Heroism in war is the most sexually attractive trait to women, according to new research.
The opposite is true of men, the study from the University of Southampton found - men do not find heroism to be a sexually attractive trait in women.
In the study, published online in the journal Evolution And Human Behaviour, 92 women studying in the UK were presented with hypothetical profiles of the opposite sex, representing varying levels of heroism in different contexts such as warfare, sport and business.
They were then asked a series of questions designed to determine how attracted they were to the different profiles.
Women were more likely to find a soldier attractive, and were more inclined to date him, if he had been awarded a medal for bravery in combat.
But whether or not a non-decorated soldier had seen combat in a warzone or remained in the UK did not have a statistically significant effect on his attractiveness.
Displays of heroism in other fields, such as in sports or in business, also had no effect on how likely women were to find them attractive.
In a subsequent experiment by the researchers, 159 women and 181 men studying in Holland took part in a similar exercise to determine their level of sexual attraction to the opposite sex. This time, the soldier profiles displayed various levels of bravery, either in combat or by helping in a natural disaster zone.
Again, heroism in combat increased women's levels of sexual attraction towards male soldiers, but heroism in a disaster zone had no impact.
Female heroes, both in combat and in disaster zones, were deemed less attractive by men than their non-hero counterparts.
Joost Leunissen, a psychologist at the University of Southampton, said: "This provides evidence for the hypothesis that gender differences in intergroup conflict can have an evolutionary origin, as only males seem to benefit from displaying heroism.
"In light of the physical dangers and reproductive risks involved, participating in intergroup aggression might not generally be a viable reproductive strategy for women.
"Heroism also seems to be a context-specific signal, as it only had an effect on attractiveness in a setting of intergroup conflict.
"Indeed, soldiers who displayed heroism were only considered to be more attractive when this was displayed in a warfare context and not in another situation which is frequently associated with the army - helping during and after natural disasters."
The experiments follow on from a historical analysis undertaken by the research team, which looked at numbers of children fathered by US Medal of Honor recipients in the Second World War compared to the numbers of children fathered by regular veterans.
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The analysis shows Medal of Honor recipients had an average of 3.18 children, while regular veterans averaged 2.72 children, suggesting decorated war heroes sired more offspring than other veterans.
Mr Leunissen said: "Raids, battles, and ambushes in ancestral environments, and wars in modern environments, may provide an arena for men to signal their physical and psychological strengths.
"Of course, women may not always witness these heroic acts in person, but such information is likely to be widely communicated within a tribal community, particularly when the actions of male warriors are outstandingly brave."
The study team was made up of researchers from the University of Southampton, UK; University of Giessen, Germany; Technical University of Munich, Germany; and VU University Amsterdam, the Netherlands.