We've all heard the oft-cited gender role stereotypes. Men are promiscuous. Women are choosy. Biology programs men to want to widely spread their seed while women are programmed to want to guard their eggs. According to a new study these gender roles that sound oversimplified, are oversimplified.

Researchers set about testing conventional sex roles as a way to better understand them and found evidence supporting their opinion that human mating strategies do not subscribe to just one universal, predictable pattern.

The findings, which appear in the April 20 issue of the journal Trends in Ecology and Evolution, challenge the long-held view that evolutionary theory sets rigid sex roles in human beings.

The roles were originally based on fruit-fly experiments by Angus Batemen. He found that male fruit flies had a greater variance in the number of sexual partners and the number of offspring compared to female counterparts. Since one egg is more costly to produce than one sperm, concluded Batemen, the number of offspring produced by a female fruit fly was limited by her ability to produce eggs; a male's reproductive success was limited by the number of females he inseminated. Thus the conventional assumption was born that male animals are competitive slash promiscuous and female animals are non-competitive slash choosy.

The new findings suggest that human mating strategies are much more complex than that. "Factors such as sex-biased mortality, sex-ratio, population density and variation in mate quality are likely to impact mating behavior in humans," said lead study author Dr. Gillian R. Brown from the School of Psychology at the University of St. Andrews in a press release. The study results may impact future investigations of human mating behaviors.