Oddbean

The idea that we are the descendants of people who were in the sun 10-30 minutes per day just does not make any sense. Nor does it make sense that we spent most of our time outdoors for nearly all of human evolution and now - suddenly - minimizing sunlight is essential for our health. Today's science shows (probably quite elegantly) how we convert sunlight on the skin into vitamin D. We don't know what tomorrow's science will show, but I think it's pretty much a given that reducing something as fundamental as sunlight to a single beneficial compound (that we've identified in the lab) is absurd.

I didn't say that we are descendants of people who stayed in the sun for 10 to 30 minutes a day. Yes clearly our ancestors spent more time outdoors but science now concluded that it wasn't necessarily a good thing. I think our ancestors didn't worry much about getting melanomas at 60 years old, considering that not many of them lived to that age, and even worse they didn't care much about the premature aging caused by the sun. a lot of things are great and beneficial in moderation but can turn toxic when abused. You talk about the fact that the sun is fundamental for the human body, yes it surely has an effect on boosting mood and the production of vitamin D, but honestly I see no benefit in overexposure. Personally I feel much better when I have healthy skin.

If our ancestors spent hours in the sun, that means - by definition - that sunlight is basic to our physiology. We're descended from the folks who thrived outside. The ones who didn't thrive outside are not our ancestors. That we don't understand all the ways in which sunlight is basic to our physiology is a separate issue, but our current limited understanding certainly doesn't mean that our ancestral exposure to the sun is toxic ,and recent history is littered with examples of how "science has now concluded" is an early stage of what turns out to be terrible medical advice (DDT, smoking, lobotomies, innumerable pharma products, saturated fats... it's a long list). Obv you get to decide what healthy skin means for you, and how much sunlight you think you need. Go for it 😉 I'm not trying to convince you about what to do; just pushing back on your general statements on what's healthy.

I have a little problem with this theory that something is good just because our ancestors did it. They did what they had to do with what they knew back then and they had to be outdoors because they didnt have the choice.Think about it, there's tons of stuff they did we now know was crazy, like incestious mariages in ancient cultures to keep the bloodline pure, And let's be real, our ancestors weren't exactly living to 120 so I dont understand the idea of 'let's copy their lifestyle'. Totally agree that a 'nice skin' is 100% subjective. Some people might not care about wrinkles caused by the sun or sunspots. But there is an objective part about a 'healthy skin': too much sun exposure can lead to skin cancer, just like cigarettes and lung cancer.

Actually, I agree; it's not that something is automatically good because our ancestors did it; it's that our bodies are tuned to the biological expectations of our species. I have no doubt that there are changes we can make that will extend our health and lifespan. And I also agree that we shouldn't necessarily their lifestyle (or whatever we assume their lifestyle was). I would just argue that a good starting point is the environment that our physiology expects. We can then build (or take away) from there, but we should do so cautiously, and modern science has a nasty habit of reducing an entire spectrum of the environment (i.e. sunlight) to one or two measurable factors (vitamin D, for instance) and coming to ridiculous conclusions. In any case - are we doing better now? our brains have shrunk over the last few thousand years, and I'm not so sure about lifespan. Early agriculturalists seemed to have lived relatively short (and diseased) lives, but the hunter gatherers before them may have lived quite a lot longer, especially if you factor out the early vulnerable years (i.e. taking the average of lifespan from adolescence or adulthood rather than from infancy) and the dangers of their environment. I suspect that if we took our current humans - with our 80yo-ish life span - and put them in the wild, we would go extinct. That's it for me on this exchange. Best to you!