Scott A. Williams

Ape and human evolution; Evolutionary morphology; Fossil hominins; Upright posture; Bipedalism; Spine and torso; Vertebral column

I am an evolutionary morphologist and paleoanthropologist with primary research interests in the evolution of positional behavior (posture and locomotion) during human evolution. My research focus is not on a particular time period; rather, I am interested in evolutionary transitions in the hominoid fossil record, from 20 million-year-old extinct apes to modern human and ape variation and the entirety of human evolution in between. The major focus of my academic work has been on the primate postcranial skeleton and specifically the vertebral column (spine).

Faculty, Center for the Study of Human Origins

Core Faculty, New York Consortium in Evolutionary Primatology

Honorary Research Affiliate, Evolutionary Studies Institute, University of the Witwatersrand

Peer-reviewed Journal Articles 

López-Rey JM, Cambra-Moo Ó, González Martín A, Candelas González N, Sánchez-Andrés A, Tawane M, Cazenave M, Williams SA, Bastir M, García-Martínez D. Accepted. Covariation between the shape and mineralized tissues of the rib cross-section in Homo sapiens, Pan troglodytes, and Sts 14. American Journal of Biological Anthropology.

2023. Spear JK, Grabowski M, Sekhavati Y, Costa CE, Goldstein DM, Petrullo KA, Peterson AL, Lee AB, Shattuck MR, Gómez-Olivencia A, Williams SA. The evolution of vertebral numbers in primates, with a focus on hominoids and the last common ancestor of hominins and panins. Journal of Human Evolution 179, 103359. https://doi.org/10.1016/j.jhevol.2023.103359

2023. Meyer MR, Jung J, Araiza I, Spear JK, Galway-Witham J, Williams SA. Knuckle-walking in Sahelanthropus? Locomotor inferences from the ulnae of fossil hominins and other hominoids. Journal of Human Evolution 179, 103355. https://doi.org/10.1016/j.jhevol.2023.103355

2023. Williams SA, Prang TC, Russo GA, Young NM, Gebo DL. African apes and the evolutionary history of orthogrady and bipedalism. Yearbook of Biological Anthropology   181 (S76), 58-80. https://doi.org/10.1002/ajpa.24684

2023. Eyre JE, Semaw S, DeSilva JM, Williams SA. Unusual pubic bone morphology in A.L. 288-1 (Australopithecus afarensis) and MH2 (Australopithecus sediba). American Journal of Biological Anthropology 180, 573-582. https://doi.org/10.1002/ajpa.24649

2022. Williams SA, Zeng I, Guerra JS, Nalla S, Elliott MC, Hawks J, Berger LR, Meyer MR. Homo naledi lumbar vertebrae and a new 3D method to quantify vertebral wedging. American Journal of Biological Anthropology. https://doi.org/10.1002/ajpa.24621

2022. Cofran Z, VanSickle C, Valenzuela R, García-Martínez D, Walker CS, Hawks J, Zipfel B, Williams SA, Berger LR. The immature Homo naledi ilium from the Lesedi Chamber, Rising Star Cave, South Africa. American Journal of Biological Anthropology https://doi.org/10.1002/ajpa.24522

2022. Williams SA, Zeng I, Paton GJ, Yelverton C, Dunham C, Ostrofsky KR, Shukman S, Avilez MV, Eyre J, Loewen T, Prang TC, Meyer MR. Inferring lumbar lordosis in Neandertals and other hominins. PNAS Nexus 1, pgab005. https://doi.org/10.1093/pnasnexus/pgab005

2022. López-Rey JM, Cambra-Moo Ó, González Martín A, Candelas González N, Sánchez-Andrés Á, Tawane M, Cazenave M, Williams SA, Bastir M, García-Martínez D. Mineral content analysis in the rib cross-sections of Homo sapiens and Pan troglodytes and its implications for the study of Sts 14 costal remains. American Journal of Biological Anthropology. 177, 784-791. https://doi.org/10.1002/ajpa.24491

2022. Turcotte CM, Mann EHJ, Stock MK, Villamil CI, Montague MJ, Dickinson E, Cayo Biobank Research Unit, Surratt SB, Martinez M, Williams SA, Antón SC, Higham JP. The ontogeny of sexual dimorphism in free-ranging rhesus macaques. American Journal of Biological Anthropology. 177, 314-327. https://doi.org/10.1002/ajpa.24442

2021. Williams SA, Prang TC, Meyer MR, Nalley TK, Van Der Merwe R, Yelverton C, García-Martinez D, Russo GA, Ostrofsky KR, Eyre J, Grabowski M, Nalla S, Bastir, M, Schmid P, Churchill SE, Berger LR. A nearly complete lower back of Australopithecus sediba. eLife 10:e70447. https://doi.org/10.7554/eLife.70447

2021. Williams SA, Pilbeam D. Homeotic change in segment identity derives the human vertebral formula from a chimpanzee-like one. American Journal of Physical Anthropology 176, 283-294. https://doi.org/10.1002/ajpa.24356

2021. Prabhat AM, Miller CK, Prang TC, Spear J, Williams SA, DeSilva J. Homoplasy in the evolution of modern human-like joint proportions in Australopithecus afarensis. eLife 10:e65897. https://doi.org/10.7554/eLife.65897

2021. Prang TC, Ramirez K, Grabowski M, Williams SA. Ardipithecus hand provides evidence that humans and chimpanzees evolved from an ancestor with suspensory adaptations. Science Advances 7, eabf2474. DOI: 10.1126/sciadv.abf247

2021. Araiza I, Meyer, MR, Williams SA. Is ulna curvature in the StW 573 (‘Little Foot’) Australopithecus natural or pathological? Journal of Human Evolution 151, 102927. https://doi.org/10.1016/j.jhevol.2020.102927

2020. Spear JK, Williams SA. Mosaic patterns of homoplasy accompany the parallel evolution of suspensory adaptations in the forelimb of tree sloths (Folivora: Xenarthra). Zoological Journal of the Linnean Society zlaa154, https://doi.org/10.1093/zoolinnean/zlaa154

2020. Williams SA, Prang TC, Meyer MR, Russo GA, Shapiro LJ. Reevaluating bipedalism in Danuvius. Nature 586, E1-3. https://doi.org/10.1038/s41586-019-1731-0

2020. Bastir M, García-Martínez, D Torre-Tamayo N, Palancar CA, Beyer B, Barash A, Villa C, Sanchis-Gimeno JA, Riesco-López A, Nalla S, Torre-Sánchez I, García-Rio F, Been E, Gómez-Olivencia A, Haeusler M, Williams SA, Spoor F. Rib cage anatomy in Homo erectus suggests a recent evolutionary origin of modern human body shape. Nature Ecology and Evolution. 4, 1178–1187 https://doi.org/10.1038/s41559-020-1240-4

2020. Bastir M, García-Martínez, D Torre-Tamayo N, Palancar CA, Beyer B, Barash A, Villa C, Sanchis-Gimeno JA, Riesco-López A, Nalla S, Torre-Sánchez I, García-Rio F, Been E, Gómez-Olivencia A, Haeusler M, Williams SA, Spoor F. Rib cage anatomy in Homo erectus suggests a recent evolutionary origin of modern human body shape. Nature Ecology and Evolution. https://doi.org/10.1038/s41559-020-1240-4

2020. Roseman CC, Capellini TD, Jagoda E, Williams SA, Grabowski M, O’Connor C, Polk JD, Cheverud JM. Variation in mouse pelvic morphology maps to locations enriched in Sox9 Class II and Pitx1 regulatory features. Journal of Experimental Zoology (Molecular and Developmental Evolution) 334, 100-112. https://doi.org/10.1002/jez.b.22926

2019. Meyer MR, Williams SA. Earliest axial fossils from the genus Australopithecus. Journal of Human Evolution 132, 189-214.  https://doi.org/10.1016/j.jhevol.2019.05.004  

2019. Williams SA, Spear JK, Petrullo L, Goldstein DM, Lee AB, Peterson AL, Miano, D.A., Kaczmarek E, Shattuck MR. Increased variation in numbers of vertebrae in suspensory mammals. Nature Ecology and Evolution 3, 949-956. https://doi.org/10.1038/s41559-019-0894-2 

2018. Williams S.A. Lead Book Review: Was the last common ancestor aping a chimp or just monkeying around? Journal of Human Evolution 121, 72-74. https://www.sciencedirect.com/science/article/pii/S0047248418300381

2018. Williams S.A., Meyer M.R., Nalla S., García-Martínez D., Eyre J., Prang T.C., Bastir M., Schmid P., Churchill S.E., Berger L.R. The vertebrae, ribs, and sternum of Australopithecus sediba. PaleoAnthropology 2018, 156-233. http://www.paleoanthro.org/media/journal/content/PA20180156.pdf

2018. Williams S.A., DeSilva J.M., de Ruiter D.J. Malapa at 10: Introduction to the special issue on Australopithecus sediba. PaleoAnthropology 2018, 49-55. http://www.paleoanthro.org/media/journal/content/PA20180049.pdf

2018. DeCasien A.R., Thompson N., Shattuck M.R., Williams S.A. Encephalization and longevity evolved in a correlated fashion in Euarchontoglires but not in other mammals. Evolution 72, 2617-2631. https://onlinelibrary.wiley.com/doi/full/10.1111/evo.13633

2018. VanSickle C., Cofran Z.D., García-Martínez D., Williams S.A., Churchill S.E., Berger L.R., Hawks J. Homo naledi pelvic remains from the Dinaledi Chamber, South Africa. Journal of Human Evolution. 125, 122-136. https://www.sciencedirect.com/science/article/pii/S0047248417304050

2018. Spear J.K., Williams S.A. Scapular breadth is associated with forelimb-dominated suspensory behavior in Atelidae: Comments on Selby and Lovejoy (2017). American Journal of Physical Anthropology 167, 194-196. https://onlinelibrary.wiley.com/doi/full/10.1002/ajpa.23599

2017. Bastir M., García-Martínez D., Williams S.A., Recheis W., Torres I., García Río F., Oishi M., Ogihara N. 3D geometric morphmetrics of thorax variation in Hominoidea. Journal of Human Evolution 113, 10-23. https://www.sciencedirect.com/science/article/pii/S0047248417303421

2017. Meyer M.R., Williams S.A., Schmid P., Churchill S.E., Berger L.R. The cervical spine of Australopithecus sediba. Journal of Human Evolution 104, 32-49. https://www.sciencedirect.com/science/article/pii/S0047248417300027

2017. Hawks, J., Elliott, M., Schmid, P., Churchill, S.E., de Ruiter, D.J., Roberts, E.M., Hilbert-Wolf, H., Garvin, H.M., Williams, S.A., Delezene, L.K., Feuerriegel, E.M., Randolph-Quinney, P., Kivell, T.L., Laird, M.F., Tawane, G., DeSilva, J.M., Bailey, S.E., Brophy, J.K., Meyer, M.R., Skinner, M.M., Tocheri, M.W., VanSickle, C., Walker, C.S.., Campbell, T.L., Kuhn, B., Kruger, A., Tucker, S., Gurtov, A., Hlophe, N., Hunter, R., Morris, H., Peixotto, B., Ramalepa, M., van Rooyen, D., Tsikoane, M., Boschoff, P., Dirks, P.H.G.M., Berger, L.R., 2017. New fossils of Homo naledi from the Lesedi Chamber, South Africa. eLife e24232. http://dx.doi.org/10.7554/eLife.24232

2017. DeCasien, A.R., Williams, S.A., Higham, J.P. Primate brain size is predicted by diet but not sociality. Nature Ecology & Evolution 1, 0112. https://www.nature.com/articles/s41559-017- 0112

2017. Williams, S.A., García-Martínez, D., Meyer, M.R., Nalla, S., Schmid, P., Hawks, J., Churchill, S.E., Berger, L.R., Bastir, M. The vertebrae and ribs of Homo naledi. Journal of Human Evolution. 104, 136-154. https://doi.org/10.1016/j.jhevol.2016.11.003

2016. Randolph-Quinney, P.S., Williams, S.A., Steyn, M., Meyer, M.R., Smilg, J.S., Churchill, S.E., Odes, E., Augustine, T., Tafforeau, P., Berger, L.R. Primary osteogenic tumor of the spine in Australopithecus sediba: earliest evidence for neoplastic disease in the human lineage. South African Journal of Science. 112 (7/8), 1-7. http://dx.doi.org/10.17159/sajs.2016/20150470

2016. Williams, S.A., Russo, G.A. The fifth element (of Lucy’s sacrum): Reply to Machnicki, Reno, and Lovejoy. American Journal of Physical Anthropology 161, 374-378. http://onlinelibrary.wiley.com/doi/10.1002/ajpa.23035/abstract

2016. Antón, S.C., Toboada, H., Middleton, E.R., Rainwater, C.W., Taylor, A.B., Turner, T.R., Turnquist, J.E., Weinstein, K.J., Williams, S.A. Morphological variation in Homo erectus and the origins of developmental plasticity. Philosophical Transactions of the Royal Society B 371, 20150236. http://rstb.royalsocietypublishing.org/content/371/1698/20150236

2016. Tawane, G., García-Martínez, D., Eyre, J., Bastir, M., Berger, L., Schmid, P., Nalla, S., Williams, S.A. A hominin first rib discovered at the Sterkfontein caves. South African Journal of Science. 112 (5/6), 1-7. http://dx.doi.org/10.17159/sajs.2016/20150278  

2016. Williams, S.A., Middleton, E.R., Villamil, C.I., Shattuck, M.R. Vertebral numbers and human evolution. Yearbook of Physical Anthropology 159 (S61), 19-36. http://onlinelibrary.wiley.com/doi/10.1002/ajpa.22901/full

2015. Russo, G.A., Williams, S.A.. Giant pandas (Carnivora) and living hominoids (Primates) converge on lumbar vertebral adaptations to orthograde trunk posture. Journal of Human Evolution 88, 160-179. https://doi.org/10.1016/j.jhevol.2015.06.015

2015. Berger, L.R., Hawks, J., DeRuiter, D., Churchill, S.E., Schmid, P., Delezene, L., Kivell, T., Garvin, H.M., Williams, S.A., DeSilva, J.M., Skinner, M., Musiba, C.M., Cameron, N., Holliday, T.W., Harcourt-Smith, W., Ackermann, R.R., Bastir, M., Brophy, J., Cofran, Z.D., Congdon, K.A., Deane, A.S., Dembo, M., Elliot, M., Feuerriegel, E.M., García- Martínez, D., Green, D.J., Gurtov, A., Kruger, A., Laird, M.F., Marchi, D., Meyer, M.R., Nalla, S., Negash, E.W., Radovcic, D., Scott, J.E., Schroeder, L., Throckmorton, Z., VanSickle, C., Walker, C.S., Wei, P., Zipfel, B. Homo naledi, a new species of the genus Homo from the Dinaledi Chamber, South Africa. eLife 4, e09560. http://dx.doi.org/10.7554/eLife.09560

2015. Meyer, M.R., Williams, S.A., Smith, M., Sawyer, G. Lucy's back: reassessment of fossils associated with the A.L. 288-1 vertebral column. Journal of Human Evolution 85, 174-180. https://doi.org/10.1016/j.jhevol.2015.05.007

2015. Williams, S.A., Russo, G.A. Evolution of the hominoid vertebral column: the long and the short of it. Evolutionary Anthropology 24, 15-32. http://onlinelibrary.wiley.com/doi/10.1002/evan.21437/full

2015. Williams, S.A., Shattuck, M.R. Ecology, longevity, and naked mole-rats: confounding effects of sociality? Proceedings of the Royal Society B. 282, 20141664. http://rspb.royalsocietypublishing.org/content/282/1802/20141664

2015. Russo, G.A., Williams, S.A. Lucy (A.L. 288-1) had five sacral vertebrae. American Journal of Physical Anthropology 156, 295-303. http://onlinelibrary.wiley.com/doi/10.1002/ajpa.22642/full

2013. Williams, S.A., Ostrofsky, K.R., Frater, N., Churchill, S.E., Schmid, P., Berger, L.R. The vertebral column of Australopithecus sediba. Science 340, 1232996. http://science.sciencemag.org/content/340/6129/1232996

2012. Williams, S.A. Modern or distinct axial bauplan in early hominins? Comments on Haeusler et al. (2011). Journal of Human Evolution 63, 552-556. https://doi.org/10.1016/j.jhevol.2012.01.007

2012. Williams, S.A. Placement of the diaphragmatic vertebra in catarrhines: implications for the evolution of dorsostability in hominoids and bipedalism in hominins. American Journal of Physical Anthropology 148, 111-122. http://onlinelibrary.wiley.com/doi/10.1002/ajpa.22049/full

2011. Williams, S.A. Variation in anthropoid vertebral formulae: implications for homology and homoplasy in hominoid evolution. Journal of Experimental Zoology B (Molecular and Developmental Evolution) 318, 134-147. http://onlinelibrary.wiley.com/doi/10.1002/jez.b.21451/full

2010. Williams, S.A. Morphological integration and the evolution of knuckle-walking. Journal of Human Evolution 58, 432-440. https://doi.org/10.1016/j.jhevol.2010.03.005

2010. Shattuck, M.R., Williams, S.A. Arboreality has allowed for the evolution of increased longevity in mammals. Proceedings of the National Academy of Sciences USA 107, 4635- 4639. http://www.pnas.org/content/107/10/4635.abstract

2010. Polk, J.D., Williams, S.A., Peterson, J.V., Roseman, C.C., Godfrey, L.R. Subchondral bone apparent density and locomotor behavior in extant primates and subfossil lemurs  Hadropithecus and Pachylemur. International Journal of Primatology 31, 275-299. 10.1007/s10764-010- 9401-y 

2009. Polk, J.D., Williams, S.A., Peterson, J.V. Body size and joint posture in primates. American Journal of Physical Anthropology 140, 359-367. http://onlinelibrary.wiley.com/doi/10.1002/ajpa.21083/full

Editor-reviewed Papers and Books

2019. Williams SA, Gomez-Olivencia A, Pilbeam D. Numbers of vertebrae in hominoid evolution. In Been E, Gomez-Olivencia A, Kramer P. (eds.), Spinal Evolution: Morphology, Function, and Pathology of the Spine in Hominoid Evolution. Springer, p 97-124.

2019. Williams SA, Meyer MR. The spine of Australopithecus. In Been E, Gomez-Olivencia A, Kramer P. (eds.), Spinal Evolution: Morphology, Function, and Pathology of the Spine in Hominoid Evolution. Springer, p 125-151.

2019. Meyer MR, Williams SA. The spine of early Homo. In Been E, Gomez-Olivencia A, Kramer P. (eds.), Spinal Evolution: Morphology, Function, and Pathology of the Spine in Hominoid Evolution. Springer, p 153-183.

2018. Williams, S.A., Australopithecus Group. Encyclopedia of Evolutionary Psychological Science.

2015. Williams, S.A. Earliest Hominins. McGraw-Hill Yearbook in Science and Technology (2015).

2015. Williams, S.A. (invited contribution). Review of Apes and Human Evolution by R.H. Tuttle (2014). Current Anthropology.

Updated August 2023

I am an evolutionary morphologist and paleoanthropologist with primary research interests in the evolution of positional behavior (posture and locomotion) during human evolution. My research focus is not on a particular time period; rather, I am interested in evolutionary transitions in the hominoid fossil record, from 20 million-year- old extinct apes to modern human and ape variation and the entirety of human evolution in between. The major focus of my academic work has been on the primate postcranial skeleton and specifically the vertebral column (spine). I have described and analyzed in large comparative datasets the vertebral columns of a two new species of hominins, Australopithecus sediba and Homo naledi. Work on that material continues, and I recently completed a research project funded by the Leakey Foundation to study the evolution of lordosis in hominins in the context of a global sample of modern humans. New research projects focus on the evolutionary morphology of Miocene apes, continued work on fossil hominins, including some of the earliest purported hominins, and reconstructing the last common ancestor of hominins and panins (chimpanzees and bonobos).

In addition to continuing PhD students Monica Avilez, Jordan Guerra, Madelynne Dudas, Xue Wang, and Ailis Daly, we are joined this year by Monica Msechu. Monica M. is interested in Miocene ape postcranial evolution, Ailis is interested in the evolution of bipedalism and has worked on the neck and knee, Xue is working on the ontogeny of lumbar vertebrae, Madelynne on the plasticity of radius and ulna shaft shape, Jordan is working on morphological character definitions as well as lower thoracic vertebra morphology, and Monica is working on the evolution of the pelvis in anthropoids, with a focus on hominoids and the evolution of suspensory behavior. Finally, Jeff Spear is defending his dissertation on the evolution of upper limb morphology and its convergence in suspensory primates in late September. I do not plan to take new PhD students in the 2024-2025 academic year.

Currently, I direct the Masters in Science program in Human Skeletal Biology housed in the anthropology department. I continue to teach undergraduate courses like Human Evolution and Human Origins and graduate courses such as Integrative Paleoanthropology I, Interpreting the Human Skeleton: Morphological and Statistical Methods, and History and Philosophy of Biological Anthropology. I hope to offer new graduate and undergraduate courses in the future.