Biologists at the University of Florida have found a reason why men’s ring fingers are generally longer than their index fingers — and why the reverse usually holds true for women.
The finding could help medical professionals understand the origin of behavior and disease, which may be useful for customizing treatments or assessing risks in context with specific medical conditions.
Writing this week in the Proceedings of the National Academy of Sciences, developmental biologists Martin Cohn, Ph.D., and Zhengui Zheng, Ph.D., of the Howard Hughes Medical Institute and the department of molecular genetics and microbiology at the UF College of Medicine, show that male and female digit proportions are determined by the balance of sex hormones during early embryonic development. Differences in how these hormones activate receptors in males and females affect the growth of specific digits.
The discovery provides a genetic explanation for a raft of studies that link finger proportions with traits ranging from sperm counts, aggression, musical ability, sexual orientation and sports prowess, to health problems such as autism, depression, heart attack and breast cancer.