As explained in previous posts, sexual selection is constant in all living things, and is defined as the drive to preserve qualities predicted to be advantageous in the face of future, unknown selection pressures. Although the obvious method of carrying out the selection is mating, as seen predominantly in species which go through complex courtship behaviour displays, in humans this has ceased to be the case.
Today I saw a guy at college wearing a black t-shirt with bold letters saying I MAKE GOOD BABIES. Is that to say he wants lots of kids and is advertising his availability? Probably not. Then what is the point of wearing that t-shirt? Well, he's advertising his sense of humour, and perhaps cynicism at the idea that humans are all looking for babies.
Two main reasons have led to the difference in sexual selection between humans and other animals. For the purpose of calling humans more intelligent than other species, we will define intelligence as the ability to modify the natural environment, and create an artificial environment. The two reasons are:
- the just mentioned increased intelligence
- the artificial environment which results from it.
Consider the amount of dedication and work needed to create works of art, build up cities, and find cures for diseases. The energy spent doing those things has been of better use in the long run than if it had been spent solely bringing up children into a less developed world. Compared to other species, humans now reproduce for the purpose of life itself, rather than as a method of applying sexual selection.
Human intelligence has shifted the drive of sexual selection towards the creation of artificial environments and the propagation of the resulting knowledge, by using the same principles as sexual selection in other species: the selection of properties thought to survive future selection pressures.
That is why, to the puzzle of evolutionary psychologists, humans do not exhibit the expected behaviour in sexual selection. If they truly did, then all of us would be indeed very attractive, and perhaps there would be increased sexual dimorphism (i.e. peacocks are a lot more physically different than peahens). The fact this isn't the case is a clue that indeed, sexual selection itself has been made artificial in humans in some instances. For example, the world of the Internet is not just an expression of intelligence, but a battleground for several sexual selection pressures: "like" buttons on facebook, "follow"s on Twitter, comment activity on forums, website competition, photo ratings, etc.
If you've ever wondered why facebook doesn't have a "dislike" button, find out in the next post on Positive, Negative and Neutral Sexual Selection.