Why Zebras Don’t Get Ulcers Chapter 15. Personality, Temperament, and Their Stress-Related Consequences
Author Robert Sapolsky Publisher: New York, NY: Henry Holt and Company. Publish Date: 2004 Review Date: Status:⌛️
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Your style, your temperament, your personality have much to do with whether you regularly perceive opportunities for control or safety signals when they are there, whether you consistently interpret ambiguous circumstances as implying good news or bad, whether you typically seek out and take advantage of social support. Some folks are good at modulating stress in these ways, and others are terrible. These fall within the larger category of what Richard Davidson has called “affective style.” And this turns out to be a very important factor in understanding why some people are more prone toward stress-related diseases than others.
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We start with a study in contrasts. Consider Gary. In the prime of his life, he is, by most estimates, a success. He’s done okay for himself materially, and he’s never come close to going hungry. He’s also had more than his share of sexual partners. And he has done extremely well in the hierarchical world that dominates most of his waking hours. He’s good at what he does, and what he does is compete—he’s already Number 2 and breathing down the neck of Number 1, who’s grown complacent and a bit slack. Things are good and likely to get better.
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But you wouldn’t call Gary satisfied. In fact, he never really has been. Everything is a battle to him. The mere appearance of a rival rockets him into a tensely agitated state, and he views every interaction with a potential competitor as an in-your-face personal provocation. He views virtually every interaction with a distrustful vigilance. Not surprisingly, Gary has no friends to speak of. His subordinates give him a wide, fearful berth because of his tendency to take any frustration out on them. He behaves the same toward Kathleen, and barely knows their daughter Caitland—this is the sort of guy who is completely indifferent to the cutest of infants. And when he looks at all he’s accomplished, all he can think of is that he is still not Number 1.
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Gary’s profile comes with some physiological correlates. Elevated basal glucocorticoid levels—a constant low-grade stress-response because life is one big stressor for him. An immune system that you wouldn’t wish on your worst enemy. Elevated resting blood pressure, an unhealthy ratio of “good” to “bad” cholesterol, and already the early stages of serious atherosclerosis. And, looking ahead a bit, a premature death in late middle-age.
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Contrast that with Kenneth. He’s also prime-aged and Number 2 in his world, but he got there through a different route, one reflecting the different approach to life that he’s had ever since he was a kid. Someone caustic or jaded might dismiss him as merely being a politician, but he’s basically a good guy—works well with others, comes to their aid, and they in turn to his. Consensus builder, team player, and if he’s ever frustrated about anything, and it isn’t all that certain he ever is, he certainly doesn’t take it out on those around him.
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A few years ago, Kenneth was poised for a move to the Number 1 spot, but he did something extraordinary—he walked away from it all. Times were good enough that he wasn’t going to starve, and he had reached the realization that there were things in life more important than fighting your way up the hierarchy. So he’s spending time with his kids, Sam and Allan, making sure they grow up safe and healthy. He has a best friend in their mother, Barbara, and never gives a thought to what he’s turned his back on.
Not surprisingly, Kenneth has a physiological profile quite different from Gary’s, basically the opposite on every stress-related measure, and enjoys a robust good health. He is destined to live to a ripe old age, surrounded by kids, grandkids, and Barbara.
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Isn’t that something? Some baboons are driven sharks, avoid ulcers by giving them, see the world as full of water holes that are half empty. And some baboons are the opposite in every way. Talk to any pet owner, and they will give ardent testimonials as to the indelible personality of their parakeet, turtle, or bunny. And they’d usually be at least somewhat right—people have published papers on animal personality. Some have concerned lab rats. Some rats have an aggressive proactive style for dealing with stressors—put a new object in their cage and they bury it in the bedding. These animals don’t have much in the way of a glucocorticoid stress response. In contrast, there are reactive animals who respond to a menacing by avoiding it. They have a more marked glucocorticoid stress-response. And then there are studies about stress-related personality differences in geese. There’s even been a great study published about sunfish personalities (some of whom are shy, and some of whom are outgoing social butterflies). Animals are strongly individualistic, and when it comes to primates, there are astonishing differences in their personalities, temperaments, and coping styles. These differences carry some distinctive physiological consequences and disease risks related to stress. This is not the study of what external stressors have to do with health. This is, instead, the study of the impact on health of how an individual perceives, responds to, and copes with those external stressors. The lessons learned from some of these animals can be strikingly relevant to humans.
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Stress and the Successful Primate
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Baboons there work perhaps four hours a day, foraging through the fields and trees for fruits, tubers, and edible grasses. This has a critical implication for me, which has made them the perfect study subjects when I’ve snuck away from my laboratory to the Serengeti during the summers of the past two decades. If baboons are spending only four hours a day filling their stomachs, that leaves them with eight hours a day of sunlight to be vile to one another.
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Social competition, coalitions forming to gang up on other animals, big males in bad moods beating up on someone smaller, snide gestures behind someone’s back—just like us.
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I am not being facetious. Think about some of the themes of the first chapter—how few of us are getting our ulcers because we have to walk ten miles a day looking for grubs to eat, how few of us become hypertensive because we are about to punch it out with someone over the last gulp from the water hole. We are ecologically buffered and privileged enough to be stressed mainly over social and psychological matters. Because the ecosystem of the Serengeti is so ideal for savanna baboons, they have the same luxury to make each other sick with social and psychological stressors. Of course, like ours, theirs is a world filled with affiliation, friendships, relatives who support each other; but it is a viciously competitive society as well. If a baboon in the Serengeti is miserable, it is almost always because another baboon has worked hard and long to bring about that state. Individual styles of coping with the social stress appear to be critical. Thus, one of the things I set out to test was whether such styles predicted differences in stress-related physiology and disease. I watched the baboons, collected detailed behavioral data, and then would anesthetize the animals under controlled conditions, using a blowgun. Once they were unconscious, I could measure their glucocorticoid levels, their ability to make antibodies, their cholesterol profiles, and so on, under basal conditions and a range of stressed conditions.*
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The cases of Gary and Kenneth already give us a sense of how different male baboons can be. Two males of similar ranks may differ dramatically as to how readily they form coalitional partnerships with other males, how much they like to groom females, whether they play with kids, whether they sulk after losing a fight or go beat up on someone smaller. Two students, Justina Ray and Charles Virgin, and I analyzed years of behavioral data to try to formalize different elements of style and personality among these animals. We found some fascinating correlations between personality styles and physiology.
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Among males who were in the higher-ranking half of the hierarchy, we observed a cluster of behavioral traits associated with low resting glucocorticoid levels independent of their specific ranks. Some of these traits were related to how males competed with one another. The first trait was whether a male could tell the difference between a threatening and a neutral interaction with a rival. How does one spot this in a baboon? Look at a particular male and two different scenarios. First scenario: along comes his worst rival, sits down next to him, and makes a threatening gesture. What does our male subject do next? Alternative scenario: our guy is sitting there, his worst rival comes along and…wanders off to the next field to fall asleep. What does our guy do in this situation?
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Some males can tell the difference between these situations. Threatened from a foot away, they get agitated, vigilant, prepared; when they instead see their rival is taking a nap, they keep doing whatever they were doing. They can tell that one situation is bad news, the other is meaningless. But some males get agitated even when their rival is taking a nap across the field—the sort of situation that happens five times a day. If a male baboon can’t tell the difference between the two situations, on the average his resting glucocorticoid levels are twice as high as those of the guy who can tell the difference—after correcting for rank as a variable. If a rival napping across the field throws a male into turmoil, the latter’s going to be in a constant state of stress. No wonder his glucocorticoid levels are elevated. These stressed baboons are similar to the hyperreactive macaque monkeys that Jay Kaplan has studied. As you will recall from chapter 3, these are individuals who respond to every social provocation with an overactivation of their stress-response (the sympathetic nervous system) and carry the greater cardiovascular risk.
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Next variable: if the situation really is threatening (the rival’s a foot away and making menacing moves), does our male sit there passively and wait for the fight, or does he take control of the situation and strike first? Males who sit there passively, abdicating control, have much higher glucocorticoid levels than the take-charge types, after rank is eliminated as a factor in the analysis. We see the same pattern in low-ranking as well as high-ranking males.