Small mammals and paleovironmental context of the terminal pleistocene and early holocene human occupation of central Alaska Item Type Article Authors Lanoë, François B.; Reuther, Joshua D.; Holmes, Charles E.; Potter, Ben A. Citation Lanoë, FB, Reuther, JD, Holmes, CE, Potter, BA. Small mammals and paleovironmental context of the terminal pleistocene and early holocene human occupation of central Alaska. Geoarchaeology. 2019; 1– 13. https://doi.org/10.1002/gea.21768 DOI 10.1002/gea.21768 Publisher WILEY Journal GEOARCHAEOLOGY-AN INTERNATIONAL JOURNAL Rights © 2019 Wiley Periodicals, Inc. Download date 07/10/2021 13:55:14 Item License http://rightsstatements.org/vocab/InC/1.0/ Version Final accepted manuscript Link to Item http://hdl.handle.net/10150/634952 Page 2 of 42 1 2 3 1 SMALL MAMMALS AND PALEOVIRONMENTAL CONTEXT OF THE TERMINAL 4 5 2 PLEISTOCENE AND EARLY HOLOCENE HUMAN OCCUPATION OF CENTRAL 6 3 ALASKA 7 8 4 François B. Lanoëab, Joshua D. Reutherbc, Charles E. Holmesc, and Ben A. Potterc 9 10 5 11 a 12 6 Bureau of Applied Research in Anthropology, University of Arizona, 1009 E S Campus Dr, 13 7 Tucson, AZ 85721 14 bArchaeology Department, University of Alaska Museum of the North, 1962 Yukon Dr, 15 8 16 9 Fairbanks, AK 99775 17 10 cDepartment of Anthropology, University of Alaska, 303 Tanana Loop, Fairbanks, AK 99775 18 19 11 20 21 12 Corresponding author: François Lanoë, [email protected] 22 23 13 24 25 14 Abstract 26 27 15 This paper explores paleoenvironmental and paleoecological information that may be obtained 28 16 from small-mammal assemblages recovered at central Alaska archaeological sites dated to the 29 30 17 Terminal Pleistocene and Early Holocene (14,500-8000 cal B.P.). Small-mammal remains in 31 18 these open-air sites are primarily related to deposition by natural death causes and as such 32 19 provide information on site paleoenvironments and landscape heterogeneity. Their presence 33 20 within archaeological occupations likely relates to anthropogenic disturbance and features that 34 35 21 would have favored burrow construction. The co-occurrence of small-mammal remains and 36 22 archaeological occupations provides a chronological framework of presence in the locality for 37 23 most recorded small mammal species. Small-mammal remains document faunal turnover 38 24 between Pleistocene and Holocene communities. The near-contemporaneity of species that 39 25 strongly differ in their ecological requirements suggest that the Terminal Pleistocene and Early 40 41 26 Holocene in central Alaska was a period of dynamic change that may have been characterized by 42 27 patchy vegetation distribution, rather than the climax communities seen today. In addition to the 43 28 biogeographical value of small-mammal remains, the paleoenvironmental information that they 44 29 provide helps to characterize the ecology of early human settlers in the region and the processes 45 46 30 behind human dispersal in Beringia and the Americas at the end of the Ice Age. 47 48 31 49 32 Keywords: Beringia; microtines; paleoenvironments; Pleistocene; Holocene 50 51 33 52 53 34 54 55 35 Abstract 56 57 58 1 59 60 Page 3 of 42 1 2 3 36 This paper explores paleoenvironmental and paleoecological information that may be obtained 4 5 6 37 from small-mammal assemblages recovered at central Alaska archaeological sites dated to the 7 8 38 Terminal Pleistocene and Early Holocene (14,500-8000 cal B.P.). Small-mammal remains in 9 10 39 these open-air sites are primarily related to deposition by natural death causes and as such 11 12 40 provide information on site paleoenvironments and landscape heterogeneity. Their presence 13 14 15 41 within archaeological occupations likely relates to anthropogenic disturbance and features that 16 17 42 would have favored burrow construction. The co-occurrence of small-mammal remains and 18 19 43 archaeological occupations provides a chronological framework of presence in the locality for 20 21 22 44 most recorded small mammal species. Small-mammal remains document faunal turnover 23 24 45 between Pleistocene and Holocene communities. The near-contemporaneity of species that 25 26 46 strongly differ in their ecological requirements suggest that the Terminal Pleistocene and Early 27 28 29 47 Holocene in central Alaska was a period of dynamic change that may have been characterized by 30 31 48 patchy vegetation distribution, rather than the climax communities seen today. In addition to the 32 33 49 biogeographical value of small-mammal remains, the paleoenvironmental information that they 34 35 50 provide helps to characterize the ecology of early human settlers in the region and the processes 36 37 38 51 behind human dispersal in Beringia and the Americas at the end of the Ice Age. 39 40 41 52 42 43 44 53 1. Introduction 45 46 47 54 Paleoenvironmental studies have proved fundamental in characterizing and understanding the 48 49 55 major palaeoecological and biogeographical events associated with the Terminal Pleistocene and 50 51 56 early Holocene (14,500-8000 cal B.P.) of Beringia, when Beringia served as a gateway for 52 53 54 57 dispersal of animal and plant species between northeastern Eurasia and northwestern North 55 56 57 58 2 59 60 Page 4 of 42 1 2 3 58 America. These migrants, including human populations, contributed to the emergence of 4 5 6 59 radically new biotic communities. 7 8 9 60 In particular, human colonization of Beringia during the Terminal Pleistocene corresponds to one 10 11 61 of the major steps of the story of human dispersal around the globe (Hoffecker et al., 2016). 12 13 62 Archaeological and paleogenomic evidence together indicate that Beringian settlers originated 14 15 63 from northeastern Eurasian populations (Llamas et al., 2016; Moreno-Mayar et al., 2018; Sikora 16 17 18 64 et al., 2019) and became archaeologically visible during the Bølling-Allerød chronoperiod 19 20 65 (14,500-12,900 cal B.P.) (Goebel and Buvit, 2011; Meltzer, 2009; Potter et al., 2018). The 21 22 66 colonization of Beringia corresponds to the first evidence for recolonization of latitudes above 23 24 25 67 60°N after the Last Glacial Maximum and set the stage for the colonization of the Americas in 26 27 68 the subsequent millennia (Goebel et al., 2008; Potter et al., 2018; Raghavan et al., 2015). 28 29 30 69 Dispersal of people in and through Beringia was part of and took place during a larger biotic 31 32 70 turnover. Paleobiological studies have shown a biome shift from drier, steppe-like environments 33 34 35 71 over most of Beringia, to wetter biomes characterized by tundra, along the coast, and forested 36 37 72 environments, in the interior (Anderson et al., 2004; Blinnikov et al., 2011; Jones and Yu, 2010; 38 39 73 Oswald et al., 2014; Wooller et al., 2018). Megafauna communities were accordingly affected 40 41 74 with a decrease in number of species, the extinction of many grazing herbivores and 42 43 44 75 hypercarnivorous predators (Guthrie, 2006; Mann et al., 2015), and their eventual replacement 45 46 76 by dominantly mixed feeding and browsing herbivores and omnivorous and hypocarnivorous 47 48 77 predators (Guthrie, 1982; Lanoë et al., 2017). 49 50 51 78 Causes of ecological change in Beringia at the end of the Pleistocene ultimately relate to global 52 53 54 79 climate change associated with the end of the Ice Age and the beginning of the current 55 56 80 interglacial period (Mann et al., 2018). More proximate drivers of environmental change may 57 58 3 59 60 Page 5 of 42 1 2 3 81 have included regional climatic factors such as changes in atmospheric circulation and 4 5 6 82 precipitation (Guthrie, 2001). In parallel, invasion and extinction of keystone ecological species 7 8 83 such as ecological engineers and apex predators, including humans, may have triggered sudden 9 10 84 biome shifts (Guthrie, 1984; Lanoë et al., 2017; Surovell et al., 2005; Zimov et al., 1995). 11 12 13 85 Research in Beringia has long focused on characterizing paleoenvironments and their evolution 14 15 86 at a regional level, relying on proxies that provide information on past environments at a low 16 17 18 87 spatial resolution, such as pollen (Edwards et al., 2000) and megafauna fossils (Guthrie, 1990, 19 20 88 1968a). A different set of proxies that provide paleoenvironmental information at a higher spatial 21 22 89 resolution, such as macrobotanical remains (Zazula et al., 2007), insects (Elias, 2001), and 23 24 25 90 sedimentological, pedological, biogeochemical, and genetic analyses of lacustrine and terrestrial 26 27 91 sediments (Graham et al., 2016; Kaufman et al., 2016; Kokorowski et al., 2008; Reuther, 2013; 28 29 92 Vachula et al., 2019; Willerslev et al., 2014), has shown the high degree of environmental 30 31 32 93 heterogeneity in Beringia during the Terminal Pleistocene and Early Holocene. 33 34 35 94 Small-mammal remains constitute environmental proxies that, in contrast to large mammals, 36 37 95 have seen considerably less attention in Alaska since pioneering studies of Repenning et al. 38 39 96 (1964) and Guthrie (1968b). Because of their diminutive size, small-mammal remains don’t 40 41 97 preserve well, are often overlooked in geological or archaeological contexts, and/or require a 42 43 44 98 time-intensive sampling methodology. Even when recovered, such remains are seldom directly 45 46 99 dated, particularly until recent methodological improvements in the dating of small bone 47 48 100 samples. Instead, in Alaska their age has usually been inferred from stratigraphic association 49 50 51 101 with geological layers, particularly in karstic contexts (Endacott, 2008; Georgina, 2001; 52 53 102 Harington and Cinq-Mars, 2008; Morlan, 1989), and as a result they offer a very low 54 55 103 chronological resolution.