Sunday, 18 February, 2001, 20:51 GMT
Baboon key to human stress
Baboons feel the "rat race" too
The stresses and strains that afflict humans are evident in baboon societies - as are the long-term health effects.
The findings of physiologist Robert Sapolsky may suggest ways of limiting the impact of mankind's modern, stressful lifestyle.
And cultivating friendships, he suggests, may be the way to alleviate harmful long-term stresses. In many ways, the life lived by baboons holds echoes of our own.
Their societies, like Western ones, are rarely threatened by famine, plague or predators - so they invent their own ways of generating stress.
Professor Sapolsky gave details of his work to the annual meeting of the American Association for the Advancement of Science (AAAS) in San Francisco.
Fighting males
His study claims to be able to spot "Type A" baboons, who cannot cope with stress, and suggests that there may be ways to spot humans who fall into the same group.
Professor Sapolsky said: "We're ecologically privileged enough that we can invent social and physiological stress. Baboons are similarly privileged. They ulcerate because of social complexities."
Professor Sapolsky, from Stanford University, studied the Serengeti baboons. He anaesthetised them and then collected blood samples to reveal levels of stress hormones, antibodies, and cholesterol.
Those with consistently high levels of stress hormones were showing the physical signs: high levels of the "wrong" sort of cholesterol, increased blood pressure and hardening of the arteries.
Certain situations were found to be more stressful for the baboons in the study, most of whom were male. Baboons who sensed a problem and started a fight were less stressed than those who sat back and worried if a fight was about to start.
Damaged brain
In a stable hierarchy, stress levels were lower, while the introduction of a new baboon sent stress hormones up.
And males who spent most time grooming and being groomed by females not in heat and playing with infants had the lowest levels of stress hormones.
Other studies carried out by Professor Sapolsky on rats suggest that the brain cells which control stress levels can actually be damaged if the individual is too stressed.
Continually elevated levels of stress hormones appear to damage the hippocampus, an area of the brain which also has a role in learning and memory.
Moderate stress, however, appeared to be good for the brain, he said.