The University of Florida reports this research news: Male-female ring finger proportions tied to sex hormones in embryo; may offer health insights. Here are some excerpts, with bold font added by us:
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.
Writing this week in the Proceedings of the National Academy of Sciences, 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, 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.
Here’s a link to their paper: Developmental basis of sexually dimorphic digit ratios. The abstract says:
Here we report that the 2D:4D ratio [2nd digit (index finger) to 4th digit (ring finger) ratio] in mice is controlled by the balance of androgen to estrogen signaling during a narrow window of digit development. … Our results also suggest that the 2D:4D ratio can serve as an indicator of disrupted endocrine signaling during early development, which may aid in the identification of fetal origins of adult diseases.
Back to the university’s news article:
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.
Are you looking at your digits, dear reader? Is your ring finger longer than your index finger? Are you suddenly stuffing your hands in your pockets so no one will see them? That’s understandable. We continue:
“The discovery that growth of the developing digits is controlled directly by androgen and estrogen receptor activity confirms that finger proportions are a lifelong signature of our early hormonal milieu,” Cohn said. “In addition to understanding the basis of one of the more bizarre differences between the sexes, it’s exciting to think that our fingers can tell us something about the signals that we were exposed to during a short period of our time in the womb”
Here’s what you need to know:
Essentially, more androgen equated to a proportionally longer fourth digit. More estrogen resulted in a feminized appearance. The study uncovered how these hormonal signals govern the rate at which skeletal precursor cells divide, and showed that different finger bones have different levels of sensitivity to androgen and estrogen.
Since Roman times, people have associated the hand’s fourth digit with the wearing of rings. In many cultures, a proportionally longer ring finger in men has been taken as a sign of fertility.
Well, gentlemen, what does your ring finger say about you? Moving along:
In dozens of papers and two books, including the seminal “Digit Ratio” in 2002, Manning [John T. Manning, a professor at Swansea University in the United Kingdom] has studied the meaning of the relative lengths of second and fourth digits in humans, known to scientists as the 2D:4D ratio.
“When Zheng and Cohn blocked testosterone receptors, they got a female digit ratio,” Manning said. “When they added testosterone they got super male ratios, and when they added estrogen, super female ratios. And they’ve provided us with a list of 19 genes that are sensitive to prenatal testosterone and prenatal estrogen.
The press is already starting to jump on this. In the Daily Mail of London we read Passionate? Check his ring finger as it could be linked to his libido, which says:
When it comes to finding a mate, it seems size does matter – the size of the ring finger, that is. The length of a man’s fourth finger has been linked to his libido. … The more testosterone – the male sex hormone – a baby is exposed to, the longer his ring finger is likely to be.
So there you are. Whatcha gonna do if your fingers don’t measure up — wear gloves?
Copyright © 2011. The Sensuous Curmudgeon. All rights reserved.