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Comment by nostromo | Hacker News Reader

And white people that live in California or Florida should note that our complexion evolved in latitudes similar to Canada.

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And if you are in the equivalent Southern latitude to Canada (e.g. New Zealand), you still sometimes need sunscreen to avoid the extra UV due to the ozone hole. Perhaps not as bad as it was, but cannot be ignored, although it is variable: https://www.rnz.co.nz/national/programmes/ourchangingworld/a...

The NZ sun is terrible. You feel the sun burning you as soon as you get outside. Burn time can be about 10 minutes on a sunny day, and maybe 20 on a cloudy day in summer.

In NZ we get about 4000 in-situ melanoma diagnosis a year. I was one of them a couple of years ago (at 37).

Wear sunscreen!

Perhaps if we are talking about the South Island of New Zealand and the southern tip of Canada (Toronto). Most of Canada would be closer to the pole.

Yeah, good point. NZ has similar latitudes down here as the USA has up there. Weather is very different since we don’t get continental effects.

Also NZ wasn’t really affected by ozone depletion, but the effects are definitely in our neighbourhood and we were worried. “While the ozone hole does not directly affect ozone concentrations over New Zealand, when it breaks up in spring it can send ‘plumes’ of ozone-depleted air towards us. This briefly decreases column ozone levels by around 5 percent, about the same amount as normal daily variation.”. Also see graph at https://niwa.co.nz/our-services/online-services/uv-ozone and notice ozone is lowest in NZ summer. Also measuring a column of ozone is most relevant in the tropics when the sun can be directly above one at noon, and less relevant when the sun doesn’t get so high above the horizon (location further towards poles, and winter versus summer). https://pubmed.ncbi.nlm.nih.gov/9671831/

For that matter, that complexion also likely evolved with clothes, and people in a sufficiently distant past may have looked quite different. The idea of people looking just like us living without clothes or shelter, presumably like some depiction of Eden, is fanciful.

I am reminded that, in addition to not going about stark naked, mesolithic humans in the British isles were dark skinned.

Also cancer takes a fair while to develop and kill you - well after age of reproduction, at which point evolutions opinion on guiding behaviour becomes much weaker.

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