I think it may be because humans have a higher intelligence than other animals. This makes it possible for men to display genetic fitness in other ways than loo

I think it may be because humans have a higher intelligence than other animals. This makes it possible for men to display genetic fitness in other ways than looks. For women, in constrast, the most important thing to signal is their capability of carrying a baby to term, and the primary way they do that is through physical traits. Though with plastic surgery and cosmetics subverting the signal on the one hand, and with better medical science capable of saving mother and child from many issues on the other, it is becoming less relevant. Edit: Though keep in mind that this is my speculation, and furthermore a broad strokes picture and there is huge individual variation.