This may be the first solid evidence that lifespan is about the same as it has been throughout history (and maybe well back into prehistory), though it's long been suspected. However, it's well known that life expectancy has gone up significantly. Span is how long we live if illness, accident or violence does not kill us, until the body just can't hold together any longer, but expectancy averages in the effects of premature death.

Maybe why the large number of kids,Diseases would cull many,now medicines have pretty well eliminated the high death rates,although Women still die during of after delivering a child,rare,but it does happen.I understand that's the most dangerous time in a Woman life,when She's pregnant....

I think this isn't actually the entire story. Certainly the limit of human life hasn't dramatically increased across the board and there is very recent evidence to suggest the average life span is falling, particularly in western countries. However some of the biggest causes of death were infectious diseases which are currently easily treatable. This may not remain the case with the overuse of antibiotics. In addition to this trauma was likely to have caused more fatal injuries. What is happening currently is that more people live longer lives. Not necessarily well but longer.