If a group of humans began to run regularly, perhaps allowing them to hunt or scavenge more effectively, anatomical changes would follow, especially among the still-developing youngsters. — Alice Roberts Copy Share Image
Other anatomical changes associated with long-duration space flight are definitely negative: the immune system weakens, the heart shrinks because it doesn't have to strain against gravity, eyesight tends to degrade, sometimes markedly (no one's exactly sure why yet). The spine… — Chris Hadfield Copy Share Image
