It's not news that certain primates pay for sex - not people, I mean, but we know about those macaques that are willing to give it up in exchange for a nice grooming.
So it's no surprise that our closer relatives do it too - but at least they have the sense to hold out for better pay. Male chimps pay with meat for mating, say researchers from the Max Planck Institute:
"By sharing, the males increase the number of times they mate, and the females increase their intake of calories," said Dr Gomes.
"What's amazing is that if a male shares with a particular female, he doubles the number of times he copulates with her, which is likely to increase the probability of fertilising that female."
As we've seen in the past, though, researchers find ways to make excuses for the relatives, arguing that this is less like prostitution and more like... marriage?
"We looked at chimps when they were not in oestrus, this means they don't have sexual swellings and aren't copulating."
"The males still share with them - they might share meat with a female one day, and only copulate with her a day or two later."
...Professor Gurven, who was not involved in this study, added that the nature of this exchange of meat for sex is "kind of like pair bonding in humans, because it's long-term."
(Full of himself chimp by Flickr user Misterqueue.)