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Dietary ecology is key to understanding the lifeways and evolutionary pathways of many animals, but determining the diets of long-extinct primates, including early hominins, is a considerable challenge. Although archeological evidence forms a pillar of our understanding of diet and subsistence in the more recent past, for early hominins, the most direct evidence is to be found in the fossils themselves. Here we review the suite of emerging biochemical paleodietary tools based on stable isotope and trace element archives within fossil calcified tissues. We critically assess the contribution of these tools to advancing our understanding of australopith, early Homo, and Neanderthal diets, and placed within the context of contributions of morphological and microwear tools. Perhaps the most significant outcomes to date are the demonstration of high trophic-level diets among Neanderthals in Glacial Europe, and the persistent inclusion of significant amounts of C4 grass-related foods in the diets of both the South African australopiths and Homo in the Pliocene and Pleistocene. These results raise new questions that require improved contextual understanding of these tools from modern ecosystems, but they also clearly show a good deal of promise as quantitative indicators of hominin diets that nicely complement morphological and microwear tools.
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Contributions of Biogeochemistry to Understanding
Hominin Dietary Ecology
Julia Lee-Thorp
and Matt Sponheimer
Archaeological Sciences, University of Bradford, Bradford BD1 7DP, UK
Department of Anthropology, University of Colorado at Boulder, Boulder, CO 80309
KEY WORDS fossil teeth; stable isotopes of carbon; nitrogen and oxygen; trace elements;
microwear; dental morphology; australopiths; Homo; Neanderthals
ABSTRACT Dietary ecology is one key to understand-
ing the biology, lifeways, and evolutionary pathways of
many animals. Determining the diets of long-extinct hom-
inins, however, is a considerable challenge. Although
archaeological evidence forms a pillar of our understand-
ing of diet and subsistence in the more recent past, for
early hominins, the most direct evidence is to be found in
the fossils themselves. Here we review the suite of emerg-
ing biochemical paleodietary tools based on stable isotope
and trace element archives within fossil calcified tissues.
We critically assess their contribution to advancing our
understanding of australopith, early Homo, and Neander-
thal diets within the broader context of non-biogeochemi-
cal techniques for dietary reconstruction, such as mor-
phology and dental microwear analysis. The most signifi-
cant outcomes to date are the demonstration of high
trophic-level diets among Neanderthals and Late Pleisto-
cene modern humans in Glacial Europe, and the persis-
tent inclusion of C
grass-related foods in the diets of
Plio–Pleistocene hominins in South Africa. Such studies
clearly show the promise of biogeochemical techniques for
testing hypotheses about the diets of early hominins.
Nevertheless, we argue that more contextual data from
modern ecosystem and experimental studies are needed if
we are to fully realize their potential. Yrbk Phys Anthro-
pol 49:131–148, 2006. V
C2006 Wiley-Liss, Inc.
It is widely recognized that the pursuit and consump-
tion of food exerts a major influence on the behavior,
ecology, and biology of all animals. Most large primates
spend a large proportion of their waking hours searching
for, consuming, and digesting food (e.g., Altmann and
Altmann, 1970; Teleki, 1981; Goodall, 1986; Whiten
et al., 1991), and diet underlies ecological niche distinc-
tions. Consequently, dietary adaptations can be consid-
ered as one of the key drivers determining the pathways
of hominin evolution. The nature of hominin diets has
been the subject of lively debate and not a little specula-
tion for many years (e.g., Dart, 1926, 1957; Robinson,
1954, 1956; Jolly, 1970), although in recent years the
topic has received somewhat less attention than bipedal-
ism and brain expansion (Teaford and Ungar, 2000). The
importance of dietary ecology is clear, but determining
the diets of extinct hominins remains a considerable
challenge. Most primates are generalists, so pinpointing
their diets and dietary differences is no simple matter
even among extant animals, where observational studies
continue to generate new information and surprises. For
instance, more detailed observations of gorillas in a vari-
ety of environments have shown that they are less
devoted to folivory than previously believed, and that
their diets overlap considerably with those of chimpan-
zees in many areas (Tutin and Fernandez, 1992). The
difference lies to a significant extent in their fallback
foods; in times of stress gorillas can better rely on foli-
age. So how best can we investigate the diets of species
that have been extinct for many thousands or millions of
We can glean paleodietary information from many
sources. However, some of the conventional sources of
contextual evidence may be inappropriate, or at best pro-
vide very indirect, limited, or ambiguous information
about diet. Archeological evidence in the form of stone
tools, animal bone scatters and their spatial contexts is
the conventional source of information about past human
diet and subsistence. There are, however, severe limita-
tions in applications to the early fossil record, particu-
larly where stratified archeological evidence is rare.
Moreover, even where stratigraphy (or good spatial con-
text) exists, the nature of association between the animal
bones and human behavior is often controversial (e.g.,
Binford, 1981; Brain, 1981). There are significant inter-
pretive problems associated with most Pliocene and
Lower Pleistocene bone accumulations, where the sites
are essentially palimpsests and the assemblages may
have accumulated over hundreds to thousands of years.
Traces that survive best are scatters of bones and stone
tools which may indicate procurement strategies and
butchery of vertebrate animal foods (e.g., Binford, 1981;
Brain, 1981; Blumenschine, 1987; Stiner, 1994; Marean
and Assefa, 1999; Speth and Tchernov, 2001). Yet, even
where these traces occur, the information they provide
can be ambiguous. For instance, the function of stone
Grant sponsors: National Research Foundation (South Africa),
National Science Foundation (USA), University of Bradford, Univer-
sity of Cape Town, University of Colorado at Boulder, the Leakey
Foundation, the Palaeoanthropology Scientific Trust.
*Correspondence to: Julia Lee-Thorp, Department of Archaeologi-
cal Science, University of Bradford, Richmond Road, Bradford BD1
7DP, UK. E-mail:
DOI 10.1002/ajpa.20519
Published online in Wiley InterScience (
tools and the identities of their manufacturers (i.e.,
whether early Homo or australopith) is often uncertain
(Brain, 1981). At present, the earliest known stone tools
and cut-marked bones are from Gona and Bouri in
Ethiopia, dated to *2.5 Ma (Semaw et al., 1997; de
Heinzelin et al., 1999; Dominguez-Rodrigo et al., 2005),
while the first potential hominins (Leakey et al., 2001;
Senut et al., 2001; Brunet et al., 2002; White et al.,
2006) precede these earliest archeological traces by mil-
lions of years. Thus archeological traces can tell us noth-
ing about the diets of our lineage for most of its history.
Finally, the prominence of bones and stone tools in the
record inevitably focuses attention on animal foods,
whereas plant foods make up the bulk of most primate
diets (Milton, 2002) and are likely to have been just as
important for early hominins. Overall, technological
attributes and spatial distributions of Oldowan and
Acheulian stone tools may tell us more about the cogni-
tive and fine-motor capabilities of their makers (Ambrose,
2001) and their use of the landscape (Isaac, 1981; Fe
Augustins, 1997) than they do about their dietary ecology.
As a result, paleoanthropologists have had to develop
other sources of palaeodietary information to fill these
gaps. Many are focused largely on teeth—dental mor-
phology and allometry, dental microwear, and trace ele-
ment and stable isotope analysis. These techniques have
advantages and limitations that are peculiar to each
approach. Morphology and allometry, for instance, pro-
vide general indications about the capability of a species
to process foods with certain mechanical properties, rely-
ing heavily on comparisons with living primates (Kay,
1975a, b, 1985). Dental microwear and chemical tools
also rely on comparisons with modern systems for inter-
pretation, but they are more immediate and direct indi-
cators of palaeodiet. Microwear, in turn, is largely lim-
ited to telling us about the mechanical properties or con-
sistency of foods eaten (Walker, 1981; Teaford, 1988a;
Teaford and Ungar, 2000). The information available
from chemical analyses in the form of stable light isotope
and trace element patterns in bones and teeth is limited
to certain broad dietary classes. Postmortem taphonomy
and diagenesis remains an ever-present problem that
can compromise or destroy dietary information for both
microwear and chemical approaches (Teaford, 1988b;
Sillen, 1989; Koch et al., 1997; Kohn et al., 1999; Lee-
Thorp, 2000; Pe
´rez et al., 2003; Lee-Thorp and
Sponheimer, 2005).
Given the distinct limitations for each approach,
ideally, they should form a complementary suite. Since
we cannot observe what early humans were eating,
inferences about early human diets are perforce indirect.
Several comprehensive reviews of dental allometry, mor-
phology, and microwear exist in the literature (Kay,
1985; Ungar, 1998; Teaford and Ungar, 2000; Teaford
et al., 2002). In this article, we provide brief overviews
of these approaches to give sufficient contextual informa-
tion to gauge the contributions of biogeochemical tools to
hominin diets. We concentrate largely on applications to
dietary ecology of the australopiths and Neanderthals,
simply because this is where we have most biogeochemi-
cal data.
The function of teeth is to process foods, and they are
abundant in the fossil record; hence the relative size and
shape of teeth has been an important source of informa-
tion for many years. Robinson (1954, 1956) observed that
the \robust"australopith, Paranthropus robustus, had
absolutely smaller incisors and larger molars than did the
gracile australopith, Australopithecus africanus, and he
deduced that these differences reflected functional spe-
cializations. Specifically, Robinson argued that Paranth-
ropus had an herbivorous diet that required grinding
large quantities of tough plant foods, while A. africanus
had a more omnivorous diet that required relatively more
incisal preparation of meat and other foods (Robinson,
1956). This work was influential and set the stage not
only for subsequent allometric and morphological studies
of teeth, but also for hypothesis testing of the dietary pro-
clivities and differences between the South African aus-
tralopiths (e.g., Grine, 1981, 1986; Grine and Kay, 1988;
Scott et al., 2005; Sponheimer et al., 2005a).
While continuing to consider the functional implica-
tions of relative tooth size of both anterior and posterior
teeth in primates, subsequent studies have attempted to
deal with a central problem. That is, since basal meta-
bolic rate and molar occusal surfaces are generally
scaled in a similar way to body size (by *0.75), molar
size should be positively scaled to body size, because
larger surfaces can process greater amounts of food (Pil-
beam and Gould, 1974). Therefore, tooth size (particu-
larly molar occlusal area) must be considered in relation
to body size. However, this information is often unavail-
able or poorly known for the majority of fossil primates,
including hominins. A related problem is that certain
foods need a great deal more chewing or preparation
than others. In an attempt to control this problem, Kay
(1975a) compared primate taxa with similar diets. He
showed that primate posterior tooth surface area varied
isometrically, rather than allometrically, with body size
in primate taxa with frugivorous, folivorous, and insec-
tivorous diets, respectively. The implication is that posi-
tive allometry amongst the larger and smaller australo-
piths probably does denote different foods (Kay, 1975b),
as Robinson had originally proposed.
Reasonable estimates for body weights of the three
\gracile"australopiths—A. anamensis,A. afarensis, and
A. africanus—have allowed an assessment of the scaling
of incisors against body size (Kay, 1975b, 1985; Ungar
and Grine, 1991; Teaford and Ungar, 2000). Their rela-
tive sizes are very similar, and they fall close to the
regression line for a number of primates. These results
suggest that the gracile australopiths tended to eat foods
that required moderate amounts of incisal preparation
(Teaford and Ungar, 2000).
One of the distinguishing features of the australopiths
is their large and relatively flat molars (Robinson, 1956;
Wolpoff, 1973; Wood and Abbott, 1983; Kay, 1985; Tea-
ford et al., 2002). \Megadontia quotients"(relative size
of molars scaled against body size) for australopiths
increased over time from A. anamensis to Paranthropus,
suggesting changes in the physical properties of their
foods (e.g., hardness, size, and shape) to those that
required a good deal of force (Demes and Creel, 1988).
Another approach is to compare molar tooth areas of the
M1 and M3, since this ratio is inversely correlated with
percentage of leaves, flowers, and shoots in the diets of
modern primates (Lucas and Peters, 2000; Teaford et al.,
2002). The earlier australopiths, including Ardipithecus,
have clearly higher M1:M3 ratios than Paranthropus,
suggesting perhaps lower consumption of leaves, flowers,
and shoots, and conversely greater degrees of frugivory
(Teaford and Ungar, 2000).
American Journal of Physical Anthropology—DOI 10.1002/ajpa
Tooth size alone is insufficient to address questions
about changing amounts of fruit (or other foods) in the
diets of early hominins, shape must also be considered
(Wood, 1981). Changes in tooth morphology tend to
reflect changes in properties of typical foods, such as
their toughness (Ungar, 1998). Food is orally prepared
by the shearing, crushing, and grinding actions of teeth,
and these functions have different morphological corre-
lates (Strait, 1997; Lucas and Peters, 2000). Shearing
requires blades or crests, while crushing and grinding
require occlusion of two relatively flat or smooth surfaces
in opposition. Hence, the relative importance of these
actions, which are related to the properties of typical
foods, should be reflected in tooth morphology, or rather,
in the capabilities of tooth forms to accomplish these
actions (Strait, 1997). Hard and brittle foods, for exam-
ple, require crushing between flat planar surfaces
whereas tough, pliant foods require shearing by recipro-
cally concave, highly crested teeth. The shearing poten-
tial of molar teeth can be assessed by means of a
\shearing quotient"based on observations that extant
folivorous primates exhibit higher shearing quotients
than brittle or soft fruit feeders, which are higher in
turn than hard-object feeders (Kay, 1985). In general,
australopiths had relatively flat, blunt molars and lacked
prominent shearing crests (Grine, 1981; Kay, 1985; Tea-
ford et al., 2002), suggesting that they were more capa-
ble of processing soft or brittle, rather than tough, pliant
foods. Following this reasoning, it has also been sug-
gested that the early australopiths may have lacked the
capabilities for orally processing meat, while early Homo,
which had relatively greater occlusal relief, might have
had greater success processing tough, elastic foods such as
meat (Lucas and Peters, 2000; Ungar, 2004). Nonetheless,
variability undoubtedly exists within the australopiths, as
A. africanus and A. afarensis have greater occlusal relief
compared to P. robustus, again suggesting dietary differ-
ences between these species (Teaford et al., 2002).
In spite of this improved understanding of the func-
tional drivers for dental morphology and allometry, the
functional relationships between form and diet remain
unclear (Grine et al., 2006). Moreover, ultimately these
approaches imply dental capabilities rather than evi-
dence of diet per se. Indeed, morphology is an ambiguous
dietary predictor and studies have in many cases yielded
conflicting results. It has been suggested, for instance,
that A. africanus was anything from primarily herbivo-
rous, omnivorous, to faunivorous on the basis of tooth
morphology (Robinson, 1954; Jolly, 1970; Wolpoff, 1973;
Szalay, 1975; Kay, 1985). The central problem is that
dental morphology reflects both phylogenetic history and
dietary adaptations. Dental adaptations reflect dietary
drivers over geological or evolutionary timescales and
they are not necessarily concordant with the actual
behavior of any given individual. For instance, the rela-
tively large incisors and bunodont molars of modern
Papio baboons suggest a frugivorous diet (Hylander,
1975; Ungar, 1998; Fleagle, 1999), and yet many Papio
populations consume large quantities of grass (Altmann
and Altmann, 1970; Dunbar, 1983; Strum, 1987) for
which they have no apparent dental capabilities. Fur-
thermore, dietary behavior can be altered over time and
space, and the facility for change is particularly evident
in taxa which are dietary generalists. Pointing to these
problems, Ungar (2004) proposed that dental morphology
may be a better predictor of fallback dietary behavior or
dietary limitations than of more typical trophic behavior.
Wear-related techniques can address some of these limi-
tations. The results of gross wear pattern studies, how-
ever, have been inconclusive, resulting in opposing conclu-
sions about the variability and distinctiveness between
the South African australopiths, for instance (Robinson,
1956; Wallace, 1973, 1975; Wolpoff, 1973). Antemortem
chipping occurred in both taxa (Wallace, 1973, 1975) but
the dietary implications were never satisfactorily re-
solved. Amongst Neanderthals, rounded labial wear of
incisors coupled with frequent damage in the form of chip-
ping, microfractures, and striations is thought to be asso-
ciated with use of the anterior dentition as a tool rather
than with dietary wear (e.g. Klein, 1999).
Dietary microwear patterning, by contrast, has received
a great deal of attention over the last two decades. Oral
processing of food leaves microscopic damage on tooth
enamel surfaces, which is ultimately related to the me-
chanical properties of foods and to the presence of exoge-
nous grit. Thus, unlike dental allometry and morphology
which reveal something about the foods that challenge an
individual’s ancestors, dental microwear reflects its actual
experience. In fact, the immediacy is such that it reflects
food processing over the previous few days to weeks at the
most, as microwear is quickly obliterated (Teaford and
Oyen, 1989a). In short, dental microwear can distinguish
among dietary categories when they correspond to differ-
ences in physical characteristics of foods (El Zataari et al.,
2005), and when the influence of taphonomic factors is
excluded (Teaford, 1988b).
A particular advantage is that microwear patterns may
be able to detect subtle dietary differences amongst
related primate species under certain circumstances (e.g.,
Walker, 1976; Teaford, 1985, 1988a; Teaford et al., 2002).
Most studies have concentrated on patterns of small pits
and scratches resulting from chewing and crushing, and
both extant and extinct primates have been extensively
studied. For instance, primates that make frequent use of
their front teeth tend to have high densities of microwear
striations on their incisors (Ryan, 1981; Ungar and Grine,
1991). Folivores show high incidences of long narrow
scratches on their molar occlusal surfaces, whereas frugi-
vores have relatively more pits. Among frugivores, hard-
object feeders have higher pit incidences than soft-fruit
eaters. Hence, hard fruit- and seed-eaters, such as manga-
beys (Lophocebus albigena and Cebus apella), show dis-
tinct microwear patterns compared to leaf-eaters, like
mountain gorillas (Gorilla gorilla beringei) (Grine and
Kay, 1988; Ungar, 1998). These and other relationships
between microwear and feeding behaviors in living pri-
mates have been used to infer diet in fossil forms.
Observer differences and low repeatability have been
major disadvantages in microwear studies (Teaford and
Oyen, 1989b; Grine et al., 2002), and an area of active
and ongoing development is to quantify patterns of mi-
croscopic pitting and scratching damage in as objective
and repeatable a manner as possible (e.g., Ungar, 2004;
Scott et al., 2005). Micrographs of small sections of tooth
facets are obtained using scanning electron microscopy
of high-precision molds, at high magnification (5003). A
major advance was the combination of scanning confocal
microscopy methods (Boyde and Fortelius, 1991) with
fractal analysis to analyze tooth topography (Ungar
et al., 2003). Current techniques use automated image
processing of scanned micrographs using a software
package (Ungar, 1995; El Zataari et al., 2005) to quantify
American Journal of Physical Anthropology—DOI 10.1002/ajpa
the variables—percentage of pits, scratch breadth, pit
breadth, and pit length. Scale-sensitive fractal analysis
has been recently applied to a hominin study to better
characterize the complexity and anisotropy of three-
dimensional microwear damage (Scott et al., 2005).
Microwear analyses have been frequently applied to
diets of fossil primates, including Miocene Dryopithe-
cines (Ungar, 1996), and applications to early hominin
diets are ongoing. An early application to the South Afri-
can australopiths provided an independent test of Robin-
son’s hypothesis for dietary distinctions between the
South African robust and gracile australopiths (Rob-
inson, 1954, 1956). Grine (1981, 1986), and Grine and
Kay (1988) demonstrated that Paranthropus molars
showed more pitting than those of A. africanus, while
the scratches in the latter are longer, narrower and
more directed (or anisotropic) (Fig. 1a). These authors
deduced that while Paranthropus concentrated on small,
hard objects, A. africanus ate softer foods more fre-
quently, such as fruits and leaves. Microwear features
on A. africanus incisors show higher densities on all sur-
faces compared to Paranthropus (Ungar and Grine,
1991), suggesting that the former processed more foods
with the anterior teeth. The results are consistent with
craniodental measurements which suggest that they
used a great deal of force to process hard foods (e.g.,
Demes and Creel, 1988). Subsequent assessments of
molar microwear using automated confocal 3D image mi-
croscopy and fractal image analysis have been largely
consistent with the earlier studies, although they have
tended to emphasize also inter-individual dietary vari-
ability and overlap between these two species (Fig. 1b)
(Scott et al., 2005).
Most recently, Grine et al. (2006) showed that the
molar microwear on the enamel of A. afarensis was most
similar to that of gorillas and dissimilar to hard object
feeders (Fig. 2), suggesting an unexpected reliance on
terrestrial herbaceous vegetation rather than small hard
objects, as suggested by their dental morphology and
thick enamel. They also noted that Australopithecus
microwear patterns did not change with shifting envi-
ronments over a period of some 400 Ka. An earlier quali-
tative microwear study on the anterior teeth of A. afar-
ensis (Puech et al., 1983) had also suggested that a
mosaic of gorilla-like fine wear striae and baboon-like
pits and microflakes implied use of incisors to strip
gritty plant parts, such as seeds, roots, and rhizomes
(Ryan and Johansen, 1989). Other than this, little micro-
wear data is available for the earlier australopiths, and
none for A. anamensis and Ardipithecus ramidus,
although a report on the microwear of the former species
is forthcoming (P. Ungar, personal communication).
There has also been little emphasis on dental micro-
wear in later hominins. This is partly a result of the
unknown influence of cultural factors in processing of
Fig. 1. Occlusal molar microwear differences and similarities between A. africanus (filled circles) and Paranthropus (open
circles). (a) A bivariate plot of microwear feature width versus feature length (in lm) on M
protoconal facets using scanning elec-
tron microscopy shows that the former has more scratches and the latter more pit features (data from Grine, 1986: Table 9). (b)A
bivariate plot of anisotropy (epLsar
) and complexity [log
(Asfc)], calculated from fractal analysis of occlusal molar topography,
suggests that Paranthropus features show less anisotropy (i.e. less directionally dependent microwear) and greater complexity, but
also that there is some overlap between patterns of the two taxa (redrawn from Scott et al., 2005).
Fig. 2. A comparison of the two most distinguishing micro-
wear features (scratch width and % pitting) for Australopithecus
afarensis (or Praeanthropus afarensis) against similar data for a
range of extant primates shows greatest similarity with Gorilla
gorilla and not with hard object feeders (Cebus apella and Lopho-
cebus albigena) as might have been predicted from morphology
and enamel thickness (data from Grine et al., 2006: Table 7).
American Journal of Physical Anthropology—DOI 10.1002/ajpa
foods, as well as the lack of appropriate comparisons.
Primate comparisons are a central pillar of microwear
(and morphological) applications to hominin diets, but
they are less relevant to more recent populations, and
comparative studies are relatively rare. One exception is
the study of Pe
´rez et al. (2003) which suggested
that the microwear feature density, length, and orienta-
tion on Middle Pleistocene hominin molar buccal sur-
faces were consistent with more abrasive diets than
those of Late Pleistocene individuals. They suggested
that microwear density appeared to increase during cold
intervals and argued that this resulted from hominins
eating more abrasive plant foods, such as roots and
bulbs. A corollary is that Neanderthals ate more nonab-
rasive foods during warmer periods, and the authors
argue that the most likely item was animal meat. This is
a somewhat counter-intuititive outcome when one con-
siders that animal foods were likely to be the most acces-
sible items under glacial conditions. A forthcoming study
on molar microwear of Neanderthals should resolve this
argument (S. El-Zataari, personal communication).
The underlying rationale of these techniques is that
the chemical composition of a mammal’s tissues, includ-
ing bones and teeth, reflects that of its diet, following
the old adage, \you are what you eat". Thus, they can
provide direct chemical means for investigating paleo-
diets. This is the case as long as several crucial condi-
tions are met. One is that various food sources can be
distinguished by means of isotopic or chemical composi-
tion differences, which is not always the case. The path-
ways of these natural abundance tracers into tissues
must also be predictable and understood. Finally, the
original chemical composition, or at least something
close to it, must survive. Thus, the over-arching con-
straints for applying these tracers are related to our
understanding of the pathways of essential elements and
isotopes in ecosystems, and to preservation issues. Stud-
ies of isotope and trace elemental behavior in modern
ecosystems are large-scale, ongoing, undertakings (e.g.,
Burton et al., 1999; Codron et al., 2005; Sponheimer
et al., 2005b). Efforts to address problems of preserva-
tion have included a shift to tooth enamel as sample ma-
terial where it is feasible and the development of reliable
protocols for identifying purity and assessing whether
the dietary signals are real or not.
Chemistry was first used to address questions related
to diet in the more recent archeological past to detect
use of maize (e.g., Vogel and van der Merwe, 1977; van
der Merwe and Vogel, 1978), pastoralism (Ambrose,
1986), marine food use (Tauber, 1981), and trophic levels
and dietary change (Schoeninger, 1979; Sillen, 1981).
Subsequently, a good deal of effort has been devoted to
pushing these tools further back in time. Over the last
decade or so, several studies have emerged that have
provided new insights into dietary behavior of early and
later hominins. The earlier pioneering stable isotope
work concentrated exclusively on bone collagen, with the
first applications to early hominin diets, based on tooth
enamel, appearing later (Lee-Thorp, 1989; Lee-Thorp
et al., 1994). Stable isotopic studies of the diets of Late
Pleistocene hominins—Neanderthals and modern
humans—have so far relied on the conventional bone col-
lagen-based methods. Similarly, trace element studies
focused for some time on bone, and only recently have
applications explored tooth enamel as sample material.
The discussion below briefly outlines the principles of
stable light isotope and trace element pathways in eco-
systems and follows first the work on Neanderthals
using bone collagen, and next the isotope and trace ele-
ment work on earlier hominins based on analyses of
enamel and bone mineral. The emphasis on European
Neanderthals and South African australopiths is a
reflection of the limited degree to which stable isotopes
and trace elements have been used to investigate the
diets of Plio–Pleistocene hominins.
Stable light isotopes in ecosystems
A simplified, diagrammatic illustration of the stable
isotope pathways described in the following paragraphs
is shown in Figure 3.
During photosynthesis plants take in CO
and convert
it to sugars. This process discriminates strongly against
but to different degrees depending on the pathway
(Smith and Epstein, 1971) and on environmental condi-
tions to a smaller extent. Plants following the C
(all trees, shrubs and herbs, and temperate or shade-
adapted grasses) are strongly depleted in
C relative to
atmospheric CO
, and consequently have distinctly lower
values compared to C
plants (mainly tropical
grasses). Environmental influences acting on C
include the \canopy effect"in dense forests (leading to fur-
ther depletion in
C) (Vogel, 1978; van der Merwe and
Medina, 1989) and aridity/temperature effects (leading to
By convention, stable isotope ratios are expressed as dvalues rel-
ative to an international standard in parts per thousand (per mil),
as follows in an example for carbon isotopes: d
–1)31,000 where R¼
C and the international
standard is Vienna Peedee Belemnite (VPDB).
Standards for nitrogen (
N) and oxygen (
O) isotopes
are atmospheric nitrogen (AIR), and VPBD or Standard Mean
Ocean Water (SMOW), respectively.
Fig. 3. Schematic representation showing the patterning of
stable carbon (d
C) and nitrogen (d
N) isotopes in typical food-
webs. Global mean d
C values are given for trophic steps in
the carbon cycle (middle panel), while mean differences are
given for steps in the nitrogen cycle (right panel). This is
because soil d
N values depend on the balance of nitrogen fixa-
tion and denitrification, which is affected by a host of environ-
mental factors. Two tissues (collagen and apatite) are shown for
herbivores and carnivores.
American Journal of Physical Anthropology—DOI 10.1002/ajpa
enrichment in
C under more arid and/or warm condi-
tions and vice versa) (for a review see Tieszen, 1991). A
third photosynthetic pathway, the Crassulacean Acid Me-
tabolism (CAM) pathway, effectively utilizes both path-
ways with resulting d
C values that vary extensively
depending on whether they are \obligate"CAM or not and
upon environmental conditions (Winter and Smith, 1996).
CAM plants are primarily succulents like euphorbias that
are rare outside of desert environments, and are moreover
rarely used by animals (but see Codron et al., 2006 for use
by baboons). They are not considered as important compo-
nents of the environments inhabited by Plio–Pleistocene
hominins (Reed, 1997; Peters and Vogel, 2005).
Nitrogen enters the terrestrial foodweb via N
bacteria in soils or plants to form nitrates or ammonium
ions which are utilized by plants. The net effect of bio-
logical nitrogen fixing and subsequent denitrification
during decay of organic matter is slight enrichment in
N in plants and soils compared to atmospheric N
the balance is affected by environmental conditions such
as aridity (Heaton, 1987; Sealy et al., 1987; Handley and
Raven, 1992; Amundson et al., 2003), although other
effects such as leaching (high precipitation) and anoxia
can also contribute.
Isotopic variability in plants is reflected in the bones
and teeth of animals that consume them. Here under-
standing of the bio- and physico-chemical routes from food
to tissue fixation is required, since diet-tissue fractiona-
tion varies according to the tissue and its chemistry. Iso-
tope ratios of carbon (
C) and nitrogen (
N) can
be studied in collagen, which is the main organic compo-
nent of bone and dentine. The mineral phase of bone and
enamel, crystalline calcium phosphate structures known
as biological apatites, yield
C and
O ratios
from carbonate ions or
O alone from phosphate ions.
Both the structural and the isotope chemistry between
diet and the organic or inorganic (mineral) compartments
of skeletal tissues differ. Further, the timespan of dietary
behavior reflected differs depending on whether bone or
tooth tissues are analyzed; bone isotope values tend to
reflect long-term averages (at least 10 years or more)
whereas tooth isotope values reflect dietary behavior at
the time of deposition since both enamel and dentine are
incremental tissues. Where skeletal tissues are preserved
at all, enamel in particular survives remarkably well for
millions of years, apparently with only subtle alteration.
Collagen has a much shorter \shelf-life"since it denatures
and dissolves away far more quickly than the mineral,
where the latter is preserved. On the other hand, where it
does survive, it is relatively straightforward to obtain
demonstrably intact collagen for analysis. A number of
safeguards are routinely employed to demonstrate the
quality of the collagen (Ambrose, 1990). Hence, the sample
tissue chosen is important because this choice (often
imposed by circumstances) directly affects the isotope
tools and the type of information available, the age limits
for the study, and the measures that must be taken to
guard against diagenesis.
Stable isotopes in bone collagen
The difference (D) between diet and collagen d
about +5%, but controlled feeding studies have shown
that the relationship is largely between dietary protein
and collagen because dietary amino acids are preferen-
tially utilized for collagen tissue construction, while car-
bon from dietary carbohydrate and lipids makes a lesser
contribution (Ambrose and Norr, 1993; Tieszen and
Fagre, 1993). A stepwise trophic shift of +3–5%in d
from plants to herbivores, and from herbivores to carni-
vores has been widely documented in marine and terres-
trial foodwebs (Minigawa and Wada, 1984; Schoeninger
and DeNiro, 1984; Sealy et al., 1987). A significant out-
come of the routing of dietary protein to tissue proteins
is that d
C in bone collagen (and d
N by default) is \bi-
ased"towards the high protein component of an individ-
ual’s diet. Consequently, animal foods will be overrepre-
sented in bone collagen at the expense of low-protein
(vegetable) foods, and this bias must be considered when
interpreting collagen stable isotope data.
Progress in extracting good quality collagen from older
material has demonstrated that under the right condi-
tions, bone collagen can survive for up to 200,000 years
(Ambrose, 1998; Jones et al., 2001). This has made it
possible analyze the bone collagen of Late Pleistocene
hominins in certain cases. At these time depths, strict
quality controls that demonstrate collagen preservation
are essential because degradation is known to alter colla-
gen stable isotope ratios significantly (Ambrose, 1990).
Neanderthal diets. Bocherens et al. (1991) performed
the first stable isotope analysis of a single Neanderthal
individual and associated fauna from 40,000-year-old
bones at the site of Marillac in France. Although the
quality control methods relied on amino acid profiles
that might not be considered adequate today, subsequent
analyses from this site (Fizet et al., 1995) have shown
the original observations to be robust. The study paved
the way for subsequent analyses of Neanderthals from
Marillac (Fizet et al., 1995), Scladina Cave, Awirs Cave,
and Betche-al-Roche Cave in Belgium (Bocherens et al.,
1997, 2001), and Vindija Cave in Croatia (Richards
et al., 2000).
All native European plants are C
, and consequently
have similar d
C values with the exception of plants in
densely wooded environments that are more depleted in
C due to the canopy effect (Vogel, 1978; van der Merwe
and Medina, 1989). Thus, d
C composition of bone colla-
gen reveals little about the diets of Neanderthals, except
that they likely utilized few food resources from closed,
densely forested environments (Bocherens et al., 1999;
Richards et al., 2000). The d
N composition of Neander-
thal bone collagen is more revealing. Although nitrogen
isotope distributions in foodwebs are often complicated
due to heterogeneity in plant d
N and the disparate
physiological adaptations and requirements of different
animals (Ambrose, 1991; Sponheimer et al., 2003), the
general pattern of stepwise shifts in d
N of about +3–
4%is robust (Fig. 3). Thus, d
N analysis of Neanderthal
bone collagen can address the question of trophic level
and hence of meat consumption. This is particularly rele-
vant as the degree of carnivory and manner of carcass
acquisition (hunting or scavenging) amongst Neander-
thals has been the subject of debate (e.g., Binford, 1981;
Stiner, 1994; Marean and Assefa, 1999; Speth and Tcher-
nov, 2001).
All published isotopic studies have shown that Nean-
derthals have much higher d
N than that of contempo-
raneous (or near-contemporary) herbivores such as horse
(Equus caballus), reindeer (Rangifer tarandus), and bi-
son (Bison priscus) and similar to that of carnivorous
wolves (Canis lupus), hyenas (Crocuta spelaea), and
lions (Panthera spelaea) (Bocherens et al., 1991, 1997,
2001, 2005; Fizet et al., 1; Richards et al., 2000). Overall,
American Journal of Physical Anthropology—DOI 10.1002/ajpa
Neanderthal d
N is not only significantly higher than
herbivore d
N, but also slightly higher than carnivores
(Fig. 4) (Sponheimer and Lee-Thorp, 2006b). Even given
the bias towards animal foods in bone collagen, these
data suggest that Neanderthals were significantly car-
nivorous, and that little of their dietary protein came
from plant foods (Richards et al., 2000, 2001; Bocherens
et al., 2005). These authors have argued that enrichment
N compared to (other) carnivores could be taken as
an indication of dependence on herbivores with relatively
high d
N, such as mammoths (Mammuthus primige-
nius), or even the consumption of omnivorous bears
(Ursus spp.)(Richards et al., 2000; Bocherens et al.,
2001). Bocherens et al. (2005) used a mixing/resource
partitioning model developed in modern ecosystem stud-
ies (Phillips, 2001; Phillips and Gregg, 2003) to calculate
on the basis of statistical probability that a major compo-
nent of Neanderthal diet was mammoth. However, a
number of problems underlie the use of this statistical
model, not the least of which is that values for all
resources must be known.
It has not yet been possible to compare directly the
stable isotope composition of Neanderthals and Upper
Paleolithic Homo sapiens (UPHs) from similar periods
and places. However Richards et al. (2001) were able to
compare data from nine near-contemporaries from the
mid-Upper Paleolithic (*28–20 Ka) at Brno-Francouz-
ska and Dolni Vestonice (Czech Republic), Kostenki,
Mal’ta, and Sunghir (Russia), and Paviland (Great Brit-
ain) with data from the five Neanderthals that had been
published at the time. They observed that the modern
humans were even more elevated in d
N, suggesting, if
one follows the same arguments applied to Neander-
thals, that these modern humans were also highly de-
pendent on animal foods. In this case, however, they sug-
gested contributions from freshwater aquatic resources
such as fish and waterfowl, which can be more enriched
N than terrestrial resources (Dufour et al., 1999)
and that this implied diversification of the resource base
(Richards et al., 2001). This suggestion was unexpected,
as there is little archeological evidence for exploitation of
such foods at this time. With the subsequent addition of
several new Neanderthal and mid-Upper Paleolithic
human analyses (Bocherens et al., 2001; Pettitt et al.,
2003); however, there is no longer any statistically sig-
nificant difference in the d
N of Upper Paleolithic
humans and Neanderthals (Sponheimer and Lee-Thorp,
2006b) (Fig. 4).
Interpretation of these data is not straightforward and
there remain a number of unanswered questions. For
instance, why are both hominins so enriched in
N com-
pared to associated carnivores? The consumption of her-
bivores with unusually high d
N such as mammoths, or
aquatic resources, offers one possible, but nevertheless
rather unsatisfactory explanation. There may be an al-
ternative physiological explanation for their extremely
high d
N values. Controlled feeding studies have shown
that when herbivores are fed diets with protein contents
much greater than their nutritional requirements, their
diet-tissue spacing (D, denoting the isotopic difference
between dietary and tissue values) exceeds the average
of +3–4%(Sponheimer et al., 2003). Hence, if the con-
sumption of animal-rich high-protein diets in the pre-
vailing glacial environment led to Neanderthals’ exceed-
ing their protein requirements, their Dmight well
exceed +3–4%and increase their d
N compared to other
taxa. The anomalously high d
N of mammoths and low
N of cave bears (Bocherens et al., 1997; Ambrose,
1998) also hints at the importance of unknown physio-
logical adaptations in determining an organism’s nitro-
gen isotope composition. These studies of glacial-age
Neanderthals and modern humans in Europe illustrate
the complexity in interpreting d
N data in a paleo-eco-
system for which we have incomplete information and no
modern analogue.
It is worth noting that even if the Neanderthals did
have an unusually increased diet-tissue spacing due to a
high-protein intake, it might erase their distinctiveness
from other carnivores but would certainly not make
them look herbivorous. The d
N data leave little doubt
that Neanderthals and mid-upper Pleistocene modern
humans consumed large quantities of animal foods.
Stable isotopes in enamel apatite
Bone collagen is rarely preserved beyond the Late
Pleistocene (Jones et al., 2001), so this avenue is not an
option for analysis of older hominin material. However,
the carbon isotopes in the mineral component can also
be used as dietary proxies (Sullivan and Krueger, 1981;
Lee-Thorp and van der Merwe, 1987). Although bone
mineral clearly persists beyond bone collagen, it is inevi-
tably altered postmortem, often (but not always) result-
ing in the loss of the biogenic dietary signal (Lee-Thorp,
2000; Lee-Thorp and Sponheimer, 2003). This is due to
bone’s high organic content, porosity, and small crystal
size (LeGeros, 1991; Elliot, 1994), which make it suscep-
tible to dissolution/reprecipitation phenomena that facili-
tate the incorporation of exogenous carbonate ions. Thus
paleodietary studies based on bioapatite were forestalled
until it could be shown that dental enamel from ancient
fauna with well-understood diets reliably retained bio-
genic isotope compositions. This was accomplished by
demonstrating that known fossil grazers had d
C values
indicative of C
-grass diets, while known fossil browsers
Fig. 4. Neanderthal bone collagen d
N data from the sites
of Marilac, Scladina, Vindija, Engis, and Spy shown in relation
to herbivores and carnivores from the same sites (combined),
and compared against data for mid-Upper Paleolithic humans
(labeled H. sapiens for brevity). Mean values are shown as
boxes along with standard deviations and the number of indi-
viduals in each case. Neanderthal data are summarized from
Bocherens et al. (1991, 1999, 2001), Fizet et al. (1995), and
Richards et al., (2000), while the Upper Paleolithic human data
is from Richards et al. (2001) and Pettitt et al. (2003).
American Journal of Physical Anthropology—DOI 10.1002/ajpa
had d
C values indicative of browsing diets (Lee-Thorp
and van der Merwe, 1987). Numerous empirical and the-
oretical studies have substantiated this finding (e.g.,
Cerling et al., 1997; Sponheimer and Lee-Thorp, 1999b;
Zazzo et al., 2000), which is hardly surprising given that
enamel is denser, has a very low organic content and is
more crystalline (LeGeros, 1991; Elliott, 1994) which
renders it effectively more inert and \pre-fossilized."
Therefore, only tooth enamel has been used for stable
isotope analysis of hominin and non-hominin specimens
that are millions of years old. Although at first relatively
large samples (*200 mg) were needed, rendering this a
destructive method of analysis, subsequent advances in
mass spectrometry have reduced the required sample to
a few milligrams (Lee-Thorp et al., 1997; Sponheimer,
1999). As a result, it has become possible to remove
small samples with minimal, barely observable damage,
and consequently larger numbers of analyses became
possible. It is worth noting that different pretreatment
protocols designed to eliminate contamination (Koch
et al., 1997; Lee-Thorp et al., 1997; Sponheimer, 1999)
can lead to small but significant differences in a sample’s
stable isotope composition (especially for oxygen), and
therefore one must compare stable isotope values for
teeth analyzed following different protocols with caution.
Apatite carbonate forms from blood bicarbonate, and
isotopic fractionation is tightly controlled by physico-
chemical processes during apatite formation. The rela-
tionship between dietary, breath CO
(which is equili-
brated with blood bicarbonate), and enamel apatite d
has been well-studied (Passey et al., 2005). Overall, the
diet to enamel shift averages about 13%for most large
mammals (Fig. 3) (Lee-Thorp et al., 1989; Passey et al.,
2005). Nevertheless, some variability has been docu-
mented, for instance measurements on small rodents on
controlled diets indicate a diet-apatite spacing of just
less than 10%(Ambrose and Norr, 1993; Tieszen and
Fagre, 1993), while studies of some large ruminants
indicate values of up to +14%(Cerling and Harris,
1999). This variation likely reflects mass balance differ-
ences related to metabolism and/or dietary physiology.
Unlike collagen, apatite reflects the d
C of the bulk
diet, and not just the protein component (Krueger and
Sullivan, 1984; Lee-Thorp et al., 1989; Ambrose and
Norr, 1993; Tieszen and Fagre, 1993). Thus, apatite and
bone collagen d
C provide different perspectives on an
individual’s diet, and indeed analysis of both components
would provide the most complete picture. Most impor-
tant, for our purposes, is that enamel apatite provides a
good average dietary signal that equally reflects the con-
sumption of vegetable and animal foods.
Australopith and early Homo diets. Isotopic dietary
studies of early hominins are founded primarily upon
the distinct d
C composition of C
and C
plants, which
in African savanna environments reflect carbon sources
from trees, bushes, shrubs, and forbs for the former, and
tropical grasses and some sedges for the latter. In the
early 1990s, it was widely believed that A. africanus had
a diet that consisted primarily of fleshy fruits and
leaves, much like the modern chimpanzee, while
P. robustus consumed more small, hard foods such as
nuts (Grine, 1981; Grine and Kay, 1988; Ungar and
Grine, 1991). As these are all C
foods, it could then be
predicted that A. africanus and P. robustus should have
C values indistinguishable from those of C
and frugivores.
This turned out not to be the case. A total of 40 cer-
tain hominin specimens from the sites Makapansgat,
Sterkfontein, Kromdraai, and Swartkrans have now
been analyzed. The data demonstrate unequivocally that
the d
C of both australopiths is very distinct from that
of C
-consuming coevals (P<0.0001), but that A. africa-
nus and P. robustus cannot be distinguished from each
other (Sponheimer and Lee-Thorp, 1999a; Lee-Thorp
et al., 1994, 2000; van der Merwe et al., 2003; Spon-
heimer et al., 2005b) (Fig. 5). The distinction between
the hominins and other fauna cannot be ascribed to dia-
genesis, as there is no evidence that browser or grazer
C has been altered, and diagenesis should affect all
fauna alike. If we take the mean d
and C
suming herbivores as indicative of pure C
and C
respectively, it would indicate that both Australopithecus
and Paranthropus obtained about 30% or more of their
carbon from C
sources. Thus, both taxa were eating
considerable quantities of C
resources, and these
resources must have consisted of grasses, sedges, or ani-
mals that ate these plants.
Fig. 5. Enamel d
C data for Australopithecus africanus,
Paranthropus robustus, and Homo specimens from the sites of
Makapansgat, Sterkfontein, and Swartkrans compared with C
plant consumers (browsers) and C
plant consumers (grazers);
all data are shown as means (boxes), standard deviations, and
numbers (n) of individuals except for the three Swartkrans
Homo values which are shown as stars. Data are from Lee-
Thorp et al. (1994, 2000) for Swartkrans, Sponheimer, and Lee-
Thorp (1999a) for Makapansgat, van der Merwe et al. (2003) for
Sterkfontein, and Sponheimer et al. (2005a) for the remaining
Sterkfontein data.
American Journal of Physical Anthropology—DOI 10.1002/ajpa
This result was unexpected, since extant apes consume
minimal C
resources if at all (McGrew et al., 1981, 1982;
Goodall, 1986). Even in more open environments where
foods are readily available, d
C analyses of chimpan-
zees do not indicate any C
consumption (Schoeninger
et al., 1999; Carter, 2001; Sponheimer et al., 2006). Thus,
the d
C data suggests a fundamental niche difference
between the australopiths and extant apes. Furthermore,
this association with C
resources persists through dia-
chronic environmental trends from relatively closed habi-
tats in the Pliocene at the sites of Makapansgat (*3 Ma)
and Sterkfontein Member 4 (*2.5 Ma) through to the
later, open environments of Swartkrans Member 1 (*1.5–
1.8 Ma) (Fig. 5). The hominin d
C data are also more vari-
able than virtually all modern and fossil taxa that have
been analyzed in South Africa (Lee-Thorp et al., 1994,
2000; Sponheimer and Lee-Thorp, 1999a, 2001, 2003;
Codron, 2003; van der Merwe et al., 2003). This suggests
that australopiths were opportunistic primates with wide
habitat tolerances, an observation which is consistent
with Wood and Strait’s (2004) suggestion that these early
hominins were eurytopic (dietary generalists) rather than
ecological specialists.
How do these data compare with early Homo? Based
on the prediction that if Homo consumed more animal
foods (as is widely held), their d
C should be more posi-
tive compared to P. robustus from the same Swartkrans
Member 1 deposits, data from three early Homo speci-
mens were compared with the australopith data (Lee-
Thorp et al., 2000). Again this turned out not to be the
case; Homo d
C was very similar to that of the australo-
piths (Fig. 5), and the results must be interpreted in the
same way. Roughly 25% of their dietary carbon came
from C
sources that included C
plants, C
animal prod-
ucts, or some combination of these. However, only three
Homo specimens from one site have been analyzed and
published so far, and thus comparisons with the more
numerous australopith data must be viewed with cau-
tion. Unpublished d
C data from East Africa show a
strong difference between Paranthropus and Homo;in
this case the former is strongly enriched in
C, while
values for the latter resemble those for the Swartkrans
individuals (van der Merwe, personal communciation).
This leaves us with the question about what exactly
these C
resources were? The answer to this question is
significant, because the outcome has a variety of physio-
logical, social, and behavioral implications. For instance,
if australopiths had a grass-based (graminivorous) diet
similar to the modern gelada baboon (Theropithecus
gelada), it would suggest that their diets were less nutri-
ent rich than those of modern apes, placing limitations on
brain expansion and sociality (Aiello and Wheeler, 1995;
Milton, 1999). The converse that australopiths ate diets
rich in animal foods would indicate a leap in dietary qual-
ity over modern apes (Milton, 1999). At the time Lee-
Thorp et al. (1994, 2000) argued that savanna grasses are
unlikely staple food sources for hominins and that con-
sumption of C
-consuming insects and vertebrates was a
more plausible explanation. This argument was based
partly on the lack of dental and digestive \equipment"to
deal with grasses per se, and partly on the limited sea-
sonal availability and difficulties of harvesting grass
seeds, which are denser, if tiny, food packages.
This list of possibilities has been reconsidered (e.g.,
Peters and Vogel, 2005; Sponheimer and Lee-Thorp,
2006b). Recently edible sedges have received attention as
potential C
foods for hominins (Conklin-Brittain et al.,
2002), argued to have been part of a strategy focused on
wetlands. Sedges are common in these habitats and in
some cases can represent reasonably high quality foods,
for which there was likely little competition (Conklin-
Brittain et al., 2002). However, the distribution of C
sedges has different climate or environmental controls
compared to C
grasses (Stock et al., 2004), and it cannot
be assumed that most sedges utilize the C
pathway even
in African savannas. Only 35% of sedges in South Africa
overall are C
(Stock et al., 2004), and a study of sedges
in riverine habitats similar to those inhabited by austral-
opiths found <30% abundance (Sponheimer et al., 2005a),
with very few being edible. Unless the distribution of
sedges was markedly different during the Pliocene, and/
or the australopiths sought out large quantities of C
sedges, sedge consumption could not produce the
observed 35–40% C
contribution to hominin diets. Thus,
a sedge specialization is unlikely in South Africa,
although that does not rule out some contribution. In con-
trast, some habitats in East Africa where C
sedges, such
as the Olduvai Gorge wetlands, are far more common
(Hesla et al., 1982; DeoCampo et al., 2002) likely provided
richer edible C
sedge opportunities. The very positive
C values obtained for P. boisei would be consistent
with heavy utilization of C
The other possibility considered in Lee-Thorp et al.
(2000)—that of animal foods—has also been more closely
examined. It was envisioned at the outset as a broad cat-
egory comprising insects, lizards, rodents, hyraxes, eggs,
and small antelopes (as suggested originally by Dart
(1926) for the Taung hominin), rather than necessarily
flesh from large vertebrate mammals. It was assumed
that a majority of such animal foods would be enriched
C, as the bulk of the biomass in savanna environ-
ment derives from C
sources. A recent analysis of pred-
ators from all size classes in the Kruger National Park,
South Africa, has shown this to indeed be the case
(Codron, Sponheimer, Lee-Thorp, unpubl. data). These
foods can be acquired by gathering. Baboons are known
to eat grass-eating grasshoppers (Acrididae) (Hamilton,
1987), and grass-eating termites represent another plau-
sible source, particularly since bone tool wear studies
have suggested that they were used for excavating ter-
mite mounds (Backwell and d’Errico, 2001). Savanna ter-
mites are widely distributed and range from C
to pure
consumers, but most consume significant proportions
of C
plants, and termites in the Kruger National Park
ate 35% C
vegetation on average (Sponheimer et al.,
2005a). Again, it’s unlikely that termite consumption
alone was the source of the strong C
signal in australo-
piths because it would require a diet of nearly 100% ter-
mites, or at least, a very large amount of grass-specialist
termites. Thus, termite consumption plausibly contrib-
uted to the d
C values of australopiths, but other C
resources were almost certainly consumed as well.
Clearly, carbon isotope ratios alone cannot address the
question of the source of C
carbon in australopith diets,
or indeed that of the slightly larger C
component. One
other possible source of information may come from d
in enamel apatite. Oxygen isotopes are not usually con-
sidered as dietary but rather as climate indicators, since
the primary input in ecosystems is from environmental
drinking water, which is subject to a range of strong cli-
mate influences (e.g., vapour source, storm paths, tem-
perature, and altitude) (Dansgaard, 1964).
Recent studies have shown that d
O from apatite car-
bonate or phosphate can also be influenced by dietary
American Journal of Physical Anthropology—DOI 10.1002/ajpa
ecology (Bocherens et al., 1996; Kohn, 1996; Kohn et al.,
1996; Sponheimer and Lee-Thorp, 1999b). In herbivores
this occurs largely because of the input of oxygen from
plant water and carbohydrates in leaves that are
enriched in
O as a result of evapo-transpiration isotope
effects. Consequently, animals such as giraffes that rely
less on free drinking water and feed in the upper canopy
(Cerling et al., 1997) have higher d
O values than obli-
gate drinkers in the same environment. Distribution of
O in bioapatites, unexpectedly, also reflects trophic
behavior. In southern Africa, the faunivores, Otocyon
megalotis,Crocuta crocuta, and Orycteropus afer, are sig-
nificantly depleted in
O compared to herbivores in two
modern ecosystems (Lee-Thorp and Sponheimer, 2005).
Low values for faunivores are likely linked to their high
lipid, high protein diets (Sponheimer and Lee-Thorp,
1999b). Suids and many primates also have relatively
lower d
O (Sponheimer and Lee-Thorp, 1999b; Carter,
Australopith d
O data from Makapansgat and
Swartkrans overlap with those of carnivores in the same
strata (Lee-Thorp, 2002; Lee-Thorp et al., 2003) (Fig. 6).
Although at first sight, this could be seen as reinforce-
ment of the animal-food hypothesis, it is not that simple.
The causes of the relatively low d
O values for many
primates and suids are obscure: they may be linked to
frugivory, the use of underground storage organs, or
water dependence, but given our present limited under-
standing of d
O patterning in foodwebs, this is merely
speculative. Clearly there is overlap in the inputs from
different sources and, fuller interpretation of these data
awaits more detailed ecosystem studies.
Despite these uncertainties, we should not lose sight
of a significant finding from these isotope data, namely
that australopiths increased their dietary breadth com-
pared to extant apes by consuming novel C
whatever these resources were. Thus, a fundamental dif-
ference between australopiths and extant apes might be
that when confronted with increasingly open areas, apes
continued to use the foods that are most abundant in for-
est environments (McGrew et al., 1982), whereas aus-
tralopiths began to exploit the novel C
Trace elements
The distribution of trace elements in foodwebs forms
the basis for another important chemical means for trac-
ing diets in the past. Mammals discriminate against the
alkaline earth metals, strontium (Sr) and barium (Ba),
with respect to calcium (Ca) in the digestive tract and
kidneys in a process known as biopurification of Ca
(Spencer et al., 1973; Elias et al., 1982). As a result, her-
bivore tissues have lower Sr/Ca
and Ba/Ca ratios than
the plants that they eat, and carnivores in turn have
lower Ba/Ca and Sr/Ca than the herbivores they con-
sume (Elias et al., 1982; Sealy and Sillen, 1988; Burton
et al., 1999). Since Sr and Ba are found in bones and
teeth, where they substitute for calcium in the calcium
phosphate apatite structure, they can in principle be
used to investigate trophic behavior of fossil fauna (Fig.
7). Other trace elements have been applied from time to
time, for instance zinc (Zn), but applications are severely
limited since so little is known about their distribution
in foodwebs and fixation in bone.
There are two major constraints in application of Sr
and Ba to paleodietary reconstruction. One is diagenesis.
Although early researchers were largely unaware of the
extent of the problem (e.g., Toots and Voorhies, 1965;
Fig. 6. Bivariate plot of d
C versus d
O for A. africanus
and selected fauna from Makapansgat Member 3, shown as
means (boxes) and standard deviations. The hominins (n¼4),
although variable in d
C, cluster with Hyena makapania in
both d
O and d
Since Ca is a major element in skeletal tissues, with very high
concentrations, the Sr and Ba composition is usually expressed as a
ratio compared to Ca, ie. as Sr/Ca and Ba/Ca or as log Sr/Ca and log
Fig. 7. The results of the classic trace element discrimina-
tion study of a terrestrial grazing ecosystem in North America.
Sr/Ca and Ba/Ca ratios are plotted on a logarithmic scale (y-
axis), and \soil"is used as shorthand for \soil moisture". This
study was designed to calculate biopurification factors for cal-
cium with respect to strontium and barium uptake. The plant:
vole:pine marten curves nicely illustrate systematic reduction in
Sr/Ca and Ba/Ca in this foodweb, with stronger discrimination
against Ba. This study was subsequently taken as representing
trophic relations everywhere. Data are redrawn from Elias
et al. (1982).
American Journal of Physical Anthropology—DOI 10.1002/ajpa
Wyckhoff and Doberenz, 1968; Brown, 1974; Schoe-
ninger, 1979), it was subsequently widely recognized
(e.g., Sillen, 1981, 1989). Traditionally, archeological and
paleontological trace element studies have been carried
out on bone. This is because infants lack the adult
capacity to discriminate against strontium and barium
(Lough et al., 1963; Sillen and Kavanagh, 1981), and
many teeth are formed in early development. A major
drawback of bone, however, is its susceptibility to post-
mortem chemical alteration (Sillen, 1989; Tuross et al.,
1989) that can quickly obliterate the biological Sr/Ca
To address the problem, Sillen (1981, 1992) developed
a\solubility profiling"technique based on the premise
that diagenetic apatite has differing solubility to biogenic
fossil apatite. In this technique, highly soluble and
poorly soluble diagenetic apatites are, in effect, stripped
away from the biogenic material and the solutes, not the
solid materials, are measured (Sillen, 1981, 1992). While
ingenious, this method is technically challenging and la-
borious, greatly limiting wider application, but more
importantly, several studies have shown that even when
it is applied, diagenetic strontium often cannot be eradi-
cated from bone and dentine (Budd et al., 2000; Hoppe
et al., 2003; Lee-Thorp and Sponheimer, 2003; Trickett
et al., 2003). This has led to recent attempts to investi-
gate paleoecology using elemental ratios in modern
enamel (Sponheimer et al., 2005a; Sponheimer and Lee-
Thorp, 2006a), which as a denser, far more crystalline
and ordered apatitic tissue (LeGeros, 1991; Elliott,
1994), is much more resistant to postmortem elemental
alteration than bone (Budd et al., 2000; Hoppe et al.,
2003; Lee-Thorp and Sponheimer, 2003; Sponheimer and
Lee-Thorp, 2006a). The problem of poor biopurification
in infants can be easily avoided by analyzing late devel-
oping teeth.
Perhaps a more immediate constraint in current trace
element studies is the requirement for understanding
their very complex pathways in foodwebs, which can
result in significant variation between habitats and
within a trophic level. The importance of local geology in
controlling absolute availability of alkaline earth ele-
ments has been known from the early stages of develop-
ment of the trace element method (Toots and Voorhies,
1965), if sometimes ignored. However, inherent variabili-
ty within trophic levels in ecosystems and indeed within
sympatric species has been largely unappreciated. For
many years trace element paleodietary studies were
based almost entirely on an \archetypal"grazing terres-
trial foodweb study in North America (Elias et al., 1982)
(Fig. 7), and only gradually has the necessity to study
many modern foodwebs, and in more detail, been appre-
ciated. For instance, sympatric browsing and grazing
herbivores can be readily distinguished by their Sr/Ca
and Ba/Ca ratios as can be carnivores and insectivores
(Sillen, 1988; Sponheimer et al., 2005a; Sponheimer and
Lee-Thorp, 2006a), yet the mechanisms that lead to such
differences are at present poorly understood. The key
lies in plant variability as plants, and plant parts (ie.
underground, stem, fruit, leaves) differ considerably in
their strontium distributions due to capillary action in
their vascular systems (Runia, 1987). However, stron-
tium and barium distributions in plants are still poorly
studied. Probably for this reason, coefficients of variation
(CV) for Sr/Ca for a single mammalian species in a sin-
gle location are typically 30–40% (Sillen, 1988; Price
et al., 1992; Sponheimer et al., 2005a). Hence, the natu-
ral variation in mammalian elemental compositions is
such that large numbers of samples are required to
adequately characterize dietary ecology. These problems
are compounded by non-linear relationships between die-
tary and tissue Sr/Ca (Burton and Wright, 1995).
Early hominin diets. The first significant attempt to
investigate the diets of Plio–Pleistocene hominins was
made by Sillen (1992). He found that the bones of Para-
nthropus at Swartkrans had similar Sr/Ca to carnivores
and lower Sr/Ca than primarily herbivorous taxa like
Papio and Procavia (Fig. 8a.) This, in conjunction with
observations from dental microwear (Grine and Kay,
1988) and stable isotopes (Lee-Thorp, 1989) led him to
conclude that Paranthropus was unlikely to be \purely
herbivorous". Subsequently, two bone specimens of early
Homo from Swartkrans were observed to have slightly
higher Sr/Ca than P. robustus (Sillen et al., 1995), a
result that was quite unexpected given the generally
accepted belief that early Homo was the first hominin to
include significant amounts of animal food in its diet
(e.g., Aiello and Wheeler, 1995). Therefore Sillen et al.
(1995) argued that early Homo consumed significant
quantities of strontium-rich underground storage organs,
Fig. 8. Trace element data for the South African hominins
from two studies. (a) shows Sr/Ca data for Paranthropus, Homo,
and a suite of fauna from Swartkrans based on bone analysis,
shown as means (Sr/Ca 31,000) and standard deviations (data
from Sillen, 1992). (b) shows enamel data for A. africanus and
Paranthropus and associated fauna from Makapansgat, Sterk-
fontein, and Swartkans shown as means and standard devia-
tions (data from Sponheimer et al., 2005b; Sponheimer and Lee-
Thorp, 2006a). The data from the three sites were combined
because of the similarity in geology and Sr/Ca ratios for modern
fauna from the Sterkfontein and Makapans Valleys.
American Journal of Physical Anthropology—DOI 10.1002/ajpa
an argument that has since received support from other
quarters (O’Connell et al., 1999; Conklin-Brittain et al.,
2002). As intimated, however, the results from just two
specimens can have no statistical significance given the
inherent variability of the tool.
Concerned about diagenesis, we investigated Sr/Ca and
Ba/Ca ratios in enamel from late forming teeth of modern
and fossil fauna, including hominins from Makapansgat,
Sterkfontein, and Swartkrans (Sponheimer et al., 2005a).
Since these sites share a similar geology, the data from all
three could be combined. The results show that A. africa-
nus had significantly higher Sr/Ca than Paranthropus
and both taxa have higher Sr/Ca than contemporaneous
browsing herbivores and papionins (Fig. 8b). Thus, there
is no reason to believe that Paranthropus consumed
greater amounts of animal foods than contemporaneous
baboons as suggested by (Sillen, 1992). In addition, even if
the Sr/Ca of one or both of these australopith species was
low, it would still provide only limited support for omni-
vory, given our nascent understanding of Sr/Ca through-
out African foodwebs. For instance, diets rich in leaves (as
observed in browsers) also lead to low Sr/Ca, and while a
diet rich in leaves is unlikely for the australopiths given
their extremely low shearing crests (Kay, 1985; Ungar,
2004) and low d
O values (see above), we cannot rule out
the consumption of other low Sr/Ca foods. At present we
know very little about the Sr/Ca of different kinds of Afri-
can fruits, although we would expect many fruits to have
low Sr/Ca as has been shown to be the case with tomatoes
(Haghiri, 1964). Consequently, our limited knowledge of
Sr/Ca in plant foods and amongst African savanna mam-
mals, makes detailed dietary interpretation of this Sr/Ca
data difficult.
We have also applied multiple element analysis of
tooth enamel to investigate the diet of A. africanus
(Sponheimer and Lee-Thorp, 2006a). In combination, Ba/Ca
and Sr/Ba ratios suggest that this taxon was signifi-
cantly distinct compared to contemporaneous grazers,
browsers, and carnivores, which were in turn different
from each other (Fig. 9). The Australopithecus fossils are
characterized by high Sr/Ba that is quite distinct from
all other fossil specimens that have been analyzed, sug-
gesting the possibility that they consumed very different
foods than all of these groups, with unusually high Sr
and relatively low Ba concentrations (Fig. 9). One food
that could meet this requirement is grass seeds, another
is underground storage organs (roots, rhizomes, and
bulbs). The evidence for this is indirect, and based partly
on observations that three specimens of African mole rat
(Cryptomys hottentotus), a species which is known to
consume only underground roots and bulbs, had the
highest Sr/Ba of any animal we have studied. The possi-
bilities of both grass seed and underground storage
organ consumption, both of which have been suggested
as possible early hominin foods requires further consid-
Another potential explanation for the high Sr/Ca of
Australopithecus, and to a lesser extant Paranthropus,is
insectivory. Our modern pilot data show that a modern
insectivore (Orycteropus afer) has much higher Sr/Ca than
carnivores, again emphasizing that not all faunivores are
equivalent in Sr/Ca. Yet, these pilot data also show that
insectivores have high Ba/Ca, unlike the hominins, mak-
ing it less likely that the elevated hominin Sr/Ca results
from insectivory. At present we have analyzed far too few
insectivores to seriously address this possibility.
In summary, although there is clearly ecological pat-
terning to be found in the trace element ratios of early
hominins and associated fauna, interpretation of these
data remains problematic. The difficulty stems from the
lack of work on trace element distributions in modern
African ecosystems. No detailed studies have been pub-
lished that demonstrate the elemental distributions in
African plants and animals, although some promising
work has been carried out in North America (Burton
et al., 1999). The reason is two-fold. In the early days of
trace element studies, there was insufficient appreciation
for the variation that existed in plants and animals, and
therefore it was assumed that trace element ratios sim-
ply reflected trophic level. Later, as researchers became
disabused of this overly simplistic notion, concerns about
diagenesis greatly reduced the time and effort put into
trace element studies. Thus, soon after trace element
analysis was first applied to early hominins in 1992, it
lapsed into virtual disuse except for a few specialized
applications. Now that it has been demonstrated that
trace element compositions retain much of their fidelity
in enamel; studies investigating elemental distribution
in modern foodwebs are urgently required.
Neanderthal diets. Just one trace element application
to the diet of Neanderthals has been carried out based
on Sr/Ca and Ba/Ca ratios of a variety of faunal bones
and a single Neanderthal specimen from Saint Ce
(Balter et al., 2002). Recently, Balter and Simon (2006)
compared the Sr/Ca, Ba/Ca, d
C and d
N of the Saint
´saire individual to other fauna using partitioning
models (Phillips, 2001; Phillips and Gregg, 2003) similar
to that used by Bocherens et al. (2005). They concluded
that this individual ate virtually no plant food and that
its diet was dominated by bovids (71%) with smaller
amounts of horses, rhinos, and mammoths consumed.
Although this is an interesting approach, the results
must be treated with caution. First, only a single Nean-
derthal individual was analyzed, and given the inherent
natural variability of trace elements in ecosystems, very
little can be gleaned about the diets of Neanderthals in
general. Secondly, the study used bone rather than
Fig. 9. Bivariate logarithmic plot of Ba/Ca versus Sr/Ba (3
1,000) for combined fauna and hominins from Makapansgat,
Sterkfontein, and Swartkrans distinguishes Australopithecus
from Paranthropus, although they overlapped in Sr/Ca (Fig. 8).
These data suggest that Australopithecus may have consumed
foods with an unusual combination of high [Sr] and low [Ba]
(data from Sponheimer and Lee-Thorp, 2006a).
American Journal of Physical Anthropology—DOI 10.1002/ajpa
enamel and thus problems due to diagenesis cannot be
discounted. We also know little about geological variabil-
ity in the terrain that might have been used by this indi-
vidual, and geological differences could render the entire
faunal comparison and reconstruction invalid. It must be
said that application of resource partitioning models in
paleo-ecosystems is a risky undertaking. This is because
we cannot know the isotopic and more particularly the
trace element compositions of all potential dietary items,
and this is a requirement of the model which is statisti-
cally based. This is a very significant and inherent limi-
tation given that both plants (and plant parts) and mam-
mals vary widely in these compositions. Application of
trace elements to Neanderthal diets will need a great
deal more basic data to provide a framework that may
eventually inform the broader debate.
In the preceding sections we provided an overview of
what each of the various dietary tools can and cannot
tell us about hominin diets and gave some pointers to
their relative strengths and weaknesses. For instance,
although the nature of the information obtained from
morphology/allometry and microwear sources primarily
concerns the properties of foods, there are strong differ-
ences in the nature of the observations obtained. Dental
morphology and allometry essentially provides the
broader phylogenetic/historical framework for the prop-
erties of foods a species is capable of eating, while micro-
wear provides more direct information about the effects
of foods actually ingested by an individual. Information
at the level of the individual is important since it ena-
bles intragroup comparisons to be made. Amongst the
biochemical tools, isotope analysis provides quantitative
information at the individual level, facilitating intra-
group and intergroup statistical comparisons. This is not
the case for trace element methods, however, because
very high natural variability restricts available informa-
tion to general group-specific levels, and moreover, the
foodweb pathways are still very poorly understood.
How can we best summarize and combine all this evi-
dence? Or, what are the solid outcomes, where do these
approaches reinforce each other and where are they in
disagreement? In the case of Neanderthals the biochemi-
cal data can be compared mostly with archeological evi-
dence and the single microwear study published so far.
The d
N data suggest high trophic level diets for Euro-
pean Neanderthals in the last Glacial. Hence they have
been portrayed as effective top level predators with diets
consisting primarily of meat (Richards et al., 2000;
Bocherens et al., 2005). The d
N evidence is consistent
with widespread archeological evidence that suggests
that Neanderthals were efficient hunters, since large
quantities of animal flesh are extremely unlikely to have
been obtained by scavenging. As Richards et al. (2000)
and Bocherens et al. (2005) have argued, this pattern
places Neanderthals and their capabilities in a different
light, contradicting suggestions by some (e.g., Binford,
1981) that they lacked the planning resources required
for efficient hunting of large game as observed in the
Upper Paleolithic. In this case, the isotope evidence has
in effect provided a more radical solution than the arche-
ology in suggesting extreme meat-rich diets. Some prac-
titioners have further exploited the biochemical data,
using multi source mixing models to argue for heavy
reliance of the Saint-Ce
`saire I individual on woolly rhi-
noceros and mammoth based on it’s d
N and d
(Bocherens et al., 2005), while Balter and Simon (2006)
added trace element data in a similar exercise to argue
rather for 60% reliance on bovids. However, while the
conclusions may be seductive, use of such resource parti-
tioning models requires detailed knowledge of the iso-
topic and/or trace element composition of the entire paleo-
ecosystem that we simply do not have. This is a particular
concern for trace element composition given inherently
high variability and susceptibility of bone to diagenesis.
Leaving the trace element data aside, the rather more ro-
bust d
N data showing consistently high trophic diets for
Neanderthals would appear to be contradicted by the buc-
cal microwear study showing striation patterns and high
variability more consistent with processing of tough, abra-
sive plant foods and enhancement of abrasion damage in
colder periods (Perez-Perez et al., 2003). However, we also
need to consider the inherent limitations of each of these
approaches; for d
N the constraint lies in the bias
towards high protein foods while other explanations may
exist for buccal surface microwear data.
The range of paleodietary methods applied to the
South African hominins provides a good case study for
comparisons, and allows elimination of at least some pos-
sibilities. Some firm results have emerged. For one, the
C data clearly show that overall both australopith
taxa and early Homo consumed significant proportions of
or C
-derived foods. These results can only be
accounted for by consumption of C
grass, C
sedges, or
animals which ate these plants, but we cannot tell what
these possibilities are from these data alone. The low
O is consistent with consumptions of rhizomes or
other roots, as well as animal foods. The microwear data
discounts gelada-like graminivory, since the australo-
piths’ pitted molars (Grine, 1986; Grine and Kay, 1988)
are unlike those of modern geladas whose molar micro-
wear is dominated by scratches (Teaford, 1993). On the
other hand, two recent molar microwear studies of sa-
vanna Papio baboon populations noted a higher frequency
of pitting than was found in Theropithecus (Daegling and
Grine, 1999). These baboons consume moderate amounts
of savanna grasses on a seasonal basis. The trace element
data from australopith tooth enamel showed that Austral-
opithecus, and to a lesser extent Paranthropus,had
higher Sr/Ca ratios than contemporaneous carnivores,
browsers, and papionins. The unusual combination of
high Sr/Ca and low Ba/Ca in Australopithecus has only
been found in modern fauna that heavily utilize the
underground portions of grasses, such as warthogs (Pha-
cochoerus africanus) and African mole rats (Cryptomys
hottentotus) (Sponheimer et al., 2005b). These elemental
data are still preliminary, and certainly cannot be used to
state firmly that early hominins consumed grass rhi-
zomes. Nevertheless, they are entirely consistent with the
possibility and suggest avenues for future research.
Comparing the results from the various techniques
may also give us the opportunity to question some of the
assumptions on which we base interpretations of the
results. For instance, it has been suggested that hominid
dental anatomy was not well suited for the processing of
animal foods (Lucas and Peters, 2000; Teaford et al.,
2002; Ungar, 2004), while the chemical evidence points
towards some consumption of animal foods. It has per-
haps not been appreciated that these anatomical obser-
vations pertain only to a limited class of animal foods
(ie. flesh or meat-eating), while a great many animal
foods require little if any oral processing. Termites,
American Journal of Physical Anthropology—DOI 10.1002/ajpa
grasshoppers, ants, grubs, eggs, and a variety of other
insects may be eaten whole. Soft tissues can also be con-
sumed without oral processing if they can be reduced to
a suitable size through extra-oral means. Moreover, in
some cases apparent disjunctions between dental mor-
phology and actual trophic behavior can result from the
dentition being adapted for other, more mechanically
challenging foods in an animal’s diet. For example, capu-
chin monkeys (Cebus apella) have large, bunodont denti-
tion with thick enamel adapted for consuming fruits and
hard nuts. Nonetheless, close to 25% of capuchin diets
can come from animal foods (Rosenberger and Kinzey,
1976; Fleagle, 1999). Similarly, Grine et al. (2006)
showed that A. afarensis microwear closely resembled
that of gorillas while their dental and enamel morphol-
ogy suggested other affinities. These observations are
consistent with Ungar’s (2004) argument that among
hominoids, differences in dental morphology primarily
reflect their multifarious fallback foods, rather than
their preferred foods during times of plenty.
As for the australopiths, stable isotopes suggest that
they broadened the ancestral ape resource base to
include C
foods which, coupled with bipedalism, allowed
them to pioneer increasingly open and seasonal environ-
ments. Yet, there are equifinality problems that are com-
mon in stable isotope and trace element studies. That is,
many different diets can lead to the same stable isotope
(or trace element) composition (Peters and Vogel, 2005).
Although some progress has been made using further
indicators, including d
O and trace elements, there is
little reason to believe that this problem can be circum-
vented entirely by relying on chemical means. In the
end, stable isotopes are one tool among many, all of
which provide a slightly different window into the diets
of our ancestors. Stable isotopes will prove most informa-
tive when pursued as part of a larger, integrated paleodi-
etary investigation.
All of these tools also require a great deal of active de-
velopment to improve our understanding of how they
work in ecosystems today. For instance, we still have
much to learn about of the stable isotope compositions of
modern plants and mammals, and how physiology affects
diet-tissue spacing. We must also continue to test com-
fortable assumptions. As a good example, earlier notions
of a simple stepwise trophic system from trace elements
that distinguishes, herbivores, omnivores, and carnivores
has been gradually refined after a series of modern eco-
system studies in different environments (Sillen, 1988;
Burton et al., 1999; Sponheimer and Lee-Thorp, Kruger
National Park Project, unpubl. data). Rather than a sim-
ple trophic level indicator, Sr/Ca and Ba/Ca ratios may
ultimately provide just as much information about plant
foods. Hopefully, such actualistic and experimental work
will serve to further refine the entire suite of paleodiet-
ary tools.
The authors are grateful to their colleagues in the
Transvaal Museum and the University of the Witwaters-
rand for allowing them to pursue their analytical pro-
grammes. They thank Rebecca Ackermann, Thure Cerl-
ing, Daryl Codron, Darryl De Ruiter, Ben Passey, Kaye
Reed, Judith Sealy, Andrew Sillen, Andreas Spa
¨th, Fran-
cis Thackeray, Peter Ungar, and Nikolaas van der Merwe
for helpful discussions over many years.
Aiello LC, Wheeler P. 1995. The expensive tissue hypothesis.
Curr Anthropol 36:199–221.
Altmann SA, Altman J. 1970. Baboon ecology. Chicago: Univer-
sity of Chicago Press.
Ambrose SH. 1986. Stable carbon and nitrogen isotope analysis
of human diet in Africa. J Hum Evol 15:707–731.
Ambrose SH. 1990. Preparation and characterization of bone
and tooth collagen for stable carbon and nitrogen isotope
analysis. J Archaeol Sci 17:431–451.
Ambrose SH. 1991. Effects of diet, climate and physiology on
nitrogen isotope abundances in terrestrial foodwebs.
J Archaeol Sci 18:293–317.
Ambrose SH. 1998. Prospects for stable isotopic analysis of later
pleistocene hominid diets in West Asia and Europe. In: Akazawa
T, Aoki K, Bar-Yosef O, editors. Origin of Neanderthals and
humans in West Asia. New York: Plenum. p 277–289.
Ambrose SH. 2001. Paleolithic archaeology and human evolu-
tion. Science 291:1748–1753.
Ambrose SH, Norr L. 1993. Experimental evidence for the rela-
tionship of the carbon isotope ratios of whole diet and dietary
protein to those of bone collagen and carbonate. In: Lambert
JB, Grupe G, editors. Prehistoric human bone: Archaeology at
the molecular level. Berlin: Springer-Verlag. p 1–37.
Amundson R, Austin AT, Schuur EAG, Yoo K, Matzek V, Ken-
dall C, Uebersax A, Brenner D, Baisden WT. 2003. Global pat-
terns of the isotopic composition of soil and plant nitrogen.
Global Biogeochem Cycles 17:1031.
Backwell LR, d’Errico F. 2001. Evidence of termite foraging by
Swartkrans early hominids. Proc Natl Acad Sci USA 98:
Balter V, Bocherens H, Person A, Labourdette N, Renard M,
Vandermeersch B. 2002. Ecological and physiological variabili-
ty of Sr/Ca and Ba/Ca in mammals of West European mid-
Wurmian food webs. Paleogeogr Paleoclimatol Paleoecol
Balter V, Simon L. 2006. Diet and behavior of the Saint-Cesaire
Neanderthal inferred from biogeochemical data inversion. J
Hum Evol 51:329–338.
Binford L. 1981. Bones. New York: Academic Press.
Blumenschine RJ. 1987. Characteristics of an early hominid
scavenging niche. Curr Anthropol 28:383–407.
Bocherens H, Billiou D, Mariotti A, Patou-Mathis M, Otte M,
Bonjean D, Toussaint M. 2001. New isotopic evidence for die-
tary habits of Neandertals from Belgium. J Hum Evol 40:
Bocherens H, Billiou D, Patou-Mathis M, Bonjean D, Otte M,
Mariotti A. 1997. Isotopic biogeochemistry (
N) of fossil
mammal collagen from Scladina cave (Sclayn, Belgium). Quat
Res 48:370–380.
Bocherens H, Drucker DG, Billiou D, Patou-Mathis M, Vander-
meersch B. 2005. Isotopic evidence for diet and subsistence of
the Saint-Cesaire I Neanderthal: Review and use of a multi-
source mixing model. J Hum Evol 49:71–87.
Bocherens H, Fizet M, Mariotti A, Lange-Badre B, Vander-
meersch B, Borel J-P, Bellon G. 1991. Isotopic biochemistry
(13C, 15N) of fossil vertebrate collagen: Implications for the
study of fossil food web including Neandertal man. J Hum
Evol 20:481–492.
Bocherens H, Koch PL, Mariotti A, Geraads D, Jaeger J-J.
1996. Isotopic biogeochemistry (
O) of mammalian
enamel from African Pleistocene hominid sites. PALAIOS 11:
Boutton TW, Arshad MA, Tieszen LL. 1983. Stable isotope anal-
ysis of termite food habits in East African grasslands. Oecolo-
gia 59:1–6.
Boyde A, Fortelius M. 1991. New confocal LM method for study-
ing local relative microrelief with special references to wear
studies. Scanning 13:429–430.
Brain CK. 1981. The hunters or the hunted? Chicago: Univer-
sity of Chicago Press.
Brown AB. 1974. Bone strontium as a dietary indicator in
human skeletal populations. Contrib Geol 13:47–48.
American Journal of Physical Anthropology—DOI 10.1002/ajpa
Brunet M, Guy F, Pilbeam D, Mackaye HT, Likius A, Ahounta
D, Beauvilain A, Blondel C, Bocherens H, Boisserie JR, De
Bonis L, Coppens Y, Dejax J, Denys C, Duringer P, Eisen-
mann V, Fanone G, Fronty P, Geraads D, Lehmann T, Liho-
reau F, Louchart A, Mahamat A, Merceron G, Mouchelin G,
Otero O, Pelaez Campomanes P, Ponce De Leon M, Rage JC,
Sapanet M, Schuster M, Sudre J, Tassy P, Valentin X,
Vignaud P, Viriot L, Zazzo A, Zollikofer C. 2002. A new homi-
nid from the upper Miocene of Chad, Central Africa. Nature
Budd P, Montgomery J, Barreiro B, Thomas RG. 2000. Differen-
tial diagenesis of strontium in archeological human tissues.
Appl Geochem 15:687–694.
Burton JH, Price TD, Middleton WD. 1999. Correlation of bone
Ba/Ca and Sr/Ca due to biological purification of calcium.
J Archaeol Sci 26:609–616.
Burton JH, Wright LE. 1995. Nonlinearity in the relationship
between bone Sr/Ca and diet: Paleodietary implications. Am J
Phys Anthropol 96:273–282.
Carter ML. 2001. Sensitivity of stable isotopes (13C, 15N, and
18O) in bone to dietary specialization and niche separation
among sympatric primates in Kibale National Park, Uganda.
PhD Dissertation, University of Chicago.
Cerling TE, Harris JM. 1999. Carbon isotope fractionation
between diet and bioapatite in ungulate mammals and impli-
cations for ecological and paleoecological studies. Oecologia
Cerling TE, Harris JM, Ambrose SH, Leakey MG, Solounias N.
1997. Dietary and environmental reconstruction with stable iso-
tope analyses of herbivore tooth enamel from the Miocene
locality of Fort Ternan, Kenya. J Hum Evol 33:635–650.
Codron J, Codron D, Lee-Thorp JA, Sponheimer M, Bond WJ,
De Ruiter D, Grant R. 2005. Taxonomic, anatomical, and
spatio-temporal variations in the stable carbon and nitrogen
composition of plants from an African savanna. J Archaeol Sci
Codron DM. 2003. Dietary ecology of chacma baboons (Papio
ursinus (Kerr, 1792)) and Pleistocene cercopithecoidea in Sa-
vanna environments of South Africa. MSc Thesis, University
of Cape Town.
Codron D, Lee-Thorp JA, Sponheimer M, De Ruiter D, Codron
J. 2006. Inter- and intra-habitat dietary variability of Chacma
baboons (Papio ursinus) in South African Savannas based on
fecal d
C, d
N and %N. Am J Phys Anthropol 129:195–204.
Conklin-Brittain NL, Wrangham RW, Smith CC. 2002. A two-
stage model of increased dietary quality in early hominid evo-
lution: The role of fiber. In: Ungar PS, Teaford MF, editors,
Human diet: Its origin and evolution. Westport: Bergin and
Garvey. p 61–76.
Daegling DJ, Grine FE. 1999. Occlusal microwear in Papio ursi-
nus: The effects of terrestrial foraging on dental enamel. Pri-
mates 40:559–572.
Dansgaard W. 1964. Stable isotopes in precipitation. Tellus 16:
Dart RA. 1926. Taungs and its significance. Nat Hist 26:315–
Dart RA. 1957. The Osteodontokeratic culture of Australopithe-
cus prometheus. Transvaal Mus Mem 10:1–105.
de Heinzelin J, Clark JD, White TD, Hart W, Renne P, Wolde-
Gabriel G, Beyene Y, Vrba E. 1999. Environment and behav-
ior of 2.5-million-year-old Bouri hominids. Science 284:625–
Demes B, Creel N. 1988. Bite force and cranial morphology of
fossil hominids. J Hum Evol 17:657–676.
Deocampo DM, Blumenschine RJ, Ashley GM. 2002. Wetland
diagenesis and traces of early hominids, Olduvai Gorge, Tan-
zania. Quat Res 57:271–281.
´nquez-Rodrigo M, Pickering TR, Semaw S, Rogers MJ.
2005. Cutmarked bones from Pliocene archaeological sites at
Gona, Afar, Ethiopia: Implications for the function of the
world’s oldest stone tools. J Hum Evol 48:109–121.
Dufour E, Bocherens H, Mariotti A. 1999. Paleodietary impli-
cations of isotopic variability in Eurasian lacustrine fish.
J Archaeol Sci 26:627–637.
Dunbar RIM. 1983. Theropithecines and hominids: Contrasting
solutions to the same ecological problem. J Hum Evol 12:647–
Elias RW, Hirao Y, Patterson CC. 1982. The circumvention of
the natural biopurification of calcium along nutrient path-
ways by atmospheric inputs of industrial lead. Geochim Cos-
mochim Acta 46:2561–2580.
Elliot JC. 1994. Structure and chemistry of the apatites and
other calcium orthophosphates. Amsterdam: Elsevier.
El-Zaatari S, Grine FE, Teaford MF, Smith HF. 2005. Molar
microwear and dietary reconstructions of fossil cercopithecoi-
dea from the Plio–Pleistocene deposits of South Africa. J Hum
Evol 49:180–205.
`blot Augustins J. 1997. La Circulation des Matie
`res Pre-
`res au Pale
´olithique. Etudes et Recherches Archaeologi-
ques de l’Universite de Lie
`ge 75. Lie
`ge: University de Lie
Fizet M, Mariotti A, Bocherens H, Lange-Badre’ B, Vander-
meersch B, Borel JP, Bellon G. 1995. Effect of diet, physiology
and climate on carbon and nitrogen isotopes of collagen in a
late Pleistocene anthropic paleoecosystem (France, Charente,
Marillac). J Archaeol Sci 22:67–79.
Fleagle JG. 1999. Primate adaptation and evolution, 2nd ed.
New York: Academic Press.
Gilbert C, Sealy J, Sillen A. 1994. An investigation of barium, cal-
cium and strontium as paleodietary indicators in the Southwest-
ern Cape, South Africa. J Archaeol Sci 21:173–184.
Goodall J. 1986. The chimpanzees of gombe. Cambridge: Cam-
bridge University Press.
Grine FE. 1981. Trophic differences between gracile and robust
australopithecines. S Afr J Sci 77:203–230.
Grine FE. 1986. Dental evidence for dietary differences in Austral-
opithecus and Paranthropus. J Hum Evol 15:783–822.
Grine FE, Kay RF. 1988. Early hominid diets from quantitative
image analysis of dental microwear. Nature 333:765–768.
Grine FE, Ungar PS, Teaford MF. 2002. Error estimates in den-
tal microwear quantification using SEM. Scanning 24:144–
Grine FE, Ungar PS, Teaford MF, El-Zaatari S. 2006. Molar
microwear in Praeanthropus afarensis: Evidence for dietary
stasis through time and under diverse paleoecological condi-
tions. J Hum Evol 51:297–319.
Hagiri F. 1964. Strontium-90 accumulation in some vegetable
crops. Ohio J Sci 64:371–375.
Hamilton WJ. 1987. Omnivorous primate diets and human over-
consumption of meat. In: Harris M, Ross EB, editors. Food
and evolution: Toward a theory of human food habits. Phila-
delphia: Temple University Press. p 117–132.
Handley LL, Raven JA. 1992. The use of natural abundance of
nitrogen isotopes in plant physiology and ecology. Plant Cell
Environ 15:965–985.
Hatley T, Kappelman J. 1980. Bears, pigs, and plio-pleistocene
hominids: Case for exploitation of belowground food resources.
Hum Ecol 8:371–387.
Heaton THE. 1987. The N-15/N-14 ratios of plants in South
Africa and Namibia—Relationship to climate and coastal sa-
line environments. Oecologia 74:227–244.
Hesla ABI, Tieszen LL, Imbamba SK. 1982. A systematic survey
of C
and C
photosynthesis in the Cyperaceae of Kenya, East
Africa. Photosynthetica 16:196–205.
Hoppe KA, Koch PL, Furutani TT. 2003. Assessing the preser-
vation of biogenic strontium in fossil bones and tooth enamel.
Int J Osteoarchaeol 13:20–28.
Hylander WL. 1975. Incisor size and diet in anthropoids with spe-
cial reference to Cercopithecoidea. Science 189:1095–1098.
Isaac G. 1981. Stone age visiting cards: Approaches to the study
of early land-use patterns. In: Hodder I, Isaac G, Hammond
N, editors. Patterns of the past. Cambridge: Cambridge Uni-
versity Press. p 131–155.
Jolly CJ. 1970. The seed-eaters: A new model of hominid differ-
entiation based on a baboon analogy. Man 5:5–26.
Jones AM, O’Connell TC, Young ED, Scott K, Buckingham CM,
Iacumin P, Brasier MD. 2001. Biogeochemical data from well
preserved 200 ka collagen and skeletal remains. Earth Planet
Sci Lett 193:143–149.
American Journal of Physical Anthropology—DOI 10.1002/ajpa
Kay RF. 1975a. Functional adaptations of primate molar teeth.
Am J Phys Anthropol 43:195–215.
Kay RF. 1975b. Allometry in early hominids. Science 189:61–63.
Kay RF. 1977. The evolution of molar occlusion in the Cercopi-
thecidae and early Catarrhines. Am J Phys Anthropol 46:
Kay RF. 1985. Dental evidence for the diet of Australopithecus.
Ann Rev Anthropol 14:315–341.
Klein RG. 1999. The human career: Human biological and cul-
tural origins, 2nd ed. Chicago: University of Chicago Press.
Koch PL, Tuross N, Fogel ML. 1997. The effects of sample treat-
ment and diagenesis on the isotopic integrity of carbonate in
biogenic hydroxylapatite. J Archaeol Sci 24:417–429.
Kohn MJ. 1996. Predicting animal d
O: Accounting for diet and
physiological adaptation. Geochim Cosmochim Acta 60:4811–
Kohn MJ, Schoeninger MJ, Valley JW. 1996. Herbivore tooth ox-
ygen isotope compositions: Effects of diet and physiology. Geo-
chim Cosmochim Acta 60:3889–3896.
Kohn M, Schoeninger MJ, Barker WW. 1999. Altered states:
Effects of diagenesis on fossil tooth chemistry. Geochim Cos-
mochim Acta 63:2737–2747.
Krueger HW, Sullivan CH. 1984. Models for carbon isotope frac-
tionation between diet and bone. In: Turnland JF, Johnson
PE, editors. Stable isotopes in nutrition. ACS Symposium Se-
ries 258. Washington, DC: American Chemical Society. p 205–
Leakey MG, Spoor F, Brown FH, Gathogo PN, Kiarie C, Leakey
LN, McDougall I. 2001. New hominin genus from eastern
Africa shows diverse middle Pliocene lineages. Nature 410:
Lee-Thorp JA. 1989. Stable carbon isotopes in deep time: The
diets of fossil fauna and hominids. PhD Thesis, University of
Cape Town.
Lee-Thorp JA. 2000. Preservation of biogenic carbon isotope sig-
nals in Plio–Pleistocene bone and tooth mineral. In: Ambrose
S, Katzenberg KA, editors. Biogeochemical approaches to
paleodietary analysis. New York: Plenum. p 89–116.
Lee-Thorp JA. 2002. Hominid dietary niches from isotope and
trace element chemistry in fossils: The Swartkrans example.
In: Ungar P, Teaford M, editors. Human diet: Perspectives on
its origin and evolution. Westport: Bergin and Garvey. p 123–
Lee-Thorp JA, Manning L, Sponheimer M. 1997. Exploring
problems and opportunities offered by down-scaling sample
sizes for carbon isotope analyses of fossils. Bull Soc Geol France
Lee-Thorp JA, Sealy JC, van der Merwe NJ. 1989. Stable car-
bon isotope ratio differences between bone collagen and bone
apatite, and their relationship to diet. J Archaeol Sci 16:585–
Lee-Thorp JA, Sponheimer M. 2003. Three case studies used to
reassess the reliability of fossil bone and enamel isotope signals
for paleodietary studies. J Anthropol Archaeol 22:208–216.
Lee-Thorp JA, Sponheimer M. 2005. Opportunities and con-
straints for reconstructing paleoenvironments from stable
light isotope ratios in fossils. Geol Q 49:195–204.
Lee-Thorp JA, Sponheimer M, van der Merwe NJ. 2003. What
do stable isotopes tell us about hominin diets? Int J Osteoar-
chaeol 13:104–113.
Lee-Thorp JA, Thackeray JF, van der Merwe NJ. 2000. The
hunters and the hunted revisited. J Hum Evol 39:565–576.
Lee-Thorp JA, van der Merwe NJ. 1987. Carbon isotope analy-
sis of fossil bone apatite. S Afr J Sci 83:712–715.
Lee-Thorp JA, van der Merwe NJ, Brain CK. 1994. Diet of Aus-
tralopithecus robustus at Swartkrans from stable carbon iso-
topic analysis. J Hum Evol 27:361–372.
LeGeros RZ. 1991. Calcium phosphates in oral biology and med-
icine. Paris: Karger.
Lough SA, Rivera J, Comar CL. 1963. Retention of strontium,
calcium and phosphorous in human infants. Proc Soc Exp
Biol Med 112:631–636.
Lucas PW, Peters CR. 2000. Function of postcanine tooth crown
shape in mammals. In: Teaford MF, Smith MM, Ferguson
MWJ, editors. Development, function and evolution of teeth.
Cambridge: Cambridge University Press. p 282–289.
Marean CW, Assefa Z. 1999. Zooarcheological evidence for the
faunal exploitation behavior of Neandertals and early modern
humans. Evol Anthropol 8:22–37.
McGrew WC, Baldwin PJ, Tutin CE. 1981. Chimpanzees in a
hot, dry and open habitat: Mt. Assirik, Senegal, West Africa.
J Hum Evol 10:227–244.
McGrew WC, Sharman MJ, Baldwin PJ, Tutin CEG. 1982. On
early hominid plant-food niches. Curr Anthropol 23:213,214.
Milton K. 1999. A hypothesis to explain the role of meat-eating
in human evolution. Evol Anthropol 8:11–21.
Milton K. 2002. Hunter–gatherer diets: Wild foods signal relief
from diseases of affluence. In: Ungar PS, Teaford MF, editors.
Human diet: Its origin and evolution. Westport: Bergin and
Garvey. p 111–122.
Minagawa M, Wada E. 1984. Step-wise enrichment of
N along
food chains: Further evidence and the relationship between
N and animal age. Geochim Cosmochim Acta 48:1135–
O’Connell JF, Hawkes K, Blurton Jones NG. 1999. Grandmo-
thering and the evolution of Homo erectus. J Hum Evol 36:
Passey BH, Robinson TF, Ayliffe LK, Cerling TE, Sponheimer M,
Dearing MD, Roeder BL, Ehleringer JR. 2005. Carbon isotope
fractionation between diet breadth, CO
, and bioapatite in differ-
ent mammals. J Archaeol Sci 32:1459–1470.
´rez A, Espurz V, Bermue
´dez de Castro JM, de Lumley
MA, Turbon D. 2003. Non-occlusal dental microwear
variability in a sample of middle and late Pleistocene human
populations from Europe and the near East. J Hum Evol 44:
Pettit PB, Richards MP, Maggi R, Formicola V. 2003. The
Gravettian burial known as the Prince (‘Il Principe’): New evi-
dence for his age and diet. Antiquity 95:15–19.
Peters CR, Vogel JC. 2005. Africa’s wild C
plant foods and pos-
sible early hominid diets. J Hum Evol 48:219–236.
Phillips DL. 2001. Mixing models in analyses of diet using mul-
tiple isotopes: A critique. Oecologia 127:166–170.
Phillips DL, Gregg JW. 2003. Source partitioning using stable
isotopes: Coping with too many sources. Oecologia 136:261–
Pilbeam D, Gould SJ. 1974. Size and scaling in human evolu-
tion. Science 186:892–901.
Price TD, Blitz J, Burton JH, Ezzo J. 1992. Diagenesis in pre-
historic bone: Problems and solutions. J Archaeol Sci 19: 513–
Puech P-F, Albertini H, Serratrice C. 1983. Tooth microwear
and dietary patterns in early hominids from Laetoli, Hadar
and Olduvai. J Hum Evol 12:721–729.
Reed K. 1997. Early hominid evolution and ecological change
through the African Plio-Pleistocene. J Hum Evol 32:289–322.
Richards MP, Pettitt PB, Stiner MC, Trinkaus E. 2001. Stable
isotope evidence for increasing dietary breadth in the Euro-
pean mid-upper Paleolithic. Proc Natl Acad Sci USA 98:
Richards MP, Pettitt PB, Trinkaus E, Smith FH, Paunovic M,
Karavanic I. 2000. Neanderthal diet at Vindija and Neander-
thal predation: The evidence from stable isotopes. Proc Natl
Acad Sci USA 97:7663–7666.
Robinson JT. 1954. Prehominid dentition and hominid evolution.
Evolution 8:324–334.
Robinson JT. 1956. The dentition of the Australopithecinae.
Transvaal Museum Mem 9:1–179.
Rosenberger AJ, Kinzey WG. 1976. Am J Phys Anthropol
Runia LJ. 1987. Strontium and calcium distribution in plants:
Effect on paleodietary studies. J Archaeol Sci 14:599–608.
Ryan AS. 1981. Anterior dental microwear and its relationship
to diet and feeding behavior in three African primates (Pan
troglodytes troglodytes, Gorilla gorilla gorilla, and Papio ham-
adryas). Primates 22:533–550.
Ryan AS, Johanson DC. 1989. Anterior dental microwear in Aus-
tralopithecus afarensis. J Hum Evol 18:235–268.
American Journal of Physical Anthropology—DOI 10.1002/ajpa
Schoeninger MJ. 1979. Diet and status at Chalcatzingo: Some
empirical and technical aspects of strontium analysis. Am J
Phys Anthropol 51:295–310.
Schoeninger MJ, DeNiro MJ. 1984. Nitrogen and carbon isotopic
composition of bone collagen from marine and terrestrial ani-
mals. Geochim Cosmochim Acta 48:625–639.
Schoeninger MJ, Moore J, Sept JM. 1999. Subsistence strategies
of two savanna chimpanzee populations: The stable isotope
evidence. Am J Primatol 49:297–314.
Scott RS, Ungar PS, Bergstrom TS, Brown CA, Grine FE, Tea-
ford MF, Walker A. 2005. Dental microwear texture analysis
shows within-species dietary variability in fossil hominins.
Nature 436:693–695.
Sealy JC, Sillen A. 1988. Sr and Sr:Ca in marine and terrestrial
foodwebs in the Southwestern Cape, South Africa. J Archaeol
Sci 15:425–438.
Sealy JC, van der Merwe NJ, Lee-Thorp JA, Lanham JL. 1987.
Nitrogen isotopic ecology in southern Africa: Implications for
environmental and dietary tracing. Geochim Cosmochim Acta
Semaw S, Renne P, Harris JWK, Feibel CS, Bernor RL, Fesseha
N, Mowbray K. 1997. 2.5-Million-year-old stone tools from
Gona, Ethiopia. Nature 385:333–336.
Senut B, Pickford M, Gommery D, Mein P, Cheboi C, Coppens
Y. 2001. First hominid from the Miocene (Lukeino Formation,
Kenya). Comptes Rendus des Seances de l’ Academie des Sci-
ences 332:137–144.
Sillen A. 1981. Strontium and diet at Hayonim Cave. Am J
Phys Anthropol 56:131–137.
Sillen A. 1988. Elemental and isotopic analysis of mammalian
fauna from southern Africa and their implications for paleodi-
etary research. Am J Phys Anthropol 76:49–60.
Sillen A. 1989. Diagenesis of the inorganic phase of cortical
bone. In: Price TD, editor. The chemistry of prehistoric human
bone. Cambridge: Cambridge University Press. p 211–299.
Sillen A. 1992. Strontium–calcium ratios (Sr/Ca) of Australo-
pithecus robustus and associated fauna from Swartkrans.
J Hum Evol 23:495–516.
Sillen A, Hall G, Armstrong R. 1995. Strontium–calcium ratios
(Sr/Ca) and Strontium isotope rations (87Sr/86Sr) of Australo-
pithecus robustus and Homo sp. from Swartkrans. J Hum
Evol 28:277–286.
Sillen A, Kavanagh M. 1982. Strontium and paleodietary
research. Yrbk Phys Anthropol 25:67–90.
Smith BN, Epstein S. 1971. Two categories of
C ratios for
higher plants. Plant Physiol 47:380–384.
Spencer H, Warren JM, Kramer L, Samachson J. 1973. Passage
of calcium and strontium across the intestine in man. Clin
Orthop 91:225–234.
Speth JD, Tchernov E. 2001. Neanderthal hunting and meat-proc-
essing in the near east: Evidence from Kebara Cave (Israel). In:
Stanford CB, Bunn HT, editors. Meat-eating and human evolu-
tion. Oxford: Oxford University Press. p 52–72.
Sponheimer M. 1999. Isotopic ecology of the Makapansgat Lime-
works fauna. PhD Dissertation, Rutgers University.
Sponheimer M, De Ruiter D, Lee-Thorp JA, and Spa
¨th A. 2005a. Sr/
Ca and early hominin diets revisited: New data from modern and
fossil tooth enamel. J Hum Evol 48:147–156.
Sponheimer M, Lee-Thorp JA. 1999a. Isotopic evidence for the
diet of an early hominid, Australopithecus africanus. Science
Sponheimer M, Lee-Thorp JA. 1999b. The ecological significance of
oxygen isotopes in enamel carbonate. J Archaeol Sci 26:723–728.
Sponheimer M, Lee-Thorp JA. 2001. The oxygen isotope compo-
sition of mammalian enamel carbonate: A case study from
Morea Estate, Mpumalanga Province, South Africa. Oecologia
Sponheimer M, Lee-Thorp JA. 2003. Differential resource utiliza-
tion by extant great apes and Australopithecines: Towards
solving the C
conundrum. Comp Biochem Physiol 136:27–34.
Sponheimer M, Lee-Thorp JA. 2006a. Enamel diagenesis at
South African Australopith sites: Implications for paleoecolog-
ical reconstruction with trace elements. Geochim Cosmochim
Acta 70:1644–1654.
Sponheimer M, Lee-Thorp JA. 2006b. Hominin paleodiets: Con-
tribution of stable isotopes. In: Henke W, Rothe H, Tattersall
I, editors. Handbook of paleoanthropology. Berlin: Springer.
Chapter 17.
Sponheimer M, Lee-Thorp JA, DeRuiter D. Codron D, Codron J,
Baugh A, Thackeray JF. 2005b. Hominins, sedges and ter-
mites: New carbon isotope data for the Sterkfontein Valley.
J Hum Evol 48:301–312.
Sponheimer M, Loudon JE, Codron D, Howells ME, Pruetz
JD, Codron J, de Ruiter D, Lee-Thorp JA. 2006. Do savanna
chimpanzees consume C
resources? J Hum Evol 51:
Sponheimer M, Reed K, Lee-Thorp JA. 1999. Combining isotopic
and ecomorphological data to refine bovid paleodietary recon-
truction: A case study from the Makapansgat Limeworks
hominin locality. J Hum Evol 34:277–285.
Sponheimer M, Robinson T, Ayliffe L, Roeder B, Hammer J, West
A, Passey B, Cerling T, Dearing D, Ehleringer J. 2003. Nitrogen
isotopes mammalian herbivores: Hair
trolled-feeding study. Int J Osteoarchaeol 13:80–87.
Stiner M. 1994. Honor among thieves. Princeton: Princeton Uni-
versity Press.
Stock WD, Chuba DK, Verboom GA. 2004. Distribution of South
African C-3 and C-4 species of Cyperaceae in relation to cli-
mate and phylogeny. Aust Ecol 29:313–319.
Strait SG. 1997. Tooth use and the physical properties of foods.
Evol Anthropol 5:199–211.
Strum SC. 1987. Almost human: A journey into the world of
baboons. New York: Random House.
Sullivan CH, Krueger HW. 1981. Carbon isotope analysis of sep-
arate chemical phases in modern and fossil bone. Nature
Szalay FS. 1975. Hunting-scavenging protohominids: A model
for hominid origins. Man 10:420–429.
Tauber H. 1981.
C evidence for dietary habits of prehistoric
man in Denmark. Nature 292:332–333.
Teaford MF. 1985. Molar microwear and diet in the genus
Cebus. Am J Phys Anthropol 66:363–370.
Teaford MF. 1988a. A review of dental microwear and diet in
modern mammals. Scanning Microsc 2:1149–1166.
Teaford, MF. 1988b. Scanning electron microscope diagnosis of
wear patterns versus artifacts on fossil teeth. Scanning Microsc
Teaford MF. 1993. Dental microwear and diet in extant and
extinct Theropithecus: Preliminary analyses. In: Jablonski
NC, editor. Theropithecus: The life and death of a primate ge-
nus. Cambridge: Cambridge University Press. p 331–349.
Teaford MF, Oyen OJ. 1989a. In vivo and in vitro turnover in
dental microwear. Am J Phys Anthropol 80:447–460.
Teaford MF, Oyen OJ. 1989b. Live primates and dental replica-
tion: New problems and new techniques. Am J Phys Anthropol
Teaford MF, Ungar PS. 2000. Diet and the evolution of the ear-
liest human ancestors. Proc Natl Acad Sci USA 97:13506–
Teaford MF, Ungar PS, Grine FE. 2002. Paleontological evi-
dence for the diets of African Plio–Pleistocene hominins with
special reference to early Homo. In: Ungar PS, Teaford MF,
editors. Human diet: Its origin and evolution. Westport: Ber-
gin and Garvey. p 143–166.
Teleki G. 1981. The omnivorous diet and eclectic feeding habits
of chimpanzees in Gombe National Park, Tanzania. In: Har-
ding RSO, Teleki G, editors. Omnivorous primates. New York:
Columbia University Press. p 303–343.
Tieszen LL. 1991. Natural variations in the carbon isotope val-
ues of plants: Implications for archaeology, ecology, and paleo-
ecology. J Archaeol Sci 18:227–248.
Tieszen LL, Fagre T. 1993. Effect of diet quality and composi-
tion on the isotopic composition of respiratory CO
, bone colla-
gen, bioapatite, and soft tissues. In: Lambert JB, Grupe G,
editors. Prehistoric human bone: Archaeology at the molecu-
lar level. Berlin: Springer. p 121–155.
Toots H, Voorhies MR. 1965. Strontium in fossil bones and the
reconstruction of food chains. Science 149:854–855.
American Journal of Physical Anthropology—DOI 10.1002/ajpa
Trickett MA, Budd P, Montgomery J, Evans J. 2003. An assess-
ment of solubility profiling as a decontamination procedure
for the 87Sr/86Sr analysis of archaeological human skeletal
tissue. Appl Geochem 18:653–658.
Tuross N, Behrensmeyer AK, Eanes ED. 1989. Sr increase and
crystallinity changes in taphonomic and archaeological bones.
J Archaeol Sci 16:661–672.
Tutin CEG, Fernandez M. 1992. Insect-eating by sympatric low-
land gorillas (Gorilla g. gorilla) and chimpanzees (Pan t. troglo-
dytes) in the Lope Reserve, Gabon. Am J Primatol 28:29–40.
Ungar PS. 1995. A semiautomated image analysis procedure for
the quantification of dental microwear II. Scanning 17:57–59.
Ungar PS. 1996. Dental microwear of European Miocene catar-
rhines: Evidence for diets and tooth use. J Hum Evol 31:355–
Ungar PS. 1998. Dental allometry, morphology, and wear as evi-
dence for diet in fossil primates. Evol Anthropol 6:205–217.
Ungar PS. 2004. Dental topography and diets of Australopithe-
cus afarensis and early Homo. J Hum Evol 46:605–622.
Ungar PS, Brown CA, Bergstrom TS, Walker A. 2003. Quantifi-
cation of dental microwear by tandem scanning confocal mi-
croscopy and scale-sensitive fractal analyses. Scanning
Ungar PS, Grine FE. 1991. Incisor size and wear in Australo-
pithecus africanus and Paranthropus robustus. J Hum Evol
van der Merwe NJ, Medina E. 1989. Photosynthesis and
ratios in Amazonian rain forests. Geochim Cosmochim Acta
van der Merwe NJ, Thackeray JF, Lee-Thorp JA, Luyt J. 2003.
The carbon isotope ecology and diet of Australopithecus afri-
canus at Sterkfontein. S Afr J Hum Evol 44:581–597.
van der Merwe NJ, Vogel JC. 1978. Content of human collagen as
a measure of prehistoric diet in Woodland North America. Na-
ture 276:815–816.
Vogel JC. 1978. Recycling of carbon in a forest environment.
Oecol Plantar 13:89–94.
Vogel JC, van der Merwe NJ. 1977. Isotopic evidence for
early maize cultivation in New York State. Am Antiq 42:238–
Walker AC. 1976. Wear striations on the incisors of cercopithe-
coid monkeys as an index of diet and habitat preference. Am
J Phys Anthropol 45:299–308.
Walker AC. 1981. Diet and teeth: Dietary hypothesis and
human evolution. Philos Trans R Soc Lond B 292:57–64.
Wallace JA. 1973. Tooth chipping in the Australopithecines. Na-
ture 244:117–118.
Wallace JA. 1975. Dietary adaptations of Australopithecus and
early Homo. In: Tuttle R, editor. Paleoanthropology, morphol-
ogy and paleoecology. The Hague: Mouton. p 203–223.
White TD, WoldeGabriel G, Asfaw B, Ambrose SH, Beyene Y,
Bernor RL, Boisserie J-R, Currie B, Gilbert H, Haile-Selassie
Y, Hart WK, Hlusko LJ, Howell FC, Kono RT, Lehmann T,
Louchart A, Lovejoy CO, Renne PR, Saegusa H, Vrba ES,
Wesselman H, Suwa G. 2006. Asa Issie, Aramis and the origin
of Australopithecus. Nature 440:883–889.
Whiten A, Byrne RW, Barton RA, Warterman PG, Henzi SP.
1991. Dietary and foraging strategies of baboons. Philos Trans
R Soc Lond B 334:187–198.
Winter K, Smith JAC, editors. 1996. Crassulacean acid metabo-
lism: Biochemistry, ecophysiology and evolution. Berlin:
Wolpoff MH. 1973. Posterior tooth size, body size, and diet in
South African gracile Australopithecines. Am J Phys Anthro-
pol 39:375–394.
Wood BA. 1981. Tooth size and shape and their relevance to
studies of hominid evolution. Philos Trans R Soc Lond B 292:
Wood BA, Abbott SA. 1983. Analysis of the dental morphology of
Plio–Pleistocene hominids. I. Mandibular molars-crown area
measurements and morphological traits. J Anat 136:197–219.
Wood B, Strait D. 2004. Patterns of resource use in early Homo
and Paranthropus. J Hum Evol 46:119–162.
Wyckoff RWG, Doberenz AR. 1968. The strontium content of fos-
sil teeth and bones. Geochim Cosmochim Acta 32:109–115.
Zazzo A, Bocherens H, Brunet M, Beauvilain A, Billiou D,
Mackaye HT, Vignaud P, Mariotti A. 2000. Herbivore paleo-
diet and paleoenvironment changes in Chad during the Plio-
cene using stable isotope ratios in tooth enamel carbonate.
Paleobiology 26:294–309.
American Journal of Physical Anthropology—DOI 10.1002/ajpa
... range = -5.4 to -10.0). Although, as noted by Lee-Thorp and Sponheimer (2006) and Cerling et al. (2011), the d 13 C data for both australopith species are more variable than virtually all modern and extinct taxa that have been examined in South Africa, these data might still be brought to bear on the issue of the taxonomic homogeneity of the A. africanus hypodigm. To date, there has been no attempt to relate any of the carbon isotope data to individual specimens as they might relate to the proposed taxonomic groupings. ...
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The identification of species in the fossil record has long vexed paleontologists because of its inherent difficulty, and it has long preoccupied them because of its fundamental significance. Australopithecus africanus exemplifies this difficulty and importance. This species, as commonly defined, is viewed by some as having played a role in the evolution of the genus Homo, while others consider it to have been uniquely related to Paranthropus. A third opinion places it near the base of the evolutionary divergence of the “robust” australopith and human lineages. Various analyses find A. africanus to be phylogenetically unstable, and this is almost certainly owing to its craniodental variability. This has led to questions concerning the taxonomic homogeneity of the assemblages from Taung, Sterkfontein, and Makapansgat that comprise its hypodigm. Initial discoveries at these sites were attributed to different species and possibly genera, but subsequent studies suggested that these fossils represent a single, albeit variable taxon. This paradigm has become current conventional paleoanthropological wisdom, but observations about the degree and pattern of variability evinced by these fossils have raised anew the possibility that the A. africanus hypodigm is taxonomically heterogeneous. Various workers have proposed that at least some of these fossils belong to a different taxon, but there is notable lack of agreement over the manner in which they should be sorted. Morphometric studies tend to find little, if any, support for taxonomic heterogeneity, but they may not have directly addressed those features that have been suggested to differ. Novel innovative technological and quantitative approaches are required to adequately address the possible taxonomic heterogeneity of the A. africanus hypodigm.
... de hecho, en la figura 6 se observa que muchos humanos modernos tienen valores δ 15 N todavía más elevados que los Neandertales, lo que se puede interpretar como que los primeros eran al menos igual de dependientes de la carne animal que los segundos (Lee- Thorp y Sponheimer, 2006). Es por esto último por lo que es necesario reconsiderar el papel de la alimentación como factor decisivo en la sustitución de unos homininos por otros en el continente eurasiático. ...
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Durante la última década, los análisis arqueozoológicos que pretenden reconstruir los patrones de subsistencia paleolítica han encontrado aliados en la aplicación de nuevas técnicas: los análisis isotópicos y el estudio de micro-restos vegetales. Los análisis de isótopos estables del carbono y del nitrógeno en colágeno óseo dan información sobre el origen de la proteína consumida de forma constante durante varios años antes de la muerte de los individuos, así como sobre el peldaño trófico de la cadena alimentaria en que los especímenes de estudio se sitúan. El estudio de micro-restos vegetales (fitolitos y granos de almidón) conservados en cálculos dentales y útiles líticos da información sobre el probable consumo de diferentes tipos de plantas por los individuos estudiados. Son ya muchos los especímenes paleolíticos a los que se ha realizado análisis isotópicos para reconstruir la dieta, aunque menos sobre los que se ha aplicado el estudio de microrestos vegetales en cálculos dentales. Se pretende dar a conocer las bases y el potencial de estos dos tipos de técnicas en la reconstrucción de la subsistencia de Neandertales y humanos modernos paleolíticos, así como ilustrar su aplicación utilizando varios yacimientos sobre los que se ha realizado estas técnicas analíticas.
... The disadvantage of this approach is that it does not allow us to do much more than make species-level generalizations: we can say little about intersite variability in behavior and nothing at all as to how behavior might have changed in the face of changing climates and environments. Trace element analysis has provided a valuable alternative and has allowed researchers to make direct inferences about sitespecific variation (Codron et al. 2005;Lee-Thorp and Sponheimer 2006). However, it has, so far, been necessarily confined to observations about diet. ...
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We use a model of modern baboon socio-ecology to explore the behavioral ecology and biogeography of the extinct Plio-Pleistocene baboons (genera Parapapio, Gorgopithecus, Dinopithecus, and Papio). The model is based on the way climate affects the baboons’ time budgets, and focuses on intersite variability in behavior rather than on species-typical patterns of behavior, as most previous approaches have done. We use climate estimates for individual fossil sites based on matching modern habitats using faunal profiles and estimates of individual species’ body masses given in the literature. The model allows us to examine the minimum and maximum sizes of groups that individual species would have been able to support at particular localities, and hence the biogeography of a species on a continental scale. In doing so, the model allows us to examine which variables are most responsible for limiting a species’ ecological and biogeographic flexibility, and through this to explore a species’ capacity for coping with climate change. Feeding time is identified as the main constraint. In general, large-bodied species would have had more difficulty surviving in as wide a range of habitats as smaller-bodied species, and this may explain the limited geographical distribution of large-bodied baboons such as Gorgopithecus and Dinopithecus.
... The latter point is well-supported by archaeological evidence, such as stone tools and cut marks on animal bone recovered from Lower Palaeolithic sites, e.g. Gona and Bouri in Ethiopia, which suggests that our ancestors began processing foods more than two million years ago (Lee-Thorp and Sponheimer 2006). The universality and prevalence of food processing in the present day is also undisputable: all societies in the world practise food processing, regardless of their geographic, ecological and cultural circumstances. ...
Conference Paper
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This paper explores the idea that past and present food processing traditions, practiced by modern humans and our Homo ancestors, are tantamount to evolutionary niche construction. It examines how the introduction of simple processing techniques by our Homo ancestors, such as pulverizing and thermal processing (e.g. roasting, baking, boiling), may have triggered radical shifts in their dietary behaviours, which further promoted advances in associated ecological and technological knowledge, skills and tools. It is argued that the consequences of food processing niche construction, e.g. changing dietary selection, increasing diet breadth and improved access to essential nutrients, are of evolutionary significance because they can be linked to changes in the Homo brain and body, as well as increased longevity and disease prevention
... The latter point is well-supported by archaeological evidence, such as stone tools and cut marks on animal bone recovered from Lower Palaeolithic sites, e.g. Gona and Bouri in Ethiopia, which suggests that our ancestors began processing foods more than two million years ago (Lee-Thorp and Sponheimer 2006). The universality and prevalence of food processing in the present day is also undisputable: all societies in the world practise food processing, regardless of their geographic, ecological and cultural circumstances. ...
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While it is generally agreed that food processing has had a role in human evolution, the specific ways that is has affected our evolution are not well understood. Using a Niche Construction Theory (NCT) perspective, coupled with methodologies borrowed from “post-harvest” research in the plant sciences, this paper investigates the means and mechanism by which food processing is of evolutionary consequence. The central tenet of NCT is that organisms have an active role in their own evolution through reciprocal interactions with their environments; niche construction is understood to occur when organisms initiate long-term changes to their environments that modify the selection pressures on themselves and their descendants (and on other organisms in the environment). Humans and our hominin ancestors are considered to be the ultimate niche constructors due to our ability to modify selection pressures through diverse culturally generated and transmitted cultural means, i.e. cultural niche construction. In this paper, post-harvest methods are used to identify how food processing could feasibly have permitted hominins to modify their evolutionary selection pressures. Food processing is shown to facilitate access to increasing amounts of digestible nutrients and energy (kilocalories/kilojoules) as well as promoting increased dietary breadth and making possible the production of safer and more stable foods. It is argued that these advancements catalysed related technological and ecological skills and knowledge, which together with the nutritional benefits, further triggered changes in hominin brain and body and locomotory adaptations and increased longevity, disease prevention and juvenile survival rates. KeywordsFood processing–Niche construction–Human evolution–Post-harvest research
... Carbon isotope values of Au. africanus tooth enamel suggest that some 35-40% of the diet of this species consisted of C 4 plants, whereas the predominant component (ca., 65%) was C 3 -based (Sponheimer and Lee-Thorp, 1999a;Lee-Thorp and Sponheimer, 2006). Thus, while Au. ...
Determining the diet of an extinct species is paramount in any attempt to reconstruct its paleoecology. Because the distribution and mechanical properties of food items may impact postcranial, cranial, mandibular, and dental morphologies related to their procurement, ingestion, and mastication, these anatomical attributes have been studied intensively. However, while mechanical environments influence skeletal and dental features, it is not clear to what extent they dictate particular morphologies. Although biomechanical explanations have been widely applied to extinct hominins in attempts to retrodict dietary proclivities, morphology may say as much about what they were capable of eating, and perhaps more about phylogenetic history, than about the nature of the diet. Anatomical attributes may establish boundary limits, but direct evidence left by the foods that were actually (rather than hypothetically) consumed is required to reconstruct diet. Dental microwear and the stable light isotope chemistry of tooth enamel provide such evidence, and are especially powerful when used in tandem. We review the foundations for microwear and biogeochemistry in diet reconstruction, and discuss this evidence for six early hominin species (Ardipithecus ramidus, Australopithecus anamensis, Au. afarensis, Au. africanus, Paranthropus robustus, and P. boisei). The dietary signals derived from microwear and isotope chemistry are sometimes at odds with inferences from biomechanical approaches, a potentially disquieting conundrum that is particularly evident for several species.
... Perhaps the two most obvious adaptations to emergence of more open landscapes are to be found in locomotor behavior (bipedalism ) and in dietary ecology. Bipedalism is an important defining characteristic of hominins, and although no dietary information is available for very early hominin taxa, it has been suggested that participation in C 4 foodwebs is a consistent feature of later Pliocene hominins, at least (Lee-Thorp et al., 2003; Sponheimer et al., 2005; Lee-Thorp and Sponheimer, 2006). Today, C 4 grasses are a dominant component of many African ecosystems (Sage and Monson, 1999), where they are associated with high solar radiation and warm temperatures during the growing season. ...
The emergence of C(4) grass biomes is believed to have first taken place in the upper Miocene, when a series of events modified global climate with long-lasting impacts on continental biotas. Changes included major shifts in floral composition-characterized in Africa by shrinking of forests and emergence of C(4) grasses and more open landscapes-followed by large-scale evolutionary shifts in faunal communities. The timing of the emergence of C(4) grasses, and the subsequent global expansion of C(4) grass-dominated biomes, however, is disputed, leading to contrasting views of the patterns of environmental changes and their links to faunal shifts, including those of early hominins. Here we evaluate the existing isotopic evidence available for central, eastern, and southern Africa, and review interpretations in light of these data. Pedogenic and biomineral carbonate delta(13)C data suggest that clear evidence for C(4) biomass in low latitudes exists only from 7-8 Ma. This likely postdates the emergence of C(4) plants, whose physiology is adapted to low atmospheric carbon dioxide concentrations. Biomes with C(4) grasses appeared later in mid-latitude sites. Moreover, C(4) grasses apparently remained a relatively minor component of most environments until the late Pliocene and early Pleistocene. Hence establishment of C(4) grasses, even as minor components of African biomes, precedes the very earliest evidence for bipedalism by two million years, and the more abundant and secure evidence by some three to four million years. This may suggest a protracted process of hominin adaptation to these emerging, more open landscapes.
This review charts the developments and progress made in the application of stable light isotope tools to palaeodietary adaptations from the 1970s onwards. It begins with an outline of the main principles governing the distribution of stable light isotopes in foodwebs and the quality control issues specific to the calcified tissues used in these analyses, and then proceeds to describe the historical landmark studies that have marked major progress, either in their archaeological applications or in enhancing our understanding of the tools. They include the adoption of maize agriculture, marine-focused diets amongst coastal hunter–gatherers, trophic level amongst Glacial-period modern humans and Neanderthals, and the use of savannah resources by early hominins in Africa. Particular attention is given to the progress made in addressing the challenges that have arisen out of these studies, including issues related to the routing of dietary nutrients. I conclude with some firm, and some more speculative, pointers about where the field may be heading in the next decade or so.
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Accumulating isotopic evidence from fossil hominin tooth enamel has provided unexpected insights into early hominin dietary ecology. Among the South African australopiths, these data demonstrate significant contributions to the diet of carbon originally fixed by C(4) photosynthesis, consisting of C(4) tropical/savannah grasses and certain sedges, and/or animals eating C(4) foods. Moreover, high-resolution analysis of tooth enamel reveals strong intra-tooth variability in many cases, suggesting seasonal-scale dietary shifts. This pattern is quite unlike that seen in any great apes, even 'savannah' chimpanzees. The overall proportions of C(4) input persisted for well over a million years, even while environments shifted from relatively closed (ca 3 Ma) to open conditions after ca 1.8 Ma. Data from East Africa suggest a more extreme scenario, where results for Paranthropus boisei indicate a diet dominated (approx. 80%) by C(4) plants, in spite of indications from their powerful 'nutcracker' morphology for diets of hard objects. We argue that such evidence for engagement with C(4) food resources may mark a fundamental transition in the evolution of hominin lineages, and that the pattern had antecedents prior to the emergence of Australopithecus africanus. Since new isotopic evidence from Aramis suggests that it was not present in Ardipithecus ramidus at 4.4 Ma, we suggest that the origins lie in the period between 3 and 4 Myr ago.
Conference Paper
Analyses of the strontium isotope ratio (Sr-86/Sr-87) of vertebrate fossils can provide information about palaeobiological attributes such as habitat use and movement patterns. Diagenetic contaminants can alter the Sr-87/Sr-86 ratio of fossils, however, complicating palaeobiological interpretations. Several pretreatment protocols have been developed to separate diagenetic contaminants from biogenic Sr. While the methods can remove some diagenetic Sr, it has not been shown that any technique removes all contamination. The extent to which pretreatment removes diagenetic Sr can be quantified through analysis of the (87)/Sr/Sr-86 ratios of fossil marine mammal bones and teeth buried in sediments with non-marine diagenetic Sr-87/Sr-86 signatures. To do this, we examined Holocene seals recovered from archaeological sites in Greenland and California, as well as a Miocene whale from Maryland. Our results demonstrate that although pretreatment eliminated some contaminants from bone, a large percentage (up to 80%) of diagenetic Sr remained after treatment. In contrast, pretreatment does appear to remove nearly all (greater than or equal to similar to 95%) diagenetic Sr from tooth enamel.
(13)C/^(12)C ratios have been determined for plant tissue from 104 species representing 60 families. Higher plants fall into two categories, those with low δ_(PDB1) ^(13)C values (-24 to -34‰) and those with high δ ^(13)C values (-6 to -19‰). Algae have δ^(13)C values of -12 to -23‰. Photosynthetic fractionation leading to such values is discussed.
EVOLUTIONARY ANALYSIS OF CONTEMPORARY HUMAN DIETARY preferences is an aggregate science, consisting of several distinct approaches. These include: (1) analysis of early hominid diets; (2) the study of the diets of non-human primate species and possible regulating principles underlying them; and (3) theories concerned with patterns of foraging by animal species in general.