A common misconception that exists today is that the lifespan of early humans was extremely short. Often people quote numbers like 30 years as the average life span of early hunter gatherers and farmers. A look at modern day hunter-gatherer societies is the best way to examine the likely life span of early humans.
The study longevity Among Hunter-Gatherers: A Cross cultural Examination covers this topic with a look at the human life span in several different cultures. The study puts forward the hypothesis that there is a prototypical pre-industrial mortality profile in humans. Or in other words, there is a normal human lifespan that can be seen across many cultures and levels of pre-industrial development.
Our conclusion is that there is a characteristic life span for our species, in which mortality decreases sharply from infancy through childhood, followed by a period in which mortality rates remain essentially constant to about age 40 years, after which mortality rises steadily in Gompertz fashion. The modal age of adult death is about seven decades, before which time humans remain vigorous producers, and after which senescence rapidly
occurs and people die.