Sigh. The penis story is now 5 days old, and I'm only just now getting to it. Sci is sad and behind the times, but that's because I don't get the awesome press releases that so many journalists are heir to. The joys of academia, I'm the last to hear about the penis study!
The coverage was so...BIG...that Knight Science Journalism Tracker has a whole pile of links. Science News, NBC (complete with the quote of the day "The human male possesses the Italian designer faucet of penises"), National Geographic. Gawker.
So after all this coverage, I went eagerly to read the paper. I mean, this must be a big deal, right?
But really...I'm not sure why all the penis coverage. I admit it's tough to give up a penis in PNAS joke, but I'm not sure what makes this study...so meaty, shall we say. I think what they did is fine and well controlled, met all the standards of scientific rigidity, but I'm not sure they...went all the way. The conclusions were, well, kind of expected, and a little limp.
You see where I'm going here.
Mautz et al. "Penis size interacts with body shape and height to inﬂuence male attractiveness" PNAS, 2013.
I think we've all heard that "it's not the size that counts, it's how you use it!". And we all ALSO heard that "no really, it's the size that counts". But is it?
Male penises are out there. They are loud, they are proud. Rather than the retractable penises of some other species (poor ducks have to hide their light under a bushel, due to sheer physiological impossibility otherwise), the human male's penis stands out.
Really, the authors say it better than I can:
The upright body posture and protruding, nonretractable genitalia of male humans make the penis particularly conspicuous, even when ﬂaccid. This observation has generated suggestions by evolutionary biologists that the comparatively large human penis evolved under premating sexual selection (19, 20).
(Let us all pause a moment, and dream of how neat and wacky it would be if humans had retractable penises...)
So the question is: do women think bigger is better? And is this a result of sexual selection?
After all, there was a time before clothing. A time when all went proud and free (or possibly shivering and free, depending on conditions). And during that time, with those stand-out penises...well you're going to get judged. So DID women judge? What there sexual selection? And does this mean that men were the first to invent clothing out of sheer self-defense?!
Obviously other studies have asked women about their penis preference. Some say longer. Some say wider. Some say size doesn't matter. And at least some of these people are lying. After all, while there's a lot of social pressure for men to be packin', there is just as much social pressure for women to say "oh honey, you know I don't care about THAT!" And when you have a questionnaire...well it's hard not to be generous. Or less generous, depending on your mood.
And how do you STUDY the role of penis size in attractiveness? Previous studies just took one drawing of a guy, and changed his penis size. While that might isolate the penis itself, it doesn't really give you a picture of how the penis stands (so to speak) among other bodily traits, like shoulder-to-hip ratio (broad shoulders and narrow waist = more attractive) and height (tall = more attractive).
So the authors of this study made computer generated images, where height, shoulder-to-hip ratio, and flaccid penis length all varied, based on a wide sample of men. They had a group of 105 women look at the figures (there were 343 in all, so they had all possible combinations of penis size, height, and shoulder-to-hip ratio), and had the women rate the attractiveness of the figures. They also looked at how long the women's eyes lingered on the images. Just in case.
And DID it show that bigger is always better? Well...yes, but the BIGGEST effect was actually in shoulder to hip ratio. Men with shoulders that fill doorways and small hips were the most attractive, and this body shape was the MOST IMPORTANT variable in determining attractiveness. Not penis size. Body shape.
Penis size came up short (heh), in second place, roughly tied with height. In fact, it scored a little BELOW height in the linear selection gradient. The Shoulder-to-hip ratio linear selection gradient was 1.020, while the penis size was 0.249 and height was 0.269. So while yes, size does matter, it doesn't appear to matter as much as other determinants of attractiveness. Worried men, you can relax. As long as you're tall, and have broad shoulders and a narrow waist. Or clothing. Clothing works, too.
And really, it doesn't even seem like it's the size that counts, it's
how you use it the proportionality. The penis has to look proportional or better. If a super tall guy has an average penis, it doesn't look proportional, the bigger penis is needed just to look the right size all over. The size is important in relation to the other traits. And for taller men, the larger penis served them better than for shorter men. Size can only make up for so much, apparently.
Interestingly, this study actually had a lot more to it than penis size (not that the media reported on any of it). It looked at how the WOMEN related to the men they picked as attractive. Taller women? They rated taller men as more attractive (there's a lot of pressure there, no matter what novels you read, the lady is always supposed to look up at the man becomingly through her lashes, and this becomes increasingly hard to do as the poor damsel approaches 6 feet). Heavier women showed a larger effect of penis size on attractiveness rating (does that mean anything?). There was no effect of menstrual phase (though the authors note that they didn't actually check the fertility phases) or of the pill (which is interesting in itself).
The authors also found that the relationship between penis size and attractiveness is non-linear.
You can see here the attractiveness ratings (controlled for height and shoulder-to-hip ratio, so just based on the peen) as a function of size. At first ratings go up quickly, but after about 7.6 cm (3 inches, keep in mind these penii were all flaccid), the slope decreases. Though I'll note they never reached the peak. I'd be interested to see whether the attractiveness forms an inverted U shape when you get above, say, 17cm. I mean, if it practically IS a third leg, how attractive is that really?
The conclusion is that...size matters. Size matters, in fact, about as much (thought slightly less than) height. But what really matters? Shoulder-to-hip ratio. But I guess "Shoulder-to-hip ratio counts most!" Doesn't make NEARLY as good of a headline.
And WHY does size matter? Well obviously they didn't investigate that, but they hypothesize that larger penises may lead to better vaginal orgasm and that's totally why the ladies like 'em large. I'm pretty skeptical of this, considering that a relatively small percentage of women have HAD vaginal orgasms. I'd be more likely to hypothesize that a larger member might go along with a larger everything else. Larger penis? It's a good bet he's tall. Tall? It's a good bet he's healthy. So if there is sexual selection going on here (which this study can't conclusively claim, it can only show that size matters in attractiveness), it could well be for the other traits first, and the penis is merely another indicator.
But there are two issues I have with this study: First, the population. All the viewers were heterosexual women (yeah, ok), and they were all Australian. I've never heard anything that speaks particularly to Australian opinions on penis size, but this is a Western culture we're dealing with, where we are told since middle school that bigger is better. So I'd be very interested to see how much of this is a cultural phenomenon. After all:
...novels, magazines, and popular articles often allude to the existence of a relationship between penis size and sexual attractiveness or masculinity (21, 22). Many cultures have fashion items, like penis sheaths and codpieces, that draw attention toward male genitalia.
There is a very large culture around the penis, is what they're saying. Some may be biology, yes, but how much is penis size...magnified...by culture?
The second issue I have is...well the study didn't go all the way, as it were. The women only rates the attractiveness of FLACCID members. Not erect ones. Presumably, if, as the authors argue, females can see the male's...morphology...all the time, they'd see it in various states of arousal. Wood happens, you know? And there is, of course, the phenomenon of "showers" vs "growers". The concept is that some men "grow" during an erection while the flaccid penis is unimpressive, while others "show" with an eye-popping flaccid penis that then doesn't inflate as much. I actually don't know if this phenomenon exists, or if it is merely hearsay (SOMEONE needs to study this. It's not THAT hard...oh wait...I guess in some respects it's hard...), but if it does exist, it would be an interesting question: what about the size of the erect penis? How does that rate in terms of attractiveness (once you get over the inevitable giggles involved in looking at hardons in silhouette)?
And in the end...did this study really blow us out of the water with new information? Penis size matters...but only in the sense that the overall package matters, and overall, the shoulder-to-hip ratio matters a whole lot more. A man's attractiveness is more than his penis, but hey, a good penis can help. Stop the presses!
Now, I'm not saying the study is bad! It's fine! It's well controlled! I really love that they pulled in the shoulder-to-hip ratio instead of just studying penis size, I think it gives a much better picture. But you know, I feel like it didn't go all the way to answer the question. I felt like the study could have been more substantial, had more girth...I could go on.
So really, I can only conclude that the reason this study got so much coverage is because...well it was about penis size. And size matters! Really, who needs another reason? I can't fault them, I never do!