Posted on 07/06/2004 2:35:35 PM PDT by Pharmboy
WASHINGTON (Reuters) - Old people may hold the key to human civilization, U.S. researchers said on Tuesday.
They found evidence that, around 30,000 years ago, many more people started living into old age, in turn fueling a population explosion.
Rachel Caspari of the University of Michigan and Sang-Hee Lee of the University of California at Riverside believe that groups in which old people survived better were more successful, in turn allowing more people to live into old age.
"There has been a lot of speculation about what gave modern humans their evolutionary advantage. This research provides a simple explanation for which there is now concrete evidence -- modern humans were older and wiser," Caspari said.
"We think with increases in longevity two things happened to increase survivorship," Caspari, an anthropologist specializing in evolution, added in a telephone interview.
"First, individual people have more kids because if you live longer you can continue to have kids after your kids have kids. And second, you can contribute to your extended family and increase the survival of your progeny. This can increase population size, and it can happen quite quickly."
The finding, published in this week's issue of the Proceedings of the National Academy of Sciences (news - web sites), supports the so-called "grandma hypothesis," Caspari said.
This credits grandmothers with helping to raise their extended families, contributing to a group's success.
Caspari and Lee studied 768 different human fossils, including examples of Cro-Magnon, which are early Homo sapiens who lived in Europe, Neanderthals, an earlier type of Homo sapiens that died out about 35,000 years ago, and earlier prehumans such as Homo erectus and australopithecenes, which date back as long ago as 3 million years.
JUMP IN LONGEVITY
"What we looked at is differences in the proportion of people who were living to be older," Caspari said. Some individuals may have lived to great age, but at some point humans as a species began living longer on average than other primates and Caspari and Lee wanted to find out when and why.
They divided the fossils into two groups -- adults of reproductive age, which they settled on as 15 years, and adults that lived to be twice as old, 30, based on tooth wear.
In primitive societies, people are often grandparents at 30, Caspari pointed out.
"We found this proportion of older to young adults in the fossil record increased over time," Caspari said.
"In the Upper Paleolithic that proportion just skyrocketed. It was just unbelievable. It increased five-fold. We didn't expect that."
Caspari and Lee rechecked their numbers and analysis.
"But then we started to think about it and thought we really shouldn't be surprised, because there is a behavioral change that took place over time at the same time," Caspari said.
"You start to see a change in symbolic behavior. You see art. You see a large number of people being buried with jewelry, with body ornaments."
Perhaps around this time people started to value and take care of the weak and the old, and in turn benefited from their help and experience, Caspari sad.
This could be when the uniquely human condition of menopause evolved and started to have an effect, Caspari said. Women not burdened by childbearing could focus on their grandchildren and other kin.
"We live in a society that is so geared toward younger people. It is nice to realize that it might be older people that make us human after all," Caspari said.
Evolution *ping*
Who knew that endless haggling in supermarket checkout lines could benefit society to such an extent?
This credits grandmothers with helping to raise their extended families, contributing to a group's success.
Wouldn't these findings merely support a "grandparent hypothesis"?
LOL! The coupons...the coupons!
Check out the "Key Words" above...
Perhaps around this time people started to value and take care of the weak and the old, and in turn benefited from their help and experience, Caspari sad.
Interesting that they aren't looking at technological changes that allowed humans to suddenly start living longer. That was my first thought--what technology change took place 30K years ago?
Good question...and the answer might lie in the domestication of plants and animals. It used to be thought that farming was only 15,000 years old, but they just made discoveries that pushed it back to 20k. Another 10k would not be hard to imagine.
I was thinking about something as simple as cooking meat (sanitizing food with fire and heat), thereby reducing food-borne diseases and extending lives. What time in our past is it thought that we tamed fire?
It's disappointing that what appear to be serious scientists would make such an elementary mistake. The infestation of politically correct science is pretty bad in anthropology, but I associate it more with cultural than with paleo-anthropologists.
Most of the important individual people in history lived to over 45. It apparently takes that long to notice a few things.
Perhaps it was a combination of better weapons (atlatl throwing spear?) and the domestication of the dog.
A tribe that isn't having to work themselves to death just to keep from starving actually has time to develop a culture.
Things like planning for lean years--which young people might not think to do--could make the difference in survival of a city. Old people know there could be 7 years of famine after 7 years of surplus.
Thanks for the post. I'd appreciate being added to your evolution ping list.
Barf! Leftist academics refuse to accept the basic truth that modern man is the optimized product of war making. Having older people around has little to do with better child care. It has everything to do with being better at war. If a tribe with an average age of 18 goes to war against a tribe with an average age of 30, the older and wiser tribe will usually win. And in prehistoric times they typically killed off the losers, for example the Neanderthals.
I am a grannie!
One thing that worries me is how many technologies are dying out as the only people who know about them are dying off. To be sure, many newer technologies are better in many ways, but they often put increasing reliance upon fewer and fewer key societal points of failure.
While some people might question the value of knowing, e.g., how to design a mechanical typewriter so as to provide optimal key feel, type clarity, and reliability; or how to tweak a three-tube amplifier for optimal sound quality; or how to fit a complete usable Pascal development system in less than 27,000 bytes; nonetheless, these are skills that--even as applications change--could well be useful in the future. Unfortunately, in fifty years' time I don't know that anyone will know how to do any of these things.
Alexander
Jesus
Right basis (war is the primary shaper of all things known to man), slightly wrong details. The winning side would have similar characteristics as an NFL team ie peak size/strength/agility in the early-mid 20s. However, coupled with an experienced 'couch' (say, someone in their 30s), they would be a formidible foe. Hmmm, Alexander, anyone?
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