Posted: Apr 10, 2018 1:53 pm
Papa Smurf wrote:The_Piper wrote:Skin cancer would have to regularly be contracted in the first 20 years of life for it to be the major driving force for dark skin, would be my guess.
Perhaps that's not actually a requirement for it to be a selective force. I believe humans are perhaps the only species where individuals live well past their fertility age, possibly because grandmothers/fathers helping to take care of their grandchildren offers an advantage. So if you lose your parents due to them contracting skin cancer at an older age, you and your ofspring are at a disadvantage so even in this case it would still be an evolutionary selective force.
I'm aware of and considered that, which I've read also may be a reason for menopause (before Rachel's post, I mean
). I said before age 20 because surviving to sexual maturity is more important to having offspring than having caring relatives. But I said "the major driving force", assuming that there's more than just one factor involved. I've already conceded the point that skin cancer may be the major factor. My cause for doubt is that if people can reproduce, those genes will make it into the next generation. But we don't even need to think about grandparents (or aunts and uncles, and other relatives who contribute to reproductive success), if the parents don't survive long enough to see their offspring reach sexual maturity because they got skin cancer and died.