Bone Density Illustration (image) American Museum of Natural History Share Print E-Mail Caption This illustration shows that modern people (right) have unusually low density in bones throughout the skeleton, including the hand bone joints (metacarpal heads) shown here. This new study found that bone joint density remained high throughout human evolution spanning millions of years, until it decreased significantly in recent modern humans, probably as a result of an increasingly sedentary lifestyle. From left to right: modern chimpanzee, Australopithecus, Neanderthal, and modern human. Credit © AMNH/J. Steffey Usage Restrictions Can be used with appropriate credit Share Print E-Mail Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.