Premium
Calcaneal allometry in humans and nonhuman primates
Author(s) -
Harper Christine,
Ruff Christopher,
Sylvester Adam
Publication year - 2021
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.2021.35.s1.02111
Subject(s) - allometry , arboreal locomotion , biology , primate , phylogenetic tree , phylogenetics , evolutionary biology , linear regression , phylogenetic comparative methods , zoology , anatomy , ecology , statistics , mathematics , genetics , habitat , gene
Body mass critically impacts locomotion because it largely determines the mechanical requirements for supporting and propelling the body against gravity. Primate long bone proportions relative to body mass and locomotion have been extensively studied; however, these relationships are less well understood in the foot. The scaling of the calcaneus is particularly important because of its weight‐bearing role during locomotion. Here, we analyze calcaneal allometry in humans (n=120) and nonhuman primates (n=278) to investigate scaling relationships relative to known locomotor differences. Twelve linear measures, as well as articular facet surface areas, were collected on calcaneus surface models in Avizo Lite 9.0.1. Femoral head superoinferior breadth and established regression equations were used to estimate body mass (EBM). Calcaneal measures were regressed against EBM using phylogenetic least squares regression analyses conducted at different taxonomic levels to determine how the inclusion of multiple (sub)species within a genus impacted the presence of phylogenetic signal in our dataset. Reduced major axis ANCOVAs were used to test for significant differences between humans and (pooled) nonhuman primates. Residuals from isometry both among and within genera were evaluated with ANOVAs and post hoc multiple comparison tests. When analyzed at the (sub)species level, all but two dimensions relative to EBM exhibit phylogenetic signals. These signals are no longer apparent at the genus level, suggesting variation among the genera is driven by some factor other than phylogeny, such as body size or locomotion. Bipedally adapted humans display relatively larger calcaneal dimensions than nonhuman primates. Among nonhuman great apes, more arboreal taxa exhibit relatively larger cuboid facet surface areas, increasing midfoot mobility for movement over unpredictable substrates. More terrestrial taxa exhibit relatively longer calcaneal tubers for EBM, which serves to increase the muscle lever arm, and thus mechanical advantage, of the triceps surae muscle.