Chuck Bednar for redOrbit.com – @BednarChuck
While its scientific fact that baboons like big butts (and they cannot lie), a new study appearing in the advanced online edition of the journal Animal Behaviour indicates that a sizable posterior is not quite as important to the Old World monkeys as previously believed.
While biologists have long believed that baboon males viewed females with larger rear ends as better potential mothers, a new study of the primates indicates that female fertility may actually play a greater role when it comes to choosing a potential mate, the authors report.
Tracking baboon mating habits
Courtney Fitzpatrick, a researcher at the Duke University Department of Biology in Durham, North Carolina, and her colleagues used a camera technique originally developed to measure elephants and other large animals from a distance to monitor baboon mating habits.
The primates typically breed throughout the year, and mating takes place when the female’s backside is swollen – an indication that she could be ovulating, the researchers explained. Her hindquarters are typically swollen for 10 to 20 days per month, and reaches peak size when she is at her most fertile before shrinking back to normal size, they added.
Fitzpatrick’s team used a digital caliper attached to a telephoto zoom lens to measure how far a female baboon was from her location, then use that information to monitor the size and variation of her swellings. Measurements were collected from 34 female baboons, with their posterior sizes increasing by anywhere from 4.0 to 6.5 inches as they approached ovulation.
Bigger isn’t necessarily better
They combined those size measurements with long-term data on the offspring of each female, and after controlling for factors such as age and rank, they would that those baboons with bigger backsides are not necessarily better mothers. That conclusion was based in part on the fact that females with larger keisters did not necessarily produce more surviving offspring.
Furthermore, Fitzpatrick and her associates also recorded male courtship behaviors when females were swollen, and found that those males were no more likely to be attracted to larger-bottomed females than smaller-bottomed ones. Instead of instinctively going for the larger posteriors, male baboons actually preferred females that had more cycles since last becoming pregnant.
Female baboons, like humans, do not immediately resume ovulation right after giving birth, and until they do, they are less likely to become pregnant. The observations appear to suggest that the male baboons are deeper than biologists initially gave them credit for, and that they aren’t merely attracted to the size of a potential mate’s posterior.
“It’s almost as if the males are counting. Our study suggests that, at least in part, males follow a rule along the lines of ‘later is better’ rather than ‘bigger is better,’” Fitzpatrick said. She and her colleagues now plant to see if females mate with more males after they’ve had a higher number of postpartum menstrual cycles, and if that increases their offspring’s survival rates.
—–
Follow redOrbit on Twitter, Facebook, Google+, Instagram and Pinterest.
Comments