Locomotor and Cognitive Evolution in Early Hominins: An Evo-Devo Perspective

BACKGROUND: Research on the relationship between the evolution of ontogenetic locomotor milestones and the emergence of advanced cognition in early hominins is reviewed and discussed from an evo-devo perspective that incorporates theoretical underpinnings from the extended evolutionary synthesis. Comparative ontogenetic data from chimpanzee and human infants shed light on likely derivations in hominin locomotor milestones, their effect on the emergence of habitual bipedalism, and the latter's probable contribution(s) to cognitive evolution. SUMMARY: Human babies' locomotor milestone of crawling on hands and knees is hypothesized to have been derived during hominin evolution in place of a knuckle-walking developmental stage that likely existed in the apelike predecessors of the earliest hominins. A review of comparative research suggests that evolutionary modifications in crawling, sitting, and pointing in addition to selection for bipedalism, contributed to the progressive evolution of both locomotion and advanced cognition in hominins. KEY MESSAGES: Comparisons of the ontogenetic development of locomotor stages in chimpanzee and human infants suggest that locomotor evolution and the emergence of advanced cognition were deeply intertwined during hominin evolution.