I suggest scientists should be selected by virtue of their contribution to the development of the research discoveries,Although I should not hesitate to say that the young scientists as in below 35 years need strong consideration to ensure sustainablity of that research field is propagated from the old to the young.Gone are the days for the Researchers to be in the retiring age. I think if an individual got exposure to the research career ealier and therefore for a longer time period of his lifespan assuming the survival time is constant he will be most probably more productive than if he got exposure at 60 years!This is my opinion that can be subjected to critism.