Fig. 2.

(A) Anthropoid primates exhibit consistent developmental modularity of limbs. Within-limb modularity reflects varying functional signals (e.g., bipedalism in the hindlimb of humans and forelimb suspension in apes). Modules (partial correlations P < 0.05) are illustrated as boxes between elements. Modules are shaded relative to the strength of the estimated Fisher-z transformed correlation. Estimated Pearson correlation coefficient is shown. (MC, metacarpal; MT, metatarsal; R, radius; T, tibia; H, humerus; F, femur). Species arranged by phylogenetic relationship as shown at Bottom. (B) Humans are significantly less integrated compared to quadrupedal monkeys and similar to apes, indicating that reductions to integration and more independently evolvable limbs characterize both fossil hominins and hominoids. Box plots show the lower and upper quartile, median of resampled eigenvalue variance (VE) (10,000 replicates). Whiskers indicate the 95% confidence limit of the estimate. Dashed lines and shaded boxes show the average VE for hominoids (=1.79), cercopithecoids (=3.32), and ceboids (=2.90) and the 95% confidence interval, respectively.