Bone strength and subsistence activities at Point Hope

Introduction: Long bone robusticity, which is associated with high activity and mobility levels in the Pleistocene (Trinkaus et al., 1994; Churchill et al., 1996, 2000; Holt, 2003; Shackelford, 2007; Holt and Formicola, 2008), is assumed to generally decrease in Holocene and recent humans (Frayer, 1980; Jacobs, 1985; Smith, 1985; Marchi, 2008; Holt et al., 2012). The archaeological site of Point Hope, Alaska, however, appears to represent an exceptionally robust population relative to other samples of similar antiquity. Excavations at Point Hope, Alaska, conducted from 1939 to 1941 by a team led by Helge Larsen and Froelich Rainey, were the source of thousands of artifacts and hundreds of human skeletons mostly attributed to two precontact archaeological cultures, the Ipiutak, dating from c. 1,600 to 1,100 years BP, and the later Tigara, dating from c. 800 to 300 years BP (Larsen and Rainey, 1948; Jensen, Chapter 2, this volume). Archaeological and artifactual evidence indicates both cultural groups exploited fish and sea mammals, but the Ipiutak relied heavily on caribou hunting (Larsen and Rainey, 1948; Giddings, 1967). The Tigara population was similar to modern Inuit populations occupying the same region, with whaling as the primary subsistence activity (Larsen and Rainey, 1948). Although not tested directly at the time, the presumably high level of appendicular robusticity associated with the Point Hope skeletons was attributed to the intense work effort involved in these subsistence activities in an arctic environment (Larsen and Rainey, 1948; Giddings, 1967). The present study attempts to determine whether the effects of an active, Arctic subsistence pattern are discernible in the long bones of the Point Hope Inuit postcranial skeletons. In order to assess the work effort related to subsistence activities in the Point Hope sample, it is necessary to address two simple, interrelated questions: (1) Are the individuals from Point Hope robust relative to other samples from the same general time period; and (2) if so, is this robusticity related to their presumed subsistence activities? Robusticity of the upper and lower limbs is analyzed in Holocene samples representing different subsistence activities. If there is a relationship between robusticity and mechanical loading, then these activities are expected to result in localized patterns of diaphyseal strength congruent with their behavior.