A quantitative genetics analysis of evolution in the hominoid appendicular skeleton

Hominoidea are a diverse superfamily, with potential selection on the postcranium from divergent locomotor patterns. The scarcity of postcranial primate fossil remains, however, means that selection on the appendicular skeleton has been difficult to study directly. Here, we use complementary methods from evolutionary quantitative genetics to assess selection versus drift within hominoids and an outgroup of cercopithecoid monkeys. While most branches were characterized by drift or stabilizing selection, directional selection was indicated on the branch leading to Homo sapiens and potentially on the branch to Hylobates lar. Directional selection gradients were then assessed for each trait on these two lineages. Strong selection was detected on limb length and traits of the os coxa in both lineages. Our results are consistent with prior studies of evolution in the hominoid postcranium and indicate that these methods may be useful in studying multiple elements in conjunction for a holistic assessment of evolution in the primate skeleton in the absence of extensive fossil data.