PMS may exist to break up infertile relationships

Premenstrual syndrome (PMS) may have evolved in women to break up infertile relationships and improve their chances of reproduction, according to a new study.
PMS affects up to 80 per cent of women and symptoms include anxiety/tension, mood swings, aches and cramps, cravings and disinterest in usual activities.
Michael Gillings, Professor of Molecular Evolution at Macquarie University in Australia, believes that in our evolutionary past there was a hidden selective advantage to PMS, because it increased the chance that infertile pair bonds would dissolve.
"In the past, women had many fewer menstrual cycles than women in modern societies, because they did not have control over reproduction and were either pregnant or breastfeeding most of the time," said Gillings.

"Imagine that a woman was pair bonded with a sterile or infertile male. Then, even in the past, they would have had regular cycles.
"If women in these relationships exhibited PMS and this increased the likelihood of the pair bond dissolving, this would be a huge reproductive advantage.

"This simple phenomenon might explain the frequency of PMS. There are various lines of evidence from DNA and behavioural studies that confirm this idea," Gillings said.
The hypothesis is supported by the high heritability of PMS, and the fact that gene variants associated with PMS can be identified, not to mention the data that show animosity exhibited during PMS is preferentially directed at current partners.

"Under this view, the prevalence of PMS might result from genes and behaviours that are adaptive in some societies, but are potentially less appropriate in modern cultures," said Gillings.
"Understanding this might help the management of PMS and will help change attitudes, for example, towards cycle-stopping contraception. PMS is a simple and natural behaviour that arose as a consequence of our evolutionary past," Gillings added.