A 130,000-year-old archaeological site in southern California, USA

Abstract

The earliest dispersal of humans into North America is a contentious subject, and proposed early sites are required to meet the following criteria for acceptance: (1) archaeological evidence is found in a clearly defined and undisturbed geologic context; (2) age is determined by reliable radiometric dating; (3) multiple lines of evidence from interdisciplinary studies provide consistent results; and (4) unquestionable artefacts are found in primary context. Here we describe the Cerutti Mastodon (CM) site, an archaeological site from the early late Pleistocene epoch, where in situ hammerstones and stone anvils occur in spatio-temporal association with fragmentary remains of a single mastodon (Mammut americanum). The CM site contains spiral-fractured bone and molar fragments, indicating that breakage occured while fresh. Several of these fragments also preserve evidence of percussion. The occurrence and distribution of bone, molar and stone refits suggest that breakage occurred at the site of burial. Five large cobbles (hammerstones and anvils) in the CM bone bed display use-wear and impact marks, and are hydraulically anomalous relative to the low-energy context of the enclosing sandy silt stratum. Th/U radiometric analysis of multiple bone specimens using diffusion-adsorption-decay dating models indicates a burial date of 130.7 ± 9.4 thousand years ago. These findings confirm the presence of an unidentified species of Homo at the CM site during the last interglacial period (MIS 5e; early late Pleistocene), indicating that humans with manual dexterity and the experiential knowledge to use hammerstones and anvils processed mastodon limb bones for marrow extraction and/or raw material for tool production. Systematic proboscidean bone reduction, evident at the CM site, fits within a broader pattern of Palaeolithic bone percussion technology in Africa, Eurasia and North America. The CM site is, to our knowledge, the oldest in situ, well-documented archaeological site in North America and, as such, substantially revises the timing of arrival of Homo into the Americas.

Strong population structure in Venezuelan populations ofCoccidioides posadasii

“…The divergence between the Venezuela and North America lineages of C. posadasii goes back to at least ~145,000-390,000 years ago, within the Middle and Upper Pleistocene (69). The confidence intervals of these dates do not overlap with the more well accepted understanding of human colonization of the Americas (less than 17,000 years ago; (70–72) but see (73)). Nonetheless, there are several caveats and alternative hypotheses that need to be taken into account.…”

Natural Uranium Radioactivity Solution Standard: SRM 4321d

“…The mass of the cleaned metal was determined first by quickly weighing the metal in a weighing boat with a Mettler AT20 electronic microbalance (Mettler-Toledo, Columbus, OH., USA). 3 The mass was also determined with a large-capacity (3 kg) mechanical balance with optical scale (Voland Jupiter 3000) 4 from the mass difference of a 1 L master solution reagent bottle before and after the metal was added to the bottle. The relative difference in the two mass determinations was 0.04 %.…”

“…The efficiencies for the individual results were renormalized and summed to give a total efficiency for each isotope. The computational results for these efficiencies as a function of the 3 For the first trial, a preliminary evaluation of the total massic activity of the SRM solution by LS spectrometry was performed using three different cocktail compositions with UGAB scintillation fluid. This was intended to evaluate the effects of chemical quenching by varying aqueous fractions faq (by the addition of dilute HNO3), and the effects of color quenching by varying the mass of the yellow SRM solution.…”

“…They are needed by wide segments of the environmental measurement community and for geophysical research, particularly in examining uranium series disequilibrium and for 230 Th/U dating methods. For example, SRM 4321b was recently used to calibrate and make corrections for uranium-series isotope analysis by thermal-ionization mass spectrometry that was part of a study of a 130 000 year old archaeological site in southern California, USA [3], showing evidence of human manipulation of broken stones and mastodon bone fractures. Even critics of the study's conclusions concur that the geochronology dating of the site was flawless [4].…”

Elephant and Mammoth Hunting during the Paleolithic: A Review of the Relevant Archaeological, Ethnographic and Ethno-Historical Records

“…Such remains are also common in prehistoric sites in late Pleistocene North America [83][84][85] (but see [86,87]). Furthermore, zooarchaeological data, including age profiles, breakage patterns and bone spatial distribution, provide indirect evidence supporting scenarios of elephant hunting (see below).…”