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It's stressful at the top, at least for male baboons, according to a new study that finds that alpha males — those at the pinnacle of the social hierarchy — are significantly more stressed out than a group's No. 2, or beta male.

The research contrasts with earlier studies in both humans and other primates that have found that stress levels generally tend to drop the higher you ascend on the social ladder. It also suggests that being king of the group isn't all it's cracked up to be.

The researchers studied 125 male baboons living in five social groups over a nine-year period in Amboseli, Kenya. The scientists measured stress hormone levels by analyzing 4,500 fecal samples from the animals. (Female baboons were not studied because of the complexity of analyzing stress hormone levels during pregnancy and nursing.) They found that alpha males had very high stress hormone levels, just as high as those of the lowest ranking males.

Why? Probably because they were constantly forced to defend their position in the group and protect their access to females. Beta males, in contrast, had lower levels of stress, as low as those that have traditionally been associated with high social status, likely because they fought less and had less to lose than the higher-ranking males.

But although being the alpha had its costs, it also had benefits: alphas mated more and had more surviving offspring.

"It's a very cool [finding] and in a lot of ways unexpected," says Robert Sapolsky, professor of biology at Stanford and a pioneer in research on stress, status and health, who was not associated with the study. Studies by Sapolsky, who has also spent many years studying baboons in the wild, have previously shown that high-ranking males tend to have lower levels of stress hormones than low-ranking ones, except when hierarchies are unstable and the rank order is being challenged.

"Baboons are poster children for psychosocial stress, living in troops with bruising and shifting dominance hierarchies among males and high rates of male aggression," Sapolsky wrote in a commentary published along with the new study.

Research on rank and stress could potentially have wide-ranging social implications for humans because it can help explain the strong correlations found between economic inequality and poor health. Countries and states with greater differences between rich and poor tend to have worse health and shorter life expectancies in their populations.

The culprit may be stress hormones. When facing short-term challenges, stress hormones help humans and animals cope, but over the long term, constant exposure to uncontrollable stress can damage both brain and body. And having low social status, being at the mercy of the higher ranking is typically a recipe for uncontrollable stress.

In both humans and baboons, previous research has shown that chronic elevation of stress hormones caused by living on the bottom rungs of society increases risk for heart attack, stroke, diabetes and other diseases. And since this effect is seen in baboons, not just humans, the excess risk cannot simply be attributed to lack of access to health care or to lifestyle choices like overeating, smoking or drinking. Low-ranked baboons don't have these issues, of course.

Now, the new study may help shed light on why highly unequal human societies don't only have worse health among the poor, but also have lower life expectancies overall. Some of this effect may be linked to the long-term stress that comes with getting and keeping high status.

"We found that the overall pattern [of lower stress hormones in higher ranking animals] does occur, but that alpha males are a significant exception," says Jeanne Altman, an author of the study and professor emerita of ecology and evolutionary biology at Princeton.

Perhaps it is the unique stress of being at the pinnacle of power that may help explain why American presidents seem to age so much faster in office than their immediate deputies. "Being president does seem a lot more stressful than being vice president," notes Sapolsky.

But power struggles in the baboon world cannot be easily translated to human populations. For one thing, baboon hierarchies involve only physical aggression, while human status systems are more complex and, Sapolsky thinks, do more harm. "When humans invented inequality and socioeconomic status, they came up with a dominance hierarchy that subordinates like nothing the primate world has ever seen before," he says.

Surprisingly, the new study did not find a connection between instability in the social hierarchy and stress levels among the higher-ranked baboons. Instability was linked to higher stress levels overall, but it wasn't related to specific ranks.

Sapolsky thinks this may be due to the fact that the new study measured instability differently than past research. Some studies define instability as involving a high frequency of attempts to unseat the powerful, but other studies may recognize instability on when these challenges actually resulted in a coup.

"The definition in their study is, 'Is there an actual change?' Mine is more, 'Is there the threat of change?' I think threat of change is pretty potent," says Sapolsky. "In humans, blood pressure doesn't go up when people get laid off: it goes up when they first hear rumors that layoffs are coming at the end of the month."

Altman agrees that more investigation into the issue is needed, but she thinks that at least in terms of the difference in stress hormones between alphas and betas, "the amount of challenges to rank would not account for the differences."

So what would the world be like if we eliminated the hard-charging top ranked folks and had more kinder, gentler males around? One baboon troop that Sapolsky studied seemed to illustrate the scenario vividly. The meanest and most aggressive males in that troop often fought males of another troop in order to gain access to garbage that included meat discarded by humans at a lodge.

When that meat supply became tainted by disease, it killed off the most aggressive top ranked males and left gentler males in charge; it also resulted in a ratio of two females to each male.

Not surprisingly the troop became much mellower. "You get a totally different troop culture," Sapolsky says. "There's less aggression and less displacement of aggression onto innocent bystanders. In a typical troop, if any one of high rank [is in a bad mood], your ass is going to get slashed."

In the new troop culture, however, this type of aggression was greatly reduced. And so were the stress levels of the lower ranking animals. "The cruddy physiology you get in low-ranking males in typical troops, you don't see in this troop," he says.

Of course, if there were two females for every male, human men might be a lot nicer too. But Sapolsky discovered that it wasn't just the female-to-male ratio that mattered. Other troops with similarly large female populations did not become peaceful.

And, fascinatingly, the gentler culture was passed on to the next generation. Less aggression led to more time for grooming, which relieved stress even further, and affected the offspring. "I think the [young] growing up in that troop are reaping some of the advantages of having calmer mothers," Sapolsky says.

"Textbook primatology presents male baboons as inevitably aggressive, innately and genetically," he notes. "If this [cultural change] can happen in baboons, you can't say we don't have behavioral flexibility," he says.

So, hang in there, nice guys. Perhaps being a beta male means you'll land on top in the end.

• MAIA SZALAVITZ