A new study suggests looking at a man's hands will tell you a lot about his heart.
Researchers at McGill University in Canada examined the hands of 155 adult men and women, measuring the length of their ring fingers and pointer fingers. Over the course of 20 days, participants tracked every social interaction that lasted more than five minutes.
The results showed no link between finger length and behavior for women. For men, if their index fingers were shorter than ring fingers, then the more likely they were to smile, listen attentively, compliment and compromise with another person - and they were less argumentative with women than other men.
These findings might also support a previous study that found men with smaller digit ratios - meaning more even fingers - have more children.
"Our research suggests they have more harmonious relationships with women; these behaviors support the formation and maintenance of relationships with women. This might explain why they have more children on average."
But small ratios aren't everything. Another study published earlier this month suggested that men and women with small digit ratios are more likely to stray in a relationship.
Previous research suggests finger length is determined by male hormone levels, particularly testosterone, that a baby is exposed to while in the womb. The lower the male hormone levels are, the kinder the man is toward a woman.
More from AOL
Children have fewer allergies when families do chore one specific way
Arctic air heads to northern New England, parts of New York
Wesleyan: 11 students hospitalized with drug symptoms