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" The Origin and Evolution of Human Bipedalism as Revealed by Foot Morphology "
Prang, Thomas Cody
Williams, Scott A.
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Latin Dissertation
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English
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| Record Number
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1052495
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TL51612
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| Main Entry
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Prang, Thomas Cody
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| Title & Author
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The Origin and Evolution of Human Bipedalism as Revealed by Foot Morphology\ Prang, Thomas CodyWilliams, Scott A.
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| College
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New York University
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| Date
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2019
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| Degree
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Ph.D.
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2019
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| Note
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600 p.
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| Abstract
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This is a study of the origin and evolution of human bipedal locomotion from the perspective of the foot. Human bipedal locomotion is unique among all living mammals and understanding its evolution is one of the major foci of biological anthropology. The skeletal morphology of the foot is central to reconstructing the evolutionary shift from an unknown form of primate quadrupedalism to striding human-like bipedalism. Recently, debates about the origin of bipedalism have been influenced by interpretations of the morphology of the 4.4 million-year-old hominin Ardipithecus ramidus. The foot of Ar. ramidus was originally argued to possess monkey-like propulsive and midfoot stabilizing anatomies that were inferred to be primitive retentions from a more generalized Homo-Pan last common ancestor (LCA). Whether the LCA was monkey-like or ape-like in its locomotor adaptation alters the evolutionary context of hominin bipedalism. The uncertainty surrounding this debate impedes our understanding of the origin of bipedalism because adaptive hypotheses are often based on directional change (i.e., ancestral species to descendant species). This dissertation tests hypotheses about the foot morphology of the LCA, the loss of hallucal and non-hallucal grasping in the hominin lineage, and the evolution of the longitudinal arch. The data include observations of original foot fossils focusing mainly on Ardipithecus kadabba, Ardipithecus ramidus, Australopithecus afarensis, and the Burtele foot from Woranso-Mille, Ethiopia. These early hominin fossils are evaluated against a large sample of anthropoid primates using a combination of linear metric analysis, three-dimensional geometric morphometrics, and phylogenetic comparative methods (i.e., ancestral estimation and evolutionary modeling). The results demonstrate that early hominins retain foot morphologies that are uniquely similar to living African ape species among anthropoids. These characteristics are interpreted to reflect a combination of terrestrial plantigrade quadrupedalism and vertical climbing in the locomotor repertoires of the African apes. The Ardipithecus foot therefore provides evidence that bipedalism was derived from a semi-terrestrial ancestor with vertical climbing adaptations. Hominins likely retained a small degree of pedal and hallucal grasping capability long after the evolution of obligate bipedality in early Australopithecus. A new partial hominin foot from Ileret, Kenya attributed to Homo provides evidence that hominins had a well-developed longitudinal arch c. 1.8 Ma. The evolution of bipedalism is better understood through the lens of an African ape-like ancestry rather than a generalized, monkey-like one.
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| Descriptor
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Physical anthropology
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Williams, Scott A.
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New York University
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