Figure 4 shows modal ages at deaths on page 334 of this paper: http://www.anth.ucsb.edu/faculty/gurven/papers/GurvenKaplan2007pdr.pdf The modal ages at death for hunter-gatherers peak at, as that tiny square shows, age 69 (or is that 70? It looks like 69). A hunter-gatherer lives 69 years? I don’t know if I can imagine that long of a lifespan for the native americans when Columbus discovered America, or for our ancestors in the middle paleolithic. Am I just being too pessimistic, or am I missing something?
I’m sure it’s not a linear graph from 0 years beginning 30,000 BC to the present average life expectancy.
Why not? Sounds entirely reasonable and the graphs look exactly how I expect they would: high mortality rate in the first few years of life, low mortality in the 20s and 30s. Apart from warfare, what would you expect to be killing hunter-gatherers between the ages of 30 and 60 – at least more than other groups of people?
I wouldn’t be too terribly surprised to see a median age at death somewhere in that vicinity: If you manage to consistently fight off starvation, disease, and the sabretooths, then you live about as long as a modern human before dying of old age. But I would have expected the modal age of death to be in the vicinity of 1 year, or probably less. The mean, of course (the more often-quoted figure), is in between those.
Figure 4 doesn’t include deaths before the age of 15.
If you look at the date in Figure 1 you’ll notice that about half the population dies before adulthood.
Infantile to juvenile deaths have to be treated separately. Otherwise, you’ll have bimodalism.
The paper is using three different statistical terms that are very different and even get confused by the average person today. The first is life expectancy. That is the median age (average age in common parlance) that people die when you aggregate all data including infant mortality, epidemics, war deaths and everything else. No primitive societies had a life expectancy as high as 69 but that is not what the authors are saying.
The second term is life span. That has not changed significantly in human history. It is a built-in death rate that almost all animals have. For humans, the limit is about 120 years but much lower for most individuals. That is the age when little can be done to sustain your life anymore and everyone hits it at a certain point. All stable cultures no matter how far back they were had people that lived to be very old even if there weren’t very many of them. It is just a crapshoot year by year that slowly culls down the older population until only a very few winners are left.
The third term, and the one they focus on the most is the modal age of death. That number just represents the specific age at which the most adults in those populations died. It seems to be filtering out infant and early childhood deaths because those should be the highest overall but I don’t see that specific age among those populations being implausible at all.
Their claim is lower than most developed countries today except for a few places like Russian males that have problems that didn’t exist in the populations in question. I take that to mean that very modern medicine can extend the modal age of death but not the lifespan. The limits of human lifespans still hasn’t budged an inch despite all the scientific research on the matter. Believe it or not, human progress caused somewhat of a bathtub curve on average life expectancy and also the modal age of death for adults. Packing people densely into cities introduced diseases, hazardous work environments and poor nutrition for several hundred years at least in Western Civilization. Hunter-gatherers had hazards of their own but it was a sustainable lifestyle well into old age because they generally had the social structures to support it.
I don’t see anything implausible in the paper but I only took a first pass over it rather than using a magnifying lens.
Oh, OK, I can certainly buy that there’d be a local maximum around the late 60s or early 70s. It’d be smaller than the the infant one, but if you’re excluding that one…
Starvation and childbearing. It’s not true everywhere, but in a lot of places the hunter-gatherer lifestyle is precarious in terms of calories expended vs. consumed. All you need is a couple of bad years per generation to lower that number dramatically. Also, childbirth has traditionally been a source of high mortality for women; it’s not clear from a casual reading of the graphs what the gender distribution in the sample was.
Since the graphs don’t show that, these are either smaller factors than I’d expect, or they’ve been accounted for some other way (like the child mortality omitted by starting the graph at age 15).
This is a really good summary of life expectancy statistics.
Lots of people who start learning about historical life statistics read that the “average life expectancy” was 35 in some part of Europe in the Middle Ages and figure that means that there were 30-somethings dropping dead all the time. This wasn’t the case. What was more typical was for people to live to 50, 60, or maybe 70 but have had many brothers and sisters who died as babies or little kids. Even as late as 1800’s America it was like this - I have a great-great-great grandma and grandpa who are buried out on the prairie with most of their kids who died in the first few years of their lives. I’m descended from, I believe, the only boy who lived to age 20. G-g-g-grandpa lived to his seventies.
Accidents, malnutrition, poisoning. Indeed, a glance at Figure 4 shows far more hunter-gatherers, percentage-wise, dying in their 20’s and 30’s than is the case in modern societies. The death percentage appears to be about 10 times as high in the 20’s, tapering down to twice as high in the 50’s.
More hunter-gatherers died at age 69 than at age 45. That absolutely, positively does not mean that “most hunter-gatherers lived to 69”. Many were also dying at 24, 30, 44, 46, and so on. The number dying at 69 is greater than the number dying at any other single age–that’s all.
There are several things I need to know.
- What is the definition of “peak modal age at death”, expressed in common language that we can intuitively grasp?
- What is the peak modal age at death for modern western man?
- What is the peak modal age at death for modern man in pre-industrialized economies?
I googled /peak modal age/, and aside from questions in numerous forums about this very article, all I got was hits to /peak model agency/.
I would presume that 69 would be accurate for a person of any era whose death was not directly caused by an unnatural event. or whose life was not extended by unnatural intervention. (E.g., I have a stent.)
This one has already been answered in this thread a couple of times. The peak modal age of death refers to the age (expressed in whole years) that have the absolute greatest number of adult deaths. To calculate it, you simply list the number of deaths that happen at every age and pick the one that has the most.
You have to break it out by country and demographics but here is a good paper that talks about modal age of death changes over time in several first-world countries. The adult modal age of death was around 80 years for these first-world countries in 2000. The life expectancy is in the 70’s for most of those countries (life expectancy is almost always much lower than modal age of deaths for adults because of what these two different statistics represent.
But here’s one difference, one that I have noticed even just in my lifetime. In the past, when you were 60 or 70 you were OLD. Now, what with what we know about eating right, not smoking, exercise, and modern medicine, one can have a happy active lifestyle up thru 90 even.
This brings up a weird point sometimes used by smokers, that sure they live 10 years less, but who wants those last ten years of life anyway? Except that those last ten years of being OLD is just moved down, and in many cases extended.
I found more information. According this link, ro.uow.edu.au/cgi/viewcontent.cgi?article=1591&context=hbspapers humans are one of a few mammal species that live longer than they should based on body size. It says that the lifespan of humans should only be 26 years. I myself believe that humans were meant to have a lifespan of 25 years, because human skeletons usually finish development at age 25. In other words, they’re full fledged skeletons at this age. But if a human lives past age 25, maybe they’re just lucky. That’s my opinion, at least.
However, it is stated that humans live 35 years in the wild, Teaching Science Fact with Science Fiction - Gary Raham - Google Books and that the range of their lifespan in the wild is 35-40 years: http://www.ellisonfoundation.org/content/functional-tests-replicative-aging-organotypic-skin-equivalents
Although that other paper I linked shows the modal age of hunter-gatherers (none of which have much contact with modern medicine) as being 69 years, and is the first study to track ages at deaths for all hunter-gatherer populations on earth, there are very few hunter-gatherer populations around. A human who is out in the earth as he/she is born to, who has to look for food and water, and without ever going to a hospital, or any other form of medicine; this is the natural way humans live. Only (some) hunter-gatherers live like this, but they are only a minority in the world population. And 69 years is the modal age at death for this minority. But if everyone in the world was a lived like this, the modal age at death might be (and most likely, it would be), 35 years, with a range of 35-40 years. So to summarize:
Lifespan of most people who are currently still living the natural way (out in the earth as he/she is born to, who has to look for food and water, and without ever going to a hospital, or any other form of medicine): 69 years
Lifespan of most people living the natural way, if everyone on earth lived that way: 35 years (range of 35-40 years)
I think I’ll just post my opinion again. I don’t know, seems like a good opinion to me. My opinion: the natural lifespan of humans is 25 years, because human skeletons usually finish development at age 25 and are full fledged skeletons at this age.
Somewhat unrelated, but from what I have read of North Korean prison camps, most people do not make it past their 40s and 50s. However despite the beatings, lack of medical care, lack of social support, starvation, exposure, torture, executions, etc. a lot of people make it to early/middle middle age. However they don’t make it much longer than that.
As **Shagnasty **says lifespan hasn’t changed much if at all, while life expectancy has gone up. The maximum lifespan is about 120, but most humans fall in the 70-95 range (I think almost 20% of people live to be 90 anymore though, but the % who live to 100 is something like 1-2%). The elimination of childhood diseases has created a situation where up until around the mid-50s, about 95% of people can be expected to survive.
http://healthyfoodscience.com/wp-content/uploads/2013/04/ft096n99tf_00004.gif
Around age ~55, the survival rates start to drop off a cliff. The biggest medical advances we have are public health ones. Protect the body from trauma, infection, malnutrition, exposure, predators, violence, etc. and people live fairly long. But the body starts falling apart in middle age, and accelerates rapidly after 60. I don’t see why hunter gatherers would be different.
But most people don’t. Most of the people born in 1923 have died.
Even discounting childhood mortality, life was typically shorter than that. The average age of death for French kings (who reached adulthood) between 1000 and 1500 was something like 46 years, with only one living to be 60. English kings during the same period did a bit better (may 53, with several reaching 60).
Statistics might let people think that life was shorter than it really was, but the examples of famous people let them think that life was longer than it really was on the other hand. You don’t get to become a famous writer/general/politician/whatever who will be remembered for centuries if you kick the bucket at 40, typically. So you live longer than most of your contemporaries, long enough to become important/famous and people think of you when they picture “renaissance” or whatever and assume that your unusuallly long life was more or less typical.
Even with kings, you can see this bia. Essentially all famous kings are those who had long reigns, and essentially all kings who had a long reign are famous. You don’t need to have been a good king to be perceived as a major historical figure. Only to have a long reign, so that a lot of stuff would happen while you’re sitting on the throne.
Minor nitpick: life expectancy is generally reported as mean age at death, not median. Other than that, great post.