Meat for sex? A blown "fact"

Do male chimpanzees try to trade meat for sex? It's been assumed by many people that they do. However, a recent report shows this isn't so. The original research report can be found here. The summary of the field project conducted at two sites in East Africa reads as follows:

"The meat-for-sex hypothesis posits that male chimpanzees (Pan troglodytes) trade meat with estrous females in exchange for short-term mating access. This notion is widely cited in the anthropological literature and has been used to construct scenarios about human evolution. Here we review the theoretical and empirical basis for the meat-for-sex hypothesis. We argue that chimpanzee behavioral ecology does not favor the evolution of such exchanges because 1) female chimpanzees show low mate selectivity and require little or no material incentive to mate, violating existing models of commodity exchange; and 2) meat-for-sex exchanges are unlikely to provide reproductive benefits to either partner. We also present new analyses of 28 years of data from two East African chimpanzee study sites (Gombe National Park, Tanzania; Kanyawara, Kibale National Park, Uganda) and discuss the results of previously published studies. In at least three chimpanzee communities, 1) the presence of sexually receptive females did not increase hunting probability, 2) males did not share preferentially with sexually receptive females, and 3) sharing with females did not increase a male's short-term mating success. We acknowledge that systematic meat sharing by male chimpanzees in expectation of, or in return for, immediate copulations might be discovered in future studies. However, current data indicate that such exchanges are so rare, and so different in nature from exchanges among humans, that with respect to chimpanzees, sexual bartering in humans should be regarded as a derived trait with no known antecedents in the behavior of wild chimpanzees."

Among the important points to be made, as the authors point out, perhaps future research will show that there is a strong(er) relationship between using meat for sex but for now that's not the case no matter how seductive the idea might be. And, of course, there might be differences among various populations of chimpanzees so that this sort of bartering might not be a general pattern. There are similar trends in geographical variation for tool-use in chimpanzees. And, it's all too easy to make comparisons between what animals do, or supposedly do, and what humans do.

The bottom line is that we need to be very careful when we look at some phenomenon in non-human animals and use it in an attempt to understand ourselves. And, when one exclaims "Oh, you're acting like animal" we need to be careful in saying "thanks" or "no thanks". Animals do amazing things and what's really exciting is how behavior patterns vary among different populations of the same species and why this is so.