In 1996, Sandweiss, Reitz and three other scientists co-authored a paper in Science presenting new evidence that conditions indicating the onset of El Nio about 5,000 years ago. Their conclusions were based on the identification of mollusk and fish remains from archeological sites.
Some critics of that paper suggested that the mollusks might have lived in warm water embayments that would not accurately reflect temperatures in the open ocean.
"The evidence in this paper, based on fish that live off shore, strongly supports the conclusions that we reached in 1996," says Sandweiss.
The current paper in Science is allied to two other papers by Andrus and Crowe, now in press at the Journal of Archaeological Sciences and the journal Paleoceanography.
The JAS paper showed that that cooking and subsequent burial for 5,000 to 8,000 years didn't alter the oxygen isotope signatures. The research to be published soon in Paleoceanography establishes the use of otoliths as proxies for temperature-using modern fish to show the technique works. The new Science paper in a sense brings the research together.
Andrus has participated in archeological activities led by Sandweiss in Peru. He performed analyses of oxygen isotopes on otoliths from modern fish as well as seven sea catfish otoliths collected from the Ostra site in 1991 and five from the Siches site in 1995. Siches is located in far northern Peru near the border with Ecuador, whereas Ostra is located about midway between Siches and Lima, the Peruvian capital.
The results at Ostra showed that, although winter water temperatures were similar to those of today, summer temperatures prior to 5,000 years ago were much warmer than they are today. Thus, the average annual temperature was about three degrees Celsius warmer than present. At Siches, although there was little seasonal varia
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Contact: Phil Williams
phil@franklin.uga.edu
706-542-8501
University of Georgia
21-Feb-2002