If it’s male, attack it; if female, mate with it.

From The New York Times:Fly_2

Last month researchers reported on the role of genes in the sexual behavior of both voles and fruit flies. One gene was long known to promote faithful pair bonding and good parental behavior in the male prairie vole. Researchers discovered how the gene is naturally modulated in a population of voles so as to produce a spectrum of behaviors from monogamy to polygamy, each of which may be advantageous in different ecological circumstances. The second gene, much studied by fruit fly biologists, is known to be involved in the male’s elaborate suite of courtship behaviors. New research has established that a special feature of the gene, one that works differently in males and females, is all that is needed to induce the male’s complex behavior.

The male mouse’s rule for dealing with strangers is simple – if it’s male, attack it; if female, mate with it. But male mice that are genetically engineered to block the scent-detecting vomeronasal cells try to mate rather than attack invading males.

More here.