Your destiny just might be in your digits.
Measure your fingers from the crease they make with the palm to the top of the digits — if the index finger is shorter than the ring finger, you might just have a higher chance of becoming an alcoholic.
German researchers recently studied 131 patients detoxing from alcohol addiction and compared their hands to those of 185 “healthy volunteers.” The ratio between the length of the index and ring fingers “was lower in the [alcohol addicted] patients,” according to Johannes Kornhuber, director of the psychiatry clinic at the University of Erlangen-Nurmberg.
“We found both a lower digit ratio in alcohol-dependent women compared to healthy women, and a lower digit ratio in alcohol-dependent men compared to healthy men.”
Simply by studying someone’s hand, Kornhuber says, science can identify people who are at risk, or could benefit from preventative measures: “It’s astonishing.”
Kornhuber’s addiction study is just the latest research in the growing study of finger length and “digit ratio” — the depth of difference in length between a subject’s index and ring fingers. For about 10 years, biologists, psychologists and economists have linked digit ratio to promiscuous sexual proclivities, heart disease, ADHD, eating disorders, sports ability, musical genius, autism, sexual orientation, fertility, penile length — even the success of high-frequence financial traders.
Finger lengths are fixed at birth and are determined by the amount of prenatal testosterone a fetus receives in the womb. Exposure to higher levels of testosterone in utero — the hormone surges between the ninth and the 18th week of gestation in the womb — result in stubbier index fingers that are shorter than ring fingers.
Men tend to have ring fingers that are longer than their index fingers, while women generally have index and ring fingers of the same length. The differences in digit ratios between races, however, is large. Caucasians, for example, generally have a higher ratio between their index and ring fingers — i.e., a bigger difference in length — and blacks and Asians have a lower ratio. It’s unclear why.
But because brain development is affected by the same prenatal exposure to sex hormones that determine finger length, scientists are parsing the hand to try and explain more opaque developments in the brain.
And researchers at the University of Texas Health Science Center at San Antonio, have manipulated the pre-natal testosterone levels in baboons to learn more about how these steroids affect neurology.
Anthropologists have been aware of “fingerology,” or the study of finger lengths, for over a hundred years. It has long been accepted science that the disparity in length between fingers is accentuated in the right hand versus the left.
But it wasn’t until the late 1990s that biologists started employing the second-to-fourth finger ratio — referred to as the 2D:4D ratio — as a way to predict a person’s future behavior and health.
The field has exploded over the past few years, with researchers across the globe trying to add to the growing list of behaviors correlated with finger length.
If their findings are true, a visit to the physician or the shrink might be as simple as faxing over a Xerox of your palm.
Women with high digit ratios — index and ring fingers that are the same length — are said to be more fertile and carry a higher risk of breast cancer, according to numerous studies.
Studies even suggest a correlation between prenatal hormones and future food hang-ups. Anorexic and bulimic women have significantly lower digit ratios — much shorter index than ring fingers — than their healthier counterparts.
Researchers at Berkeley have found lower digit ratios among homosexual women, positing that these women were exposed to higher levels of testosterone in the womb.
For men, differences in digit ratios between gay and straight men were strongest among whites, according to an experiment commissioned by the BBC.
In men, however, a ring finger that towers over the index is considered a sign of high fertility, according to the studies.
Among men who suffered heart attacks in their 30s and 40s, a larger number were shown to have high digit ratios.
More masculine digit ratios, i.e., a shorter index finger in both men and women, have been correlated with Attention Deficit Hyperactive Disorder, or ADHD.
The masculine digit ratio has also been correlated with people who are more aggressive, have higher musical aptitude and are better at sports — in particular, football.
In recent years, even economists have even entered the field.
“A low digit ratio makes you more likely to take calculated risks,” says Aldo Rustichini, an economist at the University of Minnesota, who used digit ratio to accurately predict how long traders would survive in the business.
Traders with a lower digit ratio made, on average, six times more in profits than their colleagues who were doing the same job and analyzing the same data.
“This is a very simple measure of your personality,” Rustichini says. “It’s revealing.”
Korean scientists, publishing their findings in the Asian Journal of Andrology, have even found digit ratio to be a predictor of adult penile length.
The researchers studied 144 Korean men, ages 20 and up. One researcher measured the lengths of their fingers, while another researcher measured their flaccid and “stretched” penile lengths while the test group were under anesthesia.
The findings, published last month, concluded there was a strong correlation and that “digit ratio can predict adult penile size and that the effects of prenatal testosterone may, in part, explain the differences in adult penile length.”
But boiling down a person’s behavior and physiognomy to the length of his index finger, not surprisingly, has attracted its share of skeptics.
“It’s possible that androgens [i.e., testosterone] affect digit length,” NYU biologist Claude Desplan says. “But, for sure, our brain is much more than just how much androgens we got during gestation.”
Other critics said studying fingers for clues about personality is nothing but a gimmick.
“In my mind, digit length would neither be the most direct nor accurate way to figure out something about a person,” said Clifford Tabin, chairman of the genetics department at Harvard Medical School. “While we can speculate about what [this] means for behavioral imprinting, there’s no hard evidence of it having a definable effect.”
For now, digit ratio has remained a sideshow to Ivy League researchers, with the bulk of studies taking place abroad. It’s been ignored by prominent science journals such as Nature and the Journal of the American Medical Association (JAMA).
But the growing body of research has many contemplating the implications of wearing your medical history and personality on your hand.
Would you list your digit ratio on a resume, or an online dating site? Would it be unethical for potential employers to take a long, hard look at your hand when greeting you for a job interview?
“It’s like not trying to measure IQ,” says Rustichini, who conducted the study on traders. “If we think we are interested in putting the right people in the right job, it’s a bad idea not to look at this information.”
But Tabin says that “there’s a difference between finding something statistically significant, and looking at a particular person and predicting something based on finger length. In terms of saying, ‘look at these fingers, [this guy] is going to have a heart attack,’ you don’t know the entire genetic background . . . I find the work to be in the marginally significant, over-interpreted category. Others may feel differently.”
Nora Charles, a post-doc fellow in the psychiatry department at the University of Texas Health Science Center, who has studied digit ratio and its association with women’s interest in uncommitted “riskier” sexual relationships, defends the study.
“It’s a newer tool that’s on the market and there’s a lot of debate in the field,” says Charles. “A lot of scientists think it’s useful and some are still skeptical, but that’s just the nature of science.”
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akarni@nypost.com