I spoke with my eye doctor about this as I'm almost blind (8& vision left in one eye, none in the other). He explained to me that all eyes wear down due to sun exposure. In previous times this wasn't such a problem because we would die before our eyes got too bad. As our life expectancy increased this wearing down becomes a problem and therefore sunglasses are in fact recommended, especially if you hav elow eye sight.

Here is a post by Mark sisson from last year, it's not definitive but it's very interesting all the same. http://www.marksdailyapple.com/sunlight-myopia/#axzz2IHDaxqLp

I have contemplated this as well. I think letting sun exposure on as much of your body on a daily/near daily basis is ideal. I also think that there is point of diminishing marginal returns, not just by "hours in sun without sunglasses/clothing" but also at certain points "driving when there's a glare" or "wearing them because they look good on you" or "trying to hide your dilated pupils."

So, that's what I go by. Also, I'm a private pilot so wearing Ray Ban Aviators is part of being in the club. But mainly, I think exposure on skin and just seeing the sun with your eyes helps maintain healthy circadian rythms.

Oh, and yes, they are "paleo," just more advanced technology. What, you don't think our ancestors ever put a hand over their eyes to block out sun?

i hate the 'is x object paleo' questions, but as a person who's never worn sunglasses - ever - i do feel like people that get used to using them are at a disadvantage. they don't seem to be able to go out without them. get used to squinting! it won't kill ya.