Sure, but you don't need to know about disinfectant to notice that people who drink the water from the stream get sick and people who drink beer don't. (Nor nee

Sure, but you don't need to know about disinfectant to notice that people who drink the water from the stream get sick and people who drink beer don't. (Nor need to realize that it's because the people and animals upstream are shitting in it. Not a big problem for hunter-gatherers, but it would have become an issue once large-scale agriculture became a thing.)