I am a Caucasian male of German descent. A gastrointestinal disease called Celiac disease affects at least 1% of the Caucasian population. It is a disease that causes damage to the lining of the GI tract, which is the main organ for digestion and nutrient absorption in the body. It is a chronic disease that inflames the small intestine, and it is caused by an immune reaction to gluten in wheat, barley, and rye (Murray). The disease is found all over the world, but it is mostly found in the Western world, specifically Caucasians, because of different levels of genetic susceptibility and wheat consumption. Most patients with Celiac disease carry the gene pairs encoding the human leukocyte antigen types DQ2 or DQ8, which creates the immune response to the gluten. Caucasians must have had their genes mutated at some point in history through natural selection. Their genes were mutated, and the mutations were passed down to successive Caucasian generations. Other races may not have had this type of mutation and it was not passed down as much, so Celiac disease is less common in those races. Social determinants likely also play a part. The most prevalent race in the United States is Caucasian, and the United States grows a lot of wheat. Countries like China or the Middle East don’t grow as much wheat, so they are not eating as much gluten as Americans, so most of them would not even know if they had Celiac disease. Even if people with Celiac disease are eating gluten, 83% of people with Celiac disease are undiagnosed in the United States (Murray). The disease can be very mild in some cases, so countries that do not eat a lot of wheat would not even notice they had the disease.
Genetically, it seems to not make sense that natural selection would pick genes that don’t allow gluten in the diet, but there may be other reasons that favor survival. Maybe too much gluten is bad for the body, or there was a type of plant that contained gluten that was poisonous, leading to the selection of certain genes. Genetic mutations like this caused some people to be more resistant to Malaria. Many people living in environments with prevalent Malaria have developed sickle cell anemia. The mutation to Hemoglobin from Sickle Cell slows blood flow, causing a resistance to Malaria. This disease normally causes anemia, but in certain climates with Malaria, a heterozygous mutation can help resist the spread of Malaria. Because of the globalization of people all across the world, people may move to an area where a genetic mutation may do more harm than good. This may be a reason why Caucasians are more susceptible to Celiac disease than other races.
Murray, Joseph A., and Alberto Rubio-Tapia. “Diarrhoea due to Small Bowel Diseases.” Best Practice & Research 26.5 (2012): 581-600. ProQuest. Web. 12 July 2013.