Robert Sapolsky has spent much of his life studying Baboon society. While Baboons are not human, they, along with other higher primates, share with humans the ability to be stressed out.

Like many of us, these primates don’t spend most of the day worrying about their next meal, and so like many of us, they are prey to mental stress. Baboon societies are ironically a lot like Westernized humans,” Sapolsky says. We’re ecologically privileged enough that we can invent social and psychological stress. Baboons in the Serengeti, who only work three hours a day to meet their caloric needs, are similarly privileged. They ulcerate because of social complexities.”

And, like humans, Baboons suffer the physical consequences associated with long-term stress:

Sapolsky’s been able to match up his knowledge of individual baboons’ psychological stress with what’s happening in their bodies. In blood samples, analyzed in the field, he measures the stress hormones that trigger the fight or flight response. They should be present only briefly, but in psychologically stressed baboons they can be there over the long term, with serious consequences.

What is particularly interesting about Sapolsky’s studies is the relationship he’s found between status and stress:

my initial assumption that I sort of squandered my first 15 years on with them was dominance rank. That’s the thing. If you’re a low-ranking baboon you’re gonna have the stress-related diseases. And what I’ve learned since then is, yeah, rank’s important. Far more important is what sort of society you have that rank in. Is it a troop that treats its low-ranking animals miserably? Is it a troop whose hierarchy is unstable? Those are both much more stressful situations. And then even more important than your rank in the sort of society in which it occurs is your personality. Which is basically saying, What’s your filters with which you see the world around you? And that’s the single-biggest predictor. You look at a single question, How often — if you’re a male baboon — How often do you sit there, in contact with another baboon, grooming another baboon, being groomed back? Get sort of an aggregate measure of that, a sociality score, and that’s the single strongest predictor I have ever found of stress hormone levels in these animals.

So in order of importance for determining stress hormone levels, first comes baboon personality,” and second comes the structure of the baboon society in which they live. Rank is a distant third. Experiments on Macaques monkeys, done in controlled environments rather than in the wild, confirm these findings. Fed a high-fat diet, it was the dominant monkeys who were most likely to develop clogged arteries.

It’s not subordinate, but dominant monkeys that are most stressed — with higher heart rates, blood pressure, and stress hormone levels. … Some of the experiments run for two years, and over that time the dominant, stressed monkeys develop twice the artery clogging atherosclerosis as the subordinate animals.

Personality has also been shown to be very important in how humans respond to stress. Another study covered in the Scientific American Frontiers episode on stress rated people on a hostility” scale before measuring their response to stressful situations. The results were very clear:

Even low hostile people do get angry. I mean, everybody gets angry if provoked enough. And the fascinating thing is that when high hostile people get angry, they have this very large fight-flight response. But when low hostile people get angry, their response, their biological response is much smaller. It’s as though they are wired in a different way. The connection between anger and that arousal, that biological arousal for fight or flight is not so tight in low hostile people as it is in high hostile people.

Similarly, a study by Janice Kiecolt-Glaser looked at how stress affects healing by studying couples. Couples were subject to minor skin blisters, and the healing of the blisters was tracked over time. The couples were also rated according to how stressful their relationship was. It was found that couples which were relatively (and only relatively) more hostile towards each other healed much slower!

The couples who tended to be nastier or more hostile toward each other had higher elevations in stress hormones, particularly the women. And they had greater changes 24 hours later, in terms of a whole battery of different immunological assays. We were surprised because the conflicts, the discussions of disagreement, weren’t what you’d call heated or nasty, by and large — it’s only a relative kind of thing. These were very happy couples. They only represented, among the sample we had only 3% would be what we would call distressed couples based on the way they described their marriages. And yet we could find these reliable relationships between physiology and behavior.

So what does this all mean? I think it means that it is OK not to be an alpha baboon, maybe even better for you, but you want to be in a good institution and a positive relationship. Next I plan to talk more about how to deal with stress, but here I’d simply like to point out that there are tremendous differences between people’s ability to take charge of their own lives and remove the sources of stress. This is one of the things that makes inequality important. It isn’t surprising that, as economist Amartya Sen has show, the degree of inequality in a society, rather than individual income or wealth, is a better indicator of how long people on the bottom of that society will live. [To see other posts about stress, click on the

health category link.]