Girls who want to know if a potential boyfriend is a spend-thrift or the tight-fisted kind should check out his fingers, say Belgium researchers.
If they find a big difference in length between ring and index finger, he is likely to be more aggressive and dominant, a study has found.
Men whose index and ring fingers are closer in size tend to be physically weaker and more prone to compromise.
The trend is thought to be linked to the amount of the male sex hormone testosterone a baby is exposed to in the womb.
In the study, 121 adults were shown an aggressive video from German heavy-metal band Rammstein.
They were each given 9 pounds and asked how much they would like to give to another person.
The researchers found that participants with a greater difference between the two fingers offered less money after the video than in a repeat experiment when they were not shown it. Those with less difference in finger length did the opposite.
Previous studies have found a correlation between finger length and pre-natal testosterone exposure.
In women, ring and index digits are usually almost the same length but in men the ring finger tends to be much longer.
However, men exposed to less testosterone are likely to have more feminine finger lengths and less aggressive personalities.
“Levels of testosterone people are exposed to before birth go on to affect their behaviour throughout their lives and there might be a real-life explanation for our results,” the Daily Express quoted researcher Kobe Millet, as saying.
“It’s likely that people with large differences in finger length, reflecting more testosterone, are also physically strong, so after a violent stimulus an aggressive response may be appropriate for them.
“However, those people with smaller differences in finger length may not be so physically strong, and so reacting to aggression by trying to please the other person, rather than acting aggressively, may be their best option,” Millet added.