Despite more than a century of investigations, archaeologists have found few prehistoric sites over 3,000 years old in California's Central Valley. Yet, recent surface inventory, geoarchaeological trenching, and archaeological excavations along the Sacramento River near Hamilton City, California, identified 10 archaeological sites and 15 occupational components spanning the last 7,000 years. Half of these components occurred solely in buried contexts. Five were over 2,500 years old and include some of the earliest evidence for human occupation in the Sacramento Valley. Importantly, several key sites occur in contexts mapped as Pleistocene-aged, Modesto deposits. These results underscore the role discovery bias may play in structuring the archaeological record of the Sacramento Valley and the need for more careful assessment of the geomorphological setting and age of potential deposits when approaching archaeological investigations. A pesar de mas que un siglo de investigacions, arqueologos han encontrado pocos sitios arqueologicos con mas que tres mil anos de edad. Sin embargo, investigaciones y excavaciones por el Rio Sacramento cerca Hamilton City, California identificaron 10 sitios arqueologicos y 15 componentes ocupacionales abarcando los ultimos 7,000 anos. La mitad de estos componentes ocurrieron solamente en contextos enterrados. Cinco tenian mas que 2,500 anos de edad y incluyen algun de la evidencia mas temprana por ocupacion humana en el Valle de Sacramento. Discutimos el contexto geomorfologico de estos descubrimientos en relacion con su edad y el sesgo observado en la distribucion temporal de sitios en el Valle Central ademas de las claves para identificar sitios tempranos en contextos similares.

Researchers increasingly rely on aggregations of radiocarbon dates from archaeological sites as proxies for past human populations. This approach has been critiqued on several grounds, including the assumptions that material is deposited, preserved, and sampled in proportion to past population size. However, various attempts to quantitatively assess the approach suggest there may be some validity in assuming date counts reflect relative population size. To add to this conversation, here we conduct a preliminary analysis coupling estimates of ethnographic population density with late Holocene radiocarbon dates across all counties in California. Results show that counts of late Holocene radiocarbon-dated archaeological sites increase significantly as a function of ethnographic population density. This trend is robust across varying sampling windows over the last 5000 BP. Though the majority of variation in dated-site counts remains unexplained by population density. Outliers reveal how departures from the central trend may be influenced by regional differences in research traditions, development-driven contract work, organic preservation, and landscape taphonomy. Overall, this exercise provides some support for the "dates-as-data" approach and offers insights into the conditions where the underlying assumptions may or may not hold.

From 2014 to 2020, we compiled radiocarbon ages from the lower 48 states, creating a database of more than 100,000 archaeological, geological, and paleontological ages that will be freely available to researchers through the Canadian Archaeological Radiocarbon Database. Here, we discuss the process used to compile ages, general characteristics of the database, and lessons learned from this exercise in “big data” compilation.

We are indebted to C. Vance Haynes Jr for his careful reading of our 2017 report and for proposing alternative explanations for our field observations. In response, we consider each of the alternatives, present additional data, and find that our main conclusion - namely that some Clovis points in California may be of early Holocene age - does not require emendation in light of current knowledge.

We conduct a global comparison of the consumption of energy by human populations throughout the Holocene and statistically quantify coincident changes in the consumption of energy over space and time-an ecological phenomenon known as synchrony. When populations synchronize, adverse changes in ecosystems and social systems may cascade from society to society. Thus, to develop policies that favor the sustained use of resources, we must understand the processes that cause the synchrony of human populations. To date, it is not clear whether human societies display long-term synchrony or, if they do, the potential causes. Our analysis begins to fill this knowledge gap by quantifying the long-term synchrony of human societies, and we hypothesize that the synchrony of human populations results from (i) the creation of social ties that couple populations over smaller scales and (ii) much larger scale, globally convergent trajectories of cultural evolution toward more energy-consuming political economies with higher carrying capacities. Our results suggest that the process of globalization is a natural consequence of evolutionary trajectories that increase the carrying capacities of human societies.

Large portions of the archaeological record in central California have been submerged by sea-level rise, and/or buried by alluvial and sand dune deposition, complicating site discovery efforts. This problem is compounded in dense urban areas where historic-era and modern activities such as artificial cutting and filling and stream channelization have been extensive. Successful site identification in these urban contexts requires a robust knowledge of environmental and landscape change over time, applied predictive modeling, and appropriate identification methods. Using case studies, we illustrate how cumulative findings from over a decade of cultural resources management studies are used to successfully identify buried archaeological sites and reconstruct latest Pleistocene and Holocene landscape evolution throughout the highly urbanized San Francisco Bay Area.

Considerable prior research has focused on the interconnected pluvial basins of Owens Lake and Searles Lake, resulting in a long record of paleohydrological change in the lower Owens River system. However, the published record is poorly resolved or contradictory for the period encompassing the terminal Pleistocene (22,000 to 11,600 cal BP) and early Holocene (11,600–8200 cal BP). This has resulted in conflicting interpretations about the timing of lacustrine high stands within the intermediate basin of China Lake, which harbors one of the most extensive records of early human occupation in the western Great Basin and California. Here, we report a broad range of radiocarbon-dated paleoenvironmental evidence, including lacustrine deposits and shoreline features, tufa outcrops, and mollusk, ostracode, and fish bone assemblages, as well as spring and other groundwater-related deposits (a.k.a. “black mats”) from throughout China Lake basin, its outlet, and inflow drainages. Based on 98 radiocarbon dates, we develop independent evidence for five significant lake-level oscillations between 18,000 and 13,000 cal BP, and document the persistence of groundwater-fed wetlands from the beginning of the Younger Dryas through the early Holocene (12,900–8200 cal BP); including the transition from ground-water fed lake to freshwater marsh between about 13,000 and 12,600 cal BP. Results of this study support and refine existing evidence that shows rapid, high-amplitude oscillations in the water balance of the Owens River system during the terminal Pleistocene, and suggest widespread human use of China Lake basin began during the Younger Dryas.

Although more than 500 Clovis points have been found at no fewer than 60 locations in California, the age of these points remains problematic. Here we report stratified deposits more than 3 meters deep at a site in the central Sierra Nevada from which a Clovis point was recovered in 1969. Five radiocarbon (14C) dates provide temporal control for terminal Pleistocene and early Holocene strata at the site, including the sediments in which the point reposed. We also report the analysis of pollen samples from these strata. Our research indicates that the Clovis point most likely dates to ∼11,900–11,400 cal yr BP. We interpret this, in the context of other fluted-point discoveries, to mean that Clovis lithic technology evidently persisted longer in the Far West than it did elsewhere in the U.S.