Lactose intolerance is only an issue in infants who cannot digest breast milk. Mammals including humans lose the ability to produce lactase to digest milk around the time of weening. That changed when humans domesticated animals. Humans with persistent lactase production could continue feeding on a unique, highly nutrient dense food source. This advantaged those traits in reproduction over thousands of years, allowing those with persistent lactase to survive and reproduce in some environments to the point it became part of that ethnic background.
Lactose intolerance is only an issue in infants who cannot digest breast milk. Mammals including humans lose the ability to produce lactase to digest milk around the time of weening. That changed when humans domesticated animals. Humans with persistent lactase production could continue feeding on a unique, highly nutrient dense food source. This advantaged those traits in reproduction over thousands of years, allowing those with persistent lactase to survive and reproduce in some environments to the point it became part of that ethnic background.
African and Asian ethnic groups who historically frequently drink unfermented milk have often the lactose tolerance mutation. It exists in small clusters in Africa and Asia.
Mongolian typically drank fermented milk though, so they didn’t need the mutation.
Drinking milk and using condensed milk in desserts got much more popular in some parts of Asia recently (East Asia in particular), most of them don’t have the mutation since it needs to be selected for by having people who don’t have it die, which only happens for communities that depend on milk during times of famine. They usually either live with it (the effects of lactose intolerance are mild for most people) or take lactase pill or lactose-free milk.
African and Asian ethnic groups who historically frequently drink unfermented milk have often the lactose tolerance mutation. It exists in small clusters in Africa and Asia.
Mongolian typically drank fermented milk though, so they didn’t need the mutation.
Drinking milk and using condensed milk in desserts got much more popular in some parts of Asia recently (East Asia in particular), most of them don’t have the mutation since it needs to be selected for by having people who don’t have it die, which only happens for communities that depend on milk during times of famine. They usually either live with it (the effects of lactose intolerance are mild for most people) or take lactase pill or lactose-free milk.
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