sapolsky on stress

Posted on: July 19, 2010 11:49 AM, by Jonah Lehrer

I've got a new article in the latest Wired on the science of stress, as seen through the prism of Robert Sapolsky. The article isn't online yet (read it on the iPad!), but here are the opening paragraphs:

Baboons are nasty, brutish and short. They have a long muzzle and sharp fangs designed to inflict deadly injury. Their bodies are covered in thick, olive-colored fur, except on their buttocks, which are hairless. The species is defined by its social habits: The primates live in troops, or small groupings of several dozen individuals. These troops have a strict hierarchy, and each animal is assigned a specific ranking. While female rank is hereditary--a daughter inherits her mother's status--males compete for dominance. These fights can be bloody, but the stakes are immense: A higher rank means more sex. The losers, in contrast, face a bleak array of options: submission, exile, or death.
In 1978, Robert Sapolsky was a recent college graduate with a biology degree and ajobinKenya.Hehadsetoffforayearof fieldwork by himself among baboons before he returned to the US for grad school and the drudgery of the lab. At the time, Sapol- sky's wilderness experience consisted of short backpacking trips in the Catskill Moun- tains; he had lit a campfire exactly once. Most of what he knew about African wildlife he'd learned from stuffed specimens at the Museum of Natural History. And yet here he was in Nairobi, speaking the wrong kind of Swahili and getting ripped off by everyone he met. Eventually he made his way to the bush, a sprawling savanna filled with zebras and wildebeests and marauding elephants. "I couldn't believe my eyes," Sapolsky remem- bers. "There was an animal behind every tree. I was inside the diorama."

Sapolsky slowly introduced himself to a troop of baboons, letting them adjust to his presence. After a few weeks, he began recog- nizing individual animals, giving them nick- names from the Old Testament. It was a way of rebelling against his childhood Hebrew school teachers, who rejected the blasphemy of Darwinian evolution. "I couldn't wait for the day that I could record in my notebook that Nebuchanezzar and Naomi were off screwing in the bushes," Sapolsky wrote in A Primate's Memoir. "It felt like a pleas- ing revenge."

Before long, Sapolsky's romantic vision of fieldwork collided with the dismal reality of living in the African bush. His feet itched from a fungal infection, his skin was cov- ered in bug bites, the Masai stole his stuff, he had terrible diarrhea, and he was des- perately lonely. Sapolsky's subjects gave him no glimpse of good fellowship. They seemed to devote all of their leisure time--and baboon life is mostly leisure time--to mischief and malevolence. "One of the first things I discovered was that I didn't like baboons very much," he says. "They're quite awful to one another, constantly scheming and backstabbing. They're like chimps but without the self-control."

While Sapolsky was disturbed by the behavior of the baboons--this was nature, red in tooth and claw--he realized that their cruelty presented an opportunity to investi- gate the biological effects of social upheaval. He began to notice, for instance, that the males at the bottom of the hierarchy were thinner and more skittish."They just didn't look very healthy," Sapolsky says. "That's when I began thinking about how damn stressful it must be to have no status. You never know when you're going to get beat up. You never get laid. You have to work a lot harder for food."

And so Sapolsky set out to test the hypothesis that the stress involved in being at the bottom of the baboon hierarchy led to health problems. At the time, stress was mostly ignored as a scientific subject. It was seen as an unpleasant mental state with few long- term consequences. "A couple of studies had linked stress to ulcers, but that was about it," he says. "It struck most doctors as extremely unlikely that your feelings could affect your health. Viruses, sure. Carcinogens, absolutely. But stress? No way." Sapolsky, how- ever, was determined to get some data. He wasn't yet thinking lofty thoughts about human beings or public health. His transformation into one of the leading researchers on the sci- ence of stress would come later. Instead, he was busy learning how to shoot baboons with anesthetic darts and then, while they were plunged into sleep, quickly measure the levels of stress hormones in their blood.

In the decades since, Sapolsky's speculation has become scientific fact. Chronic stress, it turns out, is an extremely dangerous condition. And it's not just baboons: People are just as vulnerable to its effects as those low-ranking male apes. While stress doesn't cause any single disease--ironically, the causal link between stress and ulcers has been largely disproved--it makes most diseases significantly worse. The list of ailments connected to stress is staggeringly diverse and includes everything from the common cold and lower-back pain to Alzheimer's disease, major depressive disorder, and heart attack. Stress hollows out our bones and atrophies our muscles. It triggers adult onset diabetes and is a leading cause of male impotence. In fact, numerous studies of human longevity in developed coun- tries have found that "psychosocial" factors such as stress are the single most important variable in determining the length of a life. It's not that genes and risk factors like smoking don't matter. It's that our levels of stress matter more.

Furthermore, the effects of chronic stress directly counteract improvements in medical care and public health. Antibiotics, for instance, are far less effective when our immune system is suppressed by stress; that fancy heart surgery will work only if the patient can learn to shed stress. As Sapolsky notes, "You can give a guy a drug-coated stent, but if you don't fix the stress problem, it won't really matter. For so many conditions, stress is the major long-term risk factor. Everything else is a short-term fix."

The emergence of stress as a major risk factor is largely a testament to scientific progress: The deadliest diseases of the 21st century are those in which damage accumulates steadily over time. (Sapolsky refers to this as the "luxury of slowly falling apart.") Unfortunately, this is precisely the sort of damage that's exacerbated by emotional stress. While modern medicine has made astonishing progress in treating the fleshy machine of the body, it is only beginning to grapple with those misfortunes of the mind that undo our treatments.

The power of this new view of stress--that our physical health is strongly linked to our emotional state--is that it connects a wide range of scientific observations, from the sociological to the molecular. On one hand, stress can be described as a cultural condition, a byproduct of a society that leaves some people in a permanent state of stress. But that feeling can also be measured in the blood and urine, quantified in terms of glucocorticoids and norepinephrine and adrenal hormones. And now we can see, with scary precision, the devastating cascade unleashed by these chemicals. The end result is that stress is finally being recognized as a critical risk factor, predicting an ever larger percentage of health outcomes.

There's a lot more in the article. Here's one example of how stress destroys the body. Elissa Epel, a former grad student of Sapolsky's and a professor of psychiatry at UCSF, has demonstrated that mothers caring for chronically ill report much higher levels of stress. That's not surprising. What is surprising is that these women also have dramatically shortened telomeres, those caps on the end of chromosomes that keep our DNA from disintegrating. (Women with the highest levels of stress had telomere shortening equal "to at least one decade of additional aging.") When our telomeres run out, our cells stop dividing; we've run out of life. Stress makes us run out of life faster.