Lactase persistence
Cultural adaptation

For example, in East Asia, historical sources also attest that the Chinese did not consume milk, whereas the nomads who lived on the northern and western borders did. This reflects modern distributions of intolerance. China is particularly notable as a place of poor tolerance, whereas in Mongolia and the Asian steppes, milk and dairy products are a main nutrition source. However, modern East Asian steppe people mainly consume fermented milk, kumis, which has almost no lactose, as the lactose is almost completely destroyed during the fermentation process, which makes the product safe to drink for anyone who is lactose intolerant.
language:response_language[French], keywords:frequency