I disagree. I think there are many minds that would be capable of what these people did (not everyone, certainly not myself, but thousands of people alive today

I disagree. I think there are many minds that would be capable of what these people did (not everyone, certainly not myself, but thousands of people alive today). It is a case of having the right person in the right place at the right time, Einstein would have not had his theories had he been around 20 years earlier, or if he had not had the opportunities that he did. And if he had not been around then I think it would have been others. It is about the environment, Calculus was developed by two people simultaneously. As to why we haven't had someone who has done this, well who's to say that we haven't and they are just overlooked? Or that greater capital expenditure it has to be groups of people (finding DNA, cloning, Graphene, etc). Or that there has simply not been the right environment.