The Paisley Caves, also called the Paisley Five Mile Point Caves complex, are a group of eight caves in a dry and empty area of south-central Oregon, United States, located north of the modern city of Paisley, Oregon. The caves are found in the Summer Lake basin at an elevation of 4,520 feet (1,380 meters) and face west. They were formed in a ridge made of rocks from the Miocene and Pliocene eras, including basalt and softer volcanic materials, by waves from Summer Lake during the Pleistocene era. One of the caves may contain evidence of the oldest confirmed human presence in North America. The site was first studied by Luther Cressman in the 1930s.

Since 2002, scientific research in the Paisley Caves has uncovered important findings, such as fossilized human feces with the oldest DNA evidence of human life in North America, along with tools, artifacts, and animal remains. The DNA was dated to about 14,300 years ago, which is around 12,000 BC. The caves were added to the National Register of Historic Places in 2014.

Significant findings

In the summer of 2007, a field school from the University of Oregon found the oldest human DNA discovered in the Americas. This claim is based on analysis of several coprolite samples found in the Paisley Caves complex. Workers have collected over 280 radiocarbon dates and DNA analysis from more than 60 coprolites at the site. Analysis of coprolites from different time periods showed that the people who lived there ate a variety of foods, including foraged plants, seeds, small mammals like rodents, fish, and insects such as beetles. This evidence supports the idea that the coprolites are from humans. Some researchers have questioned the reliability of the DNA and stratigraphy evidence and the accuracy of identifying the coprolites as human. It is also unclear whether damage to ancient animal bones at the site was caused by humans or by animals.

The coprolites were found in the same layer as a small rock-lined hearth located about 7 feet (2 meters) below the current ground surface. At that same level, many bones from waterfowl, fish, and large mammals, including extinct camels, horses, and bison, were also discovered. Radiocarbon dating places these coprolites at about 14,400 years ago, likely from a time before the Clovis culture. DNA analysis suggests a genetic connection to Siberia or Asia, rather than a separate migration wave.

The Clovis people, once believed to be the first humans in the Americas, are now thought to have crossed the Bering Strait into North America around 12,000 years ago. However, sites like Paisley Caves and Monte Verde in South America have been dated to times earlier than the Clovis culture. Scientists now debate the long-held belief that the Clovis people were the first to arrive in the Americas.

Earlier evidence from other sites and work at Paisley Caves in the 1930s raised questions, but poor excavation methods made it hard to confirm. To avoid past mistakes, the University of Oregon team carefully collected evidence. Some theories suggest that people arrived in North America along the Pacific Coast, passing through areas now in Oregon. DNA from coyotes, foxes, and dogs or wolves was also found at the site.

Coprolite controversy

Recent studies have raised concerns about the accuracy of radiocarbon dates from these coprolites, based on their shape and possible contamination from human DNA in the surrounding soil. Coprolites found in lower rock layers contained both canid (dog-like animal) DNA and human DNA. Other coprolites mixed with different materials had no human DNA and were instead linked to animals like camels and lions, with dates of 12,265 radiocarbon years. Nearby soil samples also showed human DNA, supporting the idea that water may have moved DNA into the coprolites.

Although DNA results are unclear, other findings from the coprolites suggest human activity before the Clovis culture. Coprolites contain lipids and other organic chemicals from digestion, called fecal biomarkers. These chemicals are stable and resistant to water, making them more reliable than DNA for studying buried coprolites. A human-made tool made from bulrush was found above a coprolite and dated to 12,270 years before present, further showing human presence before Clovis. These findings support the idea that the Western Stemmed Tradition points are the oldest known stone tools in the Americas and older than Clovis points.

Western Stemmed Tradition at the Paisley Caves

Artifacts discovered in the Paisley Caves, including coprolites, do not look like traditional Clovis points. Instead, they belong to a group of people now called the Western Stemmed Tradition. The Western Stemmed Tradition uses tools similar to Clovis technology, such as projectile points, and has shapes and methods that match tools from Africa, Europe, and Asia. It was once believed to have developed after Clovis technology, but findings in the Paisley Caves show they existed at the same time. Dating methods using fecal samples support this idea. Additionally, the projectile points from the Paisley Caves were preserved better than anywhere else in the western United States, making it easier to study their features.

Western Stemmed Tradition points have a different shape from Clovis points. They have narrow, two-sided tools, shoulders, and thicker, curved bases, unlike the longer, triangular blades of Clovis points. The way these points were made also differs. Signs of repeated sharpening on Western Stemmed Tradition points suggest they might have been used as knives for cutting and skinning animals.