Craniofacial Morphology

Identification of Group Affinity from Cross‐sectional Contours of the Human Midfacial Skeleton Using Digital Morphometrics and 3D Laser Scanning Technology

by sebastian wärmländer

Zygomaticomaxillary suture shape analyzed with digital morphometrics: Reassessing patterns of variation in American Indian and European populations

by sebastian wärmländer

A probabilistic approach to the craniometric variability of the genus Homo and inferences on the taxonomic affinities of the first human population dispersing out of …

by Juan Manuel Jiménez-Arenas

Kurki, H. K., Pfeiffer, S., Stynder, D. D. (in press). Allometry of head and body size in Holocene foragers of the South African Cape. American Journal of Physical Anthropology.

by Deano Stynder

Later Stone Age;stature;body mass;body proportions; craniofacial

Opportunities to assess morphological allometry in small-bodied human populations are rare. The foragers of the Later... more Opportunities to assess morphological allometry in small-bodied human populations are rare. The foragers of the Later Stone Age of the South African Cape are characteristically small-bodied. Previous studies have shown that during the period of ca. 3500 to 2000 years BP (uncalibrated 14C dates), the regional population shows transient reduced stature, body mass, and cranial size, a pattern that has been tentatively tied to demographic pressure on resources. This study examines the relationships among cranial size (centroid size) and body size (femoral length, femoral head diameter, and bi-iliac breadth) during the second half of the Holocene (N = 62). Reduced major axis regression indicates negative allometry of cranial centroid size with body size. Residuals (from ordinary least squares regression of cranial centroid size on body size) are regressed on radiocarbon date to examine temporal changes in the relationship between cranial and body size. Cranial and pelvic sizes are most conserved through time, while more ancient skeletons possess shorter femora and smaller femoral heads. The relationship between cranial centroid size and femoral length shows larger and more variable residuals at more recent dates, indicating a greater or more variable disassociation between cranial size and stature relative to more ancient skeletons. A similar, but nonsignificant relationship exists between cranial size and bi-iliac breadth. These results provide insights into the use of aspects of body size and proportionality in the assessment of health in past populations.

Morphological Integration of Soft-Tissue Facial Morphology in Down Syndrome and Siblings

by John Starbuck

Down syndrome (DS), resulting from trisomy of chromosome 21, is the most common live-born human aneuploidy. The... more Down syndrome (DS), resulting from trisomy of chromosome 21, is the most common live-born human aneuploidy. The phenotypic expression of trisomy 21 produces variable, though characteristic, facial morphology. Although certain facial features have been documented quantitatively and qualitatively as characteristic of DS (e.g., epicanthic folds, macroglossia, and hypertelorism), all of these traits occur in other craniofacial conditions with an underlying genetic cause. We hypothesize that the typical DS face is integrated differently than the face of non-DS siblings, and that the pattern of morphological integration
unique to individuals with DS will yield information about underlying developmental associations between facial regions. We statistically compared morphological integration patterns of immature DS faces (N 5 53) with those of non-DS siblings (N 5 54), aged 6–12 years using 31 distances estimated from 3D coordinate data representing 17 anthropometric landmarks recorded on 3D digital photographic images. Facial features are affected differentially in DS, as evidenced by statistically significant differences in integration both within and between facial regions. Our results suggest a differential affect of trisomy on facial prominences during craniofacial development.

Oldfield, C. C., McHenry, C. R., Clausen, P.D., Chamoli, U., Parr, W.C.H., Stynder, D. D. and Wroe, S. (in press). Finite Element Analysis of ursid cranial mechanics and the prediction of feeding behaviour in the extinct giant Agriotherium africanum. Journal of Zoology.

by Deano Stynder

Historically, predicting ursid feeding behaviour on the basis of morphometric and mechanical analyses has proven... more Historically, predicting ursid feeding behaviour on the basis of morphometric and mechanical analyses has proven difficult. Here, we apply three-dimensional finite element analysis to models representing five extant and one fossil species of bear. The ability to generate high bite forces, and for the skull to sustain them, is present in both the giant panda and the gigantic extinct Agriotherium africanum. Bite forces for A. africanum are the highest predicted for any mammalian carnivore. Our findings do not resolve whether A. africanum was more likely a predator on, or scavenger of, large terrestrial vertebrates, but show that its skull was welladapted to resist the forces generated in either activity. The possibility that A. africanum was adapted to process tough vegetation is discounted. Results suggest that the polar bear is less well-adapted to dispatch large prey than all but one of the five other species considered.

Stynder, D. D., Ackermann, R. and Sealy, J. (2007). Early to mid-Holocene South African Later Stone Age human crania exhibit a distinctly Khoesan morphological pattern. South African Journal of Science 103: 349-352.

by Deano Stynder

The sample of South African early to mid-Holocene Later Stone Age(LSA) human crania is small and quite fragmentary,... more The sample of South African early to mid-Holocene Later Stone Age(LSA) human crania is small and quite fragmentary, limiting our knowledge of human craniofacial morphology for this period. Previous limited analyses have described the morphology displayed by these early crania as a combination of Khoesan and non-Khoesan traits. Although essentially Khoesan-like in terms of facial morphology, their overall large size and robust neurocranial structure were regarded as atypical of Khoesan craniofacial morphology, leading to questions about the role of these early populations in the ancestry of recent Khoesan populations. Here we provide a quantitative analysis in which we compare five well-preserved pre-5000 BP LSA crania with (i) a large sample of post-5000 BP LSA Khoesan crania; and (ii) a sample of crania from recent South African Bantu-speakers. We show that these pre-5000 BP crania fall comfortably within the range of variation observed for the post-5000 BP Khoesan sample, in terms of both size and shape, suggesting that distinctive Khoesan craniofacial morphology was already present in South African LSA populations by the first half of the Holocene.

Stynder, D. D., Ackermann, R. and Sealy, J. (2007). Craniofacial variation and population continuity during the South African Holocene. American Journal of Physical Anthropology 134: 489-500.

by Deano Stynder

We assess craniometric variation in 153 individually dated human crania from South Africa with the aim of... more We assess craniometric variation in 153 individually dated human crania from South Africa with the aim of investigating genetic continuity/discontinuity during the Holocene. Evidence from the archaeological record is used to pinpoint likely episodes of genetic discontinuity. Craniometric data are then used to assess the likelihood of genetic change having occurred. Two periods of possible genetic discontinuity are identified: i) c. 4,000 BP, when an increase in overall population size, shifts in site organization and diet, and reduced mobility, were accompanied by reductions in stature; ii) c. 2,000 BP, when the herding of domesticates and the use of pottery vessels were introduced into the region. Results indicate that there was a decrease in cranial size and concomitant size-related changes in craniofacial shape between c.4,000 BP and 3,000 BP. This was followed almost immediately by a recovery in craniofacial size and a return to pre-4,000 BP craniofacial shape at c. 3,000 BP. This recovery continued gradually, extending into the herder period without any major shifts in morphology at 2,000 BP. It is suggested that the fluctuations in craniofacial size/shape were related to changes in environmental factors. Results obtained are consistent with long term continuity in South African Later Stone Age populations during the Holocene.

Stynder, D. D. (2009). Craniometric evidence for South African Later Stone Age herders and hunter–gatherers being a single biological population. Journal of Archaeological Science 36: 798-806.

by Deano Stynder

Later Stone Age (LSA) huntergatherers and herders co-existed in South Africa during the last 2000 years. In spite of... more Later Stone Age (LSA) huntergatherers and herders co-existed in South Africa during the last 2000 years. In spite of being the focus of intensive research over the years, the biological status and origins of the herders are still unclear. Did they represent a genetically distinct immigrant population who remained separate from the indigenous huntergatherers, or where they indigenous huntergatherers who took up herding after contact with herders, probably in northern Botswana? Here, this issue is investigated using craniometric data collected on a large sample of individually dated human crania from coastal LSA context. Mahalanobis distances (D), calculated from the raw metric data, show that there was a small increase in inter-individual craniofacial variation after the introduction of herding at ca. 2000 BP. Here it is argued that this small increase in variation is neither consistent with a large-scale immigration of genetically distinct herders into South Africa, or the long-term co-existence of two genetically distinct populations. Two alternative explanations fit the data better: (1) herding entered South Africa via the small-scale immigration of genetically distinct herders; and (2) local huntergatherer populations adopted herding after coming in contact with herders in northern Botswana. While small-scale immigration would not have had a major influence on the local gene pool, it would have increased variation to some extent as immigrants mixed with local populations. If small-scale external gene flow was not a factor in the introduction of herding, secular issues related to the introduction of herding could explain the increased variation in post-2000 BP populations.

Stynder, D. D., Braga, J. and Crubézy, E. (2009). Craniometric evidence for biological continuity between Meroitic and post-Meroitic populations buried at the necropolis of Missiminia, Middle Nubia. South African Archaeological Bulletin 64: 122-129.

by Deano Stynder

Functional Units and Their Evolution

by Kurt Schwenk

Horned Lizards (Phrynosoma) Incapacitate Dangerous Ant Prey With Mucus

by Kurt Schwenk

Basicranial flexion in the evolution of Homo: new analyses of an old model

by Jose Manuel de la Cuétara

Bastir M, Rosas A, Stringer C, Cuétara JM, Kruszynski R, Ross CF, Ravosa MJ. 2009. Basicranial flexion in the evolution of Homo: new analyses of an old model. American Journal of Physical Anthropology S48:90

Understanding variation in the basicranium is of central importance to paleoanthropology because of its fundamental... more Understanding variation in the basicranium is of central importance to paleoanthropology because of its fundamental structural role in skull development and evolution. At the beginning of the 20th century it was suggested that encephalisation plays a role in producing flexion between midline basicranial elements. It has been proposed that basicranial flexion is also influenced by the size or shape of the face. This hypothesis was further refined during the 1950s by the Swiss anatomist Biegert, who suggested that brain size and facial size act as antagonists on basicranial lexion. Biegert’s model is particularly relevant for understanding aspects of Neanderthal skull evolution because one important and unresolved problem s that these large-brained hominins have slightly less flexed basicrania than equally large-brained modern humans. We addressed this hypothesis by applying geometric morphometrics to a large comparative dataset of radiographic and/or CT images of adult nonhuman primates, hominin fossils and humans (29 species, 142 individuals). Multiple, multivariate regression and thin plate splines analyses suggest that basicranial evolution is highly significantly influenced by both brain size and face size. Our data show that in addition to brain size, the prime factor of basicranial evolution in Homo, facial size importantly influences basicranial morphology and orientation. These interactions can explain why, despite their similar brain sizes, eanderthals as well as some Mid-Pleistocene humans have less flexed cranial bases than modern humans. To gain a detailed understanding of the multifactorial inputs into basicranial flexion, future studies should also focus on the underlying factors of facial size evolution. Grant information: CGL-2006-02131 (Spanish Ministry of Science), MRTN-CT-2005-019564-EVAN, NSF: BNS-8813220.

Effects of brain and facial size on basicranial form in human and primate evolution

by Jose Manuel de la Cuétara

Bastir M, Rosas A, Stringer C, Cuetara JM, Kruszynski R, Weber GW, Ross C, Ravosa MJ. 2010. Effects of brain and facial size on basicranial form in human and primate evolution. Journal of Human Evolution, 58:424–431.

Understanding variation in the basicranium is of central importance to paleoanthropology because of its fundamental... more Understanding variation in the basicranium is of central importance to paleoanthropology because of its fundamental structural role in skull development and evolution. Among primates, encephalisation is well known to be associated with flexion between midline basicranial elements, although it has been proposed that the size or shape of the face influences basicranial flexion. In particular, brain size and facial size are hypothesized to act as antagonists on basicranial flexion. One important and unresolved problem in hominin skull evolution is that large-brained Neanderthals and some Mid-Pleistocene humans have slightly less flexed basicrania than equally large-brained modern humans. To determine whether or not this is a consequence of differences in facial size, geometric morphometric methods were applied to a large comparative data set of non-human primates, hominin fossils, and humans (N=142; 29 species). Multiple multivariate regression and thin plate spline analyses suggest that basicranial evolution is highly significantly influenced by both brain size and facial size. Increasing facial size rotates the basicranium away from the face and slightly increases the basicranial angle, whereas increasing brain size reduces the angles between the spheno-occipital clivus and the presphenoid plane, as well as between the latter and the cribriform plate. These interactions can explain why Neanderthals and some Mid-Pleistocene humans have less flexed cranial bases than modern humans, despite their relatively similar brain sizes. We highlight that, in addition to brain size (the prime factor implicated in basicranial evolution in Homo), facial size is an important influence on basicranial morphology and orientation. To better address the multifactorial nature of basicranial flexion, future studies should focus on the underlying factors influencing facial size evolution in hominins.

A Bivariate Approach to the Variation of the Parietal Curvature in the Genus Homo.

by Jose Manuel de la Cuétara

Bruner E, de la Cuétara JM, Holloway R. 2011. A Bivariate Approach to the Variation of the Parietal Curvature in the Genus Homo. The Anatomical Record: Advances in Integrative Anatomy and Evolutionary Biology, 294: 1548–1556.

The parietal bones approximately cover the extension of the underlying parietal lobes. Although the boundaries of... more The parietal bones approximately cover the extension of the underlying parietal lobes. Although the boundaries of these two anatomical elements do not coincide, during morphogenesis the growth of the parietal bones is largely induced by the pressure exerted by the parietal lobes. Modern humans display larger parietal chords and arcs compared with non-modern human species. However, the variation of these variables have not been analyzed before according to the covariation with the general endocranial diameters. When the curvature of the parietal bones is regressed onto the main neurocranial distances, modern humans show larger relative values, suggesting not only an absolute enlargement but a definite allometric change. Taking into account the morphogenetic relationships with the parietal lobes, these results further support previous hypotheses suggesting a relative enlargement of these cortical areas in Homo sapiens, by using simple and reliable homologous neurocranial arcs.

Primate cranial base: analysis of mid and lateral elements in a cercopithecid sample using geometric morphometrics

by Jose Manuel de la Cuétara

De la Cuétara JM, Bastir M. 2009. Primate cranial base: analysis of mid and lateral elements in a cercopithecid sample using geometric morphometrics. Paleontologia i Evolució, memòria especial nº3, 47-48.

In the last century, the study of the cranial base has gained much importance for paleoanthropology due to its... more In the last century, the study of the cranial base has gained much importance for paleoanthropology due to its structural and functional roles during development and evolution of the skull. Most studies have been centred on the analysis of basicranial morphology, mainly focused on the different factors that may influence cranial base flexion. Consequently diverse hypotheses have been proposed, being the neural ones the most important due to the close relationship between the brain and the basicranium and also because of the importance of encephalisation during primate and human evolution. Additionally, recent studies have shown how different parts of the cranial base are tightly related with the facial block, in the way that the anterior and middle cranial fossa (ACF and MCF) are integrated with the upper face and the midface respectively. In this context, the MCF gets special interest because of its interaction with the temporal and parietal lobes, parts of the brain which are thought to increase substantially during evolution. Several authors have suggested that evolutionary transformations of the MCF (mainly in the temporal region) may influence craniofacial morphology, affecting cranial base flexion and the facial block. Despite much research about basicranial flexion in the sagittal plane, its lateral variation is still quite unknown, being studied mostly in human-hominid samples. Here we analyse shape covariation between midline and lateral basicranial elements using geometric morphometrics in a relatively wide Cercopithecid sample (23 species, 126 individuals), combining lateral and axial X-rays images of each individual. Partial least squares and thin plate spline analysis suggest that cranial base morphology is related with variation in brain and face relative sizes. Preliminary results of ongoing research also suggest that increase in relative parietal and temporal lobes size (MCF) contributes substantially to brain size increase, so that larger MCF proportions appear to be related with flexed basicrania. These results may indicate possible structural and functional relationships that could explain the high degree of flexion observed in modern human. Future research analysing more taxa of the primate lineage, including modern humans and their ancestors, is expected to give more information about complex interactions between different craniofacial elements and its evolutionary relationships. Funding: CGL-2006-02131 (Ministerio de Ciencia e Inovacion)

Evolution of ruminant headgear: a review

by K Brakora

Open access / free download of full paper

The horns, ossicones and antlers of ruminants are familiar and diverse examples of cranial appendages. We collectively... more The horns, ossicones and antlers of ruminants are familiar and diverse examples of cranial appendages. We collectively term ruminant cranial appendages ‘headgear’; this includes four extant forms: antlers (in cervids), horns (in bovids), pronghorns (in pronghorn antelope) and ossicones (in giraffids). Headgear evolution remains an open and intriguing question because phylogenies (molecular and morphological), adult headgear structure and headgear development (where data are available) all suggest different pictures of ruminant evolution. We discuss what is known about the evolution of headgear, including the evidence motivating previous hypotheses of single versus multiple origins, and the implications of recent phylogenetic revisions for these hypotheses. Inclusion of developmental data is critical for progress on the question of headgear evolution, and we synthesize the scattered literature on this front. The areas most in need of attention are early development in general; pronghorn and ossicone development in particular; and histological study of fossil forms of headgear. An integrative study of headgear development and evolution may have ramifications beyond the fields of systematics and evolution. Researchers in organismal biology, as well as those in biomedical fields investigating skin, bone and regenerative medicine, may all benefit from insights produced by this line of research.

Craniofacial shape variation in Late Pleistocene Asian hominins

by Steven Wang

2009. PaleoAnthropology 2009:A38.

Numerous scholars, beginning with Franz Weidenreich in the late 1930s, have commented on the heterogeneous nature of... more Numerous scholars, beginning with Franz Weidenreich in the late 1930s, have commented on the heterogeneous nature of the terminal Pleistocene Asian fossil record. However, most studies relied on comparisons between the Zhoukoudian Upper Cave specimens (UC 101 and 103), and very few have systematically examined other Asian specimens.

To fill this gap and to gain a better understanding of craniofacial shape variation in Late Pleistocene Asia, we collected three-dimensional landmark data on Lijiang, Liujiang, UC 101, UC 103, and Ziyang from China, Minatogawa 1 and 4 from Japan, Wajak 1 from Indonesia, and Kanalda from Australia. We compared this fossil set to a large pool of recent human crania representing 11 regional populations from Asia, Australasia, and North America. Because of incomplete preservation and missing landmarks, we performed two separate analyses. Analysis 1 focused on the neurocranium and the base (55 landmarks, n=550 specimens), and Analysis 2 focused on the face (42 landmarks, n=484 specimens).

Our results indicate that only Kanalda, Lijiang, and Wajak consistently cluster to their respective recent, regional groups. The Upper Cave and Minatogawa specimens, on the other hand, share craniofacial similarities with the Amerindian group from Point Hope, Alaska. Liujiang and Ziyang also do not show affinities to the recent Chinese group or to the East Asian group in general. Instead, they cluster more closely to South and Southeast Asian populations. Our findings agree with previous morphometric studies (e.g., Brown 1998; Cunningham and Wescott 2002; Cunningham and Jantz 2003) that there was more cranial heterogeneity in Asia during the terminal Pleistocene than in the present day.

The Story of Middle Pleistocene Hominins in Asia

by Steven Wang

2011. American Journal of Physical Anthropology 144(S52):304-305. doi:10.1002/ajpa.21502.

Over the past decade, numerous reviews of the Middle Pleistocene record have taken place in light of new fossil... more Over the past decade, numerous reviews of the Middle Pleistocene record have taken place in light of new fossil discoveries. However, with primary foci on the Euro-African records, much of the rich fossil evidence in Asia was sidelined and overlooked. It is thus unsurprising that in the minds of many, Asia remains terra incognita—and its hominin record exotic. Moreover, the accuracy of the Asian chronology remains problematic, adding another layer of impediment to our understanding of regional evolution and local adaptation.

In this context, I bring a synergistic review of the chronology of mid-Pleistocene hominins from East and South Asia, including recent new dates from key sites such as Zhoukoudian Locality 1 and Hathnora. Using 3-D geometric morphometric data, I examine cranial shape changes between H. erectus and mPH (post-erectus, non-Neandertal mid-Pleistocene Homo), as well as both to later Pleistocene hominins. A large number of not-often-discussed specimens are considered (e.g., Hexian, Nanjing 1, Maba, and Ngawi), many of them original fossils.

The cranial anatomy from the Asian mid-Pleistocene suggests the existence of at least two distinctive groups in the region. Additionally, a north-south (geographical) shape difference is observed, hinting the presence of paleodemes each evolving in relative isolation. The shape affinity of mPH to extra-Asian fossils is confirmed; however, depending on the fossil in question (Dali or Narmada), the said affinity to Kabwe and Petralona is exclusive. This, coupled with a limited number of good sample, warrants caution against lumping all Asian mPH within the H. heidelbergensis hypodigm.

Generous funding for this study was provided by NSF BSC-DDI 0648800, the Wenner-Gren Foundation Dissertation Fieldwork Grant, and NSF DGE 0333415 (NYCEP IGERT).

Some problems for the Late Pleistocene human cranium found in Liujiang of South China based on morphological analysis

by Steven Wang

2006. Acta Anthropologica Sinica 25(3):177-194 (in Chinese with English abstract).

The cranial and postcranial remains found in Liujiang are the most complete and well-preserved Late Pleistocene human... more The cranial and postcranial remains found in Liujiang are the most complete and well-preserved Late Pleistocene human fossils ever unearthed in South China. Wu Rukang, who conducted the original study, suggested that even though the Liujiang fossils preserve some primitive, Late Pleistocene features, a suite of modern Mongoloid features were also present. Wu considered the Liujiang human as proto-Mongoloid. However, because the exact layer that yielded the fossils is unclear and different radiometric dates exist, the age of the Liujiang fossils remains uncertain.

Since the Liujiang discovery (A.D. 1958) many advances have been made in paleoanthropology, with more detailed understanding of geographical and morphological variation, and the mechanisms and possible environmental influences on the evolution of our species. New hypotheses on Late Pleistocene human evolution, and the formation and differentiation of modern East Asian populations have been proposed. With these new insights, the Liujiang fossils were re-examined. We proposed the following questions related to Liujiang and Late Pleistocene human evolution in East Asia: (1) Does Liujiang’s morphological pattern fit with its suggested minimal age of 67 Ka B.P.; (2) Compared with modern East Asian populations, how morphologically modern are the Liujiang fossils, and how many derived traits do the Liujiang fossils still exhibit; (3) How different morphologically are the Liujiang fossils compared to the northern Zhoukoudian (ZKD) Upper Cave specimens (i.e., Upper Cave 102 and 103), or to the modern southern Mongoloid populations?

With these questions in mind, we analyzed and compared the crania of Liujiang and ZKD Upper Cave to 1114 modern Chinese crania of various geographic affinities. Our results show: (1) The expressions of most cranial features on Liujiang fall within the modern range of variation, but there are a few exceptions; (2) Several primitive features like lower orbit can be observed on Liujiang, indicating that it still preserves some Late Pleistocene features. However, compared to the Late Pleistocene specimens from ZKD Upper Cave, the Liujiang cranium is more modern; (3) The variation between Liujiang and ZKD Upper Cave are mainly in the retention of primitive and robust features on the ZKD Upper Cave crania. We believe that a small number of these differences may be environmental adaptations, which include the deep depressed nasion on ZKD Upper Cave and the broad nasal bones on Liujiang.

Based on these findings, we suggest that the cranial morphology of Liujiang is very close to those of modern Chinese and very few differences exist between them. Concomitantly, our study does not support the supposition that the Liujiang cranium is more primitive than ZKD Upper Cave and Ziyang. Since uncertainty exists of the exact provenience of the human fossils from Liujiang, and due to the similarity of the cranial morphology between Liujiang and modern Chinese, we suggest that the current morphological analysis does not support the earlier age (67 Ka B.P.) for the Liujiang human fossils.