Female mammals follow their noses to the r...( Female birds often choose their mate...)

Female birds often choose their mates based on fancy feathers. Female mammals, on the other hand, may be more likely to follow their noses to the right mate. That's one conclusion of Cambridge zoologist Tim Clutton-Brock and Harvard researcher Katherine McAuliffe, whose review of evidence for female mate choice is published in the March 2009 issue of The Quarterly Review of Biology.

Historically, most examples of female mate choice and its evolutionary consequences are found in birds. The classic case is the peacock's tail. The ornate tails do nothing to help peacocks survive. Rather, they emerged because peahens prefer to mate with males that have showy plumage.

Such vivid examples of female preferences in mammals are harder to find, leading to an assumption that mate choice plays a smaller role in mammals than in birds. But that's not necessarily the case, Clutton-Brock and McAuliffe conclude. Female mating preferences are likely to be just as important in mammals, though they may not be as obvious to human observers.

The researchers point out several factors that complicate the study of mammalian mate choice. One factor is the very nature of mammalian mating systems. Males compete fiercely with each other for access to female partners. Since the dominant males often chase away other males, it's hard to tell if females are choosing to mate with certain males, or are merely mating with them by default.

"The most convincing evidence for female mate choice in mammals comes from studies of captive mammals carried out under controlled conditions where the effects of male competition can be excluded ," Clutton-Brock and McAuliffe write.

Lab studies of olfactory signaling, they say, may provide the best evidence for female mate choice in mammals. Unlike birds, many mammal species are sexually active at night. So mammals may be less inclined than birds to base preferences on visual cues. Instead, females of many m
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