Competing for high status speeds up aging in male baboons
Study suggests that high social status contributes to accelerated aging in baboons, despite its other advantages
IMAGE: MALE BABOONS IN AMBOSELI NATIONAL PARK, KENYA, ENGAGE IN PHYSICAL COMPETITION FOR HIGH RANK, DEMONSTRATING THE POTENTIAL COSTS OF ATTAINING HIGH STATUS view more
CREDIT: BETH ARCHIE (CC BY 4.0)
Battling other male baboons to achieve high social status comes with physiological costs that accelerate aging, according to study published today in eLife.
The findings suggest that current life circumstances may be more important contributors to premature aging than early life hardship, at least in baboons.
Chemical changes to DNA, also called epigenetic changes, can be used as a kind of 'clock' to measure aging. While these epigenetic changes usually correspond with age, they can also be used to detect signs of premature aging.
"Environmental stressors can make the clock tick faster, so that some individuals appear biologically older than their actual age and experience a higher risk of age-related disease," explains co-first author Jordan Anderson, a PhD student in Evolutionary Anthropology at Duke University, Durham, North Carolina, US. "We sought to answer what social or early life experiences contribute to accelerated aging in baboons."
The team measured aging in 245 wild baboons from a well-studied population in Kenya using the epigenetic clock and other methods. They found that the epigenetic clock was a good predictor of chronological age overall. But contrary to what they expected, early life adversity was not a good predictor of accelerated aging in the animals.
Instead, they found that the highest-ranking males showed signs of accelerated aging. Higher body mass index, which is associated with having more lean muscle mass in baboons, was also associated with accelerated aging, likely because of the physical demands of maintaining high status. The team was also able to show that the epigenetic clock sped up as the animals climbed the social ladder and slowed down as they moved down it.
"Our results argue that achieving high rank for male baboons - the best predictor of reproductive success in these animals - imposes costs that are consistent with a 'live fast, die young,' life history strategy," says co-first author Rachel Johnston, Postdoctoral Associate in Evolutionary Anthropology at Duke University.
"While the findings reveal how social pressures can influence aging for males, we don't see the same effect of rank in female baboons, who are born into their social rank rather than having to fight for it," adds senior author Jenny Tung, Associate Professor in the Departments of Evolutionary Anthropology and Biology at Duke University, and a Faculty Associate of the Duke University Population Research Institute.
"Our results have important implications for research on the social determinants of health in humans and other animals because they show that 'high status' can mean very different things in different contexts. They also highlight the importance of examining the effects of both early life and current life environments on biological aging," Tung concludes.
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This study will be published as part of 'Evolutionary Medicine: A Special Issue' from eLife. For more information, visit https:/
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CAPTION
Teeth-baring, glaring confrontations are a normal part of being the boss male baboon. A new study shows that the guys at the top will age faster as a result of constantly having to defend their higher status.
CREDIT
Courtney L. Fitzpatrick
Being top baboon costs males their longevity
Struggle for dominance leaves a mark on genes and speeds up aging
IMAGE: MALE BABOONS MAINTAIN THEIR PECKING ORDER IN THE TROOP WITH PHYSICAL DISPLAYS OF AGGRESSION. A NEW STUDY SHOWS THAT THE GUYS AT THE TOP WILL AGE FASTER AS A RESULT... view more
CREDIT: ELIZABETH ARCHIE
DURHAM, N.C. -- Some guys have it all: the muscle, the power, the high social status, the accelerated aging.
But wait. Faster aging? Who wants that? For male baboons, it's the price they pay to be at the top.
New research appearing April 6 in eLife by Jenny Tung, associate professor of evolutionary anthropology and biology at Duke University, and her colleagues shows that male baboons that climb the social ladder age faster than males with lower social standing. If a male drops in social status, his estimated rate of aging drops as well.
Using blood samples from 245 wild baboons in the Amboseli ecosystem in Kenya, the team analyzed chemical modifications to DNA known as DNA methylation marks.
"These marks change with age in a clock-like fashion," Tung said. "However, environmental stressors can make the clock tick faster." This would make an individual appear older than they really are, and, research in humans suggests, can put them at a higher risk of aging-related disease.
Since this cohort of baboons is one of the most intensively studied wild mammal populations in the world, the researchers already knew not only each baboon's age, but also the environment in which they grew up, their exposure to early life adversity, and a great deal about their adult environment, especially the aspects that predict how long they live and how many offspring they leave behind.
"We used DNA methylation to compare the baboons known ages to their 'biological ages,'" said Jordan Anderson, a graduate student in the Tung lab who co-led the work. These methylation markers are found across the genome, so the team first needed to measure a large number of these sites - about 400,000 of them - and then, through statistical methods and models, whittle the number of sites down to about 500 that best predicted age.
Interestingly, for males, early life adversity didn't affect how fast their biological clocks tick.
Adult social status was the strongest factor that affected aging. "Male baboons who compete successfully for high social status appear to age faster," Tung said. "We repeatedly sampled some of these males and were able to show that the clock can speed up or slow down as males move up or down the social ladder."
This is contrary to what we see in humans. Typically, high social status in humans predicts better health, not worse. The most wealthy and powerful humans have access to and can afford the best houses, schools, healthcare and more. Those who live in poverty and have lower socioeconomic status are at increased risk and have higher rates of disease, cancer and all-cause mortality.
Male baboons, though, have to fight for their social status. Because of this, it's common to see male-male competition on a regular basis, where baboon observers can see a clear winner and a clear loser.
To maintain their social status, males at the top regularly have to hold their ground and defend themselves physically. Because of this, male baboons at the top tend to have more muscle mass and better body condition than lower ranking baboons. But as their physicality starts to diminish with age, a new, younger, stronger male may overcome them for the top spot.
High ranking males also spend a lot of time mate-guarding females. Around ovulation, they follow females closely and ward off other males. Mate-guarding constrains a male's other activities, and Tung and her team think it is likely to be energetically costly -- perhaps helping to explain their accelerated aging result.
So why do these males work so hard to achieve a high stress social status? It's simple: to have offspring.
"If male baboons are going to have babies, they need to achieve high rank," Tung said. "They will have very little chance to leave offspring if they don't achieve high rank, which creates a powerful evolutionary motivation."
This study highlights one way that the social environment can influence aging. "Our research shows that the manner in which social status is attained and maintained is crucial to understanding its consequences," Tung said.
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This research was supported by the US National Science Foundation and the US National Institutes of Health, Canadian Institute of Advanced Research, North Carolina Biotechnology Center, and the Center for Population Health and Aging. (2018264636, IOS1456832, R01AG053308, R01AG053330, R01HD088558, P01AG031719, F32HD095616, 2016-IDG-1013, P30AG034424)
CITATION: "High Social Status Males Experience Accelerated Epigenetic Aging in Wild Baboons," Jordan A. Anderson, Rachel A. Johnston, Amanda J. Lea, Fernando A. Campos, Tawni N. Voyles, Mercy Y. Akinyi, Susan C. Alberts, Elizabeth A. Archie, Jenny Tung. eLife, April 6, 2021. DOI: 10.7554/eLife.661
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