Lifespan
There seems to be a lot of contention about human lifespan, particularly during hunter-gatherer times.
Currently, the world's mean (average) lifespan, across all countries, is 73 years (1). Not everyone knows this, and many people think it is higher. To be fair, this mean life expectancy is, of course, slightly higher in many western countries, and slightly lower in many non-western countries. However, even in the west, the average lifespan appears to be plateauing and, by some estimates, may have peaked already (2).
In 1651, the English philosopher, Thomas Hobbes, stated that life for anyone lacking the amenities of civilization, life would be "nasty, brutish, and short" (3). Somehow, almost everyone seems to accept this idea as a fact, one that has been propagated down the centuries. In 1961, the French anthropologist, Henri Vallois, specifically applied such a notion to our hunter-gatherer ancestors when he proclaimed that among early humans, “few individuals passed 40 years, and it is only quite exceptionally that any passed 50” (4).
So that is the truth - are Hobbes, Vallois and everyone else, correct? Let's have a look.
The Best Evidence
Whenever one is examining contentious issues, particularly in the face of sub-optimal data (as we cannot examine our hunter-gatherer ancestors, since they are no longer alive), it is usually optimal to focus on the best evidence available. With respect to hunter-gatherer mortality, an extensive 2007 study, written by a pair of United States anthropologists, Michael Gurven and Hillard Kaplan, arguably fits the bill (5).
Gurven and Kaplan examined a diversity of relatively isolated, small-scale populations still living ancestral lifestyles in several continents across the world, which was done in a "cross-cultural" manner. They picked both hunter-gatherers, as well as forager-horticulturalists that had adopted a degree of agriculture into their lifestyles. Their study sample represented the most complete set of pre-industrial populations available, and it was notably larger than any previous study that had been done until that time (or any I can find since). In essence, the modern populations they studied had lifestyles that were as similar as possible to those of ancestral times. |
Average modal (most common) ages of death for several modern hunter-gatherer and forager populations (5). |
Specifically, Gurven and Kaplan divided the populations into three groups. The first group, the hunter-gatherers, included populations such as the !Kung (from modern-day Namibia, Angola, and Botswana), the Hadza (Tanzania), the Ache (Paraguay), the Hiwi (Colombia), and the Agta (Philippines). The second group, the forager-horticulturalists, included populations such as the Tsimane of Bolivia. The third group, the acculturated foragers, included populations such as the Indigenous of Australia.
Following the analysis, Gurven and Kaplan determined that the average modal (most common) age of death for these populations was 72 years, with a range of 68–78 years. The most common causes of death were infective illnesses (70%), followed by homicide (20%). Only 9% of deaths were attributed to disorders such as the metabolic syndrome, atherosclerosis, and cancer, with little data available for neurodegenerative disorders (notably, these four disorders are now responsible for the vast majority of deaths in the west today). Since it was not uncommon for adults to reach the 70s, it was suggested that previous inferences, most of which were based on reconstructive data, were unreliable. |
Graph of the frequency distribution of ages of death, comparing ancestral populations with modern ones (5). |