Boldly Go!

Reproduction is the means that enables evolution. Because of this, what is considered sexy often has as large an effect on how a species evolves as the characteristics that help survival. In humans surviving nature has become easier than ever, this means that sexual preference is driving evolution to a greater degree than in the past.

There are many examples of sexual preference trumping survival fitness. A classic example of this is the peacock. Males have large brightly colored feathers, while females are colored to match their landscape and have small feathers that stay close to their body. Male peacock feathers are a disadvantage in terms of survival, but this trait is selected for because it increases the chances of the male reproducing.

Large female breasts are an example of this in humans. It’s a common misconception that large breasts are for giving babies lots of milk. Chimpanzees, gorillas and other apes are able to feed their children with very small breasts. The truth is that human female breasts are almost entirely fat, with a relatively low percentage of mammary tissue. If large breasts aren’t advantageous to survival, why do women have them and why are men attracted to them?

One popular theory is that breasts evolved to feed babies that did not have a prominent jaw. A flat face pressed against a flat chest might have lead to high rates of suffocation. If this theory is correct, then it would make sense that males who were attracted to prominent breasts would be more likely to have children that survived. Once this attraction was ingrained into most males, breasts may have continued to increase in size because males were still sexually selecting for them.

This type of sexual selection was not unique to our ancestors. What traits are being selected today? The answer to this lies in what characteristics are resulting in more children.

I only know of a few characteristics that have been shown to be correlated with having more children:

1. Beautiful women have more daughters

2. Men with low voices have more kids

3. Uneducated people have more children

With less need to hunt down animals and survive the elements, our continued evolution may be largely influenced by selecting for characteristics like the ones listed above.

Interestingly, there may be many characteristics which we aren’t aware of that are significantly different from the human population a few thousand years ago. For example, males might have lower voices than they used to, we wouldn’t know. Our ability to record visual and auditory information, could lead to surprising revelations about which traits are being selected.