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A simple rule governs the evolution and development of hominin tooth size

Evans, Alastair R., Daly, E. Susanne, Catlett, Kierstin K., Paul, Kathleen S., King, Stephen J., Skinner, Matthew M., Nesse, Hans P., Hublin, Jean-Jacques, Townsend, Grant C., Schwartz, Gary T., and others. (2016) A simple rule governs the evolution and development of hominin tooth size. Nature, 530 . pp. 477-480. ISSN 0028-0836. (doi:10.1038/nature16972) (KAR id:54534)

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The variation in molar tooth size in humans and our closest relatives (hominins) has strongly influenced our view of human evolution. The reduction in overall size and disproportionate decrease in third molar size have been noted for over a century, and have been attributed to reduced selection for large dentitions owing to changes in diet or the acquisition of cooking1, 2. The systematic pattern of size variation along the tooth row has been described as a ‘morphogenetic gradient’ in mammal, and more specifically hominin, teeth since Butler3 and Dahlberg4. However, the underlying controls of tooth size have not been well understood, with hypotheses ranging from morphogenetic fields3 to the clone theory5. In this study we address the following question: are there rules that govern how hominin tooth size evolves? Here we propose that the inhibitory cascade, an activator–inhibitor mechanism that affects relative tooth size in mammals6, produces the default pattern of tooth sizes for all lower primary postcanine teeth (deciduous premolars and permanent molars) in hominins. This configuration is also equivalent to a morphogenetic gradient, finally pointing to a mechanism that can generate this gradient. The pattern of tooth size remains constant with absolute size in australopiths (including Ardipithecus, Australopithecus and Paranthropus). However, in species of Homo, including modern humans, there is a tight link between tooth proportions and absolute size such that a single developmental parameter can explain both the relative and absolute sizes of primary postcanine teeth. On the basis of the relationship of inhibitory cascade patterning with size, we can use the size at one tooth position to predict the sizes of the remaining four primary postcanine teeth in the row for hominins. Our study provides a development-based expectation to examine the evolution of the unique proportions of human teeth.

Item Type: Article
DOI/Identification number: 10.1038/nature16972
Uncontrolled keywords: Biological anthropology; Evolutionary developmental biology; Palaeontology
Subjects: Q Science
Divisions: Divisions > Division of Human and Social Sciences > School of Anthropology and Conservation
Depositing User: Matthew Skinner
Date Deposited: 15 Mar 2016 11:19 UTC
Last Modified: 17 Aug 2022 12:20 UTC
Resource URI: (The current URI for this page, for reference purposes)

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