re: I wasn't implying that. - DNA, natural selection, cancer.
I think that natural selection had everything to do with it in the beginning... our ability to adapt to our surroundings... food, tools, environment (stay, or go) etc.
I'm speaking of the past, of course, since in today's world, it has become much more transit. With global trading to add to it, etc., it has.
That's not to say that cancer among us hasn't been encouraged from environmental means. Maybe it's an add-on and our DNA hasn't been able to cope (?!).
Yes, I'm among those that think that there should be agricultural regulations enforced (to benefit communities, countries and people as a whole).