In the summer of 2007, a field school from the
University of Oregon identified the oldest human
DNA yet discovered in the Americas. This assertion is based on analysis of several
coprolite samples found in the Paisley Caves complex. In total, workers have obtained over 280 radiocarbon dates and DNA analysis from more than 60 coprolites from the Paisley Caves. Coprolite analysis at varying ages revealed that these occupants were omnivorous, eating a combination of foraged plants, seeds, small mammals such as rodents, fish, and insects like beetles. Knowledge of this omnivorous mode of sustenance supports the notion that the coprolites are human in origin. Other authors have questioned the authenticity and relevance of the evidence gathered from ancient DNA and
stratigraphy and challenge the morphological assignment of the coprolites to humans. Similarly, it is uncertain if damage to pre-Clovis animal bones at the site was the result of human butchering or animal trampling. The coprolites were found in the same level as a small rock-lined hearth some below the modern surface. Also discovered at that level was a large number of bones from waterfowl, fish, and
large mammals, including extinct
camels, horses, and bison.
Radiocarbon dating dates these coprolites to 14,400 years ago, probably representing a pre-Clovis occupation. DNA analysis provides apparent genetic ties to Siberia or Asia, rather than a distinct wave of migration.
Clovis ancestors, previously thought to be the first humans to live in the Americas, are currently thought to have crossed the Bering Strait into North America 12,000 cal yr BP. However, the Paisley Caves and other archaeological sites throughout the Americas, such as
Monte Verde, have been dated to earlier than Clovis technologies. Scientific debate has shifted in recent years to question this long-held "Clovis first" hypothesis. Evidence at other archaeological sites—as well as previous work at Paisley Caves in the 1930s—had been thought to provide such evidence, but questionable excavation techniques clouded the issue. Knowing this, the University of Oregon team worked carefully to avoid the mistakes of the past. == Coprolite controversy ==