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.
We hypothesize that human bodies are designed to function well for about seven decades in the environment in which our species evolved. Mortality rates differ among populations and among periods,
especially in risks of violent death. However, those differences are small in a
comparative cross-species perspective, and the similarity in mortality profiles
of traditional peoples living in varying environments is impressive.
Industrialized societies do enjoy much higher life expectancy at birth than traditional hunter gatherers.
AVERAGE WORLDWIDE HUMAN life expectancy reached 66 years in the first quinquennium of the twenty-first century, with extremes at the country level ranging from 39 years in Zambia to 82 years in Japan (United Nations 2007). Average life expectancy has increased linearly at almost three months
per year over the past 160 yearsAmong traditional hunter-gatherers, the average life expectancy at birth varies from 21 to 37 years
It is important to understand the exact meaning of life expectancy. Life expectancy, and life expectancy at birth in particular, are often misunderstood terms. This method of measurement is often confused with the mode age of adult death. An average life expectancy at birth could be 50 years. This does not mean that an individual will on average only live to be 50. Rather it is a calculation based on all deaths, including those of infants. Averaging the age of mortality over all ages gives the average life expectancy. Life expectancy refers to additional years of predicted life based on this average. A high infant mortality rate can drastically bring down life expectancy even if the average adult life expectancy after infancy remains high. Infant mortality and early child mortality are some of the biggest differences between industrialized and non-industrialized societies.
Infant mortality is over 30 times greater among hunter-gatherers, and early child mortality is over 100 times greater than encountered in the United States.we see that on average 57 percent, 64 percent, and 67 percent of children born survive to age 15 years among hunter-gatherers, forager-horticulturalists, and acculturated hunter-gatherers.
The average hunter-gatherer mortality rate is 38% before 15 years.The world average is 6% before 5 years. Since the age specific mortality rate generally only declines before 15, the world average before 15 could not be more than 18% Modern medicine has significantly reduced the infant an child mortality rate in developed countries. For this reason looking only at life expectancy at birth does not make for a good comparison of adult life expectancy. For better comparison of adult life expectancy we can use average life expectancy at 15 years and mode age of adult mortality.
life expectancy at age 15 is 48 years for Aborigines, 52 and 51 for settled Ache and !Kung, yet 31 and 36 for peas-
ant and transitional Agta.Survival to age 45 varies between 19 and 54 percent, and those aged 45 live an average of 12–24 additional years
The modal age of mortality in hunter-gatherers can range from 68 in the Hiwi to 78 in the Tsimane. In the united states as of 2002 the mode age of mortality was 85. In most cases about 30% of of adult deaths occur at ages above the modal age of mortality.
There is, as one would expect, a clear trend towards longer live and lower infant mortality rates in industrialized societies. However the lifespan of hunter-gatherers is not as low as commonly thought and in many respects rivals that of the industrialized world . This information may give us a window into the lifespan of early humans.
Condensed Science 
July 22, 2013 at 5:43 pm |
The common perception is that modern technology and medicine is allowing us to live longer, but the research seems to be saying that it was not uncommon even for the very earliest humans to live into their 70s. The most obvious benefit to our modern technology and medicine, as your article points out, is that it has greatly increased the odds of survival in infants. Historically, then, it seems that once a person passed the first year of life, chances were relatively good that he or she would live into their 70s. The real value of our technology and medicine, therefore, is diminished somewhat when we compare ourselves to so-called primitive cultures existing today or even the earliest humans.