It need hardly be proven that life-spans have been lengthening over the last few centuries with improvements in technology and sanitation. Nor is any evidence necessary to say that the Black Death and the fall of the Roman Empire paralleled all-time lows. What I found interesting in my British studies, however, were two books written by one Molly Miller. Her researches determined that the maximum life-span in the ancient world – from 2000 B.C.E. until the fall of Rome, was usually about 55 (for the curious, 26 was the average for men and 24 for women in Arthurian Britain). Those living to 50 represented 3% of the population or less for all but two groups. The Neanderthals were entirely unrepresented after 50, and the Cro-Magnons had 10% of their population surviving.
Consider that. Modern humans are generally dated to the end of the ice age, so roughly 10,000 B.C.E. on. Cro-Magnons were active only before that date, surviving in an era of extreme temperatures, limited food sources, and no agriculture. And yet 7% more of their population survived to age 50. Humankind would only reach that number during the height of Roman civilization, in peaceful periods across China, and in scattered places and periods up until perhaps 1000 of the Common Era
Of course Molly Miller was interested in using the studies for generating the maximum life-spans, reproductive ranges, and such for post-Roman Britain so she ignored the abherrant numbers of the Cro-Magnon skeletons. But we can’t. Something changed profoundly after glaciers retreated. Regions went through drastic alerations in water and weather. Egypt, for instance, was at various times in its prehistoric post-glacial past quite wet.
The argument (let’s call it the Daniken Proposal) could be made that aliens somehow came to our world and gave us advanced techniques for living longer. But then again why didn’t those techniques at least let prehistoric humans live as long as we can in the present day? Why is there no evidence of these aliens’ technology.
Others would argue that somehow we were more advanced then than we would be again for thousands of years. They would have us believe that hordes of less enlightened people would overrun the advanced civilizations, replacing pyramids with huts and commerce with warfare. Their actions would bring us to a chaos we would be centuries in overcoming.
Whatever the case may be, something about how we lived or how we interacted with our environment or each other was fundamentally different in the time before 10,000 B.C.E. than what it is now. Without the ability to farm and the pottery, settlements, and protection of numbers that came with it, our species managed something that would not be equalled again for thousands of years. I for one would love to know the reason why.