Chemical profiling of ancient hearths reveals recurrent salmon use in Ice Age Beringia

Abstract

Current approaches to reconstruct subsistence and dietary trends in ancient hunter-gatherer societies include stable isotope analyses, but these have focused on human remains, cooking pottery, and food residues, which are relatively rare in the archaeological record. In contrast, short-term hearths are more ubiquitous worldwide, and these features can provide valuable evidence for ancient subsistence practices, particularly when faunal remains are not preserved. To test the suitability of hearths for this purpose, we conducted multiple chemical analyses: stable carbon and nitrogen isotope analyses of total organic matter (expressed as δ 13 C and δ 15 N values) and compound-specific carbon isotope analyses of individual fatty acids (δ 13 C 16:0 and δ 13 C 18:0 ) from 17 well-preserved hearths present in three occupations dating between ∼13,200-11,500 calibrated years B.P. at the Upward Sun River (USR) site in central Alaska. We combined δ 15 N and δ 13 C FA data in a Bayesian mixing model (stable isotope analysis in R) with concentration dependency to each hearth. Our model values were tested against faunal indices, indicating a strong positive relationship between marine proportional contributions to each hearth and salmon abundance. Results of the models show substantial anadromous salmon use in multiple USR components, indicating recurrent use of the site for salmon processing during the terminal Pleistocene. Our results demonstrate that salmonid and freshwater resources were more important for late Pleistocene hunter-gatherers than previously thought and highlight the potential of chemical profiling of hearth organic residues for providing greater geographic and temporal insights into resource use by prepottery societies. stable isotopes | hearths | organic residue analysis | GC-combustion-IRMS | Beringia

Experimentally Derived Sedimentary, Molecular, and Isotopic Characteristics of Bone-Fueled Hearths

“…Organic residue studies of ancient hearth sediments date from at least the late 80s (March et al 1989;March 1999;Rottländer 1989Rottländer , 1991. However, the pace of this research is increasing as access to sensitive analytical instrumentation improves, techniques of organic residue analysis mature, and fire and cooking technologies are forefronted in human prehistory (Buonasera et al 2015;Choy et al 2016;García-Piquer et al 2018;Kedrowski et al 2009;Lejay et al 2016;Lucquin 2007Lucquin , 2016March 2013;March et al 2014;Prost et al 2011). Our intent here is not to provide an exhaustive historical review, but to discuss the current state of knowledge regarding molecular and isotopic identification of animal fats in hearths.…”

“…The present study is concerned with improving our ability to identify and locate inputs from animal fats in anthropogenic combustion structures using molecular analysis, compound specific stable isotope analysis (CSIA), and soil micromorphology. Combining molecular and isotopic analysis of sediments and pyrolyzed char from archaeological combustion features is a relatively new area of study (Buonasera et al 2015;Choy et al 2016;Heron et al 2010;March 2013;March et al 2014) and microcontextualized biomarker studies are rare (Sistiaga et al 2014). Applications have the potential to inform us about ancient pyro-technologies and patterns of animal exploitation in a wide range of human contexts, from traditional farming societies to Paleolithic hunter-gatherers.…”

Small mammals and paleovironmental context of the terminal pleistocene and early holocene human occupation of central Alaska

“…Regional conditions that favored environmental diversity and high alpha and/or beta small‐mammal diversity likely favored human settlement as well. People living in the middle Tanana Valley during the Pleistocene‐Holocene transition exploited resources from various habitats and as diverse as large grazers, such as horse ( Equus lambei ), mammoth ( M. primigenius ), bison ( Bison priscus ) and wapiti ( Cervus canadensis / elaphus ); waterfowl (Anatidae); gamefowl (Tetraoninae); and anadromous fish (Salmonidae); as well as trees and berry shrubs (Choy et al, ; Halffman et al, ; Lanoë & Holmes, ; Potter et al, ; Yesner, ). In parallel, the patchy distribution of resources made their location and seasonality more predictable than in more homogeneous landscapes, thereby reducing the search costs associated with hunting and gathering (Lanoë et al, ).…”

Untangling complex organic mixture in prehistoric hearths

“…Choy et al (8) have followed analytical procedures previously used. OM studies in hearths have focused on the molecular characterization of lipids from archaeological or experimental replicates using gas chromatography mass spectrometry (GC-MS) (e.g., refs.…”

“…Although organic residue analysis of prehistoric hearths began in the late 1980s (5-7), such analyses are still an underestimated source of information and only a few studies have explored their potential. In PNAS, Choy et al (8) use isotopic and molecular analysis of organic residues from hearths to obtain new insights into salmonid exploitation and processing by Alaskan hunter-gatherers of the end of the Pleistocene.…”