People with lactose intolerance make do with fermented products that contain lactase ~ kimchi, saurkraut, yoghurt, and so on.
Eventually the old boys got a hankering for those early Rhine maidens who had something like 500 genes modified to allow for persistent lactose tolerance, and the rest is history ~ ARAB WOMEN WITH STREAKED HAIR!
That’s rather interesting. So lactose tolerance seems to be a “use it or lose it” type of thing? Kinda like civilization and now the Constitution.