|23 December 2010
Climate linked to cultural changes in prehistoric USA
Though climate change seems a particularly modern predicament, scientists are finding evidence that climate fluctuations did influence cultural change among inhabitants of prehistoric New England (USA). Research by Samuel Munoz - a graduate student at the University of Wisconsin Madison - published this month in the Proceedings of the National Academy of Sciences, found that every time the climatic needle jumped in the Northeastern United States, so did human culture.
In his study, Munoz and his collegues drew on a database of nearly 1,900 prehistoric remnants from Pennsylvania to Maine that were analyzed with radiocarbon dating. They also used pollen and charcoal records to understand shifts in vegetation and to estimate the size of the human population. They found that climate and human changes seemed to happen in step.
Paleo-Indians, hunter-gatherers known for elegant fluted arrowheads chipped from stone, lived in the region from about 13,500 to 11,250 years ago, when the area had a tundra-like landscape with spruce and sedges - they may have hunted caribou. Around 11,600 years ago, the climate warmed rapidly, and pine forests encroached. At the same time, the archeological records shifted to a different culture - that of the Archaic period, with people who were less nomadic and hunted smaller game using a different style of pointed stone. They are also thought to have started fishing.
About 3,800 years ago, when surface water temperatures cooled in the Gulf of Maine, another transition occurred: from people who buried their dead with functional stone artifacts, to a different culture - possibly outsiders - who cremated their dead. About 3,000 years ago, when there was a change in lake levels, the Woodland culture emerged, whose people used pottery and began to cultivate plants.
Researchers are careful to say this does not reflect a simple cause and effect situation, with climate changes directly altering human life. But coincident changes in people and the environment should be studied to understand the causes, they say. And artifacts that have been dug up may be signs of broader shifts. "It's not a straightforward relationship," Munoz said. "Pottery is probably symbolic of change in general, but it is what gets preserved and what's most obvious and indicative."
Brian Robinson, an archeologist at the University of Maine, says there is no doubt climate change can affect lifestyles. But he points out that environmental change would not have been uniform across such a large area, and that the radiocarbon dates are a 'shaky' signature of population and cultural change - in part because the database does not include enough details about how archeologists decided which culture each artifact is from.
Edited from The Boston Globe (20 December 2010)
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