Paisley Caves human coprolites and occupations (Oregon) (c. 14,300–12,300 BP)

  1. Early pre-Clovis occupations begin at Paisley

    Labels: Paisley Caves, Pre-Clovis

    Radiocarbon dating and later multi-method checks indicate people used the Paisley Caves during a pre-Clovis window often summarized as roughly 14,300–12,300 years before present. This period is important because it falls before (or at least at the very beginning of) the widely recognized Clovis horizon, so it tests older “Clovis-first” models. The site’s key evidence comes from directly dated coprolites and associated sediments and artifacts.

  2. Great Basin pluvial lake forms cave setting

    Labels: Pluvial Lake, Great Basin

    During the late Ice Age, wetter conditions created large temporary lakes in Oregon’s Great Basin, including pluvial Lake Chewaucan. Wave action along the lake’s shore cut rock shelters that later became the Paisley Caves. This geology matters because it created dry, protected spaces that can preserve fragile materials like fiber, bone, and coprolites.

  3. Oldest coprolites dated around 12,300 14C years

    Labels: Coprolites, mtDNA

    A central claim from the Paisley Caves work is that some coprolites were directly dated by accelerator mass spectrometry to about 12,300 radiocarbon years before present (14C years BP). Those direct dates matter because they tie human biological material to a specific time, instead of relying only on nearby charcoal or stone tools. The reported mitochondrial DNA types (A2 and B2) matched founding Native American lineages.

  4. Fieldwork expands coprolite and artifact sampling

    Labels: Excavations, Fieldwork

    Excavations in the early 2000s recovered multiple coprolites and other organic materials from well-defined cave sediments. The growing sample size enabled repeated testing, including direct radiocarbon dating and ancient DNA analysis, and made it possible to evaluate contamination and context more carefully. This step set up the later scientific debate by providing enough material for independent checks.

  5. Science paper reports human mtDNA in coprolites

    Labels: Science 2008, mtDNA

    In 2008, researchers reported human mitochondrial DNA extracted from several coprolites, along with direct radiocarbon dates placing at least some specimens earlier than accepted Clovis dates. The paper argued this was strong evidence of pre-Clovis human presence because it combined biological identification (mtDNA) with direct dating. The findings quickly became a major reference point in debates about early migration into the Americas.

  6. Concerns raised about DNA movement and attribution

    Labels: Controversy, DNA-mobility

    After the 2008 publication, some researchers questioned whether ancient DNA could have moved through wet sediments or whether some coprolites might be non-human. These critiques did not automatically overturn the dates, but they highlighted a key problem: DNA can be water-soluble, and caves can experience periodic water movement. The controversy pushed the project toward more intensive stratigraphic study and additional independent testing.

  7. High-precision dating and stratigraphy reassessed

    Labels: Stratigraphy, High-precision dating

    A later major study assembled a large set of radiocarbon dates and emphasized detailed stratigraphy (the layering and order of sediments) to show that key deposits were well organized rather than badly mixed. This strengthened the argument that the pre-Clovis-aged coprolites were genuinely associated with old layers. It also framed Paisley as part of a broader pattern of early western North American technologies.

  8. Western Stemmed points dated to Clovis-age levels

    Labels: Western Stemmed, Projectile Points

    Researchers reported Western Stemmed Tradition projectile points in deposits dated to around the Clovis time range, and noted the absence of diagnostic Clovis points at Paisley. This mattered because it suggested more than one stone-tool tradition existed early on, potentially reflecting different groups or different regional solutions. In the Paisley story, tools and coprolites together supported a picture of repeated, short-term cave use rather than a single event.

  9. Biomarker study challenges one “human” coprolite

    Labels: Biomarker Study, Fecal Lipids

    A 2014 study used steroidal fecal biomarkers (lipid molecules that can indicate the type of animal that produced feces) on a key specimen previously interpreted as human. The results suggested an herbivore origin for that particular coprolite, showing that morphology and even some earlier tests can misidentify samples. This became an important turning point because it supported using multiple methods—not just DNA—to classify coprolites.

  10. Lipid biomarkers confirm pre-Clovis human coprolites

    Labels: Lipid Biomarkers, Coprolites

    A 2020 study applied fecal lipid biomarker testing across a larger set of Paisley coprolites and reported that not all samples previously labeled “human” by mtDNA were actually human, while still confirming genuine pre-Clovis human coprolites. The authors also reported a new radiocarbon date and argued lipid biomarkers are less vulnerable to water-driven movement than DNA. This helped resolve the debate by separating misidentified samples from a core set that still indicates pre-Clovis occupation.

  11. Evidence reframed: DNA plus biomarkers as best practice

    Labels: Methodology, Best Practice

    By combining older mtDNA work with newer lipid biomarker approaches, researchers increasingly treated Paisley as a methodological case study, not just a single “yes/no” site. The key lesson was that caves can contain mixed signals, so strong claims should rely on multiple independent indicators: direct radiocarbon dating, careful stratigraphy, and chemical or genetic identification. This reframing improved confidence in the remaining pre-Clovis evidence while narrowing which individual coprolites should be used as proof.

  12. Paisley Caves becomes a benchmark pre-Clovis site

    Labels: Benchmark Site, Paisley Caves

    Today, Paisley Caves is widely cited as a benchmark for evaluating pre-Clovis claims because it pairs directly dated human-related material with extensive stratigraphic and laboratory scrutiny. The outcome is not that every early coprolite was human, but that a carefully screened subset supports human presence in the northern Great Basin before or alongside the earliest Clovis-era expansions. As a result, Paisley contributes to a broader picture of early, regionally diverse peopling of the Americas.

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Last Updated:Jan 1, 1980
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Paisley Caves human coprolites and occupations (Oregon) (c. 14,300–12,300 BP)