Beautiful minds? you're thinking. But that's a pair of... feet. Yes, and those are confident feet, many would say. (I'll tie this together in a moment.)
I'm thinking back to the movie "A Beautiful Mind" which I saw nearly a decade ago. That woman... oh, she had that nebulous thing. The way she blazed into his office -- the fictionalized John Nash's -- when he was an up and coming professor. At first, I didn't like that woman; she seemed shallow. But, oh, did I like her as the movie progressed. I talked on and on about her that evening: the woman who dug both feet into ground when things went crazy.
Is there a biological reason for people for people to be attracted to confidence? I daresay there is. What about associating that blaze with standing one's ground? Ah, perhaps there is. The problem is that a lot of the things on the it list -- the erotic capital list -- have as much to do with polytropism as they do with confidence.