Friday, May 21, 2010

Male antelopes lie to increase their chances of having sex

Replace "antelopes" with "humans" and I think most of us would nod in agreement. But this is the first time researchers have found "intentionally misleading behavior in animals for the explicit purposes of mating." Ars Technica has a great overview of the study:

The four-year study looked at the behavior of topi antelopes (Damaliscus lunatus) in the Masai Mara National Reserve in Kenya. This area is dominated by a huge number of predators, including lions, cheetahs, leopards, and hyenas, all of which prey regularly on antelopes. When topi detect a predator nearby, they often make snort-like alarm calls.

From February to March, male topi hold small territories through which receptive females pass to assess each male’s mating potential. The authors noticed that, while a female in estrus was on a male’s territory, the male would sometimes emit alarm calls, even in the complete absence of a predator. These false alarms are acoustically indistinguishable from true alarm snorts.

The authors set out to determine whether these false alarm snorts are simply predator detection errors, or if they function to deter the female from leaving the territory in order to secure more mating opportunities with her. The results overwhelmingly supported the authors' "sexual deception hypothesis." False alarms almost never occurred without a receptive female on the territory, the onset of the false snorts was highly correlated with a female’s attempts to leave the territory, and, after emitting a false snort, males managed an average of 2.8 extra booty calls.

You may be wondering why females continue to fall for the lies of males. If this behavior evolved, you think females would also evolve to detect lies, right? It boils down to probability and consequences: Lies happen a lot less frequently than truthful signals, and believing a lie has less severe consequences (mating with a less desirable male) than ignoring a true signal (getting eaten).

This questions comes up a lot when you're discussing dishonest signaling, which actually happens more than you would think in nature. One of the more popular example is bluffing in fiddler crabs. Sometimes when a fiddler crab loses its enlarged claw, it will grow back a weaker, cheaper claw. While these claws aren't as good in fighting, they're just as good at intimidating other crabs. It's not worthwhile for crabs to check and see if another crab is bluffing, because the consequences of the signal being true are so large (getting the crap kicked out of your crabby self).

Still, it's very interesting that they've now documented this type of bluffing specifically in regards to sex. I have a feeling we'll see more examples of this in the future, now that researchers will be keeping their eyes open!

(Via Carnal Nation)

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