Humans are wired to break up and move on, according to a new study drawing on the field of evolutionary psychology.

"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," says Brian Boutwell, Ph.D., associate professor of criminology and criminal justice and associate professor of epidemiology at Saint Louis University in the US.

Dr. Bountwell focused on the process of breaking up, deemed primary mate ejection for the purposes of the study, and getting over it, which is called secondary mate ejection.

"It suggests people will recover; the pain will go away with time," he says of his research. "There will be a light at the end of the tunnel."

Men are more likely to end relationships if their partner has cheated on them, according to the study, indicating that for evolutionary purposes, men are hardwired to avoid raising children of whom they are not the biological father.

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

Women are likely to end relationships if their partner is emotionally unfaithful and this also has evolved for practical reasons, according to the study, which was published in the journal Review of General Psychology.

Mate ejection by females has evolved as a way to avoid the loss of resources, such as physical protection, that their mates provide, says Dr. Boutwell.

Yet men and women have reasons in common for ending a relationship, according to Dr. Boutwell, whose research suggests neither tolerates cruelty.

Ironically, brain image scans of men and women claiming to be deeply in love yield important clues about how they break up.

Functional magnetic resonance indicates an increase in neuronal activity in the areas of the brain associated with pleasure -- the very same ones that activate with cocaine use.

This could explain the euphoric attachment that new lovers feel towards each other, says Dr. Boutwell, who implies that we could be literally addicted to love.

It's exactly that part that makes a breakup -- or, primary mate ejection -- so difficult for the partner who doesn't want it.

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

At first, this person might pursue their ex, yet failing to win back their affection could result in the brain's involuntary correction of certain emotions, leading to new attraction for new mates and, finally, new relationships.

Research into lost love is important, says Dr. Boutwell, in developing a better understanding of why relationships fail.

"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," he says.