What makes humans different from the other great apes?
• Brain size Hominoids of 6 million years ago had brains of about 400 – 450cm2. This is about the same as modern chimpanzees. Modern humans’ average brain volume is 1300cm2. This threefold increase in volume is associated with cultural trends such as development of complex language • Jaw shape Anthropoids and ancient hominoids have prognathic jaws: the upper and lower jaws protrude beyond the nose. Recall that the human face is paedomorphic with respect to that of other modern apes. The face is flatter, the prognathous jaws lost. Changes in dentition accompanied this change in jaw shape. • Bipedal posture Ancestral anthropoids and some of the earliest hominoids walked on all fours, though–like modern apes–they could probably walk on their hind legs with some degree of balance and skill. Humans are different from all other apes in that the body posture is fully upright and locomotion is entirely bipedal. A number of skeletal and muscular modifications make this possible, but there is
