So…virility.
Males, in particlar, seem to have a need for competition, and have a desire to want to be better than their peers. This is, of course, regardless of whether the given comparison requires any skill on their part, or even they have any control over said comparison. Nowhere this seems more silly than in worrying about penis length.
A couple of guys working in an English hospital teamed up to combine the results of 50 years of penis length studies. You can read the whole article here, but here are the points most salient:
- 85 per cent of women were satisfied with their partner’s penile size, but only 55 per cent of men were satisfied.
- Two studies reported that 90 per cent of women prefer a wide penis to a long one. Other studies pointed out that the issue of male attractiveness was complex, but that penile size was not the most important factor for women.
So the apparently more relevant measurement (width) goes mostly ignored–and there have probably been far fewer studies on that.
Or the more important point that it probably doesn’t matter so much, and it’s a lot of other stuff that guys need to be worrying about.