The Mate Selection Trapdoor
The evolution of sexual beauty is an ongoing experiment in every species, including our own. Variation in courtship traits arise and are judged by choosers who quickly relegate most of them to the dustbin of history. But new attempts at beauty that pass muster, that trigger a hidden preference, hit the evolutionary jackpot.
Hidden preferences are often lurking in animals’ sexual aesthetics, masked to others because there are yet no sexual traits to elicit them. But if that trait evolves, one that matches or exploits a particular sexual aesthetic, then it is immediately deemed to be sexually beautiful, and, all else being equal, it should soon evolve to be common among males. This notion of how sexual beauty can evolve was virtually unknown before 1990 until a few other researchers and I developed this theory. Now it is thought to be one of the major factors driving the evolution of sexual beauty.
To appreciate the evolutionary importance of hidden preferences, it pays to realize there are no free lunches in the sexual marketplace. Regardless of how traits and preferences evolve, they incur costs as well as reap benefits. It is the cost-benefit ratio, and how this changes through
