The human body won't tell you to avoid lifelong tanning to avoid cancer in your 60s, because living to your 60s isn't all that evolutionarily important (and hell, likely made you a drain on your hunter-gatherer tribe). There's no selection pressure.
Apparently there are some arguments that having elders around was a boon for prehistoric tribes. http://www.theguardian.com/science/2011/jul/24/prehistoric-m...
I don't know how much this is validated, but thought it was interesting nonetheless because it seems counter intuitive at first.
I'm somewhat doubtful of this claim. If anything scientists would have everyone avoid sunburn since skin cancer and cataracts.
Tans looking good are a recent phenomenon: A couple hundred years ago light skin was a sign of high status since you could afford to stay indoors instead of having to work in the fields, so light skin was deemed to be more beautiful: https://en.wikipedia.org/wiki/Human_skin_color#Social_status...
Really? This is a naturalistic fallacy. It's out precisely our instincts that cause us to overeat. As has been pointed out our instincts haven't adapted to the abundance and availability of food seen today. In an environment where food is scarce it is evolutionary advantageous to ensure your body had enough calories to make it until the next available meal. And this didn't mean picking the most nutritious food sources, we didn't have that luxury, it meant picking the most available. Only as directed by science do we now know what foods provide the most benefit or determent to our health.