We?ve increased our temporal range to the point where it?s not at all unusual to meet active and alert people who?ve passed the century mark. Society has done that by a system of care which is pre-prenatal, by seeing to it that every human being grows up in the best possible environment and receives the best possible nutrition, and by prophylactic measures of all possible sorts. In a word, we?ve eliminated from human life all the stresses and strains which can be eliminated. And that?s the nearest to immortality we?ll ever get.