This explains it very well for the beginners and non academically inclined in this subject like Honky.
http://serendip.brynmawr.edu/biology/b103/f00/web2/ramon2.html
Quote:Beginning in the 1940's, scientists began to realize that the racial map of human beings did not match what they were learning of human genes. Scientists due agree with the idea that people look different, mainly because of the varied environments in which they and their ancestors live. They have physically changed as environmental conditions warranted. Take skin color, as an example. It is essentially an adaptation to the amount of sun received. People from regions with lots of direct overhead sunlight (the tropics) tend to have darker skin than people from cloudy or oblique sunlight regions (northern temperate zones). Since melanin protects the skin from harmful ultraviolet radiation, people with more melanin in tropical areas tended to live longer, and produce more children, than people who were melanin deficient. Sunlight also stimulates vitamin D production. People from northern Europe and Asia who had little or no melanin were able to absorb more of the little sunlight there was, which enabled them to produce more vitamin D. (7)
Vast new data in human biology have completely revamped the traditional notions of race. Race is a biological term that describes the DNA structure of an individual as a fixed attribute that cannot be changed. This idea is used in biology to discuss how different peoples adapt to environments and hence, making the term "race" have no scientific basis. Today most scientists reject the concept of race as a valid way of defining human beings. Researchers no longer believe that races are distinct biological categories created by differences in genes that people inherit from their ancestors. Genes vary, but not in the popular notion of black, white, yellow, red and brown races. Many biologist and anthropologists have concluded that race is a social, cultural and political concept based largely on superficial appearances. (4)
In the past, races were identified by the imposition of discrete boundaries upon continuous and often discordant biological variation. The concept of race is therefore a historical construct and not one that provides either valid classification or an explanatory process. Popular everyday awareness of race is transmitted from generation to generation through cultural learning. Attributing race to an individual or a population amounts to applying a social and cultural label that lacks scientific consensus and supporting data. While anthropologists continue to study how and why humans vary biologically, it is apparent that human populations differ from one another much less than do populations in other species because we use our cultural, rather than our physical differences to aid us in adapting to various environments.
Its not that difficult to understand and no need to get bogged down in semantics, the term "race" is used for convenience as is the classification of humans into different racial groups.