Other societies such as East Asians and Amerindians, retain the typical mammalian genotype in which the body shuts down lactase production shortly after the normal age of weaning.

• 而其他的社会（如东亚和美洲印第安人）保持了典型的哺乳动物基因型，即机体在正常断奶年龄后不久关闭乳糖酶生产。