New research suggests that women, as a relationship back-up plan, are programmed to have affairs. Researchers involved in the study have challenged the assumption that humans are monogamous and that break-ups are a sign of failure. They have said that women have evolved to pursue affairs if they decide to leave their partners. Even though men too have a similar kind of programming, it is more prevalent in women.

Thus, the hypothesis of mate-switching means, humans have evolved to continuously look for better long-term options and test their own relationships. The researchers have also noted that this theory is more applicable to childless women whose choice of partner may have a big impact on children they may have.

In fact, early humans, who hardly lived beyond 30, experimenting with partners could have been a key to long-term survival.

“Lifelong monogamy does not characterise the primary mating pattern of humans. Breaking up with one partner and re-mating with another — mate switching — may more accurately characterise the common, perhaps the primary, mating strategy of humans,” David Buss, professor of evolutionary psychology at the University of Texas, said in the research paper, reports The Times.

Up to now, experts the evolution of female infidelity was best explained with the “good genes” theory that argues women are attracted to less-dominant men as they are considered better long-term partners as they are more likely to stick around.

However, they will covertly seek more masculine “affair partners,” more so during their fertile period. From the evolutionary perspective, this allows them to get the fittest genes for their baby from the affair partner. Then they will have the child cared by a reliable, less-dominant partner.

Even though this may sound devious, Buss, along with Cari Goetz and colleagues suggest that women keep track of their partner’s “mate value,” often comparing it with that of other single men. They also analyse the costs imposed by partners who fail to provide or behave badly, known as “relationship load,” writes The Australian.

“Affairs serve as a form of mate insurance, keeping a back-up mate should a switch become warranted in the future,” the researchers propose.

When it comes to male infidelity, they said ancestral males directly increased their reproductive success through sexual access to fertile women over and above a primary partner.