Why are most adults lactose intolerant?
In: Biology
Lactose intolerance is considered to be the default state for humans. Humans did not evolve the ability to tolerate and digest cow milk products until very recently.
When you take a step back and think about it, Cow milk is a strange thing for us to be eating. It is not part of a humans natural diet.
European populations were the first to develop the enzymes and gut bacteria needed to digest milk products properly. One theory postulates that humans living with herds of Aurochs (Wild Cows, now extinct) bred the animals for their meat, but were unable to consume the milk because it made them sick.
Attempts to preserve the milk resulted in the first cheeses. The cheese making process at a basic level is pretty straight forward, all it requires is milk + time. The bacteria that turns milk into cheese processes the lactose and converts it into something we can more easily digest.
Eating cheese as part of their diet over centuries resulted in cow gut bacteria becoming adapted to our own biome and a permanent part of our digestive tract. This resulted in Europeans developing the ability to make the enzymes needed to break down lactose and consume cow milk directly.
While Asian and African populations never developed this because they didn’t eat Aurochs cheese as part of their traditional diet.
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