It is often asked if men do not live longer now than formerly—if the length of human life is not actually increased? It is evident that two distinct problems may be hidden in this question as it is ordinarily put. The first relates to what may be called the natural term of existence. The duration of a normal life not cut off by accident or infectious disease was placed by the Psalmist at about threescore years and ten; seventy or eighty years is, indeed, to-day commonly reckoned as the normal life.
THE SPAN OF HUMAN LIFE. JAMA. 2009;302(16):1817. doi:10.1001/jama.2009.1391