June 17, 2009

Mother Baboons Aided By Male Chaperones

Some male and female baboons engage in strictly platonic, sexless relationships.  Male companionship comes in handy to females and their infants, as other baboons tend to pester less when female company is shared by their favorite male buddy.  

However, it remains a mind-boggling topic for scientists to understand why the males opt to be platonic friends.  

BBC News gave account to the study that explores baboon relationships, which was published in Behavioral Sociobiology and Ecology.  The findings of the study also suppose that male baboons may be to instinctively distinguish their offspring.  

To scrutinize the incidence of 'platonic' relationships, Primatologist Nga Nguyen, who is assistant professor at California State University Fullerton, California, along with her team of colleagues, Russell Van Horn of the Zoological Society of San Diego, California, and Susan Alberts of Duke University in Durham, North Carolina and Jean Altmann of Princeton University, New Jersey, collaboratively observed four groups of yellow baboons inhabiting Amboseli, Kenya.  

Baboons are not the only primates to exhibit these so-called 'friendships.'  Several species of female monkeys, macaques and others were observed spending quite a bit of time with a particular male companion.

Why these friendships remain platonic and don't seem to include sex is undetermined.  

"We don't really know what males or females get from these friendships," Nguyen confessed. "Males should be off trying to get other females to mate with them, not squandering their time on a female with a young infant."

Nguyen's team searched for evidence as to whether these chaperone males were playing a fathering role to the infants of their female friends.  

More than 500 males and females in the four groups were closely monitored in effort to glean accurate understanding of their behaviors, as well as genetic tests were given to determine the paternity of 183 of the baboons, including 23 young infants being cared for by a mother and her male companion.

Results indicated that 50 percent of all the male chaperones were the father of the infant whose mother they had befriended.  

Given that each of the females mated with several males around the time they conceived, the results are interestingly unexpected.  "But of these potential dads, only the genetic dads became friends," said Nguyen.

"To my knowledge, human males cannot tell their own offspring from unrelated offspring, but somehow baboon dads can tell."

But an even more astonishing surprise surfaced in the study.

"Half of the friends were not genetic fathers. But these guys weren't even potential fathers, that is, they didn't even mate with the female when she conceived the infant, and these guys didn't receive mating benefits."

"So we really don't know what these guys got out of the friendship, other than maybe spending time with a mom and a new baby and having other females seeing this."

Scientists are toying with the notion that perhaps courting a female in a strictly platonic relationship could be a strategic move by a male to market his parental abilities to other females, who then might deem him a worthy mate.  However this assumption has yet to be proven, nor has any other reason for these platonic relationships.

But for the females, the advantages of toting around a male chaperone are certain.

 "We found direct evidence that friendships provided a social benefit to mothers and infants," said Nguyen.

"We found that mother-infant pairs who spent a lot of time with their male friends received a lot less harassment from other females in the group, and the infants cried a lot less too, than pairs who spent less time hanging out with their male friends. This could translate into big gains for infants who may be more likely to survive infancy, as harassment can lead to injury," she added.
"It was especially exciting when I looked and saw what a huge difference having a friend around means for the mother and infant. We've long suspected that mother-infant pairs got some social benefit from the male friends, but this benefit had never before been documented."


On The Net:

Yellow baboons

Nga Nguyen