Approximately 90-95% of black individuals and 20-25% of white individuals throughout the world will have a partial or complete lactose intolerance. Most often people of African, Asian, and Mediterranean descent have it.
Most humans, like other mammals, gradually lose the intestinal enzyme lactase after infancy and with it the ability to digest lactose, the principle sugar in milk. At some point in prehistory, a genetic mutation occurred and lactase activity persisted in a majority of the adult population of North and Central Europe, and in some ethnic groups around the Mediterranean and Near East, in Noth Africa, and on the Indian subcontinent are those that have developed a gentic mutation to allow them to digest the lactose in milk. allowing carriers to have milk as a nutritional resource, especially useful in times of food shortage.
These people share the longest known tradition of dairying, since humans first domesticated livestock and practiced milk-based pastoralism (6000–9000 years ago), making milk abundant for adults.
Descendants of these polutations carried this genetic mutation with them to Noth America and Austalia.
For the majority of the world's populations, however, the absence of genetic challenge has meant that this genetic change did not occurred.
Lactose intolerance by group
|Human groups||Individuals Examined||Percent Intolerant||
|Europeans in Australia||160||4%||0.20|
|Northern Europeans and ScandinaviansScandinavians||N/A||5%||N/A|
|Eastern Slavs (Russians, Belarusians, Ukrainians)||N/A||15%||N/A|
|North American Hispanic||N/A||53%||N/A|
|Jews, Mizrahi (Iraq, Iran, etc)||N/A||85%||N/A|
|Jews, North American||N/A||68.8%||N/A|
|Northeastern Han Chinese||248||92.3%|