Affiliation:
1. Medical Anatomical Sciences Department, College of Osteopathic Medicine of the Pacific Western University of Health Sciences Pomona California USA
2. Department of Basic Medical Sciences University of Arizona College of Medicine‐Phoenix Phoenix Arizona USA
3. Department of Cell Systems and Anatomy University of Texas Health Science Center at San Antonio San Antonio Texas USA
4. Southwest National Primate Research Center Texas Biomedical Research Institute San Antonio Texas USA
Abstract
AbstractObjectivesDifferences between adult humans and great apes in cervical vertebral morphology are well documented, but the ontogeny of this variation is still largely unexplored. This study examines patterns of growth in functionally relevant features of C1, C2, C4, and C6 in extant humans and apes to understand the development of their disparate morphologies.Materials and MethodsLinear and angular measurements were taken from 530 cervical vertebrae representing 146 individual humans, chimpanzees, gorillas, and orangutans. Specimens were divided into three age‐categories based on dental eruption: juvenile, adolescent, and adult. Inter‐ and intraspecific comparisons were evaluated using resampling methods.ResultsOf the eighteen variables examined here, seven distinguish humans from apes at the adult stage. Human‐ape differences in features related to atlantoaxial joint function tend to be established by the juvenile stage, whereas differences in features related to the nuchal musculature and movement of the subaxial elements do not fully emerge until adolescence or later. The orientation of the odontoid process—often cited as a feature that distinguishes humans from apes—is similar in adult humans and adult chimpanzees, but the developmental patterns are distinct, with human adultlike morphology being achieved much earlier.DiscussionThe biomechanical consequences of the variation observed here is poorly understood. Whether the differences in growth patterns represent functional links to cranial development or postural changes, or both, requires additional investigation. Determining when humanlike ontogenetic patterns evolved in hominins may provide insight into the functional basis driving the morphological divergence between extant humans and apes.
Funder
American Association of Anatomists
California Academy of Sciences
Subject
Paleontology,Archeology,Genetics,Anthropology,Anatomy,Epidemiology
Cited by
1 articles.
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