Just in terms of your first example (the breast cancer) - that is exactly why cancer is one of the leading killers in developed countries today. Almost all cancers begin in middle or old age. Why? Because there was no selective advantage to staying alive to that age. After women go through menopause, they can't reproduce. Evolution picks traits that are good for continued reproduction.
If there was a gene for dying at age 50 in women, evolution would essentially ignore that gene. Because by age 50, women have had all the children they're going to have. If there was a gene for 'living past age one,' then that gene would be overrepresented in the gene pool, as people who did not have that gene would not have children. However, the gene for 'living past age 50' is not going to be overrepresented in the gene pool, as women can't have children past that age.
So it's not really a coincidence that most cancers start striking once people have reached the end of their reproductive life span. Evolution has made it that way.
That's a good one. I will add it to my list of evolutionary just-so stories.
If there was a gene for dying at age 50 in women... So it's not really a coincidence... Evolution has made it that way.
There are no such genes, but I bet you think your philosophical ramblings in a priori biology prove something about them anyway.