They could help explain the unexpected sex appeal of Mick Jagger or Jack Nicholson, and may be at work in celebrity of all kinds. Everyone wants to be unique, but when it comes to mating, imitation appears to have some powerful evolutionary advantages. Until recently, all the evidence of mate copying has come from fish and birds. That's partly because it's easier to spot in these animals than in humans. Male grouse, for example, gather at special sites called leks where all the action takes place.
Leks are the grouse equivalent of a singles bar.
Here they strut around displaying their feathers in the hope of pulling a bird. Some males on the lek have all the luck. The most successful may win up to 80 per cent of the passing females. In 1994, behavioural biologists tested this idea by placing several stuffed female dummies on a black grouse lek near randomly chosen males. The eager cocks courted and mounted the dummies, sometimes for up to half an hour, which gave passing females lots of time to notice.