I think people are not fully grasping mutations quite yet. Mutations give rise to genetic diversity and while the chance of it happening is "rare", there's so much DNA in every one of us that if you think in totals, they happen all the time. We have enzymes that try to repair our DNA as best as they can but they can't prevent all of it. We accumulate mutations as we get older. For example many things that lead to cancer are things that cause mutations. It doesn't take thousands of years to get blue eyes, that mutation could not be there in one generation, then suddenly it's there in the next. The eyes are blue because there's less pigment .. In other words, something happened to a gene that caused there to be less pigment in the eyes than usual.
It could take thousands of years until that gene has become successful and spread around in a population. However, time as such depends more on the generation time and how successful the mutated gene is compared to it's "unmutated" version.
I write "unmutated" because all our genes are results of mutations. In other words, this thread is about something entirely natural which happens in all of us and not really something controversial .. at least not yet.
|