You know that body language can tell you a lot about a guy. But new research recently published in the journal Personality and Individual Differences suggests that his hands might be just as telling: A study found that guys with similarly sized pointer and ring fingers might treat women extra well.

In the study, researchers from McGill University examined the hands of 78 adult men and 77 adult women, measuring the difference between the lengths of the pointer finger and ring finger on each person’s hand.

For a period of 20 days, each participant reported on every social interaction they had that lasted more than five minutes. In every report, each participant’s behavior was categorized as agreeable, quarrelsome, dominant, or submissive. Afterward, researchers assessed the frequency of social behaviors and compared the results to the differences in their finger lengths.

Overall, guys were more agreeable and less quarrelsome when they interacted with women — no ulterior motives there, obviously. However, guys with similarly sized index fingers and ring fingers tended to be particularly nice to women. Finger length didn’t seem to have any bearing on women’s behavior toward either sex.

While this whole finger length thing might seem totally random, experts know that prenatal exposure to certain hormones called androgens influence the length of the pointer and ring fingers. Because androgens are responsible for developing male sex features, guys tend to get more exposure to the hormones than women, and the difference in the lengths of their pointer and ring fingers often ends up more pronounced than it is for women.

Of course, different-size fingers don’t mean a guy is definitely going to be cruel. But it’s cool to know that the size of at least one of his pointers could predict a biological inclination to treat you better.

[via Cosmopolitan]