Posted by: Kelly,Stephanie K
Apparently, you can tell a lot about a person by looking at his or her hands: Attention to detail, personal hygiene, typing prowess and thumb war agility, to name a few. But researchers at the University of Florida have now divulged another tell-tale sign about our digits, finally giving evidence to a prenatal occurrence that many scientists have long suspected.
Developmental biologists, Martin Cohn and Zhengui Zheng of the Howard Hughes Medical Institute and the department of molecular genetics and microbiology at the UF College of Medicine, have recently linked ring finger proportions to levels of sex hormones in an embryo. Until now, there has been no direct experimental evidence to support this claim.
Cohn and Zheng say that during early embryonic development, the balance of sex hormones can have an effect on the growth of certain finger bones. That’s because the developing digits of males and females house receptors that respond differently to the hormones testosterone and estrogen.
By tracking the prenatal growth of the limb buds in mice, which have a digit length ratio similar to ours, the scientists controlled the gene-signaling effects of the two sex hormones. Cohn and Zheng found that higher levels of the male hormone testosterone generally equated to a proportionally longer ring finger, while increased estrogen correlated with a more feminized appearance.
Are you looking at your hands yet? In general, a man’s ring finger is longer than his index, and the opposite usually holds true for a woman. But in addition to providing insight on the conditions of one’s prenatal development, Cohn says that the potential significance of finger ratio doesn’t stop there.
“There is growing evidence that a number of adult diseases have fetal origins,” Cohn says. “With the new data, we’ve shown that the digit ratio reflects one’s prenatal androgen and estrogen activity, and that could have some explanatory power.”
Outside of this recent discovery, studies have also associated finger proportion to a host of other human traits, such as: sperm count, aggression, musical skill, sexual orientation and athletic ability. The ratio has also been studied in relation to health problems including: autism, depression, heart attack and breast cancer.