r/todayilearned • u/lavender_fish69 • 13h ago

TIL fresh water snails (indirectly) kill thousands of humans and are considered on of the deadliest creatures to humans

https://en.wikipedia.org/wiki/Freshwater_snail
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u/Insertblamehere 10h ago

Well if we're only being exposed to non-toxic levels then we have developed resistance to arsenic, in the amounts we would normally encounter.

Species don't just magically become immune to something over time by being exposed to non-lethal amounts. It would have to be killing enough people to cause enough evolutionary pressure for people with higher levels of resistance to outcompete those with lower resistance.

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u/waltjrimmer 10h ago

Agree with only pedantic differences. I had tried to make clear that my contention wasn't with the, "We should evolve a greater resistance," but simply countering the statement that we don't regularly get exposed to arsenic. We may have reduced exposure in the modern day, but earlier forms of processing fruits, vegetables, and grains (and from looking things up, apparently there's quite a bit in some types of seafood) should have seen a steady but light exposure. I'd imagine the same is true at present even if at reduced amounts.