David A. Byers

Species-specific responses of Late Quaternary megafauna to climate and humans

Despite decades of research, the roles of climate and humans in driving the dramatic extinctions of large-bodied mammals during the Late Quaternary period remain contentious. Here we use ancient DNA, species distribution models and the human fossil record to elucidate how climate and humans shaped the demographic history of woolly rhinoceros, woolly mammoth, wild horse, reindeer, bison and musk ox. We show that climate has been a major driver of population change over the past 50,000 years. However, each species responds differently to the effects of climatic shifts, habitat redistribution and human encroachment. Although climate change alone can explain the extinction of some species, such as Eurasian musk ox and woolly rhinoceros, a combination of climatic and anthropogenic effects appears to be responsible for the extinction of others, including Eurasian steppe bison and wild horse. We find no genetic signature or any distinctive range dynamics distinguishing extinct from surviving species, emphasizing the challenges associated with predicting future responses of extant mammals to climate and human-mediated habitat change.

Holocene environmental change, artiodactyl abundances, and human hunting strategies in the Great Basin

Despite a deep Great Basin tradition of incorporating paleoenvironmental change within ecologically oriented analyses of past human lifeways, there has been little attention focused on Holocene variation in artiodactyl abundances and the human hunting strategies dependent upon them. Here, we draw upon recently generated paleontological evidence from Homestead Cave of the Bonneville Basin to document a late Holocene artiodactyl population increase. We then use the prey model of foraging theory to predict late Holocene increases in the hunting of artiodactyls, relative to lagomorphs. That prediction is then tested against several fine-grained archaeological records of hunting behavior in the Bonneville Basin, Hogup Cave and Camels Back Cave, and a variety of more coarse-grained faunal records from throughout the Great Basin. Close fits are found between the deductively derived prediction and the empirical records of hunting behavior: dramatic proportional increases in artiodactyl hunting occurred during the late Holocene. The results have far-reaching implications for our understanding of prehistoric human adaptations in the Great Basin.

Prey body size and ranking in zooarchaeology: Theory, empirical evidence, and applications from the northern Great Basin

The use of body size as an index of prey rank in zooarchaeology has fostered a widely applied approach to understanding variability in foraging efficiency. This approach has, however, been critiqued—most recently by the suggestion that large prey have high probabilities of failed pursuits. Here, we clarify the logic and history of using body size as a measure of prey rank and summarize empirical data on the body size-return rate relationship. With few exceptions, these data document strong positive relationships between prey size and return rate. We then illustrate, with studies from the Great Basin, the utility of body size-based abundance indices (e.g., the Artiodactyl Index) when used as one component of multidimensional analyses of prehistoric diet breadth. We use foraging theory to derive predictions about Holocene variability in diet breadth and test those predictions using the Artiodactyl Index and over a dozen other archaeological indices. The results indicate close fits between the predictions and the data and thus support the use of body size-based abundance indices as measures of foraging efficiency. These conclusions have implications for reconstructions of Holocene trends in large game hunting in western North America and for zooarchaeological applications of foraging theory in general.

Ecosystem controls and the archaeofaunal record: an example from the Wyoming Basin, USA:

Regional palaeoenvironmental reconstructions and data on artiodactyl response to climate change suggest that large game densities would have expanded in response to increasingly mesic conditions during the late Holocene in the Wyoming Basin. We use the prey model of foraging theory to predict late-Holocene increases in artiodactyls, relative to lagomorphs and rodents, and more specifically in bison relative to pronghorn. This prediction is then tested against 284 dated archaeofaunas from the Wyoming Basin. Close fits are found between the deductively derived prediction and the empirical records. Although artiodactyls demonstrate a general increasing trend across the most recent 5000 years, during the period of most intense human occupation hunting pressure appears to have depressed large game populations.

Paleoindian fat-seeking behavior: Evidence from the Hell Gap Site, Locality II Agate Basin faunal assemblage

Abstract Analysis of the Agate Basin component faunal remains from the Hell Gap Site (48G0305) Locality II suggests that the assemblage results from a multi-dimensional formational history. Comparisons of skeletal element frequencies with models of density-mediated attrition, bison settling velocities, and several nutritional utility indices indicate that both fluvial action and the transport of high marrow value elements from kill sites to the residential base in the Hell Gap Valley may have contributed to assemblage composition. Observations of impact related conchoidal flake scars document the intensive secondary processing of long bone elements. Although skeletal part frequencies likely document several taphonomic processes, when viewed together with bone modifications they suggest that the Agate Basin Paleoindians responsible for the Locality II deposits may have practiced a fat-seeking feeding strategy stressing the transport of high bulk protein/skeletal fat utility bison parts from kill sites to the residential base at Locality II.

Pronghorn Dental Age Profiles and Holocene Hunting Strategies at Hogup Cave, Utah

In this article, we use pronghorn dental age data to document pronghorn hunting strategies at Hogup Cave, Utah, and explore their relationship with a widespread late Holocene trend in increasing large-game abundances noted in archaeofaunal contexts throughout western North America. Specifically, we test the hypothesis that at Hogup Cave, pronghorn hunting methods changed from a middle Holocene strategy dominated by encounter hunting of individual animals to a late Holocene strategy emphasizing large-scale communal hunting. Our analysis suggests that ancient hunters visiting Hogup Cave most likely employed small-scale encounter hunting during the fall and winter months and that this subsistence pattern varied little between the middle and late Holocene. Moreover, while hunting strategies appear to have remained generally similar throughout the 8,800-year occupational record at Hogup Cave, artiodactyl abundances show a dramatic increase relative to smaller, lower-ranked prey in late Holocene strata, suggesting that a temporal shift in the favored hunting strategy, by itself, cannot explain this trend in every context.

Bison Exploitation in the Wyoming Basin at the Middle/Late Holocene Transition: AView from the Graham Ranch Site

Abstract Wyoming Basin archaeojaunas dating to the Middle/Late Holocene transition typically lack bison remains and instead suggest a focus on a wide range of smaller prey species. Excavations along the Sweetwater River at the Graham Ranch site produced an extensive assemblage of highly fragmented bison bones representing the remains of at least two bison that were intensively processed for meat, marrow, and grease. We use a patch use model, in combination with data from 49 Wyoming Basin archaeofaunas to explore the reasons why ancient butchers might expend the effort to extract hard to obtain within-bone nutrients. Our study suggests that prey abundance, possibly linked to climate driven trends in forage communities, may have been one factor that conditioned processing decisions across the Holocene in the Wyoming Basin.

Skeletal Fat, Processing Intensity, and the Late Holocene Bison from Baker Cave, Southern Idaho

Abstract Although Idaho’s Snake River Plain contains a trans-Holocene record of bison exploitation, archaeologists have rarely investigated carcass butchery strategies in the region. We fill this knowledge gap with a study of bison remains from Baker Cave, a late Holocene processing site on the eastern Snake River Plain. We hypothesize that these remains resulted from fat-seeking behavior in response to winter fat scarcity. We explore this hypothesis with a series of variables designed to measure processing intensity: Impacts per Element, Percent Complete, and Number of Identified Specimens/Minimum Number of Elements. All three variables generate similarly strong correlations with skeletal fat utility, suggesting that Baker Cave’s inhabitants organized processing efforts around winter fat scarcity.

Holocene bison diminution on the Snake River Plain, Idaho, USA

Researchers have established a Holocene pattern of Bison spp. diminution on the Great Plains of North America. This pattern, however, is less clear west of the Rocky Mountains. This lack of clarity stems from a relative paucity of paleontological and archaeological bison assemblages sufficiently large enough to understand local bison diminution. To begin filling this important gap in knowledge, we analyze a large bison assemblage from Baker Cave, a Late-Holocene archaeological site located on Idaho’s Snake River Plain. Measurements of humeri, radii, tibiae, metatarsals, and calcanei demonstrate that these animals were significantly smaller than Early-Holocene bison from both the Great Plains and Snake River Plain. Middle-Holocene bison from the Great Plains are generally larger than those from Baker Cave, but this size difference varies by skeletal element. The Baker Cave bison do fall within the range of Late-Holocene morphological variation present in both Snake River Plain and Great Plains bison populations. These results provide a necessary first step for understanding bison morphology in the region, but establishing a pattern of diminution west of the Rocky Mountains will require follow-up studies with other faunas.

Heat Treatment, Ozarks Cherts, and Prehistoric Toolstone Use in Southwest Missouri

Burlington and Jefferson City cherts often dominate Ozarks lithic assemblages, and this record contains ample evidence for the heat treatment of both. In this paper, we use a technological investment model to understand why prehistoric knappers may have invested in heat treatment at the Big Eddy Site in southwest Missouri. Tech investment models offer one way to evaluate the cost-benefit relationships of various technologies and, consequently, the conditions under which a manufacturing strategy might be adopted. We conduct a heat treatment experiment to measure the untreated utilities of the two materials, the approximate time needed to heat each, and the resultant gains in utility a knapper acquires by spending the time to do so. In the Big Eddy case, the tech investment model suggests that the two toolstones were heat-treated differentially in response to differences in utility gains and availability on the landscape.