BOB HIRSHON (host):
Lighter bones from easy living. I’m Bob Hirshon and this is Science Update.
Modern humans have much lighter bones than did earlier human species and great apes. In the Proceedings of the National Academy of Sciences, Penn State anthropologist Timothy Ryan and his colleagues argue that it’s not a matter of genetics or diet, but inactivity. They found that the pelvic joints of hunting and foraging human populations from thousands of years ago were thick like our primate relatives, while people living nearby in agricultural villages had thinner bones, more like people today. This was true even when their diets were similar.
TIMOTHY RYAN (Pennsylvania State University):
We’re interpreting this as strong evidence for the need for high levels of physical activity especially at young ages but probably throughout your life in order to grow and maintain robust bone.
He says our skeletons are adapted for an active lifestyle, and deteriorate without it. I’m Bob Hirshon, for AAAS, the science society.