There's another important factor to consider, and that's how we expose ourselves to UV. Our ancestors used to be outside most of the day, allowing skin pigmentation to adapt to the regional and seasonal UV levels. Until agriculture came along fairly recently we also lived mostly in the shade of the forest and not in direct sunlight.

Compare that to today, where UV exposure mostly means exposing the skin to massive bursts of UV for short times, at best in an effort to build skin pigmentation that isn't sufficient. That's completely different and much more damaging, leading to the general feeling that any UV is bad.

We are also a lot cleaner. We remove dirt and dead skin, whereas our ancestors left it there and it may have acted as a protective shield from UV.

I think our ancestors lived in the full sun of the African savannah a lot more than the forest, and even in northern Europe, hunter gatherers were killing meat-on-the-hoof (mammoth, wild horse, etc.) so they were running about in the open a lot.

However, the change in exposure is surely true. I'm just not at all convinced that complete shielding from UV is a better choice than occasional UV.

Until recently, children would run around outside a lot during the summer, even in urban environments, and especially in suburban or rural ones.

Be careful of the natural fallacy. Life expectancy was much lower a long time ago, and causes of death from poor health were not recorded very accurately.

Choosing the natural over the artificial is a reasonable default where the science is uncertain. But just remember that science has eliminated an awful lot of problems.

Also remember that natural experiences aren't always a la carte. Picking natural foods from disperate regions might be very unnatural, as is getting natural UV light after taking a shower.

Certainly, many natural things are not good. However, the idea that a complete absence of natural light (which includes UV) is good, is suspect. It reminds one of the idea, in the early 20th century, that getting rid of all bacteria was good. It turns out that there are way more kinds of bacteria than we know, and an excess of antibiotics and disinfectants is almost certainly a big part of why we have ever-escalating rates of severe allergies and auto-immune disorders.

Not that we would wish to have a complete absence of antibiotics. But, the attitude of "you have a virus, so take this antibiotic just in case there's also a bacteria", sounds a lot like "block all UV light from hitting your skin, at all times". I am skeptical.

I mostly agree. I'm just saying that you might want to stop using soap as well ;-)

Using soap has a big effect on how the UV light hits your skin, the damage it might cause, and the benefits that it might have. Of course this is all speculation on my part, but I am just warning of the idea of picking one natural thing at a time -- natural things go together.

Maybe instead of sunscreen, we should be using mudpacks. :) I think it might hurt my chances of getting employed, unless I worked only remotely. Also, my wife would have words.

However, anecdotally, the "mud beggars" at modern Renaissance Faires are said to have healthy skin. It could be a confusion of cause and effect, though.

Do consider that your ancestors developed in a particular latitude in a particular climate. E.g. anglo-saxons developed in northern latitudes & have pale skin. The fact that they spent many hours a day in the sun unprotected does not mean that an anglo-saxon would be advised to do the same in Phoenix.

Absolutely. I do think that the typical amount of sun which a descendant of northern Europeans, now living in Phoenix, gets is probably still not as much as their ancestors got, simply because the amount of time spent outside is so much less. But your point is well taken.

Also, most descriptions of our ancestors show them to have been far more hairy than we are.