Scientists have confirmed the early appearance of the first humans in America
British and American scientists have proved that the fossilized feces in the Paisley caves in the Western United States belong to the ancient people who lived here more than 12 thousand years ago, before the advent of Clovis culture. The study is published in the journal Science Advances.
For a long time, until the second half of the twentieth century, it was believed that representatives of culture Clovis were the first people appeared on the American continent. Later Dating of the appearance of people in America have been adjusted, and the theory of the "Clovis — first" — denied. Since then, the archaeologists are constantly looking for evidence of the presence of precursors to Clovis.
In the 1930-ies in the Paisley caves, Oregon, scientists have found traces of an ancient presence, as then suggested, person in America, including a number of artifacts of the period preceding the Clovis culture. But skeletal remains not found, so definitely to date the finds did not happen.
In 2007, scientists were able to isolate a sample of human mitochondrial DNA (mtDNA) from the discovered coprolites — fossilized excrement. The results of the DNA analysis — the presence of mitochondrial haplogroups A2 and B2 indicated a kinship with the inhabitants of Siberia or Asia, and the data of radiocarbon Dating — age 14,3–12,7 thousand years.
Then many scientists were skeptical of the results, indicating morphological dissimilarity of these coprolites with human waste and inconsistent findings of the stratigraphy.
British scientists from Newcastle and the University of Bristol, together with colleagues from the University of Oregon conducted an analysis of mtDNA and lipid biomarkers of sterols and bile acids in 21 sample of fossilized excrement from the Paisley caves.
To exclude the possibility of contamination of samples of faeces of animals or the later inhabitants of the caves from leaching of organic substances from the host rocks, the researchers compared the lipids obtained from coprolites, with lipids from the surrounding sediment, and found a completely different distribution, showing minimal leaching of organic matter from the environment.
Ultimately, through the analysis of faecal biomarkers, the researchers confirmed the identity of the human feces to coprolites 13 samples, previously analyzed for mtDNA. The oldest has an age of 12.2 thousands of years.
This suggests that people lived in caves Paisley before the arrival of representatives of the Clovis culture, which was long considered the ancestors of the American Indians.
The authors note in the article that despite the fact that the analysis of lipid biomarkers provides less detailed information compared with the mtDNA analysis, it provides greater assurance of the identity of the coprolites, as well as less sensitive to contamination.
According to researchers, both methods can be used in tandem when studying traces of ancient man, especially in those cases where no skeletal remains.