Steven J C Gaulin

Steven J C Gaulin
University of California, Santa Barbara | UCSB · Department of Anthropology

PhD Harvard University, Biological Anthropology

About

107
Publications
44,870
Reads
How we measure 'reads'
A 'read' is counted each time someone views a publication summary (such as the title, abstract, and list of authors), clicks on a figure, or views or downloads the full-text. Learn more
7,143
Citations
Introduction
I am an evolutionist--interested broadly in natural history and almost anything Darwin's theory can illuminate about it. More narrowly I'm interested in sexual selection, evolutionary psychology, evolutionary anthropology, and their various intersections. I work on sex differences in anatomy, physiology, psychology and behavior. In conjunction with these interests I teach evolutionary science to roughly 1000 undergraduates per year.
Additional affiliations
July 2003 - present
University of California, Santa Barbara
Position
  • Professor
July 2003 - present
University of California, Santa Barbara
Position
  • Professor
September 1977 - June 2003
University of Pittsburgh
Position
  • Professor

Publications

Publications (107)
Article
Full-text available
Facial width-to-height ratio (fWHR) has been proposed as a sexually dimorphic signal in humans that develops under the influence of pubertal testosterone (T); however, no studies have examined the association between fWHR and T during the phase in which facial growth is canalized-adolescence. In a sample of adolescent Tsimane males, we evaluate the...
Article
Full-text available
Sexual selection theory suggests that the sex with a higher potential reproductive rate will compete more strongly for access to mates. Stronger intra-sexual competition for mates may explain why males travel more extensively than females in many terrestrial vertebrates. A male-bias in lifetime distance travelled is a purported human universal, alt...
Article
Polyunsaturated fatty acids play critical roles in brain development and function, and their levels in human breast milk closely reflect the long-term diet. The fatty acid contents of human milk samples from 28 countries were used to predict averaged 2009 and 2012 test scores in mathematics, reading, and science from the Programme for International...
Article
Full-text available
Fundamental and formant frequencies influence perceived pitch and are sexually dimorphic in humans. The information content of these acoustic parameters can illuminate the forces of sexual selection shaping vocal sex differences as well as the mechanisms that ensure signal reliability. We use multiple regression to examine the relationships between...
Article
Full-text available
While waist/hip ratio (WHR) and body mass index (BMI) have been the most studied putative determinants of female bodily attractiveness, BMI is not directly observable, and few studies have considered the independent roles of waist and hip size. The range of attractiveness in many studies is also quite limited, with none of the stimuli rated as high...
Article
Full-text available
Human sexual dimorphism has been widely misunderstood. A large literature has underestimated the effect of differences in body composition and the role of male contest competition for mates. It is often assumed that sexually dimorphic traits reflect a history of sexual selection, but natural selection frequently builds different phenotypes in males...
Article
In many species, females and males form long‐term mating bonds, but marriage—and especially arranged marriage—are uniquely human traits. While marriage practices impact many cultural phenomena, they also can have evolutionary (i.e., fitness) consequences. Strongly felt but not necessarily conscious mating preferences presumably evolved because they...
Article
Full-text available
The idea that human males are most strongly attracted to traits that peak in women in the nubile age group raises the question of how well women in that age group contend with the potential hazards of a first pregnancy. Using data for 1.7 million first births from 1990 U.S. natality and mortality records, we compared outcomes for women with first b...
Article
Full-text available
Sexual selection researchers have traditionally focused on adult sex differences; however, the schedule and pattern of sex-specific ontogeny can provide insights unobtainable from an exclusive focus on adults. Recently, it has been debated whether facial width-to-height ratio (fWHR; bi-zygomatic breadth divided by midface height) is a human seconda...
Article
Full-text available
This study aims to investigate assortative mating based on mate value from male perspective. Male participants (132 Brazilian and 106 American) evaluated hypothetical “stimulus” males described in terms of physical attractiveness, social skills, and social status (each varied in high or low levels). Participants rated each stimulus and each stimulu...
Preprint
Full-text available
Sexual selection researchers have traditionally focused on adult sex differences; however, the schedule and pattern of sex-specific ontogeny can provide insights unobtainable from an exclusive focus on adults. Recently, it has been debated whether facial width-to-height ratio (fWHR; bi-zygomatic breadth divided by midface height) is a human seconda...
Article
For humans, voice pitch is highly flexible and, when lowered, makes male speakers sound more dominant, intimidating, threatening, and likely to aggress. Importantly, pitch lowering could not have evolved as a threat signal with these effects on signal receivers unless it were honest on average. Drawing on Enquist's retaliation-cost model, we tested...
Article
Voice pitch is the primary perceptual correlate of fundamental frequency (fo) and describes how low or high a voice is perceived by listeners. Prior research showed that men whose habitual voice pitch is lower are perceived to have stronger fighting ability. However, voice pitch is also flexible and can thus be used facultatively to signal states t...
Article
Full-text available
We report the first cross-cultural and cross-organizational evidence for an evolved hazing motivation. Using experiments performed in the United States, Japan, and among members of a hazing and a nonhazing organization, we demonstrate an invariant set of core hazing predictors. In particular, we show that the perception of near-term group benefits,...
Article
Full-text available
Objectives: A core assumption of life history theory and the immunocompetence handicap hypothesis (ICHH) is that testosterone (T) upregulates energetic investment in mating effort at the expense of immunity. This tenet, along with observed positive relationships between estrogens and immunity, may contribute to the higher observed morbidity and mo...
Article
Selection should favor mating preferences that increase the chooser's reproductive success. Many previous studies have shown that the women men find most attractive in well-nourished populations have low body mass indices (BMIs) and small waist sizes combined with relatively large hips, resulting in low waist-hip ratios (WHRs). A frequently propose...
Article
This study explored undergraduate women’s mating-market expectations in Brazil and the United States. Participants (n = 387) were shown descriptions of hypothetical stimulus females that were varied to yield all combinations of 2 levels (high/low) of 3 attributes (physical attractiveness/social skills/social status). They subsequently rated each st...
Article
Full-text available
We examine the widely accepted view that very low waist-hip ratios and low body mass indices (BMIs) in women in well-nourished populations are judged attractive by men because these features reliably indicate superior fertility. In both subsistence and well-nourished populations, relevant studies of fertility do not support this view. Rather studie...
Article
Full-text available
It is widely claimed that in well-nourished populations, very low female waist-hip ratios (WHRs) together with low body mass indices (BMIs) are judged attractive by men because these features reliably indicate superior health and fertility. However, studies show that mortality rates are higher in women with low BMIs than in women with average BMIs...
Article
Full-text available
Objectives: Humans-and several other apes-exhibit a unique pattern of post-natal adrenal maturation; however, the causes and consequences of variation in adrenal development are not well understood. In this study, we examine developmental and age-related maturation of the adrenal gland (measured via dehydroepiandrosterone-sulfate [DHEA-S]) for pot...
Article
Full-text available
Sex differences in reproductive strategy and the sexual division of labor resulted in selection for and maintenance of sexual dimorphism across a wide range of characteristics, including body size, hormonal physiology, behavior, and perhaps spatial abilities. In laboratory tasks among undergraduates there is a general male advantage for navigationa...
Article
Full-text available
Males in many non-monogamous species have larger ranges than females do, a sex difference that has been well documented for decades and seems to be an aspect of male mating competition. Until recently, parallel data for humans have been mostly anecdotal and qualitative, but this is now changing as human behavioral ecologists turn their attention to...
Chapter
The evolved psychology of conflict and cooperation among kin depends on the ultimate causes of kin interaction. This chapter reviews the relevant evolutionary theory and outlines its potential application to the study of human kin interactions and concomitant psychology, within and beyond the nuclear family. The problem for sociobiology and allied...
Article
The human voice is one of the most conspicuous and dimorphic human secondary sexual characteristics; males’ low fundamental and formant frequencies barely overlap with females’. Researchers often assert that low male voices are costly signals of phenotypic quality; however, no evidence currently exists linking low voices with indicators of quality...
Article
Full-text available
The costs imposed by a romantic partner's mixed reproductive strategy (MRS) generate selection pressures for anticipatory responses to mitigate or avoid those costs. People will differ in their vulnerability to those costs, based in part on the qualities of their romantic rivals. Thus, we predicted that individuals at high risk of a partner's MRS-w...
Article
Full-text available
Evolutionary approaches to the study of romantic jealousy have principally been guided by the idea that there are two types of threats to romantic relationships—sexual and emotional—and that these two affect men and women’s fitness differently. While this approach has garnered considerable empirical support, it has not investigated the full concept...
Article
Convergent evidence from neuronal biology and hominin brain hypertrophy suggests that omega-3 fatty acids are a limiting resource for neural and cognitive development in Homo sapiens, and therefore that children from populations with higher omega-3 availability should display superior cognitive performance. Using multiple regression, we tested this...
Article
Full-text available
Background: Age at menarche is often used to measure maturational tempo in girls. Unfortunately, no parallel marker exists for boys. It is suggested that voice change has a number of advantages as a marker of the timing and degree of male pubertal development. Aim: Traditional auxological methods are applied to voice change in order to compare d...
Article
Full-text available
Breast milk fatty acid (FA) composition varies greatly among individual women, including in percentages of the long-chain polyunsaturated FAs (LCPUFA) 20:4n-6 (arachidonic acid, AA) and 22:6n-3 (docosahexaenoic acid, DHA), which are important for infant neurological development. It has been suggested that owing to wide variation in milk LCPUFA and...
Article
Full-text available
Because the first neurons evolved in an environment high in the n-3 (omega-3) fatty acid docosahexaenoic acid (DHA), this fatty acid became a major component of neural structure and function and makes up 10% of the dry weight of the human brain. Since n-3 fatty acids must come from the diet, this suggests a possible positive role for dietary n-3 fa...
Article
Current research increasingly suggests that spatial cognition in humans is accomplished by many specialized mechanisms, each designed to solve a particular adaptive problem. A major adaptive problem for our hominin ancestors, particularly females, was the need to efficiently gather immobile foods which could vary greatly in quality, quantity, spati...
Article
Full-text available
Low mean fundamental frequency (F(0)) in men's voices has been found to positively influence perceptions of dominance by men and attractiveness by women using standardized speech. Using natural speech obtained during an ecologically valid social interaction, we examined relationships between multiple vocal parameters and dominance and attractivenes...
Article
Full-text available
Men's copulatory success can often be predicted by measuring traits involved in male contests and female choice. Previous research has demonstrated relationships between one such vocal trait in men, mean fundamental frequency (F(0)), and the outcomes and indicators of sexual success with women. The present study investigated the role of another voc...
Article
Full-text available
Fluctuating asymmetry (FA) and waist-to-hip ratio (WHR) are frequently studied physical attractiveness variables in social and evolutionary psychology. FA represents deviations in bilateral symmetry—differences between left and right body parts. WHR is the ratio of the smallest part of the waist to the largest part of the hips. Although FA and WHR...
Article
Full-text available
Boserup (1970) views dowry as a payment made by women to guarantee future support for them and their children under circumstances where their own contributions to subsistence are relatively small. We call this the labor-value model. Here, building on the polygyny threshold theory from behavioral ecology (Orians 1969), we view dowry as a reproductiv...
Article
On average, men have 61% more muscle mass than women (d=3), a sex difference which is developmentally related to their much higher levels of testosterone. Potential benefits of greater male muscle mass include increased mating opportunities, while potential costs include increased dietary requirements and decreased immune function. Using data on ma...
Article
With respect to aggressiveness it is not enough to say that humans are "like other mammals." We resemble only those species where males have higher maximum reproductive rates than females. In such species males evolve a set of hormonally mediated competitive traits via sexual selection. Because humans match the predictions of this general evolution...
Article
Upper-body fat has negative effects and lower-body fat has positive effects on the supply of long-chain polyunsaturated fatty acids that are essential for neurodevelopment. Thus, waist-hip ratio (WHR), a useful proxy for the ratio of upper-body fat to lower-body fat, should predict cognitive ability in women and their offspring. Moreover, because t...
Article
Recent evidence (Skorecki et al. 1997) of significant differences between the Y chromosomes of Jewish priests (Kohanim) and laymen (Israelites) indicate very high degrees of paternity certainty (p, the probability that a man's wife's children are his own, Hartung 1985). Estimates of gene flow into the Kohanim from Israelites indicate that approxima...
Chapter
Full-text available
A materialist view of psychology requires that we eventually consider the functions for which the mind has been sculpted by natural and sexual selection. These various adaptive functions are the raisons d' être of the large array of cognitive modules that comprise the human mind. These modules are not designed for direct, conscious fitness calculat...
Article
Full-text available
We present evidence for an evolved sexually dimorphic adaptation that activates spatial memory and navigation skills in response to fruits, vegetables and other traditionally gatherable sessile food resources. In spite of extensive evidence for a male advantage on a wide variety of navigational tasks, we demonstrate that a simple but ecologically i...
Article
Men's vocal folds and vocal tracts are longer than those of women, resulting in lower fundamental frequency (F0) and closer spacing of formant frequencies (formant dispersion, Df) in men than in women. The evolutionary reasons for these sex differences are uncertain, but some evidence implicates male dominance competition. Previous manipulations of...
Article
The energy demands of pregnancy and lactation together with the accumulation of stored fat in human females during development suggest that a critical level of fat may be required for menarche; but multivariate analyses have supported the alternative view that skeletal growth is the main factor. However, significant differences between upper- and l...
Chapter
Full-text available
In the study of sex differences in spatial ability, multiple levels of explanation – functional, phylogenetic, developmental, and proximate – have made reciprocal contributions toward a more coherent view of a behavioral sex difference and its evolution, development and neurobiology. In 1985, Wimer and Wimer commented that hippocampal function: “ha...
Article
Using data from the Third National Health and Nutrition Examination Survey (NHANES III), conducted from 1988-1994, we investigated the effect of reproduction on the distribution of body fat in well-nourished American women. While women tend to gain weight and fat with succeeding pregnancies, if age and body mass index are controlled, increasing par...
Article
The developmental and anatomical causes of human voice sexual dimorphisms are known, but the evolutionary causes are not. Some evidence suggests a role of intersexual selection via female mate choice, but other evidence implicates male dominance competition. In this study, we examine the relationships among voice pitch, dominance, and male mating s...
Article
Full-text available
Much recent research has focused on the ratio of the lengths of the second to fourth manual digits (2D:4D) as a predictor of the degree of expression of sexually dimorphic and other sex-hormone-mediated traits. However, published findings are often contradictory or subject to various methodological problems. In the present study, we reassessed the...
Article
Gaulin, McBurney, and Brakeman-Wartell (1997) found that college students reported both matrilateral and sex biases in the investment of aunts and uncles (aunts invested more than uncles). They interpreted the matrilateral bias as a consequence of paternity uncertainty. We replicated that study with Orthodox Jewish college students, selected becaus...
Article
Full-text available
Gaulin, McBurney, and Brakeman-Wartell (1997) found that college students reported both matrilateral and sex biases in the investment of aunts and uncles (aunts invested more than uncles). They interpreted the matrilateral bias as a consequence of paternity uncertainty. We replicated that study with Orthodox Jewish college students, selected becaus...
Article
Full-text available
Two instances of helping behavior in Bridled Titmice (Baeolophus wollweberi) were observed. In each case, one auxiliary bird assisted in feeding chicks at a nest. Both helpers were male; one a hatching year bird and the other an after hatching year bird. It was possible to quantify the feeding efforts of all three birds at one nest, but not at the...
Article
Full-text available
In a study of the kin investment of aunts and uncles we show that the laterality effect expected as a result of paternity uncertainty is statistically reliable but somewhat smaller than the sex effect. Matrilateral aunts invest significantly more than patrilateral aunts, and the same is true for uncles. Regardless of laterality, however, aunts inve...
Article
Male and female college students played the commercial game MemoryTM, which required them to recall the location of previously viewed items, and also completed a 20-item mental rotation task. As is typical, males performed better than females (d = .67) on the mental rotation task. In contrast, females outperformed males by a large margin (d = −.89)...
Article
Darwin's principle of evolution by natural selection provides a theoretical basis for functional analyses of behaviour. This approach is complementary to traditional psychology: ideas about what behaviour was designed to do suggest how it might be organized. The cross-cultural record, because it focuses on the broadest characterization of human beh...
Article
Full-text available
In a study of the kin investment of aunts and uncles we show that the laterality effect expected as a result of paternity uncertainty is statistically reliable but somewhat smaller than the sex effect. Matrilateral aunts invest significantly more than patrilateral aunts, and the same is true for uncles. Regardless of laterality, however, aunts inve...
Article
Full-text available
Sexual selection theory provides a powerful model for the analysis of psychological sex differences. This research examined (a) tests of several sex differences in mating psychology predicted from sexual selection theory, (b) broad developmental hypotheses about sex differences in mating psychology--through the relationship of mating psychology to...
Article
It has been hypothesized (Daly and Wilson 1982) that resemblance claims about, and names given to, newborns will be biased in a paternal direction. There are also evolutionary reasons to expect that the magnitude of this bias will vary with the laterality of the speaker, the infants' birthorder, the duration of the parents' union, and the possibili...
Chapter
When articulated in genetic terms, Darwin’s (1859) theory of evolution by natural selection is the most powerful tool we have for explaining why living things are as they are (Fisher, 1958; Dawkins, 1982). The theory is powerful because its prerequisite conditions are minimal and its implications ubiquitous. Natural selection will be at work anywhe...
Article
Contemporary populations of Homo sapiens are sexually dimorphic on a variety of traits. In terms of stature, men are reliably between 4% and 10% taller than women in well-sampled human populations. Are cross-cultural differences in the magnitude of sexual dimorphism consistent with expectations from sexual selection theory? Prior studies have provi...
Article
The hippocampus plays an important role in spatial memory and spatial cognition in birds and mammals. Natural selection, sexual selection and artificial selection have resulted in an increase in the size of the hippocampus in a remarkably diverse group of animals that rely on spatial abilities to solve ecologically important problems. Food-storing...
Article
Many sex differences are likely to be adaptive consequences of sexual selection. Sex differences in spatial ability are well described for Homo sapiens and laboratory rodents, and such cognitive traits may also be shaped by sexual selection. An evolutionary model is outlined to predict the distribution of these sex differences across species. Sex d...
Article
The Trivers-Willard hypothesis joins the ideas of R.A. Fisher and A.J. Bateman to model parental investment strategies. Trivers and Willard argue that any overall investment bias favoring either daughters or sons would be maladaptive. Nevertheless, they suggest that, in effectively polygynous species, more complex, conditional sex biases could be a...
Article
Full-text available
In a study of two congeneric rodent species, sex differences in hippocampal size were predicted by sex-specific patterns of spatial cognition. Hippocampal size is known to correlate positively with maze performance in laboratory mouse strains and with selective pressure for spatial memory among passerine bird species. In polygamous vole species (Ro...
Article
Full-text available
Sex differences in spatial skills are sometimes attributed to sex differences in spatial experience. This hypothesis rests on two assumptions: Spatial experience typically differs with sex and spatial experience has lasting effects on spatial cognition. We tested the latter assumption in a controlled experiment with wild-caught prairie voles (Micro...
Article
Sex differences in spatial skills are sometimes attributed to sex differences in spatial experience. This hypothesis rests on two assumptions: Spatial experience typically differs with sex, and spatial experience has lasting effects on spatial cognition. We tested the latter assumption in a controlled experiment with wild-caught prairie voles ( Mic...
Article
Full-text available
The hypothesis that sex differences in maze learning result from sex differences in activity was tested with wild-caught prairie (Microtus ochrogaster) and meadow (M. pennsylvanicus) voles. For 38 voles error production and activity were simultaneously measured in a series of 7 symmetrical mazes. Repeated-measures analyses of variance (ANOVAS) exam...
Article
Full-text available
Attempts to explain not only the rarity of dowry, but also why it occurs in the societies it does. The model builds on theory derived from behavioural ecology and views dowry as a form of competition among women for husbands. Before developing this model, reviews an alternative explanation of dowry that views the practice as an outcome of the sexua...