The way I understood it was that the average life expectancy was low, due to the high rate of infant mortality. But the mode of the age data is up in the 60's-70's. I.e those who didn't die from infection, or being eaten alive actually lived similar lives to us.

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Page 29: The data show that modal adult life span is 68–78 years, and that it was not uncommon for individuals to reach these ages, suggesting that inferences based on paleodemographic reconstruc-tion are unreliable.