When testing the carbon in the fossilized exrement at the Paisley Caves, Jenkins and his colleagues found that in most cases, it was older than the materials it was found in, indicating it came from the surrounding environment and not from later material that filtered down into the lower soil.
"Culturally, biologically and chronologically, the theory is no longer viable.
"The dissimilar stone artifacts, as well as the DNA-profiling of the human excrement, show that humans were present before Clovis and that another culture in North America was at least as old as the Clovis culture itself." An 11,000-year-old Clovis spear point, with the characteristic notch at its base that distinguishes it from the Western Stemmed spearhead.
"What it does is raise the spectre further that glaciers blocked the way through the middle portion of the northern part of the continent — in other words, Canada was under ice," Jenkins said.
"And even if the ice-free corridor was open, we are not certain that it was a pleasant or habitable environment to be, so there's a lot of questions about the feasibility of bringing somebody through the middle portion of the continent and into the northern plains of the United States through Canada.…
The sediment contains layers and layers of dust, twigs, sand, soil, bones and other plant and animal matter, including chunks of fossilized excrement from different periods.
To establish how old the DNA is, the archeologists had to extract a fibre of hair, bone or fibrous plant material that survived the digestive process and apply radiocarbon dating methods to that — since the genetic material itself cannot be carbon dated.
(Virginia Deptartment of Historic Resources/Wikimedia Commons) The Clovis First theory of how North America was settled proposes that a group of Paleo-Indian people, dubbed Clovis after the New Mexico town where the first evidence of them was found, were the first humans to settle in North America.
They are believed to have arrived from Asia via a land bridge over the Bering Strait at the end of the last Ice Age and then spread throughout the continent.
The find suggests North America was colonized by multiple cultures, some of whom arrived possibly earlier than the Clovis.