Chimps may offer their mates food for sex

Chuck Bednar for redOrbit.com – @BednarChuck

Humans may not be the only primates that are sometimes involved in the “world’s oldest profession,” as some experts believe that chimpanzees also participate in a form of prostitution – though instead of money changing hands, food is the currency featured in those transactions.

According to National Geographic, female chimps typically go five to six years between giving birth, one of the longest spans in any mammal species. Rather than sex, their minds are focused more on food, which can lead males to try and bribe them using capture prey or stolen crops.

Male chimp pick-up lines work better with papaya

As University of New Mexico primatologist Melissa Emery Thompson told the website, female chimps will mate with “most or all of the males she knows” in order to increase the odds that she will reproduce. Males, conversely, will try to fight or compete with other potential sires.

A 2007 study published in the journal PLOS One found that female West African chimps were more likely to have relations with a male that gave her stolen papayas, prompting lead author and Oxford Brookes University postdoctoral student Kimberley Hockings to suggest that the male was giving the fruit to “reproductively cycling females” in exchange for “other currencies.”

In the absence of long-term data linking food sharing to male reproductive success, Hockings and her colleagues said that their observations revealed that the food-for-sex trade was likely as a male that shared fruit with a reproductive-age female “engaged in more consortships with her and received more grooming from her than the other adult males, even the alpha male.”

But could the males be doing more harm than good?

However, other researchers, including Emery Thompson, aren’t buying the food-for-sex theory. She told Nat Geo that people like to latch onto the theory because it is somewhat scandalous, but that her research has uncovered a vastly different link between food and reproductive behavior.

In a December 2014 Behavioral Ecology and Sociobiology paper, Emery Thompson and her co-authors assert that the presence of males wanting to mate with her reduces the ability of a female East African chimpanzee to forage and feed, reducing her fertility and the chances of producing new members of her endangered species.

They studied chimps in the Kibale National Park in Uganda for more than a decade, and found that the availability of sexually receptive females played a key role in how many males were in the parties, and that those females “experienced significantly lower C-peptide of insulin levels, indicative of reduced energy balance, during periods when they associated with more males.”

“C-peptide levels positively and significantly predicted female ovarian steroid production, indicating that the costs of associating with males can lead to downstream reproductive costs,” the authors continued, concluding that “large groupings that allow males to compete for mating opportunities” inflict “energetic and reproductive costs on females.”

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