tdaxp

Races are large groups, the members of whom are more closely related to each other than to outsiders. Races can be thought of as large-scale families. While race mixing can and does occur, the historical norm appears to have been for in-breeding within races. (It is through this inbreeding that genetic drift can ultimately lead to trouble.) Where there has been race-mixing in the past, it tends to be the males of one race interbreeding with females of another. Thus the United States has a "black" population that tends to be maternally African but often with distantly British paternity, and Mexico has a "mestizo" population that tends to be maternally American Indian and Iberan.

Some doubt the factual reality of race. That is, some claim that racial differences are only skin deep, and that the mere fact that one person has darker or whiter skin (facial features, bone structure, enzyme collection, etc) says nothing about ultimate ancestry. These skeptics would say that only a very small number of traits very among human groups in the first place, and that if one's ancestral home is nearer the equator, then it makes sense that one's ancestors evolved darker skin to avoid the sun's harmful rays.

A problem exists if we claim that race only effects skin: race as a variable explains variation. Fatality rates from a host of diseases, intelligence, and other factors are better predicted if we take race into account than if we don't. If race is not real below the skin, that means something besides biology is causing this variation. The race-skeptics answer that race is "socially constructed," that society has decided that people should be fit into this-or-that racial category based on skin color. In other words, if we would ignore race, it would go away.

However, there is another way that race can be "socially constructed": perhaps culture can cause genetic evolution. Indeed, it appears this has happened. gnxp notes an article from the Proceeds of the National Academy of Science (PNAS) entitled " Linguistic tone is related to the population frequency of the adaptive haplogroups of two brain size genes, ASPM and Microcephalin." The article notes how the long-standing view that humans are language-neutral -- an infant from any population can learn any language equally well -- appears to be false. Children whose parents come from populations that historically have a tonal language (Latvian, Chinese, etc). have a different sort of gene than children whose parents come from a tone-neutral language (English, Spanish, etc)...