Paleolithic Healthy Life Extension
A piece on evolutionary and social explanations for large increases in average human life span in the Paleolithic period is currently doing the rounds. Quoting from the Betterhumans version:
A dramatic increase in longevity that took place during the early Upper Paleolithic Period, around 30,000 BC, could explain humanity's evolutionary success....
"Increased longevity, expressed as number of individuals surviving to older adulthood, represents one of the ways the human life history pattern differs from other primates," say the researchers. "We believe it is a critical demographic factor in the development of human culture."
...
Details of how longevity increases over the course of human evolution provides a wealth of information on how human social networks developed.
The number of people living to older adulthood would have allowed early modern humans to pass down specialized knowledge from one generation to another.
Old age would have also promoted population growth and strengthened social relationships and kinship bonds.
The presence of grandmothers, for example, confers an important evolutionary advantage as they transfer knowledge and other resources to their daughters and their daughters' offspring.
An increase in the number of relatively old people therefore likely gave modern humans a competitive edge that ensured their evolutionary success.
Of course, "older" in this context means making it to 30. Romanticized notions of prehistory obscure the fact that life back then was nasty, brutish and short. Randall Parker has comments - serious and otherwise - at FuturePundit:
Here is my FuturePundit speculation on this report: the lengthening of lifespans created a selective pressure for higher intelligence. When people started living longer they accumulated more knowledge. The increase in available knowledge increased the value having a high cognitive ability to sort through, analyze, and apply that knowledge. A smarter person can notice more and learn more useful lessons from an accumulation of life experiences than can a less intelligent person. So genetic mutations that lengthened lifespans may have led to selection for mutations that increased intelligence. Then the selection for higher intelligence likely increased the value of living longer still more which would have fed back into selecting for longer lifespans.But important questions remain unanswered: Did any Upper Paleolithic civilizations collapse from spiralling taxes enacted in a futile attempt to meet unfunded pension liabilities? Were massive human migrations across the continents driven by a desire to escape from old age pension taxes?
The important point to take away from this is that the presence of more relatively older, wiser people enables a more successful society to emerge. This was true back then, and it is still true today - one more reason for us to strive to extend the healthy human life span.
The first human lived 930 years.
Some progress we're making today!
Back to reality. This is interesting, but I would like to see statisticl on the longevity spans of all the great apes. Chimps frequently live to be grandparents, and use more tools than the other apes. Just a thought.
In college remember reading about hunter gatherer tribes in what is now Namibia. Quite a few actually make it into their 50's and 60's. Do not take an AVERAGE age of 30 to mean people were keeling over at 30 and 1/2 years. In the hunter gatherer society we read about in class a lot of infants died--due to disease and genetic problems, and a lot of teenagers died due to disease (in many case seemingly genetic) and accident (teenagers -- go figure). That of course brought down the average age, but the people who were left were very healthy.
Hunter gatherer societies often had better diets than the agrarian populations later on. At least when I was in college (10 years ago!) there were articles on how after a community "settled down" the average height would drop several inches! Also, plagues did not effect nomadic peoples as much...if people were parked in an area and a disease set in they picked up and moved. Obviously this wouldn't work for all diseases, but it would nip an epidemic like cholera in the bud.
Re: Bible thumper up there: The Bible is fiction, anaology and folk tales, buddy. Get over it.
Many people misunderstand life expectancy, somehow imagining that LE of 30 means 30 year olds are decrepit. No, it means you most likely have a massive number of infants dying before their first year.
At the beginning of the 20th Century, LE was in the mid 40's. Many people lived to their 80's. It was the infant mortality that was the factor.
The real trick to defeating aging would be an increase beyond 80 years.
We seem to built for around 70 years or so (still longer than most animals our size), normal wear and tear.
We also need to make those extra years worth it. What is the point to living to 100 if you remember nothing of the first 99 or if your life consists of sitting and staring out a window.
The increase in life span 32000 years ago was more likely a drop in infant mortality. That means more people making it to breeding age, which means more people, which means both a more complex society but also an urge to expand to deal with the population pressure and a greater likelihood of new ideas (and even exceptional individuals)
More people equals more ideas. That point in time may have been the critical point where we passed beyond mere maintenance and had enough people to afford to be clever.
Carolynn is absolutely right. Infant mortality rates were high into the late 19th century, but people who made it out of childhood could look forward to 60 or so years of life, at least. Even in western Europe in the Middle Ages, where two-thirds of all children died before age 10, people living to 90 or 100 was not unheard of.
But life expectancy is irrelevant here. The article explains that the researchers arrived at their conclusion by estimating the ages at death of ancient remains. Five times more 30-year-old-plus remains were found beginning at 30,000 years ago. This indicates that indeed people suddenly started living longer, not that fewer died in infancy. The big question is why.
The usefulness of older folks to society depends on two items: One is their ability to continue to be productive. Hunting and gathering is a tough business and the accumulation of dings could mean becoming less useful by around thirty. Maybe not. But look at professional athletes in the contact sports, even as they are attended by the best physicians and trainers. Maybe it was a matter of technology (arrows and spearthrowers) which allowed killing from a distance. Did that technology show up about 33000 years ago?
The other benefit is that the older folks have experience that can be passed on to the younger folks. That requires the younger folks paid attention to the older ones. Does that sound reasonable?
How much history is repeated because "it's different this time, and besides, we just want to."?
I go with the technology change.
Uhh, a five fold increase which left lifespan at 30 years means that the previous value of lifespan was 6 years. Other things being equal, that would mean that hardly anyone reached puberty. With typical high infant mortality and the normal two year spacing between unprotected births, a population with these characteristics would vanish in a few years.
Assuming that the original researchers surely had some degree of numeracy and that most journalists are highly innumerate, it is likely that some slippage occurred in this story.