Being an alpha male stressful: Primate study

By Dr. Ananya Mandal, MDJul 14 2011

A nine year old tracking study of five troops of baboons in Kenya found that the top-ranked alpha males had more stress than the second-place beta males. In fact the top baboon was just as ‘on-edge’ as those unfortunate primates at the bottom of the pecking order. Thore Bergman, a biological psychologist at the University of Michigan who was not involved in the study said, “Being at the top may not be all it's cracked up to be.”

The researcher team from Princeton University and the Institute of Primate Research in Nairobi, Kenya followed the baboons and collected their fresh poop. They analyzed the fecal samples for the male hormone testosterone and stress hormone glucocorticoid or cortisol which helps the body gear up to deal with an immediate threat.

The study involved 125 male baboons from five different social groups in Kenya. After collecting and testing over 4,500 samples, the research team discovered that a baboon's stress level dropped as his rank rose — except for the alpha males. The top baboons had 10% more glucocorticoid than their runners-up, and matched those of the lowest-ranked baboons. (Testosterone levels, predictably, rose with rank.) The findings were published online Thursday in the journal Science.

According to lead author Laurence Gesquiere, a Princeton endocrinologist she had thought better access to food and fertile females would translate into a less fraught existence. “I was very surprised to see high levels of stress,” she said. That strain is probably due to the effort required to stay at the top of the heap Gesquiere said, fending off challenges and courting females takes time and energy. Lower-ranking baboons, on the other hand, probably experience stress for different reasons, including less access to food and the tendency to get thrashed by socially superior peers.

Professor Susan Alberts said, “We've known for decades that alpha males have an advantage in reproduction, but these results show that life at the top has a real downside, and that being an alpha male comes at a real cost.”

She explained that while short bursts of glucocorticoid can be helpful, animals with consistently high levels wear out their reproductive and immune systems, among other adverse health effects.

Martin Muller, a University of New Mexico primatologist who was not involved in the study warned that this might not be the same for humans. However Gesquiere said, “Baboons are not only genetically closely related to humans, but like humans they live in highly complex societies. An important insight from our study is that the top position in some animal – and possibly human – societies has unique costs and benefits associated with it, ones that may persist both when social orders experience some major perturbations as well as when they are stable.”

Professor Jeanne Altmann, who runs the laboratory in Princeton, also said, “Baboons are likely to be good models to provide insights for identifying the ideal position in a complex society under different conditions. Humans also live in stratified societies, and social status is well known to be associated with some but not all health outcomes in humans. It has been difficult to identify many of the mechanisms behind these associations. Our results point to the need for research that will identify and evaluate the specific costs and benefits of various status positions, in various species, types of organizations and groups, and under different ecological conditions.”