I’m always leery of doing entries like this one because they tend to attract the crazy fanatics. There’s just been too much going on in evolution research to ignore it anymore. Researchers at the University of Chicago have found over 700 regions in the human genome where strong natural selection has occurred. The changes are recent, happening only in the last ten thousand years and may be responsible for how humans in different regions continue to adapt to environmental and cultural changes. Many of the changes detected come long after the emergence of agriculture and the formation of modern human populations. In that case the genes most strongly affected by natural selection make sense. The genes most affected are genes associated with skin color, bone structure and food metabolism.
So, why are the big changes in the genome a recent thing (if you consider the past 10,000 yrs recent)? A lot of major changes occurred for human populations starting from 10,000 on. We saw changes in population sizes, diet, and exposure to pathogens. All of these are very strong selective forces.
A good example is the gene that allows humans to digest milk into adulthood. The gene is widespread among Europeans whose ancestors relied on milk products as a major food source. Another good example deals with skin color. Researchers found five different genes associated with skin pigmentation affected by natural selection. The farther you live from the equator the lighter your skin pigmentation is going to be. For people living farthest away from the equator, it’s important to have lighter skin for the production of vitamin D, which is formed in the body after exposure to the sun’s ultraviolet rays.
Researchers believe that by examining how natural selection works on different populations they may be able to genes that cause human diseases such as diabetes and obesity.