Why do peahens prefer peacocks with more elaborate trains?
Professor Marion Petrie, Professor Morris Gosling, Thomas Pike, Dr Craig Roberts and Dr Gilbert Roberts.
University of Newcastle.
The secret of sex appeal lies in how you wear your genes, according to a team of evolutionary biologists at the University of Newcastle. They have been investigating the preferences of females - from peahens to mice to humans - to find out how they are attracted to prospective mates. Pernickety females, it seems, use cues such as appearance to size up a male's genetic quality before mating with him. Surprisingly, females, including women, can even tell how different a male's genes are from hers.
'Why are females choosy?' asks Professor Marion Petrie, who heads the project. For many species, where the male provides resources such as food and help with raising offspring, the answer is obvious - they want the best provider. But for species where the males provide little help or resources, the answer seems to be that females are trying to get the best genes for their offspring.
The scientists have discovered that in peacocks at least, the offspring of males with the most attractive tails grow faster and survive longer. Males with the best tails also survive better as adults.
But what's the link between fancy tails and viability? The team thinks that the tails somehow signal the male's genetic make-up to females, who then choose mates. The best partner, genetically speaking, would be with a male with genes - such as immune system genes - that are very different from those of the female. This deals the offspring a varied 'hand' of genes to cope with any challenges their environment throws at them.
To find out more, the team studied the visual signals that may be involved, for example, the spectrum of colours created by the peacocks' tails. They discovered that males varied a lot in their colour, and that the different colours were largely genetically determined.
Of course, not all animals use elaborate tail displays to hawk their genes. The team has also found that male mice deposit scent marks around their territories and that these allow females to assess a male's genetic compatibility, as well as his dominant social status, before they even meet him. You will be able to watch mice scent marking new objects placed in their cages at the exhibit.