Spear, JK, Grabowski, M, Sekhavati, Y, Costa, CE, Goldstein, DM, Petrullo, LA, Peterson, AL, Lee, AB, Shattuck, MR, Gómez-Olivencia, A and Williams, SA (2023) 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. pp. 1-16. ISSN 0047-2484

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Abstract

The primate vertebral column has been extensively studied, with a particular focus on hominoid primates and the last common ancestor of humans and chimpanzees. The number of vertebrae in hominoids—up to and including the last common ancestor of humans and chimpanzees—is subject to considerable debate. However, few formal ancestral state reconstructions exist, and none include a broad sample of primates or account for the correlated evolution of the vertebral column. Here, we conduct an ancestral state reconstruction using a model of evolution that accounts for both homeotic (changes of one type of vertebra to another) and meristic (addition or loss of a vertebra) changes. Our results suggest that ancestral primates were characterized by 29 precaudal vertebrae, with the most common formula being seven cervical, 13 thoracic, six lumbar, and three sacral vertebrae. Extant hominoids evolved tail loss and a reduced lumbar column via sacralization (homeotic transition at the last lumbar vertebra). Our results also indicate that the ancestral hylobatid had seven cervical, 13 thoracic, five lumbar, and four sacral vertebrae, and the ancestral hominid had seven cervical, 13 thoracic, four lumbar, and five sacral vertebrae. The last common ancestor of humans and chimpanzees likely either retained this ancestral hominid formula or was characterized by an additional sacral vertebra, possibly acquired through a homeotic shift at the sacrococcygeal border. Our results support the ‘short-back’ model of hominin vertebral evolution, which postulates that hominins evolved from an ancestor with an African ape–like numerical composition of the vertebral column.

Item Type:	Article
Additional Information:	Jeffrey K. Spear, Mark Grabowski, Yeganeh Sekhavati, Christina E. Costa, Deanna M. Goldstein, Lauren A. Petrullo, Amy L. Peterson, Amanda B. Lee, Milena R. Shattuck, Asier Gómez-Olivencia, Scott A. Williams, Evolution of vertebral numbers in primates, with a focus on hominoids and the last common ancestor of hominins and panins,Journal of Human Evolution, Volume 179, 2023,103359, ISSN 0047-2484, https://doi.org/10.1016/j.jhevol.2023.103359.
Uncontrolled Keywords:	Lumbar Vertebrae; Animals; Primates; Hominidae; Humans; Pan troglodytes; Fossils; Biological Evolution; Ancestral state reconstruction; Bipedalism; Hominin evolution; Last common ancestor; Vertebral column; Humans; Animals; Hominidae; Pan troglodytes; Biological Evolution; Fossils; Primates; Lumbar Vertebrae; 0603 Evolutionary Biology; 1601 Anthropology; 2101 Archaeology; Anthropology
Subjects:	G Geography. Anthropology. Recreation > GE Environmental Sciences G Geography. Anthropology. Recreation > GN Anthropology Q Science > QH Natural history > QH301 Biology
Divisions:	Biological & Environmental Sciences (from Sep 19)
Publisher:	Elsevier
SWORD Depositor:	A Symplectic
Date Deposited:	18 Mar 2024 10:02
Last Modified:	24 Apr 2024 00:50
DOI or ID number:	10.1016/j.jhevol.2023.103359
URI:	https://researchonline.ljmu.ac.uk/id/eprint/22821

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