[rhinoceraptor]

I don't doubt that sun exposure is a contributing factor to skin cancer, but it just does not make sense that skin cancer rates have shot up over the past 100 years, while at the same time people spend less and less time outside.

IMO, there's probably some other causal factor(s), and reducing sunlight exposure is not the solution.

Sunlight exposure is important for health, not just for Vitamin D (which others have pointed out, may just be a proxy for some other factor of sun exposure). It's important for regulating circadian rhythm, as well as preventing myopia in childhood.

[copperx]

If you take a dive on PubMed, you'll see that indeed, sunlight exposure appears to be inversely correlated with all-cause mortality.

Why? It is not known, but even when controlling for physical exercise, Vitamin D status, and other factors, the correlation still holds. Some authors suggest other chemicals produced by sunlight, not only Vitamin F, might be involved.

[copperx]

(correction to above, I meant Vitamin D, not F, of course).