What Does Science Say About the Relationship between Finger Size and Penis Length?
And the media has done it again. Everybody's and their mother is picking up an LA Times story about a Korean study that "found" a correlation between penis size and the ratio of a man's 2nd and 4th finger. As far as I can tell the reporting is based on a press release of some kind. For one thing, the study was published in the Asian Journal of Andrology and well, I doubt many andrologists have even heard of that journal, let alone LA Times reporters. For another, nobody who'd read this paper and knows the tiniest bit about statistics would swallow its claims so easily (I'm pretty sure neither the authors nor the editors of this journal know shit about statistics).
The study in question looked at the lengths of the 2nd and 4th fingers (right hand only) and penis of 144 men who were hospitalized for urological surgery. The fingers were measured before surgery, while the patients were awake, but the penis measurements were done after they had been put under for their surgeries (and yes, consent was given beforehand). The length of the penis was measured while both flaccid and stretched to its fullest length. The stretching is meant to approximate erect length, since, consent or no it would be kinda creepy for the scientists to try and get a guy hard after he'd been put under for surgery. The patients were selected so that the surgery they were undergoing had nothing to do with any condition or previous surgeries that might have an effect on penis size.
The idea that penis size might be related to relative finger lengths comes from previous studies on finger length and exposure to testosterone in the womb. These studies suggest that the ratio between the 2nd and 4th finger (that'd be the length of 2 divided by the length of 4, just to be clear) is negatively correlated with the ratio of testosterone to estradiol. This is presumably because the same set of Hox genes control both finger and genital development in humans (Hox genes being genes that control morphology of a developing orgamism). These studies, or at least the ones I've seen, tend to have very small samples and I think it's going a bit far to say that the relationship is established, as this paper and most news reports are assuming.
This new study on penis length finds a weak negative correlation between penis length and finger ratio. And when I say weak I mean weak. So weak that I'd say that it can't really be said to exist at all given the number of subjects. The study is available free here. Go take a look at the plot of penis length to finger ratio and tell me if you think the line the researchers fit to their data to establish the correlation looks truly representative of the data. The data points look like a random distribution to the naked eye, and I don't have much faith in the statistics the authors use to establish correlation. For one thing, their R value for that fit is -0.216. For those not versed in statistics, the R value is a measure of "goodness of fit." It's a number between -1 and 1, with 0 being complete failure and 1/-1 being a perfect fit. Usually values in the .8-.9 range are considered a decent fit, but 0.2? That's little better than noise. Even if they had a few thousand data points instead of just 144, I'd have trouble believing that the fit represents any correlation and not just inadequate sampling. Sorry news media, this conclusion is bullshit: you still can't tell anything about the size of a man's penis by looking at his hands.
And of course, there's the question of why anyone cares. Establishing a relationship between testosterone and fetal development might be interesting, but otherwise it's sort of the same case as with the studies on vaginal orgasms. Studies that attempt to establish some relationship to penis size seem to take it for granted that there is something important about the length of a man's penis, as if it's proof of his virility or manhood. Which is a dumb ass assumption. Is it important for some people? Sure, we've all got our preferences. But should we be constantly looking for ways to determine at a glance if a guy is well hung (assuming that said glance is not directed at his erect member)? No. What's the point, really? Penis size is a deal breaker for very few women (and I assume homosexual men). Most of us care so much more about whether a guy knows what to do with his member than whether it's porno worthy. And if size really does matter to you there is one surefire way to find out: Look at his penis.
Dr. Pisaster has a doctorate in biophysics, not actually anything sexy. She does however enjoy having sex, reading about sex, and talking about sex. Especially when she's had a little whiskey.