Humans May be Hardwired to be Serial Monogamists

Scientists have taken a closer look at the process of falling in love and breaking up, and have found that humans may actually be hardwired to be serial monogamists.

"Our review of the literature suggests we have a mechanism in our brains designed by natural selection to pull us through a very tumultuous time in our lives," said Brian Boutwell, one of the researchers, in a news release. "It suggests people will recover, the pain will go away with time. There will be a light at the end of the tunnel."

In this latest study, the researchers examined the process of falling out of love and breaking up, which they called "primary mate ejection." They also looked at the process of moving on to develop a new romantic relationship, which they called "secondary mate ejection."

Men and women might break up for different reasons. For example, a man is more likely to end a relationship because a woman has had a sexual relationship with another man. For evolutionary reasons, men should be wired to try and avoid raising children that aren't genetically their own. Women, in contrast, may be more likely to break up if her partner has been emotionally unfaithful. Natural selection has designed mate ejection in females to avoid the loss of resources, such as help in raising a child and physical protection.

"Men are particularly sensitive to sexual infidelity between their partner and someone else," said Boutwell. "That's not to say women don't get jealous, they certainly do, but it's especially acute for men regarding sexual infidelity."

Interestingly, brain imaging studies revealed an increase in neuronal activity in the parts of the brain that also become active with cocaine use. Falling out of love, in contrast, might be compared to asking a cocaine addict to break his or her habit.

"To sever that bond and move on is a huge thing to ask of a person," said Boutwell. "Ultimately, trying to move on from a former mate may be similar in some ways to an attempt at breaking a drug habit."

Building off the drug addiction analogy, the researchers examined studies about the brains of former cocaine addicts. The brains of those no longer using cocaine showed a larger volume of grey matter in various brain regions. Boutwell points out that conducting functional MRI studies that examine the brains of those who have rebounded and fallen in love again may provide additional evidence to either lend credibility or dismiss the addiction hypothesis.

"If we better understand mate ejection, it may offer direct and actionable insight into ways in which couples can save a relationship that might otherwise come to stultifying and abrupt halt," said Boutwell.

The findings are published in the journal Review of General Psychology.

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