Competing models of hominin body size evolution.

Abstract

The evolutionary trajectory of hominin body size remains contested, with prior studies suggesting a gradual increase or lineage-specific shifts. Here, we apply Bayesian phylogenetic generalized linear mixed models to a dataset of 386 specimens across 21 taxa and find strong evidence for a marked body mass increase in non-<i>habilis</i> or later-occurring <i>Homo</i>, with moderate support for a general increase over time. Contrary to some existing hypotheses, we find less support for a distinct size increase across all <i>Homo</i>. By accounting for phylogenetic nonindependence, intraspecific variation, and multiple sources of uncertainty, our analysis examines competing views in a single framework, supporting a more complex explanation for hominin body size evolution and clarifying key transitions in <i>Homo</i>.