The New York Consortium in Evolutionary Primatology
Assistant Professor Department of Anthropology New York University
Ph.D. 2011, University of Illinois, Urbana-Champaign M.A. 2006, Northern Illinois University B.A. 2003, Kent State University
Email: sawilliams [at] nyu.edu
Tel: (212) 992- 9853
I am a paleoanthropologist and evolutionary morphologist with primary research interests in the evolution of upright posture and bipedal locomotion in hominoid primates. Balancing an upright torso over two legs without a tail for support or balance and walking around that way is an unusual thing to do; indeed, scientists, philosophers, and curious laypeople have been asking why we are bipedal for centuries. My research focuses on how we are upright and bipedal in an effort to attempt to understand why we are. In brief, I ask when and how upright posture and bipedalism first evolved and how it has changed over millions of years. I approach these questions by studying the morphology of the postcranial skeleton—the body below the skull.
The major focus of my academic work has been on the vertebral column (spine), but I am currently working on projects on related anatomical systems such as the ribcage and pelvis. 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. I approach this research in the context of variation, the primary material on which evolution acts. I therefore have studied a large sample of modern and extinct hominoid (humans and other apes) skeletons, in addition to a broad comparative sample of primates and other mammals.
I led a description and analysis of the vertebral column of Australopithecus sediba and am currently working on comparative analyses of its axial skeleton. In 2013, I was part of a team that excavated and cataloged a large number of hominin fossils at Rising Star Cave in the Cradle of Humankind, South Africa. I worked with an international team of researchers in 2014 to describe what is likely a new and surprising species of hominin that will undoubtedly alter the way we think about human evolution. My involvement in these projects has been recognized by my appointment as a research associate at the Evolutionary Studies Institute and Center for Excellence in PaleoSciences, University of the Witwatersrand, where I conduct research in the Cradle of Humankind, South Africa. I recently worked on a reassessment of the vertebral column of the famous Australopithecus afarensis skeleton, A.L. 288-1 (“Lucy”), and am currently starting new research projects on other vertebral fossils from East Africa and parts of Europe, including the Miocene hominoids Proconsul and Oreopithecus. Collaborative work with Dr. James Higham on hard tissue correlates of facial flanging (cheek flanges) in drills, orangutans, and fossil primates is part of an ongoing project of identifying bony correlates of sexually-selected soft tissue traits.
2015. Williams SA, Russo GA. Evolution of the hominoid vertebral column: the long and the short of it. Evol. Anthropol. 24, 15-32.
2015. Williams SA, Shattuck MR. Ecology, longevity, and naked mole-rats: confounding effects of sociality? Proc. Roy. Soc. B. 282, 20141664.
2015. Russo GA, Williams SA. Lucy (A.L. 288-1) had five sacral vertebrae. Am. J. Phys. Anthropol. 156, 295-303.
2013. Williams SA, Ostrofsky KR, Frater N, Churchill SE, Schmid P, Berger LR. The vertebral column of Australopithecus sediba. Science 340, 1232996. DOI: 10.1126/science.1232996
2012. Williams SA. Evolution of the Hominoid Vertebral Column: The Long and Short of It. Lambert Academic Publishing.
2012. Williams SA. Modern or distinct axial bauplan in early hominins? Comments on Haeusler et al. (2011). J. Hum. Evol. 63, 552-556.
2012. Williams SA. Placement of the diaphragmatic vertebra in catarrhines: implications for the evolution of dorsostability in hominoids and bipedalism in hominins. Am. J. Phys. Anthropol. 148, 111-122.
2011. Williams SA. Variation in anthropoid vertebral formulae: implications for homology and homoplasy in hominoid evolution. J. Exp. Zool. (Mol. Dev. Evol.) 318, 134-147.
2011. Williams SA. Evolution of the hominoid vertebral column. Ph.D. dissertation, University of Illinois, Urbana-Champaign, IL.
2010. Williams SA. Morphological integration and the evolution of knuckle-walking. J. Hum. Evol. 58: 432-440.
2010. Shattuck MR, Williams SA. Arboreality has allowed for the evolution of increased longevity in mammals. Proc. Natl. Acad. Sci. USA 107: 4635-4639.
2010. Polk JD, Williams SA, Peterson JV, Roseman CC, Godfrey LR. Subchondral bone apparent density and locomotor behavior in extant primates and subfossil lemurs Hadropithecus and Pachylemur. Int. J. Primatol. 31: 275-299.
2009. Polk JD, Williams SA, Peterson JV. Body size and joint posture in primates. Am. J. Phys. Anthropol. 140: 359-367.
2006. Williams SA. Anatomical variation in the hand and wrist of African apes: evidence for a single origin of knuckle-walking adaptations. M.A. thesis, Northern Illinois University, Dekalb.