DO YOU KNOW

Humans Are Also the Only Animals Whose Brains Shrink As we get older, our brains tend to shrink and can suffer from cognitive dysfunction like Alzheimer's disease and dementia. But as best researchers can tell, we are the only animals to whom this shrinkage happens. Tests on other animals have found no similar phenomena—even close evolutionary relatives like chimpanzees and rhesus monkeys. And for more facts about your body, here are the 40 Ways Your Body Changes After 40.