Sexual differences in European Neanderthal crania with special reference to the Krapina remains

Problems relating to the identification of sex in Neanderthal specimens are discussed. Three morphological features—morphology of the mastoid process and surrounding area, form of the supraorbital torus at glabella and the superciliary region, and the rugosity of the nuchal plane—were selected as most indicative of sex in Neanderthal crania based on observations from the Krapina collection and on those European specimens with pelvicly determined sex. Thirteen Neanderthal crania (eight males, five females) are sexed on the basis of these criteria, and the pattern and degree of sexual dimorphism determined for this sample is compared to those exhibited by other samples of more recent European hominids. It is concluded that the degree of sexual dimorphism in Neanderthal crania, as defined by this study, is consistent with that observed in the other fossil samples and that Neanderthals exhibit slightly more cranial sexual dimorphism than more recent Europeans. Models for explaining this are discussed as is the difference in pattern of change and degree of sexual dimorphism between the cranium and postcranium during later prehistoric hominid evolution in Europe.     

Sexual dimorphism and cultural evolution in the Late Pleistocene and Holocene of Europe

Dental, cranial and body size data are reviewed for European Upper Paleolithic, Mesolithic and Neolithic males and females. Over these three periods there is a substantial decrease in the level of sexual dimorphism. From separate analysis of trends occurring between males and females, it is shown that the major cause for this decrease in sexual dimorphism is gracilization of the males between the Upper Paleolithic and Mesolithic. Reduction in males is related to shifting technological patterns associated with hunting and changes in the types of animals hunted. Further reduction in sexual dimorphism between the Mesolithic and Neolithic and from the Neolithic to modern European populations is shown to be more closely tied to changes occurring among females. Analysis of changing patterns of sexual dimorphism in Late Pleistocene and Holocene populations of Europe suggests an interrelationship between cultural and biological evolution.     

Sexual dimorphism in relation to big-game hunting and economy in modern human populations

Postcranial skeletal data from two recent Eskimo populations are used to test David Frayer's model of sexual dimorphism reduction in Europe between the Upper Paleolithic and Mesolithic. Frayer argued that a change from big-game hunting and adoption of new technology in the Mesolithic reduced selection for large body size in males and led to a reduction in skeletal sexual dimorphism. Though aspects of Frayer's work have been criticized in the literature, the association of big-game hunting and high sexual dimorphism is untested. This study employs univariate and multivariate analysis to test that association by examining sexual dimorphism of cranial and postcranial bones of two recent Alaskan Eskimo populations, one being big-game (whale and other large marine mammal) hunting people, and the second being salmon fishing, riverine people. While big-game hunting influences skeletal robusticity, it cannot be said to lead to greater sexual dimorphism generally. The two populations had different relative sexual dimorphism levels for different parts of the body. Notably, the big-game hunting (whaling) Eskimos had the lower multivariate dimorphism in the humerus, which could be expected to be the structure under greatest exertion by such hunting in males. While the exertions of the whale hunting economic activities led to high skeletal robusticity, as predicted by Frayer's model, this was true of the females as well as the males, resulting in low sexual dimorphism in some features. Females are half the sexual dimorphism equation, and they cannot be seen as constants in any model of economic behavior. © 1993 Wiley-Liss, Inc.     

Sexual dimorphism in Southeast Asian crania: A geometric morphometric approach

Despite a number of studies stating that sexual dimorphism is population specific, sexual differences in Southeast Asian populations have received little attention. Previous studies in this region have focused on samples from Thailand or East Asian populations from China and Japan, examining sexual dimorphism predominantly of the postcranial bones, teeth and mandible with comparatively few cranial studies. These earlier studies have used traditional methods to metrically assess differences between the sexes. The aim of this study is to use geometric morphometric methods for the first time to quantify sexual dimorphism of Southeast Asian crania and extend knowledge of cranial sexual dimorphism beyond China, Japan and Thailand. A total of 35 unilateral and midline landmark coordinates were collected from 144 mainland and island Southeast Asian crania (89 male, 55 female). Using the shape analysis software Morphologika, principal components analysis and thin plate splines allowed for the statistical and visual exploration of shape differences. Differences included relative facial breadth, particularly across the zygomatic and postorbital regions and cranial vault breadth. Significant size dimorphism was also apparent. Overall expected accuracies were highest in the discriminant analysis using both shape and centroid size (86.8%).     

Sexual dimorphism and discriminant function sexing in indigenous South African crania

This study aimed to examine sexual dimorphism in, and to produce a practical discriminant function for determining the sex of indigenous, Bantu-speaking, South African crania. The types of data to be used were a small number of traditional, or mathematically transformed three-dimensional, linear measurements, comparable to those in use by most physical and forensic anthropologists. The samples to be examined, separately and pooled, were of the Cape Nguni, Natal Nguni and Sotho subgroups. In addition, three local populations (‘tribes’—Zulu, Xhosa and Southern Sotho) within these subgroups were also studied.

Univariate male/female ratios indicate significant sexual dimorphism in the pooled South African crania. Canonical variates analysis of the pooled sample showed that facial width is the strongest discriminating morphometric variable; cranial length and basi-bregmatic height are the next most significant features. Eight measurements derived from the three-dimensional data were used to produce a series of discriminant functions for sex determination in the pooled sample, for which an accuracy of 77–80% was attained. Analysis of the calvaria and face, separately, has shown that the sex of damaged material can be diagnosed with a reasonable degree of accuracy (75–76%).

The new functions for the pooled indigenous South African sample provide improved sex discrimination accuracy compared to those obtained by employing the commonly utilised statistics of Giles & Elliot (1963), even when a modified sectioning point is used. Functions calculated for the separate local populations gave variable and fairly low improvements in sexing accuracy. As the subdivisions at all levels are at present quite rapidly disappearing in South Africa, for most purposes it is now best to simply apply the pooled data functions for sexing crania.     

Craniometric sexual dimorphism inLeontopithecus Lesson, 1840 (Callitrichidae, Primates)

Lion tamarins are among the World's most critically endangered primates. Many studies have been produced under guidance of the International Management Committees for the preservation and management of these tamarins. Primates present morphological sexual differences in a wide range of characteristics, including cranial morphology. Studies of sexual dimorphism in the cranial morphology of theLeontopithecus are few in number and contradictory in their results. In order to check for the existence of sexual dimorphism in lion tamarins the present study analyzed 17 craniometric distances on 56 crania of three species of lion tamarins (Leontopithecus): 20L. rosalia (14 females and 6 males); 13L. chrysomelas (6 females and 7 males); and 23L. chrysopygus (8 females and 15 males). All crania are housed in the CPRJ-FEEMA collection (Primatological Center of Rio de Janeiro) and came from animals born in captivity.L. chrysopygus was more sexually dimorphic (10/17 measurements, 59%) thanL. chrysomelas (9/17 measurements, 53%) orL. rosalia (7/17 measurements, 41%). In all three species, male values are greater than the female ones, except for orbital breadth (m7) inL. rosalia. However, this distance is not sexually dimorphic in this species. This study reveals that some cranial distances, especially in the facial region, are sexually dimorphic in lion tamarins.     

华北人欧洲人和澳洲土著人的头骨厚度

The thickness of the cranial vault at the midline on the mid-frontal squama, pre-bregmatic einence, frontal at bregma, parietal at vertex, occipital at lambda and the external occipita1 protuberance was recorded in 40 male and 7 female Northern Chinese crania, 47 male and 52 female Australian Aboriginal crania and 13 male European crania using specially nodified vernier calipers. Comparison of vault thickness data obtained through direct measurement with those obtained fron lateral radiographs indicated that direct measurenent provided consistently more accurate results.
Male and fermale samples were processed separately so that the extent of sexbased variation could be examined.Student's t test was used to compare the sample means and the percentage of sexual dimorphism for each dimension was calculated according to Garn et al, (1964).The possibility of an allometric association between the thickness of the bones within the cranial vault, size of the cranial vault and stature was examined using Spearman's rank correlation coefficient and the Australian Aboriginal sample.
All but one of the mean thickness dimensions in the Australian Aboriginal male sample is significantly greater than the Northern Chinese and European means. The female results support those obtained with the males.In both males and females thickness at the external occipital protuberance, in all of the populations examined,did not correlate highly with that obtained from other parts of the cranial vault.This reflects the high degree of morphological variation in the position of the internal occipital protuberance and its influence on cranial vault thickness dimensions recorded at the external occipital protuberance.The European and Northern Chinese samples have similar cranial vault thickness dimensions. The Spearman's rank correlation coefficient matrix scores provide sone support for a biological association between vault thickness and overall cranial size. However, there appears to be little support for an association between stature and cranial vault thickness. The difference between the male and female mean vault thickness dimensions were significant at bregma, vertex and the external occipital protuberance in Australian Aboriginals and lambda and the external occipital protuberance in Northern Chinese. Some caution is needed in the interpretation of the Northern Chinese female data as the sample is extremely small.
Evidence of trauma, supressed fractures, is extremely common on the vaults of Australian Aboriginal crania from southern and central Australia. Traditionally Australian Aboriginals, males and females, involved in agressive dispute will use a substantial wooden implement and strike to the head of thir opponent(Meggitt 1962).The injuries that result from this are more common in females than in male. This form of social interaction must have rigorously selected against those individuals with thinner bones in their cranial vaults. To a large degree this may explain the greatly thickened vaults in Australian Aboriginals relative to Europeans and Northern Chines.This may also provide a clue to the factors resulting in the development of marked cranial vault thickness in Homo erectus.
     

The evolution of sexual size dimorphism in the house finch. IV. Population divergence in ontogeny

Differences among taxa in sexual size dimorphism of adults can be produced by changes in distinct developmental processes and thus may reflect different evolutionary histories. Here we examine whether divergence in sexual dimorphism of adults between recently established Montana and Alabama populations of the house finch (Carpodacus mexicanus) can be attributed to population differences in growth of males and females. In both populations, males and females were similar at hatching, but as a result of sex-specific growth attained sexual size dimorphism by the time of independence. Timing and extent of growth varied between the sexes: Females maintained maximum rates of growth for a longer time than males, whereas males had higher initial growth rates and achieved maximum growth earlier and at smaller sizes than females. Ontogeny of sexual dimorphism differed between populations, but in each population, sexual dimorphism in growth parameters and sexual dimorphism at the time of nest leaving were similar to sexual dimorphism of adults. Variation in growth of females contributed more to population divergence than did growth of males. In each population, we found close correspondence between patterns of sexual dimorphism in growth and population divergence in morphology of adults: Traits that were the most sexually dimorphic in growth in each population contributed the most to population divergence in both sexes. We suggest that sex-specific expression of phenotypic and genetic variation throughout the ontogeny of house finches can result in different responses to selection between males and females of the same age, and thus produce fast population divergence in the sexual size dimorphism.     

Reversed brain size sexual dimorphism accompanies loss of parental care in white sticklebacks

Uncovering factors that shape variation in brain morphology remains a major challenge in evolutionary biology. Recently, it has been shown that brain size is positively associated with level of parental care behavior in various taxa. One explanation for this pattern is that the cognitive demands of performing complex parental care may require increased brain size. This idea is known as the parental brain hypothesis (PBH). We set out to test the predictions of this hypothesis in wild populations of threespine stickleback (Gasterosteus aculeatus). These fish are commonly known to exhibit (1) uniparental male care and (2) sexual dimorphism in brain size (males>females). To test the PBH, we took advantage of the existence of closely related populations of stickleback that display variation in parental care behavior: common marine threespine sticklebacks (uniparental male care) and white threespine sticklebacks (no care). To begin, we quantified genetic differentiation among two common populations and three white populations from Nova Scotia. We found overall low differentiation among populations, although F_ST was increased in between‐type comparisons. We then measured the brain weights of males and females from all five populations along with two additional common populations from British Columbia. We found that sexual dimorphism in brain size is reversed in white stickleback populations: males have smaller brains than females. Thus, while several alternatives need to be ruled out, the PBH appears to be a reasonable explanation for sexual dimorphism in brain size in threespine sticklebacks.     

Genetic differences among populations in sexual dimorphism: evidence for selection on males in a dioecious plant

Genetic variation among populations in the degree of sexual dimorphism may be a consequence of selection on one or both sexes. We analysed genetic parameters from crosses involving three populations of the dioecious plant Silene latifolia, which exhibits sexual dimorphism in flower size, to determine whether population differentiation was a result of selection on one or both sexes. We took the novel approach of comparing the ratio of population differentiation of a quantitative trait (Q(ST) ) to that of neutral genetic markers (F(ST) ) for males vs. females. We attributed 72.6% of calyx width variation in males to differences among populations vs. only 6.9% in females. The Q(ST) /F(ST) ratio was 4.2 for males vs. 0.4 for females, suggesting that selection on males is responsible for differentiation among populations in calyx width and its degree of sexual dimorphism. This selection may be indirect via genetic correlations with other morphological and physiological traits.     

Common features of sexual dimorphism in the cranial airways of different human populations

Sexual dimorphism in the human craniofacial system is an important feature of intraspecific variation in recent and fossil humans. Although several studies have reported different morphological patterns of sexual dimorphism in different populations, this study searches for common morphological aspects related to functional anatomy of the respiratory apparatus. 3D geometric morphometrics were used to test the hypothesis that due to higher daily energy expenditure and associated greater respiratory air consumption as well as differences in body composition, males should have absolutely and relatively greater air passages in the bony cranial airways than females. We measured 25 3D landmarks in five populations (N = 212) of adult humans from different geographic regions. Male average cranial airways were larger in centroid sizes than female ones. Males tended to show relatively taller piriform apertures and, more consistently, relatively taller internal nasal cavities and choanae than females. Multivariate regressions and residual analysis further indicated that after standardizing to the same size, males still show relatively larger airway passages than females. Because the dimensions of the choanae are limiting factors for air transmission towards the noncranial part of the respiratory system, the identified sex-specific differences in cranial airways, possibly shared among human populations, may be linked with sex-specific differences in body size, composition, and energetics. These findings may be important to understanding trends in hominin facial evolution.     

The ontogeny of sexual dimorphism in the cranium of Bornean orang-utans (Pongo pygmaeus pygmaeus): I. Univariate analyses

Based on a homogeneous sample of 212 individuals spanning all postnatal age periods, we examine the ontogeny of cranial sexual dimorphism in Bornean orang-utans (Pongo pygmaeus pygmaeus) by means of univariate statistics. A distinct pattern emerges at the early juvenile stage and continues at all subsequent stages with males tending to exceed females in all cranial dimensions. In conjunction, starting at mid-juvenile stage, there is a strong tendency for an increase in number and strength of significant cranial sex differences, all of them in favor of males. Significant sex differences in the viscerocranium, reflecting stronger prognathism in males, emerge prior to those in the neurocranium. The total ontogenetic pattern of cranial sexual dimorphism in orang-utans is remarkably similar to that of gorillas, except that there is no evidence of a sex difference in timing of the adolescent growth spurt in the orang-utan. As for other catarrhine species (Wood 1976), male variance of cranial dimensions tends to be greater than that of females, thus lending support to Leutenegger & Cheverud's (1982, 1985) model on the evolution of character dimorphism by means of variance dimorphism.     

Three-dimensional geometric morphometric analysis of cranio-facial sexual dimorphism in a Central European sample of known sex

This article presents an approach for estimating the sexual dimorphism of adult crania using three-dimensional geometric morphometric methods. The study sample consisted of 139 crania of known sex (73 males and 66 females) belonging to persons who lived during the first half of the 20th century in Bohemia. The three-dimensional co-ordinates of 82 ecto-cranial landmarks and 39 semi-landmarks covering the midsagittal curve of the cranial vault were digitised using a MicroScribe G2X contact digitiser. The purposes of the investigation were to define the regions of the cranium where sexual dimorphism is most pronounced and to investigate the effectiveness of this method for determining sex from the shape of the cranium. The results demonstrate that it is better to analyse apportionable parts of the cranium rather than the cranium as a whole. Significant sexual differences (significance was determined using multivariate analysis of variance) were noted in the shape of the midsagittal curve of the vault, upper face, the region of the nose, orbits, and palate. No differences were recorded either in the shape of the cranium as a whole or in the regions of the base and the neurocranium. The greatest accuracy in determining sex was found in the region of the upper face (100% of study subjects correctly classified) and the midsagittal curve of the vault (99% of study subjects correctly classified).     

Causes of sex‐biased adult survival in ungulates: sexual size dimorphism,mating tactic or environment harshness?

Using both a conventional and a phylogenetic approach, we tested whether sexual size dimorphism, mating tactic and environmental conditions influenced the between-sex differences in adult survival among 26 populations of polygynous ungulates. As a general rule, male survival was both lower and more variable among species than female survival. Whatever the method we used, sexual size dimorphism had no direct influence on male-biased mortality. In food-limited environments, the survival of males relative to that of females was lower than in good environments, suggesting a cost of large size for males facing harsh conditions. On the other hand, the survival of males relative to that of females tended to increase with sexual size dimorphism in good environments, indicating that large size may be profitable for males facing favourable conditions. Lastly, we found that the between-sex differences in adult survival did not vary with sexual size dimorphism in harem-holding or tending species, but tended to increase with sexual size dimorphism in territorial species. Our analyses indicate that sexual size dimorphism does not lead directly to a decrease in male survival compared to that of females. Thus, environmental conditions rather than the species considered could shape between-sex differences in adult survival observed in ungulate populations.     

Selection on females can create 'larger males'

In many bird and mammal species, males are significantly larger than females. The prevailing explanation for larger-sized males is that sexual selection drives increased male size. In addition, researchers commonly assume that the extent of dimorphism indicates the strength of selection for increased size in males. Here, through reconstruction of ancestral morphology for males and females of one large avian clade we present data that contradict this assumption and illustrate that selection for decreased female size explains 'male-biased' dimorphism ca. 50% of the time. Our findings are also inconsistent with ecological niche partitioning between the sexes and increased breeding benefits from reduced female size as general explanations for the evolution of size dimorphism within the clade. We conclude that it is incorrect to assume sexual dimorphism results from a single selective factor, such as directional sexual selection on increased male size. Rather, we suggest that the selective forces leading to sexual dimorphism may vary between species and should be tested on a case-by-case basis using a phylogenetic approach.     

Patterns of growth and sexual size dimorphism in two species of box turtles with environmental sex determination

An adaptive explanation for environmental sex determination is that it promotes sexual size dimorphism when larger size benefits one sex more than the other. That is, if growth rates are determined by environment during development, then it is beneficial to match developmental environment to the sex that benefits more from larger size. However, larger size may also be a consequence of larger size at hatching or growing for a longer time, i.e., delayed age at first reproduction. Therefore, the adaptive significance of sexual size dimorphism and environmental sex determination can only be interpreted within the context of both growth and maturation. In addition, in those animals that continue to grow after maturation, sexual size dimorphism at age of first reproduction could differ from sexual size dimorphism at later ages as growth competes for energy with reproduction and maintenance. I compared growth using annuli on carapace scales in two species of box turtles (Terrapene carolina and T. ornata) that have similar patterns of environmental sex determination but, reportedly, have different patterns of sexual size dimorphism. In the populations I studied, sexual size dimorphism was in the same direction in both species; adult females were, on average, larger than adult males. This was due in part to males maturing earlier and therefore at smaller sizes than females. In spite of similar patterns of environmental sex determination, patterns of growth differed between the species. In T. carolina, males grew faster than females as juveniles but females had the larger asymptotic size. In T. ornata, males and females grew at similar rates and had similar asymptotic sizes. Sexual size dimorphism was greatest at maturation because, although males matured younger and smaller, they grew more as adults. There was, therefore, no consistent pattern of faster growth for females that may be ascribed to developmental temperature. Received: 20 March 1996 / Accepted: 10 March 1998     

The ontogeny of cranial sexual dimorphism in two old world monkeys:Macaca fascicularis (Cercopithecinae) andNasalis larvatus (Colobinae)

Allometric and heterochronic approaches to sexual dimorphism have contributed much to our understanding of the evolutionary morphology of the primate skull and dentition. To date, however, extensive studies of sexual dimorphism have been carried out only on the great apes and a few cercopithecine monkeys. To fill this gap, representative dimensions of the skull were collected among ontogenetic series of two dimorphic Old World monkeys:Macaca fascicularis (Cercopithecinae) andNasalis larvatus (Colobinae). The ontogeny of cranial sexual dimorphism was evaluated with least-squares bivariate regression, analysis of covariance (ANCOVA), and analysis of variance (ANOVA). Results indicate that within each species the sexes typically exhibit nonsignificant differences in ANCOVAs of ontogenetic trajectories, except for bivariate comparisons with bicanine breadth. AmongMacaca fascicularis, ANOVAs between males and females of common dental ages show that adult, and frequently subadult, males are significantly larger than females, i.e., sexual dimorphism develops via time and rate hypermorphosis (males primarily grow for a longer time period as well as faster). AmongNasalis larvatus, however, comparisons between males and females of common dental ages indicate that only adult males are significantly larger than females, i.e., sexual dimorphism develops primarily via time hypermorphosis (males grow for a longer time period). Within both species, females appear to exhibit an early growth spurt at dental age 2; that is, many cranial measures for females tend to be larger than those for males. Measures of the circumorbital region (e.g., browridge height), body weight, and bicanine breadth exhibit typically the highest sexual dimorphism ratios. The fact that postcanine toothrow length and neurocranial volume (less so inNasalis) demonstrate very low dimorphism ratios generally supports assertions that postnatal systemic growth (and associated selective pressures thereon) exerts a greater influence on facial, but not neural, dental, or orbital, development (Cochard, 1985, 1987; Shea, 1985a,b, 1986; Shea and Gomez, 1988; Sheaet al., 1990). Additional consideration of ontogenetic differences between species generally supports previous functional interpretations of subfamilial differences in cranial form related to agonistic displays in cercopithecine monkeys (Ravosa, 1990).     

Carnivory maintains cranial dimorphism between males and females: Evidence for niche divergence in extant Musteloidea

The evolution and maintenance of sexual dimorphism has long been attributed to sexual selection. Niche divergence, however, serves as an alternative but rarely tested selective pressure also hypothesized to drive phenotypic disparity between males and females. We reconstructed ancestral social systems and diet and used Ornstein–Uhlenbeck (OU) modeling approaches to test whether niche divergence is stronger than sexual selection in driving the evolution of sexual dimorphism in cranial size and bite force across extant Musteloidea. We found that multipeak OU models favored different dietary regimes over social behavior and that the greatest degree of cranial size and bite force dimorphism were found in terrestrial carnivores. Because competition for terrestrial vertebrate prey is greater than other dietary groups, increased cranial size and bite force dimorphism reduces dietary competition between the sexes. In contrast, neither dietary regime nor social system influenced the evolution of sexual dimorphism in cranial shape. Furthermore, we found that the evolution of sexual dimorphism in bite force is influenced by the evolution of sexual dimorphism in cranial size rather than cranial shape. Overall, our results highlight niche divergence as an important mechanism that maintains the evolution of sexual dimorphism in musteloids.     

Ontogenetic and sexual patterns in the cranial system of the brown rat (Rattus norvegicus Berkenhout, 1769) from Hai’l region,Kingdom of Saudi Arabia

The brown rat, Rattus norvegicus, is a model system in ecological and systematic science, but little is known about its skull morphology and developmental patterns. Our objective was to investigate the cranial ontogenetic patterns in the brown rats, from Hai’l, Kingdom of Saudi Arabia.Quantitative analysis of sexual shape dimorphisms (SShD) and age-classes were investigated using 28 landmarks plotted on two-dimensional images for dorsal and ventral views. Our results detected statistically significant sexual dimorphism (P-value <0.0001) in cranial shape and size for R. norvegicus. Nevertheless, males are much larger than females and display variation around the brain-case, while females tend to show greater variation around the occipital bone. In addition, there are subtle age-classes during ontogeny in the skull. However, the older age classes (i.e. age classes 3 and 4) represent well-built crania with an extended case of the brain and shortest nasal, while youngest specimens represent an elongated snout of minimum crania.Future GMM research should therefore examine the pre-defined age-classes and sex-related individuals in brown rat skulls in relation to genotype to characterize trends in skull shape variation that may affect teeth, zygomatic arches, brain case, and compartments of muscle attachments through its ecological patterns.     

Robusticity and sexual dimorphism in the postcranium of modern hunter-gatherers from Australia

Throughout much of prehistory, humans practiced a hunting and gathering subsistence strategy. Elevated postcranial robusticity and sexually dimorphic mobility patterns are presumed consequences of this strategy, in which males are attributed greater robusticity and mobility than females. Much of the basis for these trends originates from populations where skeletal correlates of activity patterns are known (e.g., cross-sectional geometric properties of long bones), but in which activity patterns are inferred using evidence such as archaeological records (e.g., Pleistocene Europe). Australian hunter-gatherers provide an opportunity to critically assess these ideas since ethnographic documentation of their activity patterns is available. We address the following questions: do skeletal indicators of Australian hunter-gatherers express elevated postcranial robusticity and sexually dimorphic mobility relative to populations from similar latitudes, and do ethnographic accounts support these findings. Using computed tomography, cross-sectional images were obtained from 149 skeletal elements including humeri, radii, ulnae, femora, and tibiae. Cross-sectional geometric properties were calculated from image data and standardized for body size. Australian hunter-gatherers often have reduced robusticity at femoral and humeral midshafts relative to forager (Khoi-San), agricultural/industrialized (Zulu), and industrialized (African American) groups. Australian hunter-gatherers display more sexual dimorphism in upper limb robusticity than lower limb robusticity. Attributing specific behavioral causes to upper limb sexual dimorphism is premature, although ethnographic accounts support sex-specific differences in tool use. Virtually absent sexual dimorphism in lower limb robusticity is consistent with ethnographic accounts of equivalently high mobility among females and males. Thus, elevated postcranial robusticity and sexually dimorphic mobility do not always characterize hunter-gatherers.