Alpha male baboons may earn the right to preside over their troops, but evidence indicates all that power takes its toll. A past study from Duke University research scientist Laurence Gesquiere, for example, indicated that alpha male baboons exhibit “much higher stress hormone levels” than their beta counterparts. At the time, however, the source of all that stress remained a mystery. According to a followup study published in the journal Proceedings of the Royal Society B, the top ranking primates not only are significantly more stressed out—they’re also expending more energy than those around them. But not necessarily for the reasons you might think.
The first evidence pointing to the unique daily problems faced by alpha male baboons arrived in 2011, when Gesquiere and colleagues identified that the animals displayed higher amounts of glucocorticoids. These and other hormones are released by the brain to help boost energy during tough situations.
Since then, Gesquiere and others from both Duke and Stony Brook University have looked more closely at baboon hormonal levels while also reviewing their daily habits. They focused on 14 years’ worth of behavioral records collected from 204 wild male baboons by the Amboseli Baboon Research Project in Kenya. The team then supplemented that information by analyzing their droppings to better understand how their hormone levels changed over time.
Consistent with previous data, the glucocorticoid levels of alpha baboons measured around six percent higher than their fellow males. At the same time, the team also noticed the top baboons had lower levels of the thyroid hormone T3—a sign they burned more calories than they consumed.
“Being alpha really has energy consequences,” Gesquiere said in an accompanying statement on Wednesday.
But all that energy expenditure isn’t entirely the result of baboons’ many brawls. The data showed that regardless how often the alphas scrapped with rivals or betas, both their stress and thyroid hormones remained at consistent levels.
“That was a big surprise,” said Gesquiere.
The team theorized there may be a couple explanations for this. One is that aggressive episodes between the males may be too short or minor to trigger a hormonal response. Another possibility may be that, once established, an alpha male simply doesn’t need to spar as intensely or as often as before.
So what actually is the reason behind all that extra stress and energy use? According to researchers, it’s likely often due to the amount of time they spend guarding and monitoring their mates.
“They’re essentially staking a claim; preventing other males from gaining access,” added Susan Alberts, a Duke University professor and study lead author.
Alberts explained that all that surveillance means an alpha male’s other needs—namely eating—is “constantly interrupted” by following their consorts around and preventing other males from getting too close. Alberts offered a common scenario in which an alpha baboon begins foraging for food, “but then the female gets up and walks away, and they have to abandon it.”
“While being high ranking has benefits for males in terms of mating and paternity success, our analysis demonstrates that it also imposes costs,” the study’s authors write in their conclusion.
Gesquiere added that for alpha males, all that stress “definitely has long-term consequences.” These costs appear to speed up their epigenetic aging, and even shorten their overall lifespans. But don’t think it’s any easier for the beta baboons in these communities.
“Low-ranking males, while being less energetically challenged than high-ranking (non-alpha) males, are probably exposed to more psychosocial stressors,” the authors wrote in their study.
Basically, it’s tough out there for baboons, no matter their social standing.
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