Lisbeth A. Louderback

Middle-Holocene climates and human population densities in the Great Basin, western USA

Much of western North America saw higher temperatures and lower precipitation during the middle Holocene. The Great Basin became much drier and warmer than it is today, causing major shifts in lake levels, treelines, plant community composition, and vertebrate distributions and abundances. To assess the impact of climate change on middle-Holocene human population densities in this region, we examine the frequency structures of radiocarbon-dated archaeological sites through time in three separate parts of the Great Basin: the Bonneville Basin, Fort Rock Basin, and western Lahontan Basin. The results of the analysis support the hypothesis that human population densities in many parts of the Great Basin dropped substantially in response to middle-Holocene climate change but also document that there were intervals during the middle Holocene in all three areas that appear to have been marked by temporary population increases. We hypothesize that these increases were associated with equally temporary increases in effective precipitation but, lacking adequate paleoenvironmental data, do not attempt to test this hypothesis.

Starch granule evidence for the earliest potato use in North America

Significance Starch granules of Solanum jamesii extracted from ground stone tools establish wild potato use as early as 10,900–10,100 calendar years B.P. in southern Utah. This discovery is the earliest documented use of potatoes in North America, an important energy source that has been largely undervalued or even ignored when diet breadth analyses and optimal foraging theory have been applied in archaeological studies. Younger deposits also contained tools with S. jamesii granules, indicating at least 4,000 years of intermittent use. Ethnographic and historical accounts from the region extend the period of use to more than 10,000 years. Given this long prehistory and history, the question arises as to whether some S. jamesii populations could have undergone transport, cultivation, and eventual domestication over such a long period of time. The prehistory of wild potato use, leading to its domestication and diversification, has been well-documented in, and confined to, South America. At least 20 tuber-bearing, wild species of Solanum are known from North and Central America, yet their importance in ancient diets has never been assessed from the archaeological record. Here, we report the earliest evidence of wild potato use in North America at 10,900–10,100 calendar years (cal) B.P. in the form of well-preserved starch granules extracted from ground stone tools at North Creek Shelter, southern Utah. These granules have been identified as those of Solanum jamesii Torr. (Four Corners potato), a tuber-bearing species native to the American Southwest. Identification was based on applying five strictly defined diagnostic characteristics (eccentric hilum, longitudinal fissure, lack of fissure branching, fissure ratio, and maximum granule size) to each of 323 archaeological granules. Of those, nine were definitively assigned to S. jamesii based on possession of all characteristics, and another 61 were either likely or possibly S. jamesii depending on the number of characteristics they possessed. The oldest granules were found in substratum 4k (10,900–10,100 cal B.P.). Younger deposits, dating to ∼6,900 cal B.P., also contained tools with S. jamesii granules, indicating at least 4,000 y of intermittent use. Ethnographic and historical accounts extend the period of use to more than 10,000 y. The question then arises as to whether some S. jamesii populations could have undergone transport, cultivation, and eventual domestication over such a long period of time.

Ethnographic and Archaeological Evidence Corroborating Yucca as a Food Source, Mojave Desert, USA

Abstract Plant subsistence economies for native peoples in the Mojave Desert have been well-documented ethnographically and historically, but less so archaeologically. Ethnographic accounts taken from southern California Native Americans (Palmer 1878), including the Panamint (Coville 1892), Kawaiisu (Zigmond 1981), Timbisha Shoshone, and Southern Paiute (Fowler 1995; Kelly 1932–1934) report that Joshua tree (Yucca brevifolia Engelm.), Mojave yucca (Y. schidigera Roezl ex Ortgies.), and other yucca species (all Asparagaceae) were harvested as reproduction progressed from early to late spring. Harvesting and processing methods varied between groups, but in general, immature and mature fruits were roasted in pits and stored for later consumption. The time depth of these subsistence practices, however, remains unknown because of a scant archaeological record. Recent archaeological excavations of several pit features yielded Yucca spp. seeds and fruit in association with fire-cracked rock (FCR) and charcoal. The mix of immature and mature seeds and fruits suggest some early spring gathering and processing, however the majority were collected later in the season. Thus, the archaeological evidence supports and elaborates on the ethnographic observations about Yucca as a food source. A combination of ethnographic and archaeological evidence allows for a more detailed and robust picture of past human behavior and dietary practices.