What You’ve Been Waiting For, A Way To Tell Whether He’s A Jerk On Sight
"These men were also less quarrelsome with women than with men, whereas the men with larger ratios were equally quarrelsome with both."
It’s all down to the hands, apparently.
A new study reveals that If his index finger is shorter than his ring finger then he’ll be nicer to women and men, as a rule, and more likely to both listen and compromise. While this might sound a bit like quackery from just the premise, it’s actually based on the much studied phenomenon of testosterone exposure while in the womb. The less testosterone exposure, the longer the index finger is likely to be as compared to the ring finger and the more argumentative he’s likely to be with everyone. From the abstract of the study published in the periodical Personality and Individual Differences:
Participants completed multiple records of their behavior in events in naturalistic settings; records included information about situational features such as the gender of the person with whom the person was interacting. Men were more agreeable towards women than men; this effect was significantly greater in those with smaller 2D:4D ratios. Men with smaller 2D:4D ratios were also less quarrelsome towards women than towards men. The 2D:4D ratio did not influence social behavior in women. The hormonal environment in which the male fetal brain develops may influence adult social behavior in specific contexts.
2D means second digit and 4D means fourth digit, index and ring finger, respectively. On average, a man’s index finger is shorter than his ring finger. The longer the index finger, the more he might be quarrelsome.
“When with women, men with smaller ratios were more likely to listen attentively, smile and laugh, compromise or compliment the other person,” says Debbie Moskowitz, lead author and Professor of Psychology at McGill. They acted that way in sexual relationships, but also with female friends or colleagues. These men were also less quarrelsome with women than with men, whereas the men with larger ratios were equally quarrelsome with both.
The study also indicates that men with shorter index fingers have more children, likely because they don’t cause fights all the time and get divorced. The findings did not track when women were the subjects of the same study. 
