, S. Sissel, C. Fingelto,
A. Garrison, and H. Smith. 1998. The Bari partible paternity
project: Preliminary results. Current Anthropology 39:
164–167. [RH]
Bird, D., and J. O’Connell. 2006. Behavioral ecology and ar-
chaeology. Journal of Archaeological Research 14:143–188.
Bird, D. W., and R. Bliege Bird. 2002. Children on the reef:
Slow learning or strategic foraging. Human Nature 13:
———. 2005. Mardu children’s hunting strategies in the
Western Desert, Australia: Foraging and the evolution of
human life histories. In Hunter gatherer childhoods,ed.B.
S. Hewlett and M. E. Lamb, 129–146. New York: Aldine
de Gruyter.
Bird, R. 1999. Cooperation and conflict: The behavioral ecol-
ogy of the sexual division of labor. Evolutionary Anthro-
pology 8:65–75.
Black, J. M., ed. 1996. Partnerships in birds: The study of
monogamy. Oxford: Oxford University Press.
Bliege Bird, R. 2007. Fishing and the sexual division of labor
among the Meriam. American Anthropologist 109:442–451.
Bliege Bird, R., and D. Bird 2008. Why women hunt: Risk
and contemporary foraging in a Western Desert Aboriginal
community. Current Anthropology 49:655–693. [AR]
Bliege Bird, R., and E. A. Smith. 2005. Signaling theory, stra-
tegic interaction and symbolic capital. Current Anthropology
46:221–248. [KL/CK]
Bliege Bird, R., E. A. Smith, and D. W. Bird. 2001. The hunting
handicap: Costly signaling in male foraging strategies. Be-
havioral Ecology and Sociobiology 50:9–19.
Blurton Jones, N., F. W. Marlowe, K. Hawkes, and J. F.
O’Connell. 2000. Paternal investment and hunter-gatherer
divorce rates. In Human behavior and adaptation: An an-
thropological perspective, ed. L. Cronk, N. Chagnon, and W.
Irons, 69–90. Hawthorne, NY: Aldine de Gruyter.
Blurton Jones, N. G., K. Hawkes, and J. O’Connell. 1997.
Why do Hadza children forage? In Uniting psychology and
biology: Integrative perspectives on human development,ed.
N. L. Segal, G. E. Weisfeld, and C. C. Weisfield, 297–331.
New York: American Psychological Association.
Bowles, S. 2006. Group competition, reproductive leveling,
and the evolution of human altruism. Science 314:
Boyd, R. 1990. The evolution of reciprocity when conditions
vary. In Coalitions and alliances in humans and other ani-
mals, ed. A. H. Harcourt and F. B. M. de Waal, 473–489.
New York: Oxford University Press.
Boyd, R., H. Gintis, S. Bowles, and P. J. Richerson. 2003. The
evolution of altruistic punishment. Proceedings of the Na-
tional Academy of Sciences, USA 100:3531–3536.
Boyd, R., and P. J. Richerson. 1985. Culture and the evolu-
tionary process. Chicago: University of Chicago Press. [TK/
Broughton, J. M., and F. E. Bayham. 2003. Showing off, for-
aging models, and the ascendance of large-game hunting
in the California Middle Archaic. American Antiquity 68:
Brown, J. K. 1970. A note on the division of labor by sex.
American Anthropologist 72:1073–1078.
Campbell, A. 2002. A mind of her own: The evolutionary psy-
chology of women. New York: Oxford University Press.
Carpenter, K. J. 1994. Protein and energy: A study of changing
ideas in nutrition. Cambridge: Cambridge University Press.
Caspari, R., and S.-H. Lee. 2004. Older age becomes common
late in human evolution. Proceedings of the National Acad-
emy of Sciences, USA 101:10895–10900. [KL/CK]
Chase, I. D. 1980. Cooperative and noncooperative behavior
in animals. American Naturalist 115:827–857.
Codding, B. F., and T. L. Jones. 2007. Man the showoff? Or
the ascendance of a just-so-story: A comment on recent
applications of costly signaling theory in American ar-
chaeology. American Antiquity 72:349–357.
Collier, J. F., and M. Rosaldo. 1981. Politics and gender in
simple societies. In Sexual meanings: The cultural construc-
tion of gender and sexuality, ed. S. B. Ortner and H. White-
head, 275–329. Cambridge: Cambridge University Press.
Cordain, L., B. A. Watkins, and N. J. Mann. 2001. Fatty acid
composition and energy density of foods available to Af-
rican hominds: Evolutionary implications for human brain
development. World Review of Nutrition and Dietetics 90:
Cosmides, L., and J. Tooby. 1994. Beyond intuition and in-
stinct blindness: Toward an evolutionary rigorous cognitive
science. Cognition 50:41–77. [TK/RM]
Cronk, L. 2005. The application of animal signaling theory
to human phenomena: Some thoughts and clarifications.
Social Science Information 44:603–620. [KL/CK]
Dahlberg, F., ed. 1981. Woman the gatherer. New Haven, CT:
Yale University Press.
Damas, D. 1972. The Copper Eskimo. In Hunters and gath-
erers today, ed. M. G. Bicchieri, 3–50. New York: Holt,
Rinehart & Winston. [RH]
de Waal, F. B. M. 1997. The chimpanzee’s service economy:
Food for grooming. Evolution and Human Behavior 18:
Domı´nguez-Rodrigo, M., and R. Barba. 2006. New estimates
of tooth mark and percussion mark frequencies at the FLK
Zinj site: The carnivore-hominid-carnivore hypothesis fal-
sified. Journal of Human Evolution 50:170–194.
———. 2007. Five more arguments to invalidate the passive
scavenging version of the carnivore-hominid-carnivore
model: A reply to Blumenschine et al. (2007a). Journal of
Human Evolution 53:427–433.
Gurven and Hill Why Do Men Hunt? 71
Elwood, R. W., and C. Mason. 1994. The couvade and the
onset of paternal care: A biological perspective. Ethology
and Sociobiology 15:145–156.
Ember, C. 1978. Myths about hunter-gatherers. Ethnology 17:
Estioko-Griffin, A. A. 1985. Women as hunters: The case of
an Eastern Cagayan Agta group. In The Agta of northeastern
Luzon: Recent studies, ed. P. B. Griffin and A. Estioko-
Griffin, 18–32. Cebu City: San Carlos.
———. 1986. Daughters of the forest. Natural History 95:
Fleming, A. S., C. Corter, J. Stallings, and M. Steiner. 2002.
Testosterone and prolactin are associated with emotional
responses to infant cries in new fathers. Hormones and
Behavior 42:399–413. [TK/RM]
Frank, R. 1988. Passions within reason. New York: Norton.
Franzen, M., and J. Eaves. 2007. Effect of market access on
sharing practices within two Huaorani communities. Eco-
logical Economics 63:776–785.
Gintis, H., S. Bowles, R. Boyd, and E. Fehr, eds. 2005. Moral
sentiments and material interests: The foundations of coop-
eration in economic life. Cambridge, MA: MIT Press.
Goodman, M. J., P. B. Griffin, A. A. Estioko-Griffin, and J.
S. Grove. 1985. The compatibility of hunting and moth-
ering among the Agta hunter-gatherers of the Philippines.
Sex Roles 12:1199–1209.
Gray, P. B., J. F. Chapman, T. C. Burnham, M. H. McIntyre,
S. F. Lipson, and P. T. Ellison. 2004. Human male pair
bonding and testosterone. Human Nature 15:119–131.
Gray, P. B., S. M. Kahlenberg, E. S. Barrett, S. F. Lipson, and
P. T. Ellison. 2002. Marriage and fatherhood are associated
with lower testosterone in males. Evolution and Human
Behavior 23:193–201.
Gray, P. B., J. C. Parkin, and M. E. Samms-Vaughan. 2007.
Hormonal correlates of human paternal interactions: A
hospital-based investigation in urban Jamaica. Hormones
and Behavior 52:499–507. [TK/RM]
Gray, P. B., C.-F. Yang, and H. G. Pope. 2006. Fathers have
lower salivary testosterone levels than unmarried men and
married non-fathers in Beijing, China. Proceedings of the
Royal Society of London B 273:333–339. [TK/RM]
Gurven, M. 2004. To give or to give not: An evolutionary
ecology of human food transfers. Behavioral and Brain Sci-
ences 27:543–583.
———. 2006. The evolution of contingent cooperation. Cur-
rent Anthropology 47:185–192.
Gurven, M., W. Allen-Arave, K. Hill, and M. Hurtado. 2000a.
“It’s a Wonderful Life”: Signaling generosity among the
Ache of Paraguay. Evolution and Human Behavior 21:
———. 2001. Reservation food sharing among the Ache of
Paraguay. Human Nature 12:273–298.
Gurven, M., K. Hill, and H. Kaplan. 2002. From forest to
reservation: Transitions in food sharing behavior among
the Ache of Paraguay. Journal of Anthropological Research
Gurven, M., K. Hill, H. Kaplan, M. Hurtado, and B. Lyles.
2000b. Food transfers among Hiwi foragers of Venezuela:
Tests of reciprocity. Human Ecology 28:171–218.
Gurven, M., H. Kaplan, and M. Gutierrez. 2006. How long
does it take to become a proficient hunter? Implications
for the evolution of delayed growth. Journal of Human
Evolution 51:454–470.
Gurven, M., H. Kaplan, and A. Zelada Supa. 2007. Mortality
experience of Tsimane Amerindians: Regional variation and
temporal trends. American Journal of Human Biology 19:
Gurven, M., and C. von Rueden. 2006. Hunting, social status
and biological fitness. Social Biology 53:81–99.
Gurven, M., and R. Walker. 2006. Energetic demand of mul-
tiple dependents and the evolution of slow human growth.
Proceedings of the Royal Society of London B 273:835–841.
Gurven, M., and J. Winking. 2008. Collective action in action:
Pro-social behavior in and out of the laboratory. American
Anthropologist 110:179–190.
Hames, R. 1990. Sharing among the Yanomamo. I. The effects
of risk. In Risk and uncertainty in tribal and peasant econ-
omies, ed. E. Cashdan, 89–106. Boulder, CO: Westview.
———. 2000. Reciprocal altruism in Yanomamo food ex-
change. In Human behavior and adaptation: An anthro-
pological perspective, ed. N. Chagnon, L. Cronk, and W.
Irons. New York: Aldine de Gruyter.
Harris, M., and E. B. Ross, eds. 1987. Food and evolution:
Toward a theory of human food habits. Philadelphia: Temple
University Press.
Hawkes, K. 1990. Why do men hunt? Benefits for risky
choices. In Risk and uncertainty in tribal and peasant econ-
omies, ed. E. Cashdan, 145–166. Boulder, CO: Westview.
———. 1991. Showing off: Tests of an hypothesis aboutmen’s
foraging goals. Ethology and Sociobiology 12:29–54.
———. 1993. Why hunter-gatherers work: An ancient ver-
sion of the problem of public goods. Current Anthropology
———. 2004. Mating, parenting and the evolution of human
pair bonds. In Kinship and behavior in primates,ed.B.
Chapais and C. Berman, 443–473. New York: Oxford Uni-
versity Press.
Hawkes, K., and R. L. Bliege Bird. 2002. Showing off, handicap
signaling, and the evolution of men’s work. Evolutionary
Anthropology 11:58–67.
Hawkes, K., J. F. O’Connell, and N. G. Blurton Jones. 1989.
Hardworking Hadza grandmothers. In Comparative socio-
ecology of mammals and man, ed. R. Foley and V. Standen,
341–366. London: Basil Blackwell.
———. 1991. Hunting income patterns among the Hadza:
Big game, common goods, foraging goals and the evolution
of the human diet. Philosophical Transactions of the Royal
Society of London B 334:243–251.
72 Current Anthropology Volume 50, Number 1, February 2009
———. 2001. Hadza meat sharing. Evolution and Human
Behavior 22:113–142.
Hawkes, K., J. F. O’Connell, N. G. Blurton Jones, H. Alvarez,
and E. L. Charnov. 1998. Grandmothering,menopause, and
the evolution of human life histories. Proceedings of the
National Academy of Sciences, USA 95:1336–1339.
Hawkes, Kristin. 2008. Comment on Bliege Bird and Bird
(2008). Current Anthropology 49:682–683. [AR]
Headland, T., and R. C. Bailey. 1991. Have hunter-gatherers
ever lived in tropical rain forest independently of agricul-
ture? Human Ecology 19:115–122.
Heinrichs, M., and G. Domes. 2008. Neuropeptides and social
behavior: Effects of oxytocin and vasopressin in humans.
Progress in Brain Research 170:337–350.
Henrich, J., R. McElreath, A. Barr, J. Ensminger, C. Barrett,
A. Bolyanatz, J. C. Cardenas, M. Gurven, E. Gwako, N.
Henrich, C. Lesorogol, F. Marlowe, D. Tracer, and J. Ziker.
2006. Costly punishment across human societies. Science
Henrich, N., and J. Henrich. 2007. Why humans cooperate.
Oxford: Oxford University Press.
Hewlett, B. S. 1991a. Demography and childcare in prein-
dustrial societies. Journal of Anthropological Research 47:
———. 1991b.Intimate fathers: The nature and context of Aka
Pygmy paternal infant care. Ann Arbor: University of Mich-
igan Press. [KL/CK]
———. 1992. Husband-wife reciprocity and the father-infant
relationship among Aka Pygmies. In Father-child relations:
Cultural and biosocial contexts, ed. B. S. Hewlett, 153–176.
New York: Aldine de Gruyter.
Hill, K. 1988. Macronutrient modifications of optimal for-
aging theory: An approach using indifference curves ap-
plied to some modern foragers. Human Ecology 16:
———. 2002. Cooperative food acquisition by Ache foragers.
Human Nature 13:105–128.
Hill, K., K. Hawkes, H. Kaplan, and M. Hurtado. 1987. For-
aging decisions among Ache hunter-gatherers: New data
and implications for optimal foraging models. Ethology and
Sociobiology 8:1–36.
Hill, K., and A. M. Hurtado. 1996. Ache life history: The ecology
and demography of a foraging people. New York: Aldine de
Hill, K., and H. Kaplan. 1993. On why male foragers hunt
and share food. Current Anthropology 34:701–710.
Hill, K., and K. Kintigh. Forthcoming. Can anthropologists
distinguish good and poor hunters? Implications for hunt-
ing hypotheses, sharing conventions, and cultural trans-
mission. Current Anthropology.
Hurtado, A. M., and K. Hill. 1990. Seasonality in a foraging
society: Variation in diet, work effort, fertility, and the sex-
ual division of labor among the Hiwi of Venezuela. Journal
of Anthropological Research 46:293–345.
———. 1992. Paternal effects on child survivorship among
Ache and Hiwi hunter-gatherers: Implications for modeling
pair-bond stability. In Father-child relations: Cultural and
biosocial contexts, ed. B. Hewlett, 31–55. Hawthorne, NY:
Aldine de Gruyter.
Hurtado, A. M., K. Hill, H. Kaplan, and I. Hurtado. 1992.
Tradeoffs between female food acquisition and childcare
among Hiwi and Ache foragers. Human Nature 3:185–216.
Hurtado, A. M., C. A. Lambourne, K. R. Hill, and K. Kessler.
2006. The public health implications of maternal caretrade-
offs. Human Nature 17:129–154.
Isaac, G. 1978. The food-sharing behavior of protohuman
hominids. Scientific American 238:90–108.
Kameda, T., M. Takezawa, R. S. Tindale, and C. Smith. 2002.
Social sharing and risk reduction: Exploring a computa-
tional algorithm for the psychology of windfall gains. Evo-
lution and Human Behavior 23:11–33. [TK/RM]
Kaplan, H. 1994. Evolutionary and wealth flows theories of
fertility: Empirical tests and new models. Population and
Development Review 20:753–791.
Kaplan, H., and K. Hill. 1985. Food sharing among Ache
foragers: Tests of explanatory hypotheses. Current Anthro-
pology 26:223–245.
Kaplan, H., K. Hill, J. B. Lancaster, and A. M. Hurtado. 2000.
A theory of human life history evolution: Diet, intelligence,
and longevity. Evolutionary Anthropology 9:156–185.
Kennedy, G. 2003. Palaeolithic grandmothers? Life history
theory and early Homo.Journal of the Royal Anthropological
Institute 9:549–572. [KL/CK]
Kramer, K. L. 2005. Children’s help and the pace of repro-
duction: Cooperative breeding in humans. Evolutionary
Anthropology 14:224–237.
Kuhn, S., and M. C. Stiner. 2006. What’s a mother to do?
Current Anthropology 47:953–980. [KL/CK]
Lancaster, J. B. 1978. Carrying and sharing in human evo-
lution. Human Nature Magazine 1:82–89.
Larsen, C. S. 2003. Animal source foods and human health
during evolution. Journal of Nutrition 133:3893S–3897S.
Lovejoy, C. O. 1981. The origin of man. Science 211:341–350.
Lupo, K. D., and D. N. Schmitt. 2004. Meat-sharing and the
archaeological record: A preliminary test of the show-off
hypothesis among central African Bofi foragers. In Hunters
and gatherers in theory and archaeology. Center for Ar-
chaeological Investigations Occasional Paper No. 31, ed. G.
Crothers, 241–260. Carbondale: Southern Illinois Univer-
sity. [KL/CK]
———. 2005. Small prey hunting technology and zooar-
chaeological measures of taxonomic diversity and abun-
dance: Ethnoarchaeological evidence from central African
forest foragers. Journal of Anthropological Archaeology 24:
335–353. [KL/CK]
Manser, M., and M. Brown. 1980. Marriage and household
decision-making: A bargaining analysis. International Eco-
nomic Review 21:31–44.
Marlowe, F. 1999. Showoffs or providers? The parenting effort
of Hadza men. Evolution and Human Behavior 20:391–404.
Gurven and Hill Why Do Men Hunt? 73
———. 2000. Paternal investment and the human mating
system. Behavioural Processes 51:45–61. [TK/RM]
———. 2001. Male contribution to diet and female repro-
ductive success among foragers. Current Anthropology 42:
Marlowe, F. W. 2003. A critical period for provisioning by
Hadza men: Implications for pair bonding. Evolution and
Human Behavior 24:217–229.
———. 2004a. The mating system of hunter-gatherers in the
standard cross-cultural atlas. Cross-Cultural Research 37:
———. 2004b. What explains Hadza food sharing? Research
in Economic Anthropology 23:69–88.
———. 2005. Mate preferences among Hadza hunter-gath-
erers. Human Nature 15:364–375.
———. 2006. Central place provisioning: The Hadza as an
example. In Feeding ecology in apes and other primates, ed.
G. Hohmann, M. Robbins, and C. Boesch, 359–377. Cam-
bridge: Cambridge University Press. [RH]
Mauss, M. 1990. The gift: The form and reason for exchange
in archaic societies. London: Routledge. [SR]
McDermott, R., J. Fowler, and O. Smirnov. 2008. On the
evolutionary basis of prospect theoretic preferences. Journal
of Politics 70:335–350. [TK/RM]
McGuire, K. R., and W. R. Hildebrandt. 2005. Re-thinking
Great Basin foragers: Prestige hunting and costly signaling
during the Middle Archaic period. American Antiquity 70:
McIntyre, M., S. Gangestad, P. B. Gray, J. F. Chapman, T. C.
Burnham, M. T. O’Rourke, and R. Thornhill. 2006. Ro-
mantic involvement often reduces men’s testosterone lev-
els—but not always: The moderating role of extrapair sex-
ual interest. Journal of Personality and Social Psychology 91:
McMillan, G. 2001. Ache residential grouping and social for-
aging. Ph.D. diss., University of New Mexico.
Merikle, P. M. 2000. Subliminal perception. In Encyclopedia
of psychology, vol. 7, ed. A. E. Kazdin, 497–499. New York:
Oxford University Press. [TK/RM]
Mesnick, S. L. 1997. Sexual alliances: Evidence and evolu-
tionary implications. In Feminism and evolutionary biology:
Boundaries, intersections, and frontiers, ed. P. A. Gowaty,
207–257. New York: Chapman & Hall.
Milton, K. 1999. A hypothesis to explain the role of meat-
eating in human evolution. Evolutionary Anthropology 8:
Milton, K., and M. Demment. 1988. Digestive and passage
kinetics of chimpanzees fed high and low fiber diets and
comparison with human data. Journal of Nutrition 118:107.
Muller, M. N., F. W. Marlowe, R. Bugumba, and P. T. Ellison.
2009. Testosterone and paternal care in East African for-
agers and pastoralists. Proceedings of the Royal Society of
London B 276:347–354. [TK/RM]
Muller, M. N., and R. W. Wrangham. 2001. The reproductive
ecology of male hominoids. In Reproductive ecology and
human evolution, ed. P. T. Ellison, 397–427. New York:
Aldine de Gruyter.
Murphy, S. P., and L. H. Allen. 2003. Nutritional importance
of animal source foods. Journal of Nutrition 133:
O’Connell, J. F., K. Hawkes, K. D. Lupo, and N. Blurton Jones.
2002. Male strategies and Plio-Pleistocene archaeology.
Journal of Human Evolution 43:831–872. [KL/CK]
Ohtsuka, R. 1989. Hunting activity and aging among the Gi-
dra Papuans: A biobehavioral analysis. American Journal of
Physical Anthropology 80:31–39.
Panchanathan, K., and R. Boyd. 2003. A tale of two defectors:
The importance of standing for the evolution of reciprocity.
Journal of Theoretical Biology 224:115–126.
Parker, G. A., N. J. Royle, and I. R. Hartley. 2002. Intrafamilial
conflict and parental investment: A synthesis. Philosophical
Transactions of the Royal Society of London B 357:295–307.
Peterson, N. 1993. Demand sharing: Reciprocity and the pres-
sure for generosity among foragers. American Anthropol-
ogist 95:860–874.
Ponce de Leo´ n, M. S., L. Golovanova, V. Doronichev, G.
Romanova, T. Akazawa, O. Kondo, H. Ishida, and C. P. E.
Zollikofer. 2008. Neanderthal brain size at birth provides
insights into the evolution of human life history. Proceed-
ings of the National Academy of Sciences, USA 105:
Potts, R. 1998. Variability selection in hominid evolution.
Evolutionary Anthropology: Issues, News, and Reviews 7:
81–96. [RH]
Quinlan, R. J., and M. B. Quinlan. 2007. Evolutionary ecology
of human pair bonds: Cross-cultural tests of alternative
hypotheses. Cross-Cultural Research 41:149–169. [KL/CK]
Robson, S., C. van Schaik, and K. Hawkes. 2006. The derived
features of human life history. In The evolution of human
life history, ed. R. L. Paine and K. Hawkes, 17–44. Santa
Fe, NM: School of American Research Press. [KL/CK]
Robson, S., and B. Wood. 2008. Hominin life history: Re-
construction and evolution. Journal of Anatomy 212:
394–425. [KL/CK]
Schmitt, D., S. E. Churchill, and W. L. Hylander. 2003. Ex-
perimental evidence concerning spear use in Neandertals
and early modern humans. Journal of Archaeological Science
30:103–114. [KL/CK]
Schoeninger, M. J., H. T. Bunn, S. S. Murray, and J. A. Marlett.
2001. Composition of tubers used by Hadza foragers of
Tanzania. Journal of Food Composition and Analysis 14:
Sear, R., and R. Mace. 2007. Who keeps children alive? A
review of the effects of kin on child survival. Evolution and
Human Behavior 29:1–18.
Silberbauer, G. B. 1972. The G/wi bushmen. In Hunters and
gatherers today, ed. M. G. Bicchieri, 271–325. New York:
Holt, Rinehart & Winston. [RH]
———. 1978. Social hibernation: The response of the G/wi
band to seasonal drought. In Proceedings of the Symposium
74 Current Anthropology Volume 50, Number 1, February 2009
on Drought in Botswana, ed. M. T. Hinchey, 113–120. Ga-
borone: Botswana Society and Clark University Press. [RH]
Simoons, F. J. 1994. Eat not of this flesh: Food avoidances from
prehistory to the present. Madison: University of Wisconsin
Smith, E. A. 2004. Why do good hunters have higher repro-
ductive success? Human Nature 15:343–364.
Smith, E. A., and R. Bliege Bird. 2005. Costly signaling and
cooperative behavior. In Moral sentiments and material in-
terests: The foundations of cooperation in economic life,ed.
H. Gintis, S. Bowles, R. Boyd, and E. Fehr, 115–148. Cam-
bridge, MA: MIT Press.
Steward, J. H. 1936. Shoshoni polyandry. American Anthro-
pologist 38:561–564. [RH]
Stiner, M. 2002. Carnivory, coevolution, and the geographic
spread of the genus Homo.Journal of Archaeological Re-
search 10:1–63.
Storey, A. E., C. J. Walsh, R. L. Quinton, and K. E. Wynne-
Edwards. 2000. Hormonal correlates of paternal respon-
siveness in new and expectant fathers. Evolution and Hu-
man Behavior 21:79–95. [TK/RM]
Sugiyama, L., and R. Chacon. 2000. Effects of injury and
illness on foraging among the Shiwar and Yora. In Adap-
tation and human behavior: An anthropological perspective,
ed. L. Cronk, N. Chagnon, and W. Irons, 371–396.Chicago:
Aldine de Gruyter. [RH]
Trivers, R. L. 1972. Parental investment and sexual selection.
In Sexual selection and the descent of man, 1871–1971,ed.
B. Campbell, 136–179. Chicago: Aldine.
Tucker, B., and A. G. Young. 2005. Growing up Mikea: Chil-
dren’s time allocation and tuber foraging in southwestern
Madagascar. In Hunter-gatherer childhoods, ed. B. Hewlett,
M. Lamb, 147–171. New York: Aldine de Gruyter.
van Schaik, C. P., and R. I. M. Dunbar. 1990. The evolution
of monogamy in large primates: A new hypothesis and
some crucial tests. Behaviour 115:30–62.
Walker, R., K. Hill, H. Kaplan, and G. McMillan. 2002. Age-
dependency in skill, strength and hunting ability among
the Ache of eastern Paraguay. Journal of Human Evolution
Walum, H., L. Westberg, S. Henningsson, J. M. Neiderhiser,
D. Reiss, W. Igl, J. M. Ganiban, E. L. Spotts, N. L. Pederson,
E. Eriksson, and P. Lichtenstein. 2008. Genetic variation in
the vasopressin receptor 1a gene (AVPR1A) associates with
pair-bonding behavior in humans. Proceedings of the Na-
tional Academy of Sciences, USA 105:14153–14156.
Washburn, S., and C. Lancaster. 1968. The evolution of hunt-
ing. In Man the hunter, ed. R. B. Lee and I. Devore,
293–303. Chicago: Aldine.
Waynforth, D. 2001. Mate-choice trade-offs and women’s
preference for physically attractive men. Human Nature 12:
Wiessner, P. 1996. Leveling the hunter: Constraints on the
status quest in foraging societies. In Food and the status
quest, ed. P. Wiessner and W. Schiefenho¨vel, 171–192. Prov-
idence, RI: Berghahn.
Winking, J. 2006. Are men that bad as fathers? The role of
men’s investments. Social Biology 53:100–115.
Winking, J., M. Gurven, H. Kaplan, and J. Stieglitz. Forth-
coming. The goals of direct parental care among a South
Amerindian population. American Journal of Physical
Winking, J., H. Kaplan, M. Gurven, and S. Rucas. 2007. Why
do men marry and why do they stray? Proceedings of the
Royal Society of London B 274:1643–1649.
Winterhalder, B. 1990. Open field, common pot: Harvest var-
iability and risk avoidance in agricultural and foraging so-
cieties. In Risk and uncertainty in tribal and peasant societies,
ed. E. A. Cashdan, 67–87. Boulder, CO: Westview.
Winterhalder, B., and E. A. Smith. 1992. Evolutionary ecology
and the social sciences. In Evolutionary ecology and human
behavior, ed. B. Winterhalder and E. A. Smith, 3–23. New
York: Aldine de Gruyter.
Wood, B. 2006. Prestige or provisioning? A test of foraging
goals among the Hadza. Current Anthropology 47:383–387.
Wood, B., and K. Hill. 2000. A test of the “showing off”
hypothesis. Current Anthropology 41:124–125.
Wood, B., and F. W. Marlowe. 2007. Do Hadza children ben-
efit from their father’s foraging? 19th Annual Meeting of
the Human Behavior and Evolution Society, College of Wil-
liam and Mary, Williamsburg, Virginia, 2007, 19. [RH]
Ziegler, T. E., S. L. Prudom, N. J. Schultz-Darken, A. V. Ku-
rian, and C. T. Snowdon. 2006. Pregnancy weight gain:
Marmoset and tamarin dads show it too. Biology Letters
Ziegler, T. E., K. F. Washabaugh, and C. T. Snowdon. 2004.
Responsiveness of expectant male cotton-top tamarins, Sa-
guinus oedipus, to mate’s pregnancy. Hormones and Behav-
ior 45:84–92. [TK/RM]
Ziker, J., and M. Schnegg. 2005. Food sharing at meals: Kin-
ship, reciprocity, and clustering in the Taimyr Autonomous
Region, northern Russia. Human Nature 16:178–210.
... Likewise, divergent foraging niches can also produce sexually dimorphic body size, perhaps the best examples being raptorial birds where, again, females are consistently larger than males (Newton, 1979;Andersson and Norberg, 1981;Schoenjahn et al., 2020). A sexual division of labor, with males concentrating on hunting mobile prey and women focusing on immobile plant foods is nearly universal among human foragers (Murdock, 1937;Gurven and Hill, 2009) and possibly primitive in the chimphuman clade given that hunting, while rare, is a nearly exclusive male activity in common chimpanzees (Mitani and Watts, 2001;Mitani et al., 2002). It has been suggested that this ecological sex difference could have generated natural selection for sexual dimorphism in human body size (Kaplan et al., 2000). ...
... Evidence from modern hunter-gatherer groups suggests that male hunting provided a major portion of calories, fat, and protein to their families (and other families of their group through meat sharing) during human evolution (Cordain et al., 2000;Gurven and Hill, 2009). Given that men's hunting ability correlates positively with their muscle mass (Apicella, 2014) perhaps natural selection played a role in shaping both the sexual division of labor and sex differences in muscle mass. ...
Full-text available
Human sexual dimorphism has been widely misunderstood. A large literature has underestimated the effect of differences in body composition and the role of male contest competition for mates. It is often assumed that sexually dimorphic traits reflect a history of sexual selection, but natural selection frequently builds different phenotypes in males and females. The relatively small sex difference in stature (∼7%) and its decrease during human evolution have been widely presumed to indicate decreased male contest competition for mates. However, females likely increased in stature relative to males in order to successfully deliver large-brained neonates through a bipedally-adapted pelvis. Despite the relatively small differences in stature and body mass (∼16%), there are marked sex differences in body composition. Across multiple samples from groups with different nutrition, males typically have 36% more lean body mass, 65% more muscle mass, and 72% more arm muscle than women, yielding parallel sex differences in strength. These sex differences in muscle and strength are comparable to those seen in primates where sexual selection, arising from aggressive male mating competition, has produced high levels of dimorphism. Body fat percentage shows a reverse pattern, with females having ∼1.6 times more than males and depositing that fat in different body regions than males. We argue that these sex differences in adipose arise mainly from natural selection on women to accumulate neurodevelopmental resources.
... Since finding larger species typically requires longer search times, knowledge of environmental conditions for travel, safety, and equipment repair is critical for accessing larger game, especially for large marine mammals (Cummins 1992;Condon et al. 1995, Rosol et al. 2016, Usher 2002Pal et al. 2013). The variability of harvesting larger species may be further offset by nonmeat foraging, food storage, and food sharing (Kaplan and Gurven 2005;Gurven and Hill 2009). When labour is divided between genders, men often pursue large game while women forage for nonmeat foods and small animals; big game hunting often increases if women's foraging returns decline. ...
... When labour is divided between genders, men often pursue large game while women forage for nonmeat foods and small animals; big game hunting often increases if women's foraging returns decline. (Bousman 1993;Gurven and Hill 2009). Devoting labour towards food processing (e.g., drying, the preparation of bone grease) and storage allows for larger game to be collected in higher quantities when seasonally accessible and preserved for times of scarcity (Binford 1978;Bettinger et al. 2015). ...
Traditional food systems based on harvest from the local environment are fundamental to the well-being of many communities, but their security is challenged by rapid socio-ecological change. We synthesized literature and data describing how a fundamental form of biodiversity, animal body size, contributes to the security of traditional food systems through relationships with species availability, accessibility, adequacy, and use. We found larger vertebrate species were more available, accessible, and used on a per kilogram basis, particularly for mammals. Conversely, larger species were no more or less adequate from a combined nutritional, health, and cultural perspective. Larger species represented more biomass, and this biomass required less time to harvest, with greater but more variable mean caloric returns over time. Smaller species provided more consistent caloric returns and were harvested during documented shortages of prey. This reliance on species with a range of body sizes is consistent with optimal foraging theory and the evolutionary value of flexibility, and highlights the importance of a biodiverse pool of species for traditional food security in times of change. Our synthesis of published literature and data highlights the many socio-ecological correlates of species size and how these relate to the security of traditional food systems.
... In contrast, humans compete in how they interact with the environment (Ridley, 1993). This also changes the economics of the group fundamentally: resources are shared freely between all members of the group in most small-scale societies (Gurven and Hill, 2009), since sharing can be translated into reputation, which is relevant for reproductive success. The adaptation to actions that are done for reputation varies historically. ...
Full-text available
This paper contributes to two debates: the debate about language evolution and the debate about the foundations of human collaboration. While both cooperation and language may give the impression of being adaptations that evolved for the “good of the group,” it is well established that the evolution of complex traits cannot be a direct result of group selection. In this paper I suggest how this tension can be solved: both language and cooperation evolved in a unique two-level evolutionary system which was triggered by a well-documented geological event—the drying out of the climate—in East Africa, which subsequently reduced the intermating between groups and thus made it possible that the mechanism that produced differences between groups (including social forms of selection such as female choice) could be the target of natural selection on the group level. If a social form of selection (e.g., sexual selection) produced differences in fitness between groups, the displacement process between groups would indirectly select those forms of social selection that produce groups that would displace all others. The main hypothesis presented in this paper is that, in this situation, a backchannel between the two levels of selection naturally evolves. A backchannel between the two levels would, for example, emerge when sexual selection (or any other form of social selection) was sensitive to the individual’s contribution to the group. Examples of systems utilizing a backchannel are nerve cells being better nourished when used more frequently, enabling them to be conducive to the survival of the whole organism, or a law firm in which all employees get paid to the extent that they contribute to the survival and success of the firm. In both cases, the selection on the higher level informs the selection on the lower level. The aim of the paper is to illuminate these rather opaque claims, to which the reader probably has many objections in this abridged form.
... In contrast, humans compete in how they interact with the environment (Ridley, 1993). This also changes the economics of the group fundamentally: resources are shared freely between all members of the group in most small-scale societies (Gurven and Hill, 2009), since sharing can be translated into reputation, which is relevant for reproductive success. The adaptation to actions that are done for reputation varies historically. ...
Full-text available
This paper contributes to two debates: the debate about language evolution and the debate about the foundations of human collaboration. While both cooperation and language may give the impression of being adaptations that evolved for the “good of the group,” it is well established that the evolution of complex traits cannot be a direct result of group selection. In this paper I suggest how this tension can be solved: both language and cooperation evolved in a unique two-level evolutionary system which was triggered by a well-documented geological event—the drying out of the climate—in East Africa, which subsequently reduced the intermating between groups and thus made it possible that the mechanism that produced differences between groups (including social forms of selection such as female choice) could be the target of natural selection on the group level. If a social form of selection (e.g., sexual selection) produced differences in fitness between groups, the displacement process between groups would indirectly select those forms of social selection that produce groups that would displace all others. The main hypothesis presented in this paper is that, in this situation, a backchannel between the two levels of selection naturally evolves. A backchannel between the two levels would, for example, emerge when sexual selection (or any other form of social selection) was sensitive to the individual’s contribution to the group. Examples of systems utilizing a backchannel are nerve cells being better nourished when used more frequently, enabling them to be conducive to the survival of the whole organism, or a law firm in which all employees get paid to the extent that they contribute to the survival and success of the firm. In both cases, the selection on the higher level informs the selection on the lower level. The aim of the paper is to illuminate these rather opaque claims, to which the reader probably has many objections in this abridged form.
... However, there is a great deal of variation both between and within foraging societies in how subsistence tasks are performed (e.g., Kelly, 1995). Men tend to spend more time and energy on hunting and women on gathering (Gurven and Hill, 2009) and men cover greater distances than women for acquiring food . Subsistence activities also vary across age categories, with children and adults focusing on different resources (Gallois, 2017), and elders dedicating more time to activities other than food acquisition, such as childcare and knowledge transmission (Kaplan et al., 2000). ...
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What present-day foragers do for their living and what they eat have long been privileged areas for exploring human behavior, global health, and human evolution. While many studies have focused on hunting and meat acquisition, less attention has been given to gathering and plant foods. Despite evidence of variation in both nutritional quality and energetic costs of gathering different plants, the overall effort spent on gathering in relation to other subsistence tasks is still under explored. In the current context of economic, climate, and social changes, many forager societies also rely on other subsistence strategies, including agriculture and wage labor. In this study, we aim to explore the place of gathering in the livelihood of a mixed economy society, the Baka forager-horticulturalists of southeastern Cameroon, by comparing the involvement and the costs of activities related to food acquisition. From a pool of 153 adult participants (97 women and 56 men), we collected 246 daily records using a GPS (Global Positioning System) tracker combined with heart rate monitor and time allocation recalls. We compared the duration, distance traveled, and the intensity of work, measured by calculating the metabolic equivalent of task (MET), of subsistence activities related to food acquisition. Results from this work show that gathering activities, performed by both women and men, are energetically costly, with higher MET values than hunting and fishing activities. Furthermore, the MET values vary depending on the targeted plant foods. We discuss these insights in the overall framework of subsistence patterns, merging them with the socio-cultural and environmental factors that might explain Baka livelihood and subsistence strategy.
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Human parents require significant support to raise multiple, highly dependent offspring. Grandmothers are often highlighted as key allomothers (non-maternal caregivers) and their presence is frequently associated with increased child survivorship, leading some to describe humans as cooperative breeders. Equally well documented is the diversity of human childcare systems, where a wide range of individuals support parents including male kin. However, the role of grandfathers has been less well documented, and they seem to have an inconsistent relationship with child survivorship, dependent on socio-ecological factors. Here, we explore the relationship between grandparental allomothering and child survivorship using demographic and time budget data from a pastoralists community in western China. We find that under-five mortality is negatively associated with grandpaternal, but not grandmaternal, living status. Pastoralists in Maqu have recently transitioned from mobile to half-settled livelihoods in which women are more economically active than males. As a result, women's childcare workloads have decreased, while older men (who are excluded from the household economy) supervise children. Our results suggest that patterns of childcare are flexible and highlight the need to consider social and ecological factors to understand allomothering and child survival.
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A key issue distinguishing prominent evolutionary models of human life history is whether prolonged childhood evolved to facilitate learning in a skill- and strength-intensive foraging niche requiring high levels of cooperation. Considering the diversity of environments humans inhabit, children’s activities should also reflect local social and ecological opportunities and constraints. To better understand our species’ developmental plasticity, the present paper compiled a time allocation dataset for children and adolescents from twelve hunter-gatherer and mixed-subsistence forager societies (n = 690; 3–18 years; 52% girls). We investigated how environmental factors, local ecological risk, and men and women’s relative energetic contributions were associated with cross-cultural variation in child and adolescent time allocation to childcare, food production, domestic work, and play. Annual precipitation, annual mean temperature, and net primary productivity were not strongly associated with child and adolescent activity budgets. Increased risk of encounters with dangerous animals and dehydration negatively predicted time allocation to childcare and domestic work, but not food production. Gender differences in child and adolescent activity budgets were stronger in societies where men made greater direct contributions to food production than women. We interpret these findings as suggesting that children and their caregivers adjust their activities to facilitate the early acquisition of knowledge which helps children safely cooperate with adults in a range of social and ecological environments. These findings compel us to consider how childhood may have also evolved to facilitate flexible participation in productive activities in early life.
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Over the last half century, anthropologists have vigorously debated the adaptive motivations underlying food acquisition choices and food-sharing among hunter-gatherer groups. Numerous explanations have been proposed to account for high-levels of generosity in food-sharing, including self- and family-provisioning, reciprocity, tolerated theft and pro-social- or skill-signaling. However, few studies have asked foragers directly and systematically about the motivations underlying their foraging and sharing decisions. We recruited 110 Hadza participants and employed a combination of free-response, yes/no, ranking and forced-choice questions to do just this. In free-response answers, respondents typically gave outcome-oriented accounts of foraging motive (e.g., to get food) and moralistic accounts of sharing motive (e.g., I have a good heart). In ranking tasks, participants gave precedence to reciprocity as a motive for sharing food beyond the household. We found small but clear gender differences in foraging motive, in line with previous predictions: women were more likely than men to rank family-provisioning highly whereas men were more likely than women to rank skill-signaling highly. However, despite these gender differences, the relative importance of different motivations was similar across genders and skill-signaling, sharing and family-provisioning were the most important motivators of foraging activity for both men and women. Contrary to the expectations of tolerated theft, peer complaints and requests for food ranked very low. There are several compelling reasons that evolutionary thinkers, typically interested in ultimate-level adaptive processes, have traditionally eschewed direct and explicit investigations of motive. However, these data may yet provide important insights.
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The Early Pleistocene (2.58-0.78 Ma) was a period of major evolutionary changes in the hominin lineage. The progressive consolidation of bipedal locomotion, alongside increases in cranial capacity and behavioural flexibility, allowed early Homo to exploit an increasing diversity of resources and environmental settings within the changing landscapes of East Africa and beyond. These complex processes were not necessarily linear or spatially uniform, given the technological diversity documented, particularly during the Oldowan-Acheulean transition. In this paper, we argue that human populations experienced a considerable demographic expansion from c.1.7-1.5 Ma onwards, expressed in the number, size, density, and distribution of archaeological sites. These patterns resulted from the interplay of high-yielding animal resource exploitation strategies, technological investment, prosocial behaviours as well as increasingly structured land use patterns. A more consolidated hominin demographic structure led to the extinction of large sympatric carnivore species, while larger group sizes would have led to more successful Out-of-Africa dispersals.
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Complementary archaeological and paleoenvironmental datasets from North Creek Shelter (Colorado Plateau, Utah, USA) are analyzed using the diet breadth model, revealing human dietary patterns during the early and middle Holocene. Abundance indices are derived from botanical and faunal datasets and, along with stone tools, are used to test the prediction that increasing aridity caused the decline of high-return resources. This prediction appears valid with respect to botanical resources, given that high-ranked plants drop out of the diet after 9800 cal BP and are replaced with low-ranked, small seeds. The prediction is not met, however, with respect to faunal resources: high-ranked artiodactyls are consistently abundant in the diet. The effects of climate change on dietary choices are also examined. Findings show that increased aridity coincides with greater use of small seeds and ground stone tools but not with increases in low-ranked fauna, such as leporids. The patterns observed from the North Creek Shelter botanical and faunal datasets may reflect different foraging strategies between men and women. This would explain why low-ranked plant resources became increasingly abundant in the diet without a corresponding decrease in abundance of high-ranked artiodactyls. If so, then archaeological records with similar datasets should be reexamined with this perspective.
"Many topics of interest to health professionals, such as vegetarianism, dietary fibers, lactose intolerance, favism, cannibalism and changes in nutritional status wrought by the decline of hunter-gathering and the rise of horticulture. Many sections will appeal to the general reader." Journal of Applied Nutrition The old adage "you are what you eat" may be more accurate than anyone could have ever imagined. This unprecedented interdisciplinary effort by scholars in primatology, biological anthropology, archaeology, nutrition, psychology, agricultural economics, and cultural anthropology suggests that there is a systematic theory behind why humans eat what they eat. Includes discussions ranging in time from prehistory to the present, and from the most simple societies to the most complex, including South American Indian groups, African hunter-gatherers, and countries such as India, Bangladesh, Peru, and Mexico. "Exceptionally well-edited. High quality individual papers are of comparable scope and are uniformly well referenced and detailed in presentation of supporting data Introductory and concluding chapters as well as section overviews create an integrated whole." Choice "Compelling...complete and...recommended." Science Books & Films "Should be of value to all nutrition educators who have an interest in the social, cultural, and international aspects of foods and nutrition." Journal of Nutrition Education.