the idea that people lived shorter lives in past is somewhat misleading. Yes, in general people lived shorter lives. However the average life expectancy of an ancient population was somewhat skewed due to absurdly high infant mortality.

Thus when someone says "in medieval england the average life expectancy was 35 years", keep in mind that this statistic takes into account infant mortality. If you lived past the age of 15 you could actually expect to have a life span roughly in line with a modern person. In ancient Rome, one would be surprised to see how many 80 year olds were around.

Mary Beard's "SPQR" spends a whole chapter on this idea if you want further reading.