East Asian Traits Explained by EDAR Gene

Summary
Within the human species, races have undergone divergent evolution. There are hundreds of differences in the genomes of east Asians from Africans and Europeans, but one in particular has been explored. This gene is the EDAR gene, and in most east Asians it has a mutated part. This mutation occurred about 35,000 years ago. Using mice genetically engineered to have the same mutation, scientists showed that the mutation causes thicker hair, more sweat glands, and smaller breasts. The gene likely also affects the shape of teeth. The prevalence of the mutated EDAR gene could be suggestive of natural selection, or sexual selection. In natural selections, people with more sweat glands that lived in a hotter environment would fare better and be more likely to have children. In sexual selection, the visible cues that the mutated EDAR gene causes, mainly thicker hair and smaller breasts, would be more attractive and therefore selected and passed on. However, the experiments with mice have not proven to answer these questions as to why the mutated EDAR gene became common.

Connection
Currently we have been focusing on evolution, and this article touches on some key concepts. One of these is natural selection, or the mechanism in which individuals with better suited traits to the environment survive to produce offspring. Another of these is directional selection, which is when individuals with more extreme traits are favored and pass on that trait to offspring until the frequency of that trait becomes average instead of extreme. Since the different EDAR gene that east Asians possess began as a mutation, it would have been rare. However now it is more frequent than rare. In addition, races are the product of convergent evolution, or the separation of similarities between groups. In regards to the human races, this was likely due to the geographic isolation that the continents caused. One topic related to evolution, as it causes species' traits to change, but that we didn't cover is sexual selection. This means individuals who are more able to obtain a mate will be selected and pass on whatever trait caused that. It can lead to traits that are harmful to the individual, such as bright colors that attract predators.

Source: The New York Times
Author: Wade, Nicholas
Date: 14 February 2013
Link: <http://www.nytimes.com/2013/02/15/science/studying-recent-human-evolution-at-the-genetic-level.html?_r=1&>