In non- Western cultures, people are not heavily dairy oriented, thus their intestinal lactase levels diminish due to the absence of that gene. This is the condition known as being lactose intolerant. When this particular individual consumes dairy products, diarrhea and flatulence may occur. The blood groups distribution frequencies differ in different geographical areas. The analysis of different populations yields striking differences in some blood group gene frequencies.
Diego system indicates a Mongolian origin.
The Duffy, Kell, and Rh systems are typical phenotypes for blacks. The A gene frequency is high in western Asia, western Europe, Australian Aborigines, and certain American Indian tribes. The B gene frequency occurs mostly in Central Asia and northern India. The O gene occurrence is high in northern and Western Europe and southern West Africa. Genetic adaptations can also be observed in the different levels of skin pigmentation.