The research team, made up of three women and two men, said that when men are thin on the ground, ‘women are more likely to choose briefcase over baby’.

And the plainer a woman is, they claim, the more she is driven to succeed in the workplace.

Central to their argument was the idea that women have evolved to become homemakers and men, providers.

They said this means that when men are scarce in a particular area, women, and particularly less attractive ladies, may decide they need to provide for themselves with a well-paid career.