New Radiocarbon Ages on Percussion-Fractured and Flaked Proboscidean Limb Bones from Yukon, Canada

Kathleen A. Holen,C. Richard Harington,Steven R. Holen

doi:10.14430/arctic4645

Abstract

Proboscidean limb bones discovered in Yukon during the 1960s and 1970s exhibit fracture patterns, notches, and bone flakes that are characteristic of percussion. Because of the unique properties of thick cortical proboscidean bone (probably woolly mammoth Mammuthus primigenius or less likely American mastodon Mammut americanum), some researchers hypothesized that these fracture patterns represent intentional hammerstone modification by humans for marrow extraction and bone tool production. As such, these fracture patterns represent evidence of early human dispersal into Eastern Beringia. Radiocarbon dating in the late 1980s indicated that the bone breakage occurred between about 25 000 and 40 000 radiocarbon years before present (14C yr BP). We report 11 new radiocarbon ages using ultra-filtration methods on a different sample of similarly fractured and flaked bones from Yukon. Only two of the radiocarbon ages fall within the expected range of 25 000 to 40 000 14C yr BP. Six other ages are non-finite, with five being more than 49 100 14C yr BP. Three finite ages range between 46 500 and 50 500 14C yr BP with large standard deviations, and these ages may also be non-finite. Two testable hypotheses to explain the observed breakage patterns were developed, the first being that humans broke the bones and the second that some presently unknown geological process broke the bones. Further research is needed to test these two hypotheses.

Highlights

In the late 1960s and 1970s, several researchers discovered proboscidean limb bones from the Old Crow River area, Yukon, that were interpreted to have been modified by humans using percussion technology to produce notches and bone flakes (Harington et al, 1975; Irving, 1978; Bonnichsen, 1979; Morlan, 1980; Morlan and Cinq-Mars, 1982; Irving et al, 1986; Cinq-Mars and Morlan, 1999)
Recent studies of the same types of fracture patterns on mammoth limb bone excavated in situ from loess and fine-grained alluvial deposits in the central Great Plains of North America support the hypothesis that humans were the modifying agent (Holen, 2006, 2007; Holen, S.R., and Holen, K., 2012, 2014), as does the presence of the same types of fracture patterns on mammoth limb bone from late Pleistocene fluted-point sites in the western United States (Hannus, 1989, 1990; Miller, 1989)
We have never recorded these fracture patterns on proboscidean limb bones that are listed as being from the Irvingtonian Land Mammal Age (LMA). We have found these fracture patterns on proboscidean limb bone listed as Sangamon in age (Oxygen Isotope Stage 5)

Summary

Introduction

In the late 1960s and 1970s, several researchers discovered proboscidean limb bones from the Old Crow River area, Yukon, that were interpreted to have been modified by humans using percussion technology to produce notches and bone flakes (Harington et al, 1975; Irving, 1978; Bonnichsen, 1979; Morlan, 1980; Morlan and Cinq-Mars, 1982; Irving et al, 1986; Cinq-Mars and Morlan, 1999). We report on finite and non-finite radiocarbon ages on percussion-fractured and flaked proboscidean limb bones from the Yukon, five from the Old Crow River area and six from the Klondike area near Dawson City.

Results

Conclusion