there is a theory that all living things have a limited amount of heartbeats, from insects to the largest animals the idea is there is a number of heartbeats is around the same number...just some creatures reach it faster...
similarly the idea that diet, exercise, and knowledge of these type of things have contribute greatly to modern humans living longer is probably less true than the fact that modern medicine now cures us of the ailments and traumas that prevented many children/people in the past from reaching old age, so while life expectancy may have changed over time, humans have always had the potential to live around 70-80+ years...