Mammals drink boob juice (it’s in the name)
Mammals grow up and stop drinking it, so they stop producing the enzyme.
If you don’t stop (i.e drink a cow’s milk after breastfeeding) then you keep producing it I’m pretty sure I read about continued ingestion can re-enable the enzyme production (as in, you can eat yourself tolerant again)
There may be genetic conditions that make the intolerance permanent though IANAD
givesomefucks@lemmy.world 1 day ago
No, all mamalls are lactaic tolerant as babies.
We become lactaic intolerant so weaning wasn’t a choice, it was something that needed to happen.
The people who started drinking animal milk as adults didn’t immediately shit themselves, they were people whose evolved method for weaning was already “broken” allowing them to tolerate lactaic acid as an adult.
In places animal milk became an important food source (protein in the winter) having the “broken” genes was beneficial and it spread among the population until it became the norm.
The people who couldn’t handle it, either died out or mated with people who could
roofuskit@lemmy.world 1 day ago
There are still populations of lactose intolerant people. East Asians being the largest group, but thereare population in Europe. It’s a cultural thing. If your culture involved eating dairy with lactose then the populations adapted. The group in Europe created a yoghurt like dish that had no lactose as their traditional dairy dish and had no need to develop a tolerance.
So it mostly lines up with climate like you mentioned but there are exceptions when groups found loopholes.
givesomefucks@lemmy.world 1 day ago
But there’s a reason their diet includes it…
Likely that in Europe there was a benefit to children who could consume milk longer. Because in lean winter protein was scarce, but a mother with fat reserves could keep producing nutritional milk. Those calories at a young age translate to a larger (and according to a lot of studies) more intelligent adults.
That’s an advantage. Because they could consume leftover milk the mother was producing for a younger sibling. And humans just kept making babies for most of human evolution. And if the younger sibling died (very common back then) that was a lot of calories the family was wasting.
Eventually that likely led to desperate people trying milk from already domesticated livestock when the mother died (also very common).
Like…
Obviously that wouldn’t be true. People had to be lactose tolerant before the food became a cultural norm. It would never catch on if it gave you diarrhea, not just because it was unpleasant, but that there’s still nutritional value from other foods there.
This isn’t a chicken and egg blurry line, one clearly had to have been before the other, and you’ve got it backwards.