Science has shown that there is no biological way to assign people to individual racial groups. Having originated in Africa and spread all over the globe, human beings share 99.8% of all their genes, the last 2% being for all human variation, not just race. Environment and culture have had a major impact on our varied appearance, but biologically, there are no genetic difference between what we think of as the Caucasian, Negroid, and Asian races.
According to the evolutionary biologist, Joseph Graves, when scientists try to group people according to the traits we connect with racial groupings—skin color, hair type, body proportions, the clusters that result do not match with what we know about human evolutionary and migratory history (see link). The Australian aborigines and people in Papua, New Guinea have the skin color of black Africans, and yet they are the most genetically distant group from them. Graves quotes Ashley Montagu, whose 1943 book, Mankind’s Most Dangerous Myth, makes the point that different genes respond to different pressures and are not correlated with just each other in different populations.
And yet, people do look different and in ways we can’t help but see as racial. It is what we have been taught.