Paleoindian subsistence strategies and late Pleistocene paleoenvironments in the northeastern and southwestern United States: a tooth wear analysis

Abstract

Paleoindians of North America entered a continent undergoing rapid climatic and environmental changes. This paper is a preliminary contribution toward obtaining a better picture regarding how climate and environmental change might have impacted the first settlers of North America. The Paleoindian sites we analyzed are, from the oldest to the youngest, Ingleside (Texas), Blackwater Draw Locality No. 1 (New Mexico), Hiscock Site (New York), and Plainview Quarry (Texas). Paleoenvironmental reconstruction involves identifying the dietary traits of ungulate species that might reflect the environmental conditions where they were living, and also where they might have been hunted by Paleoindians. Such an approach is realized through tooth microwear and mesowear analyses. Results indicate that a variety of food resources were available for the ungulates at these sites as well as the likely presence of mosaic environments around these sites which allowed Paleoindians to exploit resources in a large variety of habitats. The application of a method that allows for the estimation of the duration of occupation at archaeological sites reveals that results for Blackwater Draw and Hiscock Site indicate a long-term occupation of probably several months. However, during short events, Paleoindians were most likely hunting herds of horse and bison when these prey were available near the site. Results indicate that Plainview Quarry was likely used only for short-term occupations, with large game hunting focusing on bison. These patterns identified at the archeological sites studied are related to the fact that Paleoindians follow a high-technology forager model and frequently shifted their territory depending on the composition and distribution of the large mammal fauna.

Introduction

Paleoindians moved into North America across the Bering land bridge between eastern Siberia and present-day Alaska during the Late Glacial Maximum (LGM) when sea levels were significantly lowered due to this Quaternary glaciation (Barendregt and Duk-Rodkin, 2004; Bonnichsen and Turnmire, 1999; Meltzer, 2009).

The northeastern part of the United States was covered with glaciers until the end of the LGM. Thus, human settlement in this area was not possible until the retreat of the Laurentide ice sheet. A recent analysis of New England varves demonstrates that recession of Laurentide ice began in the northeastern United States at 12,600 BP, and that the ice had receded into Quebec by 11,600 BP (Ridge et al., 1999). In the southwestern part of the United States, the conditions were less extreme than in the north. The climate conditions of the area included cool, moist air and rain and it has been purported to have been wetter than today (Meltzer, 2009; Meltzer and Holliday, 2010). Postglacial fluctuating climates and seasonal extremes must have proven quite challenging as people traveled across the continent when humans entered North America. The first Paleoindians of North America entered into a continent undergoing rapid changes (Kelly and Todd, 1988).

The biogeography and climate of North America during the LGM have been the subjects of long-standing interest (Gray, 1885; Adams, 1902, 1905) and considerable disagreement (Deevey, 1949; Braun, 1955). New paleoecological and paleoclimatic records have improved our knowledge of LGM vegetation and environments in North America since the reviews of Peterson et al. (1979) and Wright (1981). Recent analyses of the paleovegetation in the Northeastern part of the United States suggested the presence of tundra and open Picea-dominated forest along the Laurentide ice sheet, with tundra predominantly in the west, and in the east, a Pinus-dominated vegetation (Jackson et al., 2000; McWeeney, 2007). Thus, most of the eastern United States, south of the Great Lakes, was thought to be covered by a patchwork of boreal and deciduous forests (Delcourt and Delcourt, 1981).

Paleovegetation in the southwestern part of the United States was characterized by the establishment of spruce parkland after 13.7 ka cal BP that is thought to have persisted through the Younger Dryas oscillation (Anderson et al., 2008). After 11.7 ka cal BP, there was an increase in ponderosa pine and a reduction in Artemisia (Anderson et al., 2008). The pollen evidence from the late Pleistocene of New Mexico is described by Hall (2005) with environments ranging from alpine tundra to sagebrush grasslands. Pollens from Clovis and Younger Dryas deposits indicate a “desert grassland” during Clovis times, with grass and Pinus accounting respectively for 20–25% and 10% of the pollen (Mehringer and Haynes, 1965).

Knowledge of the vegetation and environment of North America during the LGM is important to the understanding of postglacial vegetational and biogeographic dynamics, as well as to prehistoric settlements and Paleoindian behavioral ecology. To date, the understanding of LGM conditions in the region has been hampered by the possibility that LGM vegetation and climate lacked modern analogs. The reconstruction of paleoenvironments in prehistoric contexts through paleoecological studies may present difficulties when modern analogs do not exist, and consequently, such proposals may be criticized if certain and classic types of methods only are employed (Jackson and Williams, 2004; Kaiser and Rössner, 2007; Williams and Jackson, 2007; Douglas, 2011). Such methods are generally based on the taxonomic uniformitarianism principle and relate the past composition and structure of faunal communities to that of their relatives encountered today. In order to generate improved reconstructions of the LGM environment, we propose to focus on mammalian faunas mainly from Paleoindian archeological sites using a taxon-independent approach.

Recent research techniques focus on mammals and employ methods to reconstruct the dietary habits of fossil ungulates as a proxy for environmental context. Dental wear methods (mesowear and microwear) give access to the immediate behavior (and diet) of the ungulates at the time of their death, and thus provide a snapshot of the paleoenvironmental conditions at any given time. From the information gained by reconstructing the dietary traits of each ungulate species, it will be possible to deduce the nature of the habitat where each population of Paleoindians was living. Thus, it would be possible to propose a reconstruction of the environments available to the Paleoindians at the site of their subsistence activities. In addition to environmental conclusions, tooth microwear also provides evidence about the relative duration of occupations at archaeological sites. Rivals et al. (2009a) have described a new application of dental wear analyses that allows for the estimation of the relative duration of human occupations using the dietary signal encapsulated on the surface of ungulate tooth enamel.

The objective is to provide a better picture regarding how the environment impacted late-Quaternary settlers through a reconstruction of the paleoenvironments at the time of the peopling of the northeastern and southwestern part the United States during the late Pleistocene and early Holocene. Reconstruction of the habitats of the ungulates will allow for an estimate of the diversity of the habitats exploited by Paleoindians for hunting, enhancing knowledge of their subsistence strategies. The time frame selected is also of particular importance in terms of understanding the changes that occurred during the late Pleistocene to early Holocene transition as this time frame corresponds to a period of dramatic climatic and environmental changes during which faunas underwent a shift from cold to warmer climates.

We propose to test two hypotheses related to late Pleistocene paleoenvironments and Paleoindian subsistence strategies:

• Hypothesis 1. – Tooth mesowear and microwear on late Pleistocene ungulates indicate open landscapes in the southwestern part of the United States, but more forested environments in the northeastern part.

• Hypothesis 2. – Regional differences in habitats available around the sites (open vs. forested habitats) have consequences on the duration of settlement of the sites by Paleoindians (short vs. long occupations).

This paper is a preliminary contribution toward obtaining a better picture regarding how climate and environmental change impacted the late Pleistocene settlers of North America.