Intrageneric taxonomic distinction based on morphological variation in the macaque (Macaca) skeleton.

Taxonomic classification is important for understanding the natural world, yet current methods for species assessment often focus on craniodental morphology rather than the entire skeleton. Moreover, it is currently unknown how much variation could, or should, exist intragenerically. Here, we tested whether taxonomy can be accurately predicted based on patterns of morphological variation in macaques (H1 ) and whether postcranial bones reflect subgeneric macaque taxonomy similarly, or better, than the cranium (H2 ). Data included 3D scans of cranial and postcranial bones for eight macaque species (Macaca arctoides, Macaca fascicularis, Macaca fuscata, Macaca mulatta, Macaca nemestrina, Macaca nigra, Macaca radiata, and Macaca sylvanus). Fixed anatomical and semilandmarks were applied to scans of eight skeletal elements (crania = 45; mandible = 31; scapula = 66; humerus = 38; radius = 33; os coxa = 28; femur = 40; tibia = 40). For each skeletal element, regression analyses were performed to minimize the effects of sexual dimorphism. Between-groups principal components analysis was used to visualize the major patterns of among-species morphological variation, while the strength of correct taxon classification was measured with discriminant function analysis. Results suggested accepting the alternate hypothesis that different macaque species can be distinguished morphologically. Both cranial and many postcranial elements appeared to possess a taxonomic signal, and the limb bones-especially the upper limb-are reported to be more useful for taxonomic assessment than previously realized. Theoretically, certain behaviors and/or ecogeographical factors, as well as phylogeny, influenced skeletal morphology in macaques, likely contributing to taxonomic distinctions among different species.

Patterns of integration and modularity in the primate skeleton: a review.

The question of how complex morphologies evolve, given constraints imposed by genetic, developmental and functional factors, has been a topic of inquiry for many decades. In the mid-twentieth century the study of morphological trait covariation, and the implications of this for evolutionary diversification, was developed under the general concept of "morphological integration". Given the polygenic inheritance model underlying quantitative skeletal traits, and the existence of differential pleiotropic effects, it is assumed that variation in the genotype to phenotype map will lead to the emergence of semi-autonomous "modules" that share relatively stronger covariance (integration) among traits within them. Understanding these potential patterns of modularity in the primate skeleton is important for clarifying the seeming inconsistencies presented by "mosaic" morphologies found in fossil taxa, as well as providing hypothetical units of morphological evolution that can be compared across the primate order. A review of the primate skeletal integration and modularity literature was conducted with the aim of assessing (i) the general nature of primate skeletal integration patterns, and (ii) the extent to which any identified modularity patterns are ubiquitous across primates. The vast literature on cranial integration reveals some consistency in suggesting that the face and the neurocranium (and in some cases, the basicranium and vault) form distinct modules, but the intensity of this modular pattern varies across taxa. The much more modest postcranial integration literature suggests that apes show overall reduced covariation among skeletal regions compared with other anthropoid taxa, but the extent to which any identified modularity patterns hold true across primates is still very unclear. While much has been learned about primate skeletal integration in the past two decades, we still need more studies that establish benchmarks as to what constitutes an integrated modular structure, and that empirically test these potential modules across a wider range of primate taxa.

Morphological modularity in the anthropoid axial skeleton.

Previous research has found that hominoids have stronger modularity between limb elements than other anthropoids, suggesting that there is less constraint on morphological diversification (e.g., limb proportions) in hominoids in terms of evolutionary independence. However, degrees of modularity in the axial skeleton have not been investigated across a broad range of anthropoid taxa. Thus, it is unknown whether hominoids also have stronger modularity in the axial skeleton than other anthropoids, which has implications for the evolution of diverse torso morphologies in Miocene apes as well as the evolution of novel characteristics in the skull and vertebrae of fossil hominins. In this study, 12 anthropoid genera were sampled to examine degrees of modularity between axial skeletal elements (i.e., cranium, mandible, vertebrae, and sacrum). Covariance ratio coefficients were calculated using variance/covariance matrices of interlandmark distances for each axial skeletal element to evaluate degrees of modularity. The results showed that Alouatta, Hylobates, Gorilla, Pan, and Homo showed generally stronger modularity than other anthropoid taxa when considering all axial skeletal elements. When only considering the vertebral elements (i.e., vertebrae and sacrum), Alouatta, Hylobates, Gorilla, and Pan showed generally stronger modularity than other anthropoid taxa. Humans showed stronger modularity between the skull and vertebrae than other hominoids. Thus, the evolution of novel characteristics in the skull and vertebral column may have been less constrained in fossil hominins due to the dissociation of trait covariation between axial skeletal elements in hominoid ancestors, thus fostering more evolutionary independence between the skull and vertebral column.

Morphological integration of the hominoid postcranium.

Previous research has suggested that magnitudes of integration may be distinct in the postcranium of hominoids when compared to other primate species. To test this hypothesis, we estimated and compared magnitudes of integration of eight postcranial bones from three-dimensional surface scans for 57 Hylobates lar, 58 Gorilla gorilla, 60 Pan troglodytes, 60 Homo sapiens, 60 Chlorocebus pygerythrus, and 60 Macaca fascicularis. We tested the hypotheses that 1) magnitudes of integration would be distinct in the postcranium of hominoids compared to cercopithecoids, with the explicit prediction that magnitudes of integration would be lower in hominoids than in cercopithecoids, and 2) girdle elements (scapula, os coxa) would have lower magnitudes of integration across all taxa. Integration was quantified using the integration coefficient of variation from interlandmark distances reflecting anatomical and developmental modules defined according to a priori criteria. A resampling protocol was employed to generate distributions of integration values that were then compared statistically using Mann-Whitney U tests with Bonferroni adjustment. Support for hypothesis 1 was mixed: with the exception of Gorilla, hominoid taxa were less integrated than the cercopithecoids for all anatomical modules. However, Homo, Gorilla, and, to a lesser extent, Pan showed higher integration than Hylobates and the cercopithecoids for homologous limb elements, with magnitudes of integration for both modules being lowest for Hylobates. These results generally support the hypothesis of distinct patterns of magnitudes of integration in the hominoid postcranium. The high integration of Gorilla may be explained by the effects of overall body size. The results supported the predictions of the second hypothesis. Regardless of taxon, the os coxa and scapula were generally the least integrated skeletal elements, while the femur and radius were the most integrated. The lower integration of the girdle elements suggests that the geometric complexities of particular elements may significantly influence study outcomes.

An integrative skeletal and paleogenomic analysis of stature variation suggests relatively reduced health for early European farmers.

Human culture, biology, and health were shaped dramatically by the onset of agriculture ∼12,000 y B.P. This shift is hypothesized to have resulted in increased individual fitness and population growth as evidenced by archaeological and population genomic data alongside a decline in physiological health as inferred from skeletal remains. Here, we consider osteological and ancient DNA data from the same prehistoric individuals to study human stature variation as a proxy for health across a transition to agriculture. Specifically, we compared "predicted" genetic contributions to height from paleogenomic data and "achieved" adult osteological height estimated from long bone measurements for 167 individuals across Europe spanning the Upper Paleolithic to Iron Age (∼38,000 to 2,400 B.P.). We found that individuals from the Neolithic were shorter than expected (given their individual polygenic height scores) by an average of −3.82 cm relative to individuals from the Upper Paleolithic and Mesolithic (P = 0.040) and −2.21 cm shorter relative to post-Neolithic individuals (P = 0.068), with osteological vs. expected stature steadily increasing across the Copper (+1.95 cm relative to the Neolithic), Bronze (+2.70 cm), and Iron (+3.27 cm) Ages. These results were attenuated when we additionally accounted for genome-wide genetic ancestry variation: for example, with Neolithic individuals −2.82 cm shorter than expected on average relative to pre-Neolithic individuals (P = 0.120). We also incorporated observations of paleopathological indicators of nonspecific stress that can persist from childhood to adulthood in skeletal remains into our model. Overall, our work highlights the potential of integrating disparate datasets to explore proxies of health in prehistory.

Examination of magnitudes of integration in the catarrhine vertebral column.

The evolution of novel vertebral morphologies observed in humans and other extant hominoids may be related to changes in the magnitudes and/or patterns of covariation among traits. To examine this, we tested magnitudes of integration in the vertebral column of cercopithecoids and hominoids, including humans. Three-dimensional surface scans of 14 vertebral elements from 30 Cercopithecus, 32 Chlorocebus, 39 Macaca, 45 Hylobates, 31 Pan, and 86 Homo specimens were used. A resampling method was used to generate distributions of integration coefficient of variation scores for vertebral elements individually using interlandmark distances. Interspecific comparisons of mean integration coefficient of variation were conducted using Mann-Whitney U tests with Bonferroni adjustment. The results showed that hominoids generally had lower mean integration coefficient of variation than cercopithecoids. In addition, humans showed lower mean integration coefficient of variation than other hominoids in their last thoracic and lumbar vertebrae. Cercopithecoids and Hylobates showed relatively lower mean integration coefficient of variation in cervical vertebrae than in thoracolumbar vertebrae. Pan and Homo showed relatively lower mean integration coefficient of variation in the last thoracic and lumbar vertebrae in the thoracolumbar region, except for the L1 of Pan. The results suggest fewer integration-mediated constraints on the evolution of vertebral morphology in hominoids when compared with cercopithecoids. The weaker magnitudes of integration in lumbar vertebrae in humans when compared with chimpanzees likewise suggest fewer constraints on the evolution of novel lumbar vertebrae morphology in humans.

Ontogenetic changes in magnitudes of integration in the macaque skull.

OBJECTIVES: Magnitudes of morphological integration may constrain or facilitate craniofacial shape variation. The aim of this study was to analyze how the magnitude of integration in the skull of Macaca fascicularis changes throughout ontogeny in relation to developmental and/or functional modules. MATERIALS AND METHODS: Geometric morphometric methods were used to analyze the magnitude of integration in the macaque cranium and mandible in 80 juvenile and 40 adult M. fascicularis specimens. Integration scores in skull modules were calculated using integration coefficient of variation (ICV) of eigenvalues based on a resampling procedure. Resultant ICV scores between the skull as a whole, and developmental and/or functional modules were compared using Mann-Whitney U tests. RESULTS: Results showed that most skull modules were more tightly integrated than the skull as a whole, with the exception of the chondrocranium in juveniles without canines, the chondrocranium/face complex and the mandibular corpus in adults, and the mandibular ramus in all juveniles. The chondrocranium/face and face/mandibular corpus complexes were more tightly integrated in juveniles than adults, possibly reflecting the influences of early brain growth/development, and the changing functional demands of infant suckling and later masticatory loading. This is also supported by the much higher integration of the mandibular ramus in adults compared with juveniles. DISCUSSION: Magnitudes of integration in skull modules reflect developmental/functional mechanisms in M. fascicularis. However, the relationship between "evolutionary flexibility" and developmental/functional mechanisms was not direct or simple, likely because of the complex morphology, multifunctionality, and various ossification origins of the skull.

The relative efficacy of the cranium and os coxa for taxonomic assessment in macaques.

OBJECTIVES: The cranium is generally considered more reliable than the postcranium for assessing primate taxonomy, although recent research suggests that pelvic shape may be equally reliable. However, little research has focused on intrageneric taxonomic discrimination. Here, we test the relative taxonomic efficacy of the cranium and os coxa for differentiating two macaque species, with and without considering sexual dimorphism. MATERIALS AND METHODS: Geometric morphometric analyses were performed on cranial and os coxa landmarks for 119 adult Macaca fascicularis, M. mulatta, and Chlorocebus pygerythrus. Among-group shape variation was examined using canonical variates analyses. Cross-validated discriminant function analysis provided rates of correct group classification. Additionally, average morphological distances were compared with neutral genetic distances. RESULTS: Macaque species were clearly differentiated, both cranially and pelvically, when sex was not considered. Males were more often correctly classified based on the os coxa, while female classification rates were high for both morphologies. Female crania and male os coxa were differentiated approximately the same as genetic distance, while male crania were more similar (convergent), and female os coxa were more divergent than expected based on genetic distance. DISCUSSION: The hypothesis that cranial and os coxal shape can be used to discriminate among macaque species was supported. The cranium was better at differentiating females, while the os coxa was better at differentiating male macaques. Hence, there is no a priori reason for preferring the cranium when assessing intragenetic taxonomic relationships, but the effects of high levels of sexual dimorphism must be corrected for to accurately assess taxonomic signatures.

Biological diversity in an Islamic archaeological population: A radiogenic strontium isotope and craniometric analysis of affinity in Ottoman Romania.

OBJECTIVES: Written accounts, as well as a previous craniometric study, indicate that migrations of non-Europeans and conversions of Europeans to Islam define Ottoman communities in Early Modern Europe. What is less clear are the roles of migration and admixture in generating intra-communal variation. This study combines craniometric with strontium isotope data to compare the cranial affinities of locally born and immigrant individuals. We predict that locally born individuals are more likely than non-locals to show evidence of admixture. MATERIALS AND METHODS: Radiogenic strontium isotope data for 21 Ottomans were compared against archaeological faunal values. Sixteen individuals with intact crania were also measured and compared against two comparative source populations from Anatolia and Europe. Discriminant function analysis assigned unclassified Ottoans to either comparative group based on typicality probabilities, with potential admixture established via intermediate morphology between the two source populations. RESULTS: Strontium isotope values revealed relatively high proportions of non-locals, consistent with high mobility documented historically. The sexes differed, with more males classifying as "typically Anatolian" than females. Locals and non-locals also had different cranial affinity patterns, with most classifying either as "typically Anatolian" or "typically European." Contrary to expectation, none of the locals were identified as intermediate, suggesting admixture rates were relatively low. CONCLUSIONS: Consistent with historical records, the results revealed high levels of extra-regional migration, with most individuals identifiable as either typically Anatolian or European. Moreover, locals and non-locals differed craniometrically, with no signs of admixture between Anatolian migrants and European converts in locals. This suggests intra-communal divisions were maintained.

Morphological variation of the early human remains from Quintana Roo, Yucatán Peninsula, Mexico: Contributions to the discussions about the settlement of the Americas.

The human settlement of the Americas has been a topic of intense debate for centuries, and there is still no consensus on the tempo and mode of early human dispersion across the continent. When trying to explain the biological diversity of early groups across North, Central and South America, studies have defended a wide range of dispersion models that tend to oversimplify the diversity observed across the continent. In this study, we aim to contribute to this debate by exploring the cranial morphological affinities of four late Pleistocene/early Holocene specimens recovered from the caves of Quintana Roo, Mexico. The four specimens are among the earliest human remains known in the continent and permit the contextualization of biological diversity present during the initial millennia of human presence in the Americas. The specimens were compared to worldwide reference series through geometric morphometric analyses of 3D anatomical landmarks. Morphological data were analyzed through exploratory visual multivariate analyses and multivariate classification based on Mahalanobis distances. The results show very different patterns of morphological association for each Quintana Roo specimen, suggesting that the early populations of the region already shared a high degree of morphological diversity. This contrasts with previous studies of South American remains and opens the possibility that the initial populations of North America already had a high level of morphological diversity, which was reduced as populations dispersed into the southern continent. As such, the study of these rare remains illustrates that we are probably still underestimating the biological diversity of early Americans.

Diachronic changes in craniofacial morphology among the middle-late Holocene populations from Hehuang region, Northwest China.

OBJECTIVES: This study analyzes craniofacial shape variation in the Hehuang region of Northwest China within a population genetic framework, and takes a diachronic approach to explore the relationship betwee cultural discontinuity and biological continuity/discontinuity in the Hehuang region during the middle to late Holocene. MATERIALS AND METHODS: The sample comprises 76 adult skulls from five archaeological sites, ranging from 4,500 to 1,530 BP. 3D geometric morphometrics, multivariate statistics, quantitative evolutionary genetic and biodistance analyses were performed to study the diachronic variation in craniofacial morphology. Analyses were performed on two cranial modules: the face and the cranial vault, across three major diachronic groups representing the late Neolithic (LNA), the Bronze Age (BA), and the Han-Jin dynasty (HD). RESULTS: Average regional FST for both cranial modules was low, indicating relatively greater variation within diachronic groups than among them. While the LNA and BA groups did not show any significant differences in facial and vault shape, significant craniofacial shape changes were detected between the BA and HD groups. DISCUSSION: The consistent craniofacial morphology during the LNA and the BA, and the shift in morphology between the BA and the HD indicates that cultural discontinuity does not always coincide with biological discontinuity. The Hehuang population evolved in situ with few changes, despite cultural and dietary changes, until the HD when migrations from the Central Plains are associated with extra-local gene flow to the area.

Multivariate morphometrics, quantitative genetics, and neutral theory: Developing a "modern synthesis" for primate evolutionary morphology.

Anthropologists are increasingly turning to explicit model-bound evolutionary approaches for understanding the morphological diversification of humans and other primate lineages. Such evolutionary morphological analyses rely on three interconnected conceptual frameworks; multivariate morphometrics for quantifying similarity and differences among taxa, quantitative genetics for modeling the inheritance and evolution of morphology, and neutral theory for assessing the likelihood that taxon diversification is due to stochastic processes such as genetic drift. Importantly, neutral theory provides a framework for testing more parsimonious explanations for observed morphological differences before considering more complex adaptive scenarios. However, the consistency with which these concepts are applied varies considerably, which mirrors some of the theoretical obstacles faced during the "modern synthesis" of classical population genetics in the early 20th century. Here, each framework is reviewed and some potential stumbling blocks to the full conceptual integration of multivariate morphometrics, quantitative genetics, and neutral theory are considered.

Comparison of cranial fluctuating asymmetry between normal and pathological specimens from a modern Thai skeletal group.

The purpose of this study was to compare fluctuating asymmetry (FA) levels across cranial modules of normal and pathological cranial specimens. It was examined whether pathological specimens have significantly higher FA scores than normal specimens in cranial regions affected by a developmental disorder. For this study, a modern Thai skeletal sample from Chulalongkorn University was analyzed. Ninety-two cranial landmarks were digitized on 66 adult and eight sub-adult normal specimens and on five pathological specimens including two adults with abnormal palates, two sub-adults with craniosynostosis, and one sub-adult with natal absence of nasal bones. In sub-adults, FA scores of specimens with developmental disorders were significantly higher than normal specimens in the entire cranium (p = 0.041) and vault (p = 0.025). However, comparisons excluding specimen with coronal craniosynostosis were not statistically significant. In adult specimens, comparisons of FA scores in each separate cranial module were also not statistically significant. These results suggest that elevated cranial FA may not be confined to the specific cranial region with the developmental disorder.

Morphological integration of anatomical, developmental, and functional postcranial modules in the crab-eating macaque (Macaca fascicularis).

OBJECTIVES: Integration and modularity reflect the coordinated action of past evolutionary processes and, in turn, constrain or facilitate phenotypic evolvability. Here, we analyze magnitudes of integration in the macaque postcranium to test whether 20 a priori defined modules are (1) more tightly integrated than random sets of postcranial traits, and (2) are differentiated based on mode of definition, with developmental modules expected to be more integrated than functional or anatomical modules. MATERIALS AND METHODS: The 3D morphometric data collected for eight limb and girdle bones for 60 macaques were collated into anatomical, developmental, and functional modules. A resampling technique was used to create random samples of integration values for each module for statistical comparison. RESULTS: Our results found that not all a priori defined modules were more strongly integrated than random samples of postcranial traits and that specific types of modules did not present consistent patterns of integration. Rather, girdle and joint modules were consistently less integrated than limb modules, and forelimb elements were less integrated than hindlimbs. DISCUSSION: The results suggest that morphometrically complex modules tend to be less integrated than simple limb bones, irrespective of the number of available traits. However, differences in integration of the fore- and hindlimb more likely reflects the multitude of locomotory, feeding, and social functions involved. It remains to be tested whether patterns of integration identified here are primate universals, and to what extent they vary depending on phylogenetic or functional factors.

Assessing the relative impact of historical divergence and inter-group transmission on cultural patterns: a method from evolutionary ecology.

In the study of cultural evolution, observed among-group affinity patterns reflect the effects of processes such as mutation (e.g. innovation and copying error), between-group interaction (culture flow), drift and selection. As in biology, cultural affinity patterns are often spatially correlated, making it difficult to distinguish between the opposing geographically mediated forces of divergence and interaction, which cause groups to become more distinct or similar over time, respectively. Analogous difficulties are faced by evolutionary biologists examining the relationship between biological affinity and geography, particularly at lower taxonomic levels where the potential for gene flow between lineages is greatest. Tree models are generally used to assess the fit between affinity patterns and models of historical divergence. However, factors driving lineage divergence are often spatially mediated, resulting in tree models that are themselves geographically structured. Here, we showcase a simple method drawn from evolutionary ecology for assessing the relative impact of both geographically mediated processes simultaneously. We illustrate the method using global human craniometric diversity and material culture from the northern coast of New Guinea as example case studies. This method can be employed to quantify the relative importance of history (divergence) and geographically mediated between-group interaction (culture flow) in explaining observed cultural affinity patterns.This article is part of the theme issue 'Bridging cultural gaps: interdisciplinary studies in human cultural evolution'.

The evolution of hominoid cranial diversity: A quantitative genetic approach.

Hominoid cranial evolution is characterized by substantial phenotypic diversity, yet the cause of this variability has rarely been explored. Quantitative genetic techniques for investigating evolutionary processes underlying morphological divergence are dependent on the availability of good ancestral models, a problem in hominoids where the fossil record is fragmentary and poorly understood. Here, we use a maximum likelihood approach based on a Brownian motion model of evolutionary change to estimate nested hypothetical ancestral forms from 15 extant hominoid taxa. These ancestors were then used to calculate rates of evolution along each branch of a phylogenetic tree using Lande's generalized genetic distance. Our results show that hominoid cranial evolution is characterized by strong stabilizing selection. Only two instances of directional selection were detected; the divergence of Homo from its last common ancestor with Pan, and the divergence of the lesser apes from their last common ancestor with the great apes. In these two cases, selection gradients reconstructed to identify the specific traits undergoing selection indicated that selection on basicranial flexion, cranial vault expansion, and facial retraction characterizes the divergence of Homo, whereas the divergence of the lesser apes was defined by selection on neurocranial size reduction.

A craniometric analysis of early modern Romania and Hungary: The roles of migration and conversion in shaping European Ottoman population history.

OBJECTIVES: Debate persists regarding the biological makeup of European Ottoman communities settled during the expansion of the Ottoman Empire during the 16th and 17th centuries, and the roles of conversion and migration in shaping demography and population history. The aim of this study was to perform an assessment of the biological affinities of three European Ottoman series based on craniometric data. MATERIALS AND METHODS: Craniometric data collected from three Ottoman series from Hungary and Romania were compared to European and Anatolian comparative series, selected to represent biological affinity representative of historically recorded migration and conversion influences. Sex-separated samples were analyzed using D2 -matrices, along with principal coordinates and PERMANOVA analyses to investigate biological affinities. Discriminant function analysis was employed to assign Ottoman individuals to two potential classes: European or Anatolian. RESULTS: Affinity analyses show larger than expected biological differences between males and females within each of the Ottoman communities. Discriminant function analyses show that the majority of Ottoman individuals could be classified as either European or Anatolian with a high probability. Moreover, location within Europe proved influential, as the Ottomans from a location of more geopolitical importance (Budapest) diverged from more hinterland communities in terms of biological affinity patterns. DISCUSSION: The results suggest that male and female Ottomans may possess distinct population histories, with males and females divergent from each other in terms of their biological affinities. The Ottoman communities appear diverse in terms of constituting a mix of peoples from different biological backgrounds. The greater distances between sexes from the same community, and the differences between communities, may be evidence that the processes of migration and conversion impacted individual people and groups diversely.

Evolutionary population history of early Paleoamerican cranial morphology.

The nature and timing of the peopling of the Americas is a subject of intense debate. In particular, it is unclear whether high levels of between-group craniometric diversity in South America result from multiple migrations or from local diversification processes. Previous attempts to explain this diversity have largely focused on testing alternative dispersal or gene flow models, reaching conflicting or inconclusive results. Here, a novel analytical framework is applied to three-dimensional geometric morphometric data to partition the effects of population divergence from geographically mediated gene flow to understand the ancestry of the early South Americans in the context of global human history. The results show that Paleoamericans share a last common ancestor with contemporary Native American groups outside, rather than inside, the Americas. Therefore, and in accordance with some recent genomic studies, craniometric data suggest that the New World was populated by multiple waves of dispersion from northeast Asia throughout the late Pleistocene and early Holocene.

11,000 years of craniofacial and mandibular variation in Lower Nubia.

The transition to agriculture was a key event in human history. The extent to which this transition is associated with biological changes in different world regions remains debated. Cultural and osteological records in Lower Nubia throughout the Holocene have been interpreted as a result of in situ differentiation or alternatively as migratory events and possible admixture with surrounding populations. Here we investigated the patterns of craniofacial and mandibular variation from Mesolithic hunting-gathering to late farming, a period spanning 11,000 years. We analyzed 102 adult specimens spanning five cultural horizons: Mesolithic, A-group, C-group, Pharaonic and Meroitic, by means of 3D geometric morphometric methods, in order to assess shape variation and diachronic patterns at the transition to farming and in subsequent periods. Our results highlight a strong morphometric distinction between Mesolithic hunter-gatherers and farmers as well as differences between transitional and intensive farmers in mandibular variation which is consistent with differential impact of selective pressures on different regions of the skull. This study corroborates a major biological change during the transition from hunting to farming, supporting the masticatory-functional hypothesis for the mandible and suggesting population continuity among farming populations throughout the Holocene based on the overall shape of the cranium.