A Multi-proxy assessment of the impact of climate change on Late Holocene (4500-3800 BP) Native American villages of the Georgia coast

Circular shell rings along the Atlantic Coast of southeastern North America are the remnants of some of the earliest villages that emerged during the Late Archaic Period (5000 – 3000 BP). Many of these villages, however, were abandoned during the Terminal Late Archaic Period (ca 3800 – 3000 BP). Here, we combine Bayesian chronological modeling with multiple environmental proxies to understand the nature and timing of environmental change associated with the emergence and abandonment of shell ring villages on Sapleo Island, Georgia. Our Bayesian models indicate that Native Americans occupied the three Sapelo shell rings at varying times with some generational overlap. By the end of the complex’s occupation, only Ring III was occupied before abandonment ca. 3845 BP. Ring III also consists of statistically smaller oysters (Crassostrea virginica) that people harvested from less saline estuaries compared to earlier occupations. These data, when integrated with recent tree ring analyses, show a clear pattern of environmental instability throughout the period in which the rings were occupied. We argue that as the climate became unstable around 4300 BP, aggregation at shell ring villages provided a way to effectively manage fisheries that are highly sensitive to environmental change. However, with the eventual collapse of oyster fisheries and subsequent rebound in environmental conditions ca. 3800 BP, people dispersed from shell rings, and shifted to non-marine subsistence economies and other types of settlements. This study provides the most comprehensive evidence correlations between large-scale environmental change and societal transformations on the Georgia coast during the Late Archaic period.

and Thompson [9] argue that hunter-gatherer communities of this region were resilient in the sense that 78 through cooperation and collective agency these communities were able to negotiate shifting social and 79 environmental landscapes in the face of climate change. As climatic shifts changed resource bases (e.g.,

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reduced productivity of oyster reefs], people reorganized their social systems, resulting in changing 81 economies, settlement patterns, and spatial layouts of villages (e.g., the shift to non-shell ring sites that 82 evidence a much-reduced reliance on oysters and other shellfish).

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Some of the more well-studied Late Archaic shell-rings villages are located on Sapelo Island,

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Georgia. Sapelo Island, a barrier island located on the Georgia Coast some 80 km south of present-day were first used to examine homogeneity of variance and normality of the data, respectively.  [30]. Bayesian chronological analysis (49,51]. Due to the long tails in the distribution of these dates, here we 242 focus on the 68% probability range; however, we also provide the 95% ranges ( OxCal. This function provides probabilities for their relative order based on the dates for each ring. We 259 then used R to calculate the posterior probability for various chronological relationships for the start and 260 end date of the rings on Sapelo (Fig 2B). Based on these results, Ring II appears to be the longest 261 occupied seeing both the rise and abandonment of Ring I. The last generation to occupy Ring II likely 262 also saw the founding of Ring III, which was likely founded after Ring I ceased to be used.

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Our measurements show a clear distinction in oyster size between the three shell rings (Fig 3A, Table 2).

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Oyster shells from Ring I and Ring II are comparable in size and are generally larger than oysters from

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Ring III ( value within each shell profile) and predict salinity (Fig 4). Estimated salinity values ranged between 4 288 and 40 psu, indicating that inhabitants of all three rings were targeting a wide variety of habitats ( information), which consists of marine fishes from a variety of habitats that could be captured year-round and using a range of fishing technologies [13]. Moreover, recent research shows that Native American

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These new data shift our focus from not just the abandonment of shell ring villages but also their 377 emergence as an example of resilience in the face of climatic instability. Thompson (2) argues that co-

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The emergence of village life and adaptation to coastal environments are key transitions in 396 human history that occurred multiple times in a variety of geographic settings. As been the case in other 397 areas of the word (e.g., Peru) where archaeologists intensely study these phenomena, the process by 398 which people became embedded in these landscapes varied widely. Similar to other regions, the Native

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Americans that established some of North America's first villages also developed a complexity of ways to 400 adapt to environmental fluctuations and resource shortfalls. This study provides high resolution climate 401 and cultural datasets by which we examine how people reacted to and experienced climate change on a 631 Table S3: Uncorrected AMS dates and context for each sample. See Table 1 for corrected and modeled 632 dates.