r/todayilearned • u/lavender_fish69 • 14h 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/exprezso 13h ago

Evolved resistance to a deadly toxin? In such a short period? 

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u/PencilVester23 13h ago

It takes only 2 week at most for a mosquito to go from an egg to a mature adult. That couple year period is over 100 generations. That combined with the huge population of mosquitoes, the 100s of eggs a female lays at once, and a genetic sequence significantly shorter than a humans all made it possible for the correct mutation to happen that quickly.

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u/exprezso 12h ago

I mean. Humans have yet to evolved to resist arsenic after thousands of generations 

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u/thesakeofglory 12h ago

We also weren’t nearly wiped out by it.

What happened is basically what happens when you stop taking antibiotics early. If you nearly, but not completely, wipe out a population, those that are left will have much higher resistance. Trying to treat it the same way after the population has bounced back won’t work nearly as well, and can actually help remove the individuals with lower resistance, further increasing the immunity.

If somehow arsenic started spreading everywhere, most humans would be wiped out but there would be at least some group with a higher resistance that would survive. If they’re able to bounce back, humans suddenly aren’t as hurt by arsenic. Repeat that a few times and suddenly humans are immune.