I was just reading something about a fancy filtration thing that lets people safely drink water from rivers, lakes, etc., and it made me wonder why we didn’t evolve to better tolerate all the protozoa and bacteria found in the fresh water supplies on our planet. Other animals drink dirty water 100% of the time and don’t get sick from doing so. Fish live in that water their whole lives. Other than those in captivity I doubt there’s a single hippo that’s ever had a sip of clean, pure, filtered water. How come other animals don’t have to boil water to drink it safely?
We evolved drinking from these same water supplies with the same bacteria for millions of years, so why are we so sensitive to it? I’d think, by now, after millions of years we’d have a natural tolerance and would be able to dunk our heads in the Ganges and gulp up as much of the dark brown water as we want without getting sick. Yes I do realize someone living in the Ganges river will have more of a tolerance to the pathogens than someone from the US who has had nothing but bottled water his entire life. Still, they get sick too, and providing them clean water is a big problem in need of a solution (hence the fancy filtering devices that can be made inexpensively for 3rd world countries). But why? I’d think evolution would have given us a pretty strong immunity to anything living in the fresh water we need to survive. Humans didn’t even have truly clean water until pretty recently.
Note: i’m not questioning evolution nor am I seeking to debate the merits of evolution.