London, Oct 21 (IANS): If you are searching for a more masculine man for dating, remember that this is not what your ancestors looked for.

According to a study, sexual preference for masculine men and feminine women is an urban habit and probably not a consistent thread in human history.

"The highly developed environments with large, dense populations may have exposed individuals to a greater range of unfamiliar faces, providing the opportunity - and perhaps motive - to discover subtle relationships between facial traits and behaviour," said Andrew Clark, lecturer in psychology at the Brunel University in London.

This data challenges the theory that exaggerated sex-specific traits were important for social and sexual selection in ancestral environments.

To reach this conclusion, a team of psychologists, anthropologists and biologists surveyed 12 populations around the world from the primitive to the highly developed.

Surprisingly, only in the most industrialised and urbanised environments did people hold the opinion that highly feminine women and highly masculine men are attractive.

Researchers digitally morphed masculine and feminine faces from photographs of people to find out what choices people from small-scale societies made.

A total of 962 participants were shown sets of three, opposite-sex photos.

"We found that they did not place the same emphasis on 'sex typicality', that is, on highly feminine women and highly masculine men. In fact, they often favoured the neutral face and, sometimes, the least 'sex-typical' one," Clark added.

The team also found that the perception that masculine males tend to be aggressive increased with urbanisation.

The paper appeared in the journal Proceedings of the National Academy of Sciences.