Men are more concerned that they do not end up raising another males offspring, so are more jealous about sexual infidelity.

London - Women are more upset by emotional betrayal by their partners than sexual infidelity, while for men, it is the exact opposite, according to a study.

It suggests that the different responses are the result of millions of years of evolution.

Because women have traditionally been more likely to look after children, they care more that their partner will stay with them to help look after the family. They become emotionally jealous when they fear their partner will run off with another woman with whom he has fallen in love, the study says.

By contrast, it adds, men are more concerned that they do not end up raising another male’s offspring, so are more jealous about sexual infidelity.

These differences in response have endured for centuries in countries across the world, according to the researchers from the Norwegian University of Science and Technology’s department of psychology. Mons Bendixen, an associate professor who led the study involving 1 000 participants, said: “Men and women’s psychology is similar in most areas, but not when it comes to reproduction.”

Participants were randomly given one of four versions of a questionnaire about jealousy. Half were asked to check off whether the emotional or sexual aspect of infidelity was the most upsetting to them in four different scenarios.

In one example, they were asked: “Imagine you discover that your partner both formed a deep emotional and a passionate sexual relationship with another person. Which aspect of your partner’s involvement would make you more jealous?”

The differences in the way the sexes responded were marked. In one scenario, 45.9 percent of men were more upset by sexual than emotional infidelity, compared with 16.6 percent of women.

In another scenario, 37.2 percent of men were upset by sexual infidelity, compared with 8.7 percent of women. Professor Bendixen said: “We found clear sex differences in the jealousy responses among those who had to choose which aspect of infidelity was most upsetting to them.

“These sex differences are remarkable, since they were obtained using two alternative methods of measurement, and in a highly egalitarian nation with high paternal investment expectancy.”

However, the study suggested the responses could change in Norway, where the study was conducted, and other nations with high levels of sexual equality. In Norway, fathers are expected to take an active role in looking after children, from changing nappies to childcare, helped by generous paternity leave and other legal support.

At the same time, the state provides benefits that allows single parents to raise children alone without the help of a father or mother, the researchers said. This could lead to the sexes taking a broadly similar view of infidelity.

Professor Bendixen said: “Jealousy is learned, but we feel confident that these reactions are mechanisms that are part of an evolved human mind, given comparable findings across several nations.”

The study was published in the journal Personality and Individual Differences.