Measures of life expectency are misleading in this regard.<p>Much of low life expectency comes from <i>very</i> high infant mortality -- deaths to age 5 or 10.  Once you&#x27;ve passed that threshold, your odds of survival increase markedly.  Perhaps slightly lower than today&#x27;s first-world standards, but hale-and-hearty at 15 <i>doesn&#x27;t</i> mean you&#x27;re going to fall over dead at 25.<p>You <i>also</i> want to look at life expectency at any given age.  And I distantly recall that the number of (I can&#x27;t remember specifically which) Greeks or Romans surviving to age 80+ compared favourably to modern times.