Nav: Home

Why baboon males resort to domestic violence

January 18, 2017

DURHAM, N.C. -- "Desperate times lead to desperate measures," so the saying goes, and a new study finds male baboons are no exception.

Some baboon males vying for a chance to father their own offspring expedite matters in a gruesome way -- they kill infants sired by other males and attack pregnant females, causing them to miscarry, researchers report.

The behavior reduces their waiting time to breed with pregnant and nursing females, who otherwise wouldn't become sexually available again for up to a year.

The perpetrators are more prone to commit domestic violence when forced to move into a group with few fertile females, said first author Matthew Zipple, a graduate student in professor Susan Albert's lab at Duke University.

Researchers studying a baboon population around Amboseli National Park in southern Kenya found that immigrant males were responsible for roughly 2 percent of infant deaths and 6 percent of miscarriages between 1978 and 2015. But when cycling females were few, the death rates more than tripled.

"In situations where males have few opportunities, they resort to violence to achieve what's necessary to survive and reproduce," Zipple said. "When reproductive opportunities abound, this behavior is less frequent."

The findings, appearing online Jan. 18 in Proceedings of the Royal Society B, come from a long-term study of wild baboons monitored on a near-daily basis since 1971 at Amboseli.

At any given time, a troop of baboons typically contains one or two newly arrived males that have left the group where they were born in search of opportunities to reproduce and pass on their genes elsewhere.

While combing through decades of baboon census records, the researchers noticed a mysterious spike in infant deaths and lost pregnancies in the two weeks after a new male arrives in a troop.

One and 2-year-olds weren't affected, suggesting the males weren't engaging in random acts of cruelty, but were targeting pregnant females and nursing infants in particular.

Other studies of animals including baboons, lions, dolphins and rodents have documented infanticide, but rarely feticide, said Alberts, chair of evolutionary anthropology at Duke.

Amboseli researchers witnessed two killing sprees of infants and unborn babies at the hands of separate males in the 1980s, but they were presumed to be isolated incidents until now.

Over the years researchers have proposed several possible reasons why males might kill infants of their own species. One long-standing hypothesis argues that the behavior makes females fertile again faster.

Killing fetuses reduces a male's waiting time too, the researchers said.

A baboon male would normally have to wait at least a year for a pregnant or lactating female to finish gestating and nursing her infant and resume cycling for a chance to sire her next offspring. But with no baby to gestate or feed anymore, females that suffered a miscarriage or the death of an infant were ready to conceive again within 41 days.

Most killer males went on to mate with the mothers of their victims, the researchers found.

A minority of male immigrants were to blame for the killings. The most common culprits were those who quickly rose to one of the top three spots in the male pecking order.

Time is of the essence to go-getter males. Those who bite and bully their way to the top get to monopolize most of the mating, but only so long as they maintain their high rank.

To take advantage of the perks of his position a newly dominant male has to move quickly, Alberts said. Even the most competitive males only manage to reign for 12 months on average before they're overthrown and lose their edge in the mating market.

"They've got a pretty short window," Alberts said.

Shortages of fertile females were particularly common in times of food scarcity, when baboon troops distance themselves from each other and females take 15 percent longer between successive births -- which means males who don't kill have even longer to wait.

"It's not just who they are, it's the circumstances they find themselves in that makes the difference," Zipple said.
-end-
Other authors of this study include Jackson Grady, Jacob Gordon and Lydia Chow of Duke, Elizabeth Archie of the University of Notre Dame and Jeanne Altmann of Princeton University.

This research was supported by grants from the National Science Foundation (IOS 1053461, IBN 9985910, IBN 0322613, IBN 0322781, BCS 0323553, BCS 0323596, DEB 0846286, DEB 0846532, IOS 0919200), the National Institute on Aging (R01AG034513-01, P01AG031719), Duke University, the Princeton Center for the Demography of Aging (P30AG024361), the Chicago Zoological Society, the L.S.B. Leakey Foundation, the Max Planck Institute for Demography and the National Geographic Society.

CITATION: "Conditional Fetal and Infant Killing by Male Baboons," Matthew Zipple, Jackson Grady, Jacob Gordon, Lydia Chow, Elizabeth Archie, Jeanne Altmann and Susan Alberts. Proceedings of the Royal Society B, Jan. 18, 2017. http://dx.doi.org/10.1098/rspb.2016.2561

Duke University

Related Violence Articles:

The front line of environmental violence
Environmental defenders on the front line of natural resource conflict are being killed at an alarming rate, according to a University of Queensland study.
What can trigger violence in postcolonial Africa?
Why do civil wars and coups d'├ętat occur more frequently in some sub-Saharan African countries than others.
Another victim of violence: Trust in those who mean no harm
Exposure to violence does not change the ability to learn who is likely to do harm, but it does damage the ability to place trust in 'good people,' psychologists at Yale and University of Oxford report April 26 in the journal Nature Communications
Victims of gun violence tell their stories: Everyday violence, 'feelings of hopelessness'
Invited to share their personal stories, victims of urban gun violence describe living with violence as a 'common everyday experience' and feeling abandoned by police and other societal institutions, reports a study in the November/December Journal of Trauma Nursing, official publication of the Society of Trauma Nurses.
Does more education stem political violence?
In a study released online today in Review of Educational Research, a peer-reviewed journal of the American Educational Research Association, three Norwegian researchers attempt to bring clarity to this question by undertaking the first systematic examination of quantitative research on this topic.
Teen dating violence is down, but boys still report more violence than girls
When it comes to teen dating violence, boys are more likely to report being the victim of violence -- being hit, slapped, or pushed--than girls.
Preventing murder by addressing domestic violence
Victims of domestic violence are at a high risk to be murdered -- or a victim of attempted murder -- according to a Cuyahoga County task force of criminal-justice professionals, victim advocates and researchers working to prevent domestic violence and homicides.
'Love displaces violence'
Art historian Eva-Bettina Krems on persistent motifs of peace in art from antiquity to the present day -- dove, rainbow or victory of love: artists draw on recurring motifs.
Simulation model finds Cure Violence program and targeted policing curb urban violence
When communities and police work together to deter urban violence, they can achieve better outcomes with fewer resources than when each works in isolation, a simulation model created by researchers at the UC Davis Violence Prevention Research Program, Columbia University's Mailman School of Public Health and the University at Albany has found.
Is gun violence contagious?
Gun violence is mostly not contagious but rather an endemic issue for particular neighborhoods, according to researchers from the University of Pennsylvania and the University of Oxford.
More Violence News and Violence Current Events

Best Science Podcasts 2019

We have hand picked the best science podcasts for 2019. Sit back and enjoy new science podcasts updated daily from your favorite science news services and scientists.
Now Playing: TED Radio Hour

Rethinking Anger
Anger is universal and complex: it can be quiet, festering, justified, vengeful, and destructive. This hour, TED speakers explore the many sides of anger, why we need it, and who's allowed to feel it. Guests include psychologists Ryan Martin and Russell Kolts, writer Soraya Chemaly, former talk radio host Lisa Fritsch, and business professor Dan Moshavi.
Now Playing: Science for the People

#538 Nobels and Astrophysics
This week we start with this year's physics Nobel Prize awarded to Jim Peebles, Michel Mayor, and Didier Queloz and finish with a discussion of the Nobel Prizes as a way to award and highlight important science. Are they still relevant? When science breakthroughs are built on the backs of hundreds -- and sometimes thousands -- of people's hard work, how do you pick just three to highlight? Join host Rachelle Saunders and astrophysicist, author, and science communicator Ethan Siegel for their chat about astrophysics and Nobel Prizes.