See, it makes me sad that you say that, because there are many many many other people that think like you. And it's just because there's so much crap out there to sift through to get some honest, medically researched answers. To address our ancestors, its called
directional selection and
allopatric speciational evolution, meaning, our ancestors mated
sympatrically or with each other (sym) and lived in the same country (patric). Because of this, they created similar offspring with similar traits. When they began mating with other humans from different countries farther from the equator it began
allopatric speciation or different (allo) people from different countries (patric) began to make a new breed of people (speciation). These people are not like our ancient ancestors who are believed to have begun in northern Africa and the Middle East-near the equator. Resistance to sunlight is diminishing throughout the entire race due to adaptations our bodies are making and those adaptations are out of our control. A good way to tell how resistant you are to sunlight is you heritage. Are you southern? Italian? Middle Eastern? Central American? These play into your skin's ability to safely absorb UVA and UVB rays but don't dictate it. People in general in our time are less resistant to sunlight and
everyone should be careful with damaging rays, regardless of heritage, skin tone or age.
I'm definitely
not saying you should stay out of the sun. But I'd rather you tan outside than in a tanning bed, where UVA and UVB rays are stronger and more penetrating, increasing your chances of
skin cancer. About the vitamin D. That is basically a lie that tanning companies started to fight their civil cases and protect themselves. The sun damage you would recieve trying to get enough vitamin D in your blood would be detrimental to your health.
I really hope I gave you a little more information so you can make better educated decisions about yourself and the sun.