To the right, there I am in all my digit ratio glory. You can’t see it clearly but the ring finger is pretty close to the same length as the middle finger (slightly shorter) and quite a bit longer than the index/pointing finger. By the way, my wife and daughter also have longer ring fingers, albeit to varying degree.

Hmm . . . let’s see, as a guy, what the fickle fingers of fate say about me . . .  I have an extremely high sex drive, am fairly competitive, often find my rational mind flipping out the window when presented with sexual cues from those of the feminine persuasion, tend to be more aggressive and assertive than others, tend to have a higher musical and natural sports ability despite a grand lifelong push to sublimate that into PS2 and X-Box performance rather than actual physical work, have a quite a bit longer and larger than average penis, am more fertile than most men, am considered to be more sexually attrative by more women than not and those women to to find it easier to be comfortable with me, would tend to have a higher potential for lifelong reproductive success, am a social person who works well with others, am spiritual, happy, gentle, have a highly developed sense of humor, am more open-minded and friendly towards gays and bisexuals than the bulk of men, am very highly intelligent, am a natural guru, mentor, and extremely passionate and incredibly gifted lover, am cooperative and cummunicative, am a cuddler, and I am basically the cat’s pajamas.  Hmm . . . that’s a lot of information from a of couple fingers on the right hand but I’ll go along with it . .  most of that is dead on accurate so the bits I’m not sure about just may also be on the clever side of right and just maybe also must be true too.

In a recent post, I discussed a very recent study on how sex cues affect men’s decision making and noted that while the study found men in general to be susceptible to influence when presented with sexual cues (particularly from an attractive female), that the study also found that men with higher natural testosterone levels tended to be particularly susceptible to the effect.  Ask my wife and she will tell you that pretty much fits me too.

One thing that I found particularly interesting was that the researchers measured testosterone levels by comparing the length of two fingers on the right hand – the ring finger and the index finger – finding that those whose ring fingers measure longer than their index fingers are higher testosterone types. This was all news to me as I had previously never come across that little tidbit and it seems like it might be a bit far-fetched like the idea that finger length might correlate to penis size . . . well, it turns out that it’s the real deal and is in fact true (oh, and the penis thing evidently has some correlation too in that some studies have indeed found that men whose ring fingers are longer than their index fingers often, but not always do indeed have larger penises, albeit don’t go looking at fingers knowingly just yet).

For the most part, men tend to have longer ring fingers and women tend to have longer index fingers. The length of the ring finger is indicative of how much testosterone the fetus was bathed in within the womb. This early exposure to testosterone affects biological physical, emotional, behavioral, and personality characteristics in folks. Interestingly, the ratio itself tends to be related to race and culture to some degree.

In fact, there are a whole slew of interesting things one can see correlated with the 2D-4D finger ratios. The book Digit Ratio: A Pointer to Fertility, Behavior and Health by John T. Manning covers a number of the studies with data that is absolutely fascinating stuff (buy the book here).

Could the length of your fingers indicate a predisposition to breast cancer? Or musical genius? Or homosexuality? In Digit Ratio, John T. Manning posits that relative lengths of the second and fourth digits in humans (2D:4D ratio) does provide such a window into hormone- and sex-related traits. It has been known for more than a century that men and women tend to differ in the relative lengths of their index (2D) and ring (4D) fingers, which upon casual observation seem fairly symmetrical. Men on average have fourth digits longer than their second digits, while women typically have the opposite. Digit ratios are unique in that they are fixed before birth, while other sexually dimorphic variables are fixed after puberty, and the same genes that control for finger length also control the development of the sex organs. The 2D:4D ratio is the only prenatal sexually dimorphic trait that measurably explains conditions linking testosterone, estrogen, and human development; the study of the ratio broadens our view of human ability, talent, behavior, disposition, health, and fertility. In this book, Manning presents evidence for how 2D:4D correlates with traits ranging from sperm counts, family size, musical genius, and sporting prowess, to autism, depression, homosexuality, heart attacks, and breast cancer, traits that are all linked with early exposure to sex hormones.

Be sure to read the reviews on the Amazon page for the book. You might also enjoy the comprehensive review here by Michael Mills who summarizes part of the work as follows:

Manning links the proximate causes of digit ratio sexual dimorphism to the effects of sex hormones during early fetal development. He believes the evidence is persuasive, but not yet definitive, that higher levels of testosterone during this critical developmental stage facilitates the growth of the ring finger, while higher levels of estrogen facilitates the growth of the index finger. He states: “In general, it seems that 2D:4D is the most reliable of the predictors of hypermasculinization…” (p. 139). One of the consequences of hypermasculinization, as reflected by the digit ratio, may be higher levels of fertility in men and lower levels of fertility in women. He also suggests that hypermasculinization increases the likelihood of homosexuality or bisexuality, in both males and females. Manning devotes separate chapters to explore the relationship between digit ratio and a variety of characteristics, including assertiveness and attractiveness (chapter 3), reproductive success (chapter 4), hand preference, verbal fluency, autism, and depression (chapter 5), health and disease (chapter 6), homosexuality (chapter 7), musical aptitude (chapter 8) and sports aptitude (chapter 9). A brief summary Manning’s findings (some of which he notes are quite preliminary) is presented below

Some Characteristics That May Be Associated with Digit Ratio (from Manning, 2002)
Males/Females	Low 2D:4D ratio Longer Ring Finger	High 2D:4D ratio Shorter Ring Finger
Males	More fertile Higher lifetime reproductive success More aggressive and assertive Greater proclivity toward homosexuality/bisexuality Higher musical and sports aptitude Lower SES (?)	Higher risk of early heart disease
Females	Greater proclivity toward homosexuality/bisexuality More aggressive and assertive	More fertile Higher lifetime reproductive success Higher risk of breast cancer

If you google digit ratio, you will find a slew of works related to this interesting phenomenon of the ring-index finger ratio and you will find quite a few characteristics that seem to be linked to it. For instance, there is some indication that the ring finger length at a ratio to body length can correlate with physical aggressiveness in men and does bear out when measuring the ol’ ratio of men in prison for violent crimes (those with higher levels of testosterone with other factors may be more prone to physical aggressiveness). Duh.

Of course, I can bear out that my own sex drive seems to correlate to the ol’ ringer deal . . . as well as my own tendancy to be distracted by sexual cues . . . go figure. Then again, I am a guy so all that used to go without saying as it was an assumed given. Of course, now we have data to confirm and explain it as well as the exceptions that make the rule.

Here are some other references worth the looksee (many of these are variations of one another but there is a wide enough sampling to show you there’s a lot of stuff going on with this thing):

• Science Update’s Finger Length Unit (audio, transcript, and questions)
• Digit Ratio (Wikipedia entry)
• Finger Length Ratio Papers
• Hormone Facts (with explanation of why index finger length may relate to penis length)
• Sexuality: Your Telltale Fingertips Psychology Today reference piece)
• Women and Parking (testosterone levels seem to be related to spatial thinking so women with longer ring fingers tend to drive and park better lending new meaning to the whole "woman driver" stereotype)
• Testosterone and Finger Length
• Finger Length and Aggression
• Finger Length Predicts Agression in Men
• Index And Ring Finger Lengths Partially Predict Violent Tend
• Finger length predicts physically aggressive personalities, study shows
• Can Finger Length Predict Who is Aggressive? (yes, no, and maybe)
• Still More on Aggression and Finger Length
• Boing Boing on Finger Length and Agression
• Finger Length Ratios and Sexual Orientation
• Hidden Significance of a Man’s Ring Finger (the connection of longer ring fingers to adult depression)
• More on Sexual Orientation and Depression
• Academics find that Finger of Destiny Points Their Way (longer index finger in men correlates to better ability in science)
• Another entry of the above
• More on Academics and Finger Ratios
• What the Length of Your Fingers Says About You (so, women should actually make better scientists than men but culturally it’s been a male dominated profession – the lower number of kids for male scientists may correlate to fertility which would be higher for higher testosterone guys)
• Let Your Fingers do the Sobbing

And . . . a whole lot more.

So . . . now that you know . . . next time you meet someone new, you might just find yourself taking a glance at the fingers of the right hand and then giving them a knowing grin . . . or . . . not as while this stuff is certainly fascinating it is not an accurate predictor of any one individual. We can make generalities about large groups but that still doesn’t mean any single individual fits the generalization.

Of course, if you comment or link to this post . . . do be sure to include an image of your own right hand so we can see how your fickle fingers of fate measure up.

All the best,
Brian

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Brian David Phillips, PhD, CH [phillips@nccu.edu.tw]Certified Hypnotherapist
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