Do note that evolution started to optimize when the conditions were a lot harsher. (Warm clean rooms with food and clean water, clean clothes, NSAIDs, etc.)
My point was that if getting a cold made a significant difference in the likelihood of some cancer then you may be substantially undercounting the risk of that cancer to children in the counterfactual where there is no susceptibility to colds.
(To be clear, I don't think the parent's speculation is likely accurate. I do think it's interesting.)
That's a very important point, and you are of course right. (Your original comment wasn't very clear and I misinterpreted it, sorry.)
Do kids (and people in general) get substantially less colds in warmer climates? Because then we can check cancer rates there. (And spend a lot of effort on controlling for other differences.)
> Your original comment wasn't very clear and I misinterpreted it, sorry.
Yeah, there's some tension between risk of being seen as condescending and making sure everything is sufficiently clear. In a low-stakes context like this (and outside of clarifications or responses to ELI5 requests) I try not to fill in all the gaps - when it goes well it leaves us all feeling a little smarter and when it goes wrong it occasionally leads somewhere interesting. The increased risk of misinterpretation was made even worse here by the priming of several other people making the point I wasn't.
