Is the human chin a spandrel? Insights from an evolutionary analysis of ape craniomandibular form.

ABSTRACT: Humans are unique among primates in possessing a chin, yet it is currently unclear whether the form of the symphyseal region of the mandible where the chin is located is the product of direct selection or a by-product of evolutionary pressures on other craniomandibular features. Here, we conduct an evolutionary analysis of hominoid craniomandibular traits to test three hypotheses: symphyseal mandibular traits evolved (1) neutrally due to genetic drift, (2) under direct selection, and (3) as a by-product (or "spandrel") of selection on other craniomandibular traits. Evolutionary rates of morphological change, via Lande's generalized genetic distance, were estimated along each branch of a fully-resolved hominoid phylogeny to reveal patterns of neutral, stabilizing and directional selection.

SUBMITTER: von Cramon-Taubadel N 

PROVIDER: S-EPMC12854472 | biostudies-literature | 2026

REPOSITORIES: biostudies-literature