Teeth, prenatal growth rates, and the evolution of human-like pregnancy in later .

Bibliographic Collection: 
Publication Type: Journal Article
Authors: Monson, Tesla A; Weitz, Andrew P; Brasil, Marianne F; Hlusko, Leslea J
Year of Publication: 2022
Journal: Proc Natl Acad Sci U S A
Volume: 119
Issue: 41
Pagination: e2200689119
Date Published: 2022 Oct 11
Publication Language: eng
ISSN: 1091-6490
Keywords: Animals, Biological Evolution, Female, Fossils, Hominidae, Humans, Infant, Newborn, Molar, Pregnancy

Evidence of how gestational parameters evolved is essential to understanding this fundamental stage of human life. Until now, these data seemed elusive given the skeletal bias of the fossil record. We demonstrate that dentition provides a window into the life of neonates. Teeth begin to form in utero and are intimately associated with gestational development. We measured the molar dentition for 608 catarrhine primates and collected data on prenatal growth rate (PGR) and endocranial volume (ECV) for 19 primate genera from the literature. We found that PGR and ECV are highly correlated ( = 0.93, < 0.001). Additionally, we demonstrated that molar proportions are significantly correlated with PGR ( = 0.004) and log-transformed ECV ( = 0.001). From these correlations, we developed two methods for reconstructing PGR in the fossil record, one using ECV and one using molar proportions. Dental proportions reconstruct hominid ECV ( = 0.81, < 0.001), a result that can be extrapolated to PGR. As teeth dominate fossil assemblages, our findings greatly expand our ability to investigate life history in the fossil record. Fossil ECVs and dental measurements from 13 hominid species both support significantly increasing PGR throughout the terminal Miocene and Plio-Pleistocene, reflecting known evolutionary changes. Together with pelvic and endocranial morphology, reconstructed PGRs indicate the need for increasing maternal energetics during pregnancy over the last 6 million years, reaching a human-like PGR (i.e., more similar to humans than to other extant apes) and ECV in later less than 1 million years ago.

DOI: 10.1073/pnas.2200689119
Alternate Journal: Proc Natl Acad Sci U S A