How and when the Americas were populated remains contentious. Using ancient and modern genome-wide data, we find that the ancestors of all present-day Native Americans, including Athabascans and Amerindians, entered the Americas as a single migration wave from Siberia no earlier than 23 thousand years ago (KYA), and after no more than 8,000-year isolation period in Beringia. Following their arrival to the Americas, ancestral Native Americans diversified into two basal genetic branches around 13 KYA, one that is now dispersed across North and South America and the other is restricted to North America. Subsequent gene flow resulted in some Native Americans sharing ancestry with present-day East Asians (including Siberians) and, more distantly, Australo-Melanesians. Putative ‘Paleoamerican’ relict populations, including the historical Mexican Pericúes and South American Fuego-Patagonians, are not directly related to modern Australo-Melanesians as suggested by the Paleoamerican Model.

The Paisley Caves in Oregon record the oldest directly dated human remains (DNA) in the Western Hemisphere. More than 100 high-precision radiocarbon dates show that deposits containing artifacts and coprolites ranging in age from 12,450 to 2295 (14)C years ago are well stratified. Western Stemmed projectile points were recovered in deposits dated to 11,070 to 11,340 (14)C years ago, a time contemporaneous with or preceding the Clovis technology. There is no evidence of diagnostic Clovis technology at the site. These two distinct technologies were parallel developments, not the product of a unilinear technological evolution. "Blind testing" analysis of coprolites by an independent laboratory confirms the presence of human DNA in specimens of pre-Clovis age. The colonization of the Americas involved multiple technologically divergent, and possibly genetically divergent, founding groups.

Radiocarbon dating of the earliest occupational phases at the Cooper’s Ferry site in western Idaho indicates that people repeatedly occupied the Columbia River basin, starting between 16,560 and 15,280 calibrated years before the present (cal yr B.P.). Artifacts from these early occupations indicate the use of unfluted stemmed projectile point technologies before the appearance of the Clovis Paleoindian tradition and support early cultural connections with northeastern Asian Upper Paleolithic archaeological traditions. The Cooper’s Ferry site was initially occupied during a time that predates the opening of an ice-free corridor (≤14,800 cal yr B.P.), which supports the hypothesis that initial human migration into the Americas occurred via a Pacific coastal route.

Archaeological excavations at the Cooper's Ferry site (10IH73), located in the lower Salmon River canyon of western Idaho, revealed a stratified sequence of cultural occupations that included a pit feature containing stemmed points. However, radiocarbon ages determined on charcoal and bone in the pit feature range between ca. 12,000 yr B.P. and 7300 yr B.P. By considering the effects of postdepositional processes on dated samples, and by comparing the lithostratigraphy, pedostratigraphy, and stable isotope geochemistry of pedogenic carbonates from Cooper's Ferry with other well-dated stratigraphic sections in the canyon, site geochronology is clarified. Based on the presence of key radiocarbon ages and distinctive stratigraphic criteria, we argue that the initial occupation and interment of lithic artifacts in a pit feature at Cooper's Ferry occurred during the late Pleistocene, between ca. 11,410 and 11,370 yr B.P., and not during the early Holocene. Records of geomorphic change and paleoenvironmental proxy data from the site reveal that early occupation in the lower Salmon River canyon corresponds with evolving riparian ecosystems, which must be considered as a contextual aspect of local prehistoric cultural ecology.

stones and bones are the fundamental building blocks of prehistory, especially the deep hominin prehistory. The only thing that survives from the earliest humans, except in rare instances of the humans themselves, is stones and bones in that order. it was in this context that the late archaeologist Glynn isaac (1977) characterized the archaeology of the earliest humans as "squeezing blood from stones." stones and bones must, however, be placed in context, and that largely comes from profiles or rather stratigraphy. stones, bones, and profiles thus constitute the three building blocks of much of the early archaeology from the appearance of earliest humans to the advent of the neolithic or its equivalents on various continents. so it is no wonder that this book, dedicated to two prominent scholars whose careers focused on the earliest americans, the Paleoindians, is about stones, bones, and profiles. in fact, tools and tool making from raw stone material and the remains of food residues, or one of these, are what we find at nearly all Paleoindian sites in western north america. Where we find them and in what contexts are key to understanding the implications of these remains for reconstructing the lifeways of ancient peoples. and by and large, other items are rare or absent, except in a few cases, and often these are likewise made of either stone or bone. We are referring to such things as bone tools (needles, awls, gaming pieces, and others), ornaments (beads), and possibly in a few instances

Forty years ago, Knut Fladmark (1979) argued that the Pacific Coast offered a viable alternative to the ice-free corridor model for the initial peopling of the Americas—one of the first to support a “coastal migration theory” that remained marginal for decades. Today, the pre-Clovis occupation at the Monte Verde site is widely accepted, several other pre-Clovis sites are well documented, investigations of terminal Pleistocene subaerial and submerged Pacific Coast landscapes have increased, and multiple lines of evidence are helping decode the nature of early human dispersals into the Americas. Misconceptions remain, however, about the state of knowledge, productivity, and deglaciation chronology of Pleistocene coastlines and possible technological connections around the Pacific Rim. We review current evidence for several significant clusters of early Pacific Coast archaeological sites in North and South America that include sites as old or older than Clovis. We argue that stemmed points, foliate points, and crescents (lunates) found around the Pacific Rim may corroborate genomic studies that support an early Pacific Coast dispersal route into the Americas. Still, much remains to be learned about the Pleistocene colonization of the Americas, and multiple working hypotheses are warranted.

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The discovery of an artifact cache containing Western Stemmed Tradition (WST) projectile points in a clearly defined pit feature at the Cooper’s Ferry site offers a unique perspective on early lithic technology and logistical organization in western North America. A description and analysis of the cache feature reveals several new insights, including: a rocky cairn capped the surface of the pit feature; some of the artifacts were made from cryptocrystalline silicates found 16 km away; debitage analysis, including aggregate and attribute based measures, identified two distinct lithic reduction stages present in the cache; new radiocarbon assays suggest that the cache is probably not early Holocene in age and may date to associated age estimates of 11,410–11,370 radiocarbon years before present (B.P.). Unlike Clovis caches, the Pit Feature A2 cache at Cooper’s Ferry appears to be a generalized toolkit that was probably placed at the site for future use. If the 11,410–11,370 radiocarbon years B.P. assays date the creation of the Pit Feature A2 cache, then its creators were probably not pioneers in the lower Salmon River canyon but possessed local knowledge about the landscape and raw material sources; these patterns suggest greater time depth for WST foragers.