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[Josh Greenman <josh.greenman AT gmail.com>]

http://www.telegraph.co.uk/science/science-news/7858951/What-kind-of-man-are-you-chimpanzee-or-bonobo.html

What kind of man are you – chimpanzee or bonobo?

Researchers have discovered the way men's bodies react to competition
varies just like those of their closest cousins.

Whereas "status-striving" men tend to produce the macho hormone
testosterone when challenged, like chimpanzees, laid-back men produce
cortisol, nicknamed the cuddle compound, like bonobos.

Chimpanzees live in male-dominated societies where status is paramount
and aggression can be severe, with frequent fights to the death.

In bonobos, a female is always the most dominant and tolerance can
allow for more flexible co-operation and food-sharing.

They are often referred to as the "peace and love" apes.

Scientists have frequently questioned whether differences in
competitive behaviour could in part be explained by differing
physiological responses to competition.

In their new study, researchers led by Harvard University collected
saliva from the apes using cotton wads dipped in Sweet Tarts candy,
then measured hormone levels before and after pairs from each species
were presented with a pile of food.

They found that males of both species showed hormonal changes in
anticipation of competing for the food, but bonobos and chimpanzees
were completely different in which hormones increased.

Male chimpanzees showed an increase in testosterone, which is thought
to prepare animals for competition or a fight.

By contrast, male bonobos showed an increase in cortisol, which is
associated with stress and more passive social strategies in other
animals.

"Chimpanzee males reacted to the competition as if it was a threat to
their status, while bonobos reacted as if a potential competition is
stressful by showing changes in their cortisol levels," said Victoria
Wobber, a Harvard graduate student and lead author of the study.

Human males usually experience an increase in cortisol before many
types of competition in a similar way as seen in the bonobos.

However, if men have what is called a "high power motive," or a strong
desire to achieve high status, they experience an increase in
testosterone before a competition.

"These results suggest that the steroid hormone shifts that are
correlated with the competitive drive of men are shared through
descent with other apes," Ms Wobber said.

While some men may seem more bonobo-like before competition and others
more chimpanzee-like, something unique about human males is that after
competition they experience an increase in testosterone if they win or
a decrease in testosterone if they lose – which accounts for giddy or
depressed sports fans following a win or loss.

This variation in hormones post-competition was not observed in either
chimpanzees or bonobos.

"It's exciting because we can see that in some ways we're similar to
bonobos, in others we're similar to chimpanzees," said Dr Brian Hare,
an anthropologist at Duke University, North Carolina.

"But then there's also a part of our biology that seems to be entirely 
unique."

The research was published in the Proceedings of the National Academy
of Sciences journal.