Why do humans and their primate cousins get more stress-related diseases than any other member of the animal kingdom? The answer, says Stanford neuroscientist Robert Sapolsky, is that people, apes and monkeys are highly intelligent, social creatures with far too much spare time on their hands.
"Primates are super smart and organized just enough to devote their free time to being miserable to each other and stressing each other out," he said. "But if you get chronically, psychosocially stressed, you're going to compromise your health. So, essentially, we've evolved to be smart enough to make ourselves sick."
A professor of biological sciences and of neurology and neurological sciences, Sapolsky has spent more than three decades studying the physiological effects of stress on health. His pioneering work includes ongoing studies of laboratory rats and wild baboons in the African wilderness.
Sapolsky discussed the biological and sociological implications of stress at a Feb. 17 lecture at the annual meeting of the American Association for the Advancement of Science in San Francisco and in a recent interview with Stanford Report.
All vertebrates respond to stressful situations by releasing hormones, such as adrenalin and glucocorticoids, which instantaneously increase the animal's heart rate and energy level. "The stress response is incredibly ancient evolutionarily," Sapolsky said. "Fish, birds and reptiles secrete the same stress hormones we do, yet their metabolism doesn't get messed up the way it does in people and other primates."
To understand why, he said, "just look at the dichotomy between what your body does during real stress—for example, something is intent on eating you and you're running for your life—versus what your body does when you're turning on the same stress response for months on end for purely psychosocial reasons."
In the short term, he explained, stress hormones are "brilliantly adapted" to help you survive an unexpected...