If you want to know how attractive a guy is, all you have to do is look down … at his hands.
According to a recent study conducted by British Royal Society's journal Biological Sciences, published on April 19, the ratio between the length of a man’s right index and ring fingers is linked to his facial attractiveness.
Ok…so what is ‘the ratio’? It is also called the 2D:4D since it compares the length of the second digit with the fourth digit, makes sense since that ratio is driven by the sex hormone testosterone, the researchers say.
To make it simple: "What we found was that 2D:4D ratio can predict face attractiveness. The more masculine the 2D:4D is, the more attractive is the face," said study researcher Camille Ferdenzi at the University of Geneva in Switzerland. "The amount of sex hormones you are exposed to before birth contributes to how your face develops and how attractive it becomes." Past research has shown that females find caveman-like masculine faces more attractive.
Oddly enough, this is because of the amount of testosterone that a fetus is exposed to in the end of the first trimester, when the testes start to develop. The more testosterone, the higher this 2D:4D ratio is, and also, the higher-quality sperm the male produces. This is different from other sexual and masculine traits, such as voice frequency and body odor, which are regulated by levels of adult testosterone.
"There are lots of things that are regulated by testosterone during puberty and in adults," said John Manning, a researcher from Swansea University in Wales who wasn't involved in the study.
The more testosterone the fetus is exposed to, the longer its right ring finger grows (yes, just this one finger). Apparently, the index finger is more sensitive to fetal estrogen levels. If these two fingers are of the same length (measured from the bottom crease), the 2D:4D ratio is 1; if the ring finger is longer, the ratio is lower than 1. So the longer the ring finger is than the index, the higher the level of fetal testosterone is — and, eventually, a hotter guy! (facially)
While the experiments required to definitively prove this correlation (sampling testosterone during pregnancy, or treating some fetuses with testosterone and measuring finger length) would be unethical, many researchers believe in the connection. Tests in rats show that increased testosterone causes higher 2D:4D ratios, and some human hormonal diseases show differences in this ratio.
To see how this is related to attractiveness, Ferdenzi had 49 female college students judge body-odor-soaked pads taken from the armpits of men (yuck!), voice clips and face-only pictures of 49 male college students. They then compared these results with precise measurements of the guys' 2D:4D ratios and saw a connection between facial attractiveness and higher 2D:4D ratios.
"The study's main conclusion is sound, the relationship between digit ratio and perception of attractiveness fits in with what we already know," said Manning, who in his own research last year found a connection between the 2D:4D ratio and the talent for playing rugby football. "I think it's an excellent paper." (Me too!)
Health Matters too
Last year British researchers reported new confirmative findings for a link between index finger length (relative to ring finger length) and the risk of developing prostate cancer. Men featured with a longer index finger than ring finger, appear to have a 33% higher chance for NOT developing prostate cancer.
A Woman’s Finger Length Says:
Finger length may be an indication of sexual orientation too, a controversial study has shown. Scientists from California found that lesbian women have a greater difference in length between their ring finger and index finger than straight women do. The same pattern was also found for homosexual men - but only when the researchers looked at those males that had several older brothers.
In women, the ring finger and index finger tend to be about the same length. What the study showed was that lesbian women also tended to have the more "masculine" arrangement - that is, they had shorter index fingers.
A Man’s Finger Length Says:
The ratio of finger sizes in men was more complicated. In men, however, the index finger is usually the shorter of the two digits. Comparisons between all men showed no differences. Only gay men with several older brothers had an unusually "masculine" finger ratio - in other words, they had significantly shorter index fingers.
Having a large number of older brothers had previously been established as a factor predisposing men to homosexuality, and like finger length reflects prenatal androgen exposure.
Homosexual men without older brothers had finger length ratios indistinguishable from heterosexual men, indicating that factors other than hormones - such as genetic influences - also contribute to sexual orientation.
"The results in men are more complicated but also more interesting," Dr Marc Breedlove, one of the researchers, told the BBC. This is because they suggest younger brothers are being exposed to higher levels of androgen in the womb than their elders.
What Makes The Finger Grow?
"We think it is inescapable that the mother's body is remembering how many sons she has carried before, and somehow she is then increasing the amount of androgen that each subsequent son sees before birth. So the fascinating questions are: where is the memory being stored in the mother's body and what is she doing to change amount of androgen that each subsequent son sees."
The Berkeley study has been published in Nature. Scientists in the UK have given it a cautious reception. They say far more work is required to back up some of the ideas contained in the research.
"I think this is a possibility," said Dr Richard Sharpe, of the human reproductive science unit at Edinburgh University. "But no-one has actually measured the levels of androgens in fetuses or the womb - you can imagine it is difficult to do - so this is all speculation. It may be informed speculation, but I think when we get on to a subject as touchy as sexual orientation we need to clearly define what is speculation and what is fact."
So, now all I have to do is look at the hands of a man to see how attractive he is and whether he would be into women? Great! That’s much more convenient and saves a whole lot of time. Couldn't thank you researchers enough!