Gender Gap: Parasites’ bias for big animals gives female mammals longevity

Scientists often attribute the tendency of male mammals to die earlier than females to hunting, fighting for mates, and other risky behaviors that the males engage in. In the Sept. 20 Science, however, Sarah L. Moore and Kenneth Wilson of the University of Stirling in Scotland point to another reason: Parasites infect males more often than females, apparently because the males are bigger in most mammalian species, including people.