WOMEN who come off the pill immediately want to ditch their 'nurturing' partner and have sex with a muscleman, according to new research.
The study shows that women on the pill are attracted to 'feminised' men similar to themselves. But as soon as they stop using oral contraception they crave sex with ultra-masculine bodybuilder types.
And the findings are believed to go some way to explaining the soaring numbers of broken marriages in the developed world since the introduction of the oral contraceptive pill in the early 1960s.
A UK study showed that women who don't use the Pill are attracted to men with a scent which is the polar opposite of their own.
And these tend to be 'manly' men, physically bigger and with more pronounced male features.
In simple terms the more 'opposite' a couples' smells (in scientific terms their histocompatibility complex (MHC) genes) are the better the chance for the immune system of their offspring.
However women using the Pill showed a strong preference to men with a smell closer to their own.
These were often good, caring partners of the New Man variety who, it turns out , may not necessarily be so good in terms of natural selection.
And it gets worse for Metrosexual Man – when women come off the pill they turn their backs on caring man and crave sex with neanderthal man.
The study published in the Proceedings of the Royal Society B suggests that women who start or stop taking the pill, then, may be in for some relationship problems.
A further study published in Psychological Science found that women paired with MHC-similar men are less sexually satisfied and more likely to cheat on their partners than women paired with MHC-dissimilar men.
So a woman on the pill, for example, might be more likely to start dating a MHC-similar man, but he could ultimately leave her less sexually satisfied.
Then if she goes off the pill during the relationship, the accompanying hormonal changes will draw her even more strongly toward more MHC-dissimilar men.
These immune genes may have a “powerful effect in terms of how well relationships are cemented,” says University of Liverpool psychologist Craig Roberts, co-author of the paper.