magazine issue 9 2008 / Issue 8

Reconsidering Race in the Genetic Era

• written by Chris Buchholz
• edited by Abdolhossein Abdollahi

On the other hand, we need to absorb some sunlight to enable our body to metabolize vitamin D. Human populations that migrated into northern climates gradually evolved to have less pigment in their skin. Less ultraviolet (UV) radiation reaches the surface as one moves away from the equator; therefore, melanin is not as crucial for survival in northern climates. Having too much melanin could even be harmful by preventing enough radiation to penetrate the skin to metabolize vitamin D. Also, consider that much of this change happened during an ice age, where humans dressed in clothes that covered most of their skin. This might have made the transition from dark to lighter skin occur at an accelerated rate because these humans had to absorb the required dose of sunlight through smaller patches of exposed skin (Ossorio, 2006). Overall, these climatic differences led to small mutations in the genes that produce melanin. In other words, differences in skin color are caused by small variations in the genes that are responsible for melanin, not because there are fundamentally different types of humans. Arguably, if you were to relocate lighter-skinned people to the equatorial region and those populations remained there for a few thousand years, their skin color would eventually become darker.

Geneticists are discovering that there are very few biological differences between the "so-called" races (Bamshad & Olson, 2003; Bonham, Warshauer-Baker, & Collins, 2005; Foster & Sharp, 2002; Ossorio, 2006). Furthermore, this research indicates that the very notion of race is an inaccurate way to categorize human variation. and Olson (2003), for example, determined that the hair, skin color, and facial characteristics that are typically associated with race are determined by a very small number of genes. Furthermore, they found that the rest of the genes that define human beings were much more similar between the so-called "races" than different. Research that directly compares the human genome of individuals from different racial groups indicates that there is more genetic variation within these groupings than between them (Pääbo, 2001; Bamshad and Olson(2003), for example, indicate that 90% of human genetic variation occurs within a continent’s population; whereas, differences across continents can be accounted for by approximately 10% of genetic variation. At first this may seem counterintuitive; however, these statistics simply point out that most of the differences between individuals (i.e., 90%) are due to factors that have nothing to do with race, ethnicity, or where one’s ancestors lived. While, we might appear to be very different on the surface, we are more alike than we appear. To test this we could take any two individuals at random from anywhere around the world and compare their genomes. They may appear very different on the surface, but genetically, they could be strikingly similar.

Yet, another issue that complicates attempts to compare racial groups is determining how to define these groupings. When looking at the genome of the modern human, geneticists are finding that the typical individual has genetic markers from multiple ancestral sources (Ossorio, 2006). In other words, even if there were distinct races at some point in the past (which is unlikely), the average individual today descends from ancestors belonging to many different regional, ethnic, and racial groups. For instance, there is no person alive today that is distinctly of European or African descent, let alone distinctly "white" or "black." If you look within or between any group(s) of humans you will see a continuous spectrum of skin color; there is no cut- off point that determines whether someone is "black" or "white."

Nonetheless, one of the benefits of decoding the human genome is that we are finding links between certain genetic variations and disease. The genes for sickle cell disease, for example, are more likely to be found in humans that have ancestors from Africa or the Mediterranean; while, cystic fibrosis is more common among those of European descent (Bamshad & Olson, 2003). Identifying who has these and other genetic markers for disease will help us to better treat and even prevent disease in the future; however, outward appearance is not always the best indicator of an individual’s origins. An individual can have European ancestors and have brown skin; likewise, an individual can have ancestors from Africa or the Mediterranean and appear light skinned. While skin color can be an indicator of some of one’s ancestors, this is not always an accurate way to determine one’s heritage. Furthermore, while some diseases are more likely to occur in some populations, we must be careful that this information does not lead to discrimination or the reinforcement of stereotypes (see Condit et al., 2004).