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Stone Age Indians recognized environmental limits
STANFORD -- Modern archaeology tends to assume that ancient hunting-gathering societies either depleted their resources and moved on or, when their population outgrew the available food supply, developed new resources or agriculture.
Stanford University archaeologist John Rick believes he's found an exception: a Stone Age people in South America who recognized and lived with the limitations of their environment, including managing their population.
Rick studies the remains of pre-ceramic societies that lived in caves in Peru's puna, the high-altitude grasslands of the Andes, from 10,000 B.C. to 2,000 B.C. Except for the earliest occupants, these hunters appear to have settled down in a relatively cold climate for thousands of years.
"This culture really goes against the idea that population growth is a simple, driving force that leads people to settle down," Rick said. "More important, these people appear to have had a consciousness that population size had to be regulated in terms of the resources they had."
For the puna sites, that seems to have been about 200 people.
The evidence he has gathered in 13 summers of excavation at sites about 100 miles northeast of Lima indicates that, at 14,000 feet above sea level, the only vegetation available to the prehistoric Indians was grass, and the only exploitable animal was the llama-like vicuna.
Rick's clues come mostly from excavated animal bones and tools.
"The quantity of animal bones that exists on our sites, I'm thoroughly convinced, doesn't exist in any other part of the world," he said. "We are dealing with extremely high densities - probably in the range of 200 million animal bones and half a million stone tools. These very large samples across the timeline indicate a prolonged human use of a limited resource."
The ages of the animals killed help determine the hunting strategies used, he said.
"As hunting became increasingly conservation-minded across time, the puna people avoided killing the very young animals. At the same time, a lack of old animals among the bones seems to indicate that populations were groomed toward younger, more healthy animals."
The similarity in style and economic use of stone spearheads indicate that all but the earliest highlands hunter society "lasted a very long time with very little change," he said. Unlike coastal Peruvian sites where the tools at different strata indicate significant change over time, on highlands sites, "the earliest thing that shows up is what we see for 10,000 years."
"We can pretty well document that the people were settling down not because there was no place to go but because they saw no reason to be mobile," Rick said. "In order to have that option to choose, they must have been able to manage their resources very effectively.
"And the flip side of managing your resources is maintaining your population within reason.
"If you let your population grow, no matter how well you manage your resources, you are going to be in trouble eventually," he said. "We know that pretty well from the modern world."
Why did an understanding of environmental limits develop among these prehistoric hunters and not others?
"It is a very different type of environment from most," Rick said. "The main vegetation is grass, so if you got up on a high point 10,000 years ago and looked down over a valley system, you would have been able to see the animals down below. This is not like deer hunters who, after 10 years of over-exploitation, realize there are no deer left. If there is a problem in this environment, you could see it right away.
"Secondly, if you run yourself out of the primary resource, you know that what's left isn't very much."
There is no evidence of infanticide at the puna sites. Sexual abstinence or termination of pregnancies are more likely methods of population control, as well as forcing offspring to marry into other villages, he said. One cave has drawings depicting the vicuna kicking their yearlings out of family groups. Rick speculates the drawings were used as a model for human behavior.
The earliest South Americans
Rick's comparisons of Peruvian highlands and coastal Stone Age tools from around 10,000 B.C. have also led him to conclude there were humans in South America some millennia before that time - something archaeologists have had trouble proving directly.
An expert on lithic technology, Rick analyzes stone tools to determine both their economic uses and their style - non-utilitarian embellishments such as a notch on the base of a projectile or two indentations on its sides.
Tools in use in the Andes region around 10,000 B.C. fall into at least three stylistic variations, he states in a paper he is preparing for a Feb. 9 symposium on Native American Origins at the annual meeting of the American Association for the Advancement of Science. "There has to be some time for a progenitor culture to have radiated out to create these three very distinct traditions," he said.
"Given the stylistic diversity at 10,000 B.C. in the Andes region, there must have been someone either entering South America or somewhere else in South America significantly prior to that time."
In contrast, North American spearheads from that timeframe are technologically uniform and related to the earliest identifiable North American culture site at Clovis, N.M.
More answers lie in the ground in the puna, but hostilities between the Shining Path guerrillas and the Peruvian military have kept Rick and his students from fieldwork there since 1986.
"I can't work without students, and there's no way I can take students into that situation," Rick said.
"The minute peace comes, I'll be back digging for further clues."
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