Length of men's fingers associated with their behavior towards women

Prenatal androgen exposure among men, reflected as the ratio between the length of the index and ring fingers, affects their agreeable and quarrelsome behaviors towards women, according to a study recently published in Personality and Individual Differences.

Furthermore, the results indicated that men who had smaller index to ring finger ratios (2D:4D) were more agreeable towards women than men who had larger digit ratios.

“This suggests that men with greater prenatal exposure to androgens are more engaged in forging social connections with women,” the researchers wrote.

The 2D:4D ratio is defined as the length of the second digit divided by the length of the fourth digit. The relationship between 2D:4D ratio and behavior was assessed in 155 men and women who self-reported their behavior during every social interaction they encountered that lasted longer than 5 minutes for 20 days. The social behaviors that participants conveyed were categorized as agreeable, quarrelsome, dominant or submissive. Researchers also considered the relationship status between the participant and the person whom they were interacting with as either a supervisor, co-worker, supervisee, friend, acquaintance or romantic partner. Parent and sibling interaction was excluded, resulting in approximately 100 overall social interactions per participant.

The outcomes showed that despite 2D:4D ratios, men were generally more agreeable towards women than other men (P < .001), but agreeability was more prevalent in men with smaller 2D:4D ratios. The results were consistent in both right (P = .007) and left hands (P = .018).

“When with women, men with smaller ratios were more likely to listen attentively, smile and laugh, compromise or compliment the other person,” Debbie S. Moskowitz, MA, PhD, professor of psychology at McGill University, said in a press release.

When observing quarrelsome behavior, men with smaller 2D:4D ratios in their right and left hands were less quarrelsome towards women than with other men (P < .001 for both). However, men with larger 2D:4D ratios did not show a difference in quarrelsome behavior between genders. A post hoc analysis showed that, compared with men with larger 2D:4D ratios, men with smaller 2D:4D ratios were less quarrelsome with women (P = .001 for both hands).

According to the results, dominant and submissive behavior did not correlate with 2D:4D ratios, and women’s 2D:4D ratios did not impact any of their behaviors.

Researchers related their findings to an earlier study that showed men with smaller digit ratios had more children compared with men who had larger digit ratios.

“Our research suggests they have more harmonious relationships with women; these behaviors support the formation and maintenance of relationships with women,” Moskowitz said in the release. “This might explain why they have more children on average.” – by Stephanie Viguers

Disclosure: The study was funded through a grant received by Moskowitz from the Social Sciences and Humanities Research Council of Canada