EIGHT in ten women experience it and finally there’s a medical explanation for premenstrual syndrome — evolution.

The animosity that overtakes some women at certain times of the month is actually nature’s way of making them unbearable to live with.

That way they can rid themselves of an infertile male to clear the way for new partner to increase their chances of passing on their DNA.

That’s the controversial new claim from a medical expert for the depressing ten days before a period that most women abhor.

And while PMS was useful in hunter gatherer days, it is a drag in modern society.

“We’ve stigmatised a perfectly normal consequence of fertility at work,” says Professor Michael Gillings from Macquarie University’s Department of Biological Sciences.

PMS is not a disease or syndrome but a normal consequence of evolutionary adaptation “similar to morning sickness”, he says.

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Recently severe forms of PMS were decreed a mental disorder in the psychiatric bible DSM5 even though 80 per cent of women experience it.

“That gets up my nose. If 80 per cent of women have PMS, the behaviour is normal, how can you say these people are sick or mentally deranged,” Professor Gillings says.

Professor Gillings says the widespread nature of the maladaptive behaviour is what led him to question whether there was an evolutionary basis for it.

“In some cases apparently maladaptive states may be the result of our evolutionary history,” he said.

Women in hunter gatherer societies never suffered PMS but it is on the increase in the modern age when women control their fertility, he says.

“Studies of modern tribespeople with hunter-gatherer lifestyles show that fertile women have a median of two menstrual cycles per year and just over 100 per lifetime,” he says in a paper published in the journal Evolutionary Applications.

“This compares with women in developed countries who are likely to have over 400 cycles,” the paper says.

The frequency of PMS in the modern world arose “because of a mismatch between our evolutionary history and current cultural conditions,” he said.

“The rise of PMS is a consequence of our control over our reproduction not as a consequence of infertility,” he said.

Premenstrual syndrome includes a series of symptoms such as anxiety/tension, mood swings, aches, cramps, cravings and depression that afflict women in the seven to ten days before menstruation.

Some studies have found female hosility towards a partner would interrupt mating opportunities, intensifying male ardour and lead to increased chance of ovulation during the next cycle, he said.

If the behaviour is designed to rid a woman of an infertile man the animosity caused by PMS should be exhibited towards the man and numerous studies suggest such a link, he says.

Other studies show women feel more sexual in the premenstrual phase and are more likely to take risks and be competitive, increasing their chances of finding a new sexual partner, he says.

He cites various research papers that suggest the solution to PMS is for women to use cycle stopping contraception such as taking the pill without a break to mimic their ancestral state.

There is also evidence such an approach would lower the incidence of reproductive cancers which have been linked to constant changes in reproductive tissue linked to menstruation.