Aggression levels in men appear linked to index finger length

• The shorter the index finger is compared to the ring finger, the more boisterous he will be, University of Alberta researchers said.
• But the same was not true for verbal aggression or hostile behaviours, they told the journal Biological Psychology after studying 300 people's fingers.
• The trend is thought to be linked to testosterone exposure in the womb.
• It has been known for some time that there is a direct correlation between finger lengths and the amount of the male sex hormone testosterone that a baby is exposed to in the womb.
• Other studies looking at finger length ratio have suggested that, in men, a long ring finger and symmetrical hands are an indication of fertility, and that women are more likely to be fertile if they have a longer index finger.
• One study found boys with shorter ring fingers tended to be at greatest risk of a heart attack in early adulthood, which was linked to testosterone levels.
• In the current study, Dr Peter Hurd and his student Allison Bailey measured the fingers of 300 undergraduates at their university.
• Men with the shortest index fingers scored higher on measures of physical aggression than those with longer index fingers, but the study's findings did not apply to women.
• He said: "Finger length can tell you a little bit about where personality comes from.
• "A large part of our personalities and our traits are determined while we are still in the womb."
• But he said finger length should not be used to draw too many conclusions about an individual person.
• Professor John Manning from the University of Central Lancashire's department of psychology, who first realised that sex hormone exposure in the womb influences finger length, agreed.