How much genetic variation is there in Homo sapiens? How different are human populations from each other genetically, and what is the meaning of those differences biologically?
Populations of humans from different parts of the world are surprisingly similar genetically, given our large numbers and worldwide distribution. This low level of variation suggests that the size of the human population was much smaller – perhaps just a few thousand people – in the relatively recent past. This finding further supports the idea that modern humans evolved as a relatively small group in eastern Africa within the past 200,000 years and then spread out to occupy the rest of the world, with little or no interbreeding between modern humans and the archaic humans that they gradually replaced. When populations become dispersed, individuals tend to mate with others who are geographically nearby. In this way, new genetic variants that appear in a population tend to become localized, and geographically separated populations gradually diversify genetically. However, the diversification of the human species has been limited by the recency of our common ancestry and by continued mig
Related Questions
- What is the population history of modern Homo sapiens, and how did that history contribute to the current structure of human populations?
- Why don different human ethnicities have more drastic physiological differences, like pronounced forehead ridges or fangs?
- What is the importance of heterozygotes, the heterozygote advantage, in maintaining genetic variation in populations?
