Lightweight Skeletons of Modern Humans have Recent Origin

© AMNH/J. Steffey

© AMNH/J. Steffey


New research shows that modern human skeletons evolved into their lightly built form only relatively recently—after the start of the Holocene about 12,000 years ago and even more recently in some human populations. The work, based on high-resolution imaging of bone joints from modern humans and chimpanzees as well as from fossils of extinct human species shows that for millions of years extinct humans had high bone density until a dramatic decrease in recent modern humans. Published this week in the Proceedings of the National Academy of Sciences, the findings reveal a higher decrease in the density of lower limbs than in that of the upper limbs, suggesting that the transformation may be linked to humans’ shift from a foraging lifestyle to a sedentary agricultural one.