The kind of man that a woman finds attractive varies over her monthly cycle. During ovulation more masculine looking men are rated more highly. Also men with more dissimilar immune systems are more appealing. During the less fertile stages, less masculine and more similar men immunologically are the preference.
It isn’t entirely clear why this disparity occurs. It might be as simple as being a mechanism that favours selecting partners from a wider gene pool. It works both ways too. Women are more atractive to men when at their most fertile. This can be detected in something as simple as that lap dancers get a higher level of tips when at this stage of their cycle. As often seems to be the case, the details of the science behind how females work is not easy to elucidate, what motivates the males is all too obvious.
We don’t yet know the details of how these differences are signalled, but they seem to involve smell and subtle changes in the voice. But whatever the details,something is going on.
A recent paper suggests that taking the contraceptive pill breaks this cycle. The preference shown for men with different immune systems is lost. So it is possible that being on the pill might lead you to select a different mate to the one you would have chosen if you weren’t on it. Is this a good thing or a bad thing? It is hard to tell, and probably we’ll never know. Looking at one facet of our biology in isolation is interesting, but we remain hugely complex organisms and we don’t really fully understand ourselves enough to make that kind of judgment.