The most significant trend in human evolution is the dramatic increase in cranial capacity (brain size) — from ~450 cm³ in Australopithecus to ~1350–1500 cm³ in modern Homo sapiens. This expansion of the neocortex enabled language, abstract reasoning, tool use, social organisation, and cultural transmission — the defining features of humanity. Upright posture evolved earlier (in Australopithecus); binocular vision is a primate trait; jaw reduction is a consequence of dietary changes and reduced dentition.