@article{36bb6e4fadab4d919568cddd400c7f56,
title = "Homeotic change in segment identity derives the human vertebral formula from a chimpanzee-like one",
abstract = "Objectives: One of the most contentious issues in paleoanthropology is the nature of the last common ancestor of humans and our closest living relatives, chimpanzees and bonobos (panins). The numerical composition of the vertebral column has featured prominently, with multiple models predicting distinct patterns of evolution and contexts from which bipedalism evolved. Here, we study total numbers of vertebrae from a large sample of hominoids to quantify variation in and patterns of regional and total numbers of vertebrae in hominoids. Materials and Methods: We compile and study a large sample (N = 893) of hominoid vertebral formulae (numbers of cervical, thoracic, lumbar, sacral, caudal segments in each specimen) and analyze full vertebral formulae, total numbers of vertebrae, and super-regional numbers of vertebrae: presacral (cervical, thoracic, lumbar) vertebrae and sacrococcygeal vertebrae. We quantify within- and between-taxon variation using heterogeneity and similarity measures derived from population genetics. Results: We find that humans are most similar to African apes in total and super-regional numbers of vertebrae. Additionally, our analyses demonstrate that selection for bipedalism reduced variation in numbers of vertebrae relative to other hominoids. Discussion: The only proposed ancestral vertebral configuration for the last common ancestor of hominins and panins that is consistent with our results is the modal formula demonstrated by chimpanzees and bonobos (7 cervical-13 thoracic-4 lumbar-6 sacral-3 coccygeal). Hox gene expression boundaries suggest that a rostral shift in Hox10/Hox11-mediated complexes could produce the human modal formula from the proposal ancestral and panin modal formula.",
keywords = "Hox genes, bipedalism, hominoid, lumbar, vertebrae",
author = "Williams, {Scott A.} and David Pilbeam",
note = "Funding Information: The authors thank Emmanuel Gilissen for assessing bonobo coccyges at the Mus{\'e}e royal de l'Afrique centrale, Robert Martin for providing copies of Adolf Schultz's data sheets to DP two decades ago, Jeffrey Spear for examining a subset of specimens at the Smithsonian National Museum of Natural History, and an editorial board member, an associate editor, and two anonymous reviewers for helpful feedback. This research was funded by The Leakey Foundation and the American School of Prehistoric Research. The authors also thank the following individuals for granting access to specimens in their care: Gisselle Garcia, Ashley Hammond, Eileen Westwig, Eleanor Hoeger, Aja Marcato, Brian O'Toole, Marisa Surovy, Sarah Ketelsen, and Neil Duncan (American Museum of Natural History); Lyman Jellema and Yohannes Haile‐Selassie (Cleveland Museum of Natural History); Brendon Billings and Anja Meyer (Dart Collection, University of the Witwatersrand); Mark Omura, Judy Chupasko, and Jane Harrison (Museum of Comparative Zoology, Harvard University); Frieder Mayer, Saskia Jancke, and Nora Lange (Museum f{\"u}r Naturkunde, Berlin), Wim Wendelen and Emmanuel Gilissen (Mus{\'e}e Royal de l'Afrique Centrale); Darrin Lunde, Linda Gordon, and Richard Thorington (National Museum of Natural History, Smithsonian Institution), Dan Gebo (Northern Illinois University); Georges Lenglet and S{\'e}bastien Bruaux (Royal Belgian Institue of Natural Sciences, Brussels); Marcia Ponce de Le{\'o}n, Christoph Zollikofer, and Marco Milella (Anthropological Institute and Museum, Universit{\"a}t Z{\"u}rich); .Adrienne Zihlman and Carol Underwood (UC Santa Cruz); Michael Hiermeier (Zoologische Staatssammlung Munchen); and Kristof Zyskoswki, Gary Aronson, and Eric Sargis (Peabody Museum of Natural History). Funding Information: The authors thank Emmanuel Gilissen for assessing bonobo coccyges at the Mus?e royal de l'Afrique centrale, Robert Martin for providing copies of Adolf Schultz's data sheets to DP two decades ago, Jeffrey Spear for examining a subset of specimens at the Smithsonian National Museum of Natural History, and an editorial board member, an associate editor, and two anonymous reviewers for helpful feedback. This research was funded by The Leakey Foundation and the American School of Prehistoric Research. The authors also thank the following individuals for granting access to specimens in their care: Gisselle Garcia, Ashley Hammond, Eileen Westwig, Eleanor Hoeger, Aja Marcato, Brian O'Toole, Marisa Surovy, Sarah Ketelsen, and Neil Duncan (American Museum of Natural History); Lyman Jellema and Yohannes Haile-Selassie (Cleveland Museum of Natural History); Brendon Billings and Anja Meyer (Dart Collection, University of the Witwatersrand); Mark Omura, Judy Chupasko, and Jane Harrison (Museum of Comparative Zoology, Harvard University); Frieder Mayer, Saskia Jancke, and Nora Lange (Museum f?r Naturkunde, Berlin), Wim Wendelen and Emmanuel Gilissen (Mus?e Royal de l'Afrique Centrale); Darrin Lunde, Linda Gordon, and Richard Thorington (National Museum of Natural History, Smithsonian Institution), Dan Gebo (Northern Illinois University); Georges Lenglet and S?bastien Bruaux (Royal Belgian Institue of Natural Sciences, Brussels); Marcia Ponce de Le?n, Christoph Zollikofer, and Marco Milella (Anthropological Institute and Museum, Universit?t Z?rich);.Adrienne Zihlman and Carol Underwood (UC Santa Cruz); Michael Hiermeier (Zoologische Staatssammlung Munchen); and Kristof Zyskoswki, Gary Aronson, and Eric Sargis (Peabody Museum of Natural History). Publisher Copyright: {\textcopyright} 2021 Wiley Periodicals LLC.",
year = "2021",
month = oct,
doi = "10.1002/ajpa.24356",
language = "English (US)",
volume = "176",
pages = "283--294",
journal = "American Journal of Physical Anthropology",
issn = "0002-9483",
publisher = "Wiley-Liss Inc.",
number = "2",
}