I found this fascinating. Geoffrey Miller’s theory is that women have lost their oestrus – any outward sign of fertility – to keep men faithful. Otherwise a man might go hunting for another mate when he knew his mate was infertile. But this should create an evolutionary arms race among men as men evolve ever-heightened sensitivity to signs of female fertility.
Miller tested his theory in lap-dancing clubs by examining the number of dollars female performers received for their dancing. During menstruation – when women were infertile – women earned about $185 per shift – about what they earned if they were on the pill. Women who were ovulating earned $335.
This suggests a woman is sexier when she is fertile and that lap dancers should stay off the pill if their main objective is to maximise their income. Earlier studies have shown that a woman’s face, smell and even clothing become more attractive during oestrus. Clothing looks more attractive to men when women are fertile.
But I still don’t know if women advertise their sexuality better when they are fertile or men have enhanced powers to pick up their fertility status.