Baboons Don't Think Big Butts Are Sexy

The big red bottom of female baboons has always been an iconic image for the species. However, even if they knew the lyrics, no male baboon would ever be caught enthusiastically singing "Baby Got Back." New research has revealed that baboons don't actually care what sized backside "baby" has at all - a huge surprise for animal behaviorists everywhere.

Experts have long known that while baboon mating occurs all year-round, males are most likely to approach a perspective mate when her behind is swollen - a sign that she is ovulating. This swelling lasts for 10 to 20 days each month and reaches peak size when a female is most fertile.

It then makes sense for males to pick females with the largest butts, as those females will be more likely to get pregnant and mother their children. That argument seems even more sound than the reason human males seem to prefer larger behinds (actually a consequence of an ideal spine curve) - as women with this characteristic will likely find it easier to safely carry a child during pregnancy.

However, according to a study recently published in the aptly named journal Animal Behavior, male wild baboons in southern Kenya show absolutely no preference for females with larger swollen rumps.

This was the conclusion Courtney Fitzpatrick, a researcher at Duke University, reached after observing and measuring the rumps of 34 females during their ovulation periods. (Scroll to read on...)

She explained in a recent release that early on in their observations, Fitzpatrick and her colleagues determined that "some females are just bigger than others" - that is, some had butts that swelled to larger and more noticeable sizes.

The biggest butt, for instance, belonged to a female named Vow, whose rump swelled by 6.5 inches as she approached ovulation. The smallest, on the other hand, belonged to Lollipop, whose bottom grew to a maximum of just under four inches.

And surprisingly, male baboons did not seem to prefer Vow over Lollipop. After recording courtship behavior during the time each of the 34 females were swollen, the team determined that instead of being attracted to the females with the biggest backsides, males most actively persued females that had cycled more times since their last pregnancy.

Just like humans, female baboons don't start ovulating right after giving birth. Instead, they remain far less likely to get pregnant until long after their infant starts weaning.

"It's almost as if the males are counting," Fitzpatrick said. "Our study suggests that, at least in part, males follow a rule along the lines of 'later is better' rather than 'bigger is better.'"

According to the researchers, the next step is to find out if what the males seem to think is true actually is - that more postpartum menstrual cycles translates to a higher rate of pregnancy or offspring survival. Such a revelation could help experts better understand the complex dynamics of baboon and other Old World monkey mating, which could in turn aid in important population projections.

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