Abstract
This paper examines the temporal distribution of 163 distinct species recovered from 21 well-dated Holocene age archaeological sites in the Ohio River valley to determine patterns of faunal resource procurement and their response to periods of climate change. Climate change proxies include bison, long-billed curlew, pine marten, porcupine, prairie vole, and swamp rabbit. While the rice rat may be a proxy of climate change, its initial appearance in the Archaic cultural period co-occurs with storable starchy and oily seed crops such as erect knotweed, little barley, marsh elder, maygrass, and sunflower. Subsistence proxies that transcend climate change include variety of aquatic (bass/sunfish, buffalo, channel catfish, freshwater drum, gar, mussels, snails, snapping and spiny softshell turtles, and river redhorse sucker), avian (blue-wing teal, Canada goose, and turkey), and terrestrial species (dog, eastern cotton-tail, elk, gray and fox squirrels, opossum, raccoon, timber rattlesnake, and woodchuck). Caldwell’s Primary Forest Efficiency remains a valid theoretical model of Holocene subsistence strategy in the Ohio River valley.
Introduction
Faunal remains recovered from Holocene age archaeological sites in the Ohio River valley are important sources of climatic, environmental, and economic data (e.g., subsistence and raw material resources). Caldwell (1958) introduced a theoretical subsistence strategy called “Primary Forest Efficiency,” which transcended Holocene climatic and environmental change. This subsistence strategy included the seasonal gathering of wild plant foods (masts, fruit, and vegetables) fish, and shellfish, and year-round hunting of aquatic and terrestrial vertebrates.
In terms of modern Human Behavioral Ecology, also known as Human Evolutionary Ecology, Primary Forest Efficiency optimized the kilocalorie (kcal) of animal protein consumed and minimized the kcal of energy expended in the procurement and processing of food resources (Smith and Winterhalder, 1992). If we assume that a variety of vertebrate and invertebrate species in the Ohio River valley had a high tolerance to climatic and environmental change, then Primary Forest Efficiency would have provided a secure food and raw material resource base throughout the Holocene.
This study reexamines the value of Caldwell’s (1958) theoretical subsistence strategy for Holocene age archaeological sites in the Ohio River valley. It also investigates the factors that may have influenced the cultural selection of faunal food and raw material resources such as climate, environment, human choice, cultural patterns, and migration that may have changed faunal profiles during the Holocene.
Climate change
Climate is a long-term pattern of temperature, precipitation, humidity, cloud cover, and wind, affected by latitude, elevation, surface water, and human activity. American archaeologists have long acknowledged that climates change. In the Ohio River valley, Benjamin Franklin and Thomas Jefferson were the first to use vertebrate remains excavated from Big Bone Lick, Kentucky to argue that certain species lived at a time when the climate was different from the present (Jilson, 1936). After visiting Big Bone Lick in 1841, Lyell (1845) suggested that vertebrate species provided evidence for continuous climatic transformations.
A large body of interdisciplinary data has been amassed to reveal a detailed chronology of past episodes of global climate change. These data include a collection of stable-oxygen and carbon isotopes from ice cores extracted from mountain and continental glaciers in Africa, Antarctica, and Greenland (Alley, 2000; Petit et al., 1999; Stenni et al., 2003; Thompson et al., 2002), sedimentation records from cores extracted from the western Pacific and north and eastern Atlantic ocean floors (Lea et al., 2003; Stott et al., 2004; Zhao et al., 1995), inventories of global pollen and macro plant distributions (Davis et al., 2003; Grimm and Keltner, 1988; Kutzbach and Guetter, 1986; Wright et al., 1993), and distributions of mammalian species in the United States (Graham and Lundelius, 1994). Global climate syntheses of these data include Huang (2004), Jones and Moberg (2003), and Moberg et al. (2005).
These syntheses demonstrate that global climate change has been continuous and nonanalogous. The effects of continuous and nonanalogous climate change on animal taxa are both time-transgressive and disharmonious. That is, taxa that biogeographically overlap in the same biome in the past but never again since. Animal taxa that live synpatrically during one climatic period may live allopatrically during another. Likewise, a species adaptation to climate change may be significant in one region and not another. In other words, there are no modern analogues because animal adaptations to global climate change occurs as individualistic shifts in their geographic distributions (Graham, 2006; Graham and Lundelius, 1994; Semken, 1983, 1988).
Individual responses to climate change are not necessarily random and because many species share similar niche parameters, biotic communities are created without modern analogues (Graham, 2006). We simply cannot read any present ecosystem or climate back in time. The only safe to assumption from the available data is that past ecosystems were undergoing major transformations in response to continuous climate change, and these changes resulted in individualistic faunal adaptations (Graham and Lundelius, 1994).
Ohio River valley
The Ohio River valley experienced a variety of profound climatic changes during the Holocene. While there were recurrent episodes of global warming and cooling, it is important to note that they were neither cyclical nor identical climatic periods. Among the most profound of these climatic events were the Holocene Climatic Optimum, the Medieval Warm Period, and the Little Ice Age.
The Holocene Climatic Optimum was a period of global warming and moistening period, which occurred ∼5000 to 2000 BCE during the Archaic cultural period (∼8000 BC to 500 BCE). At that time, global temperatures were between 0.5°C and 2.0°C warmer than those recorded during the 20th century and the last continental glacial ice melted in Canada (Pielke, 1995). A period of global cooling and drying occurred during the Woodland cultural period (∼500 BCE to CE 1000) until the 10th-century CE. Mean annual temperature changes fell between 0.3°C and 0.75°C and correlate with mountain glacial advances (Jones and Mann, 2004).
From approximately CE 850 to 1400, the Ohio River valley experienced moistening and rises in mean annual temperatures, known as the Medieval Warm Period, which peaked ∼CE 1250. Mean annual temperatures may have reached 1.0°C to 2.0°C higher than those of the 20th century (Solomon et al., 2007). Archaeologically, this climatic period spans the Prehistoric Fort Ancient cultural period (∼1000–1400 CE). Between ∼CE 1400 and 1850, the Ohio River valley experienced a significant cooling and drying event known as the Little Ice Age. This climatic downturn occurred during the Proto to Historic Fort Ancient cultural period (∼CE 1400–1800). The peak of this cold dry climate occurred ∼CE 1500 and 1600. Although the decline in global mean annual temperatures was only 0.5°C, winters in the Ohio River valley were harsh winters, the growing seasons shorter, and the climate overall dryer, which resulted in a significant lowering of the water table (Solomon et al., 2007).
Data parameters
While there have been numerous studies on the impact of climate change and human procurement based on large fauna data sets (e.g., Burns et al., 2003; Falk, 1977) and studies of the biogeographic distribution and range expansion of species that rely on large data sets (e.g., Hody and Kays, 2018), the Ohio River valley has been largely ignored. This study examines vertebrate and invertebrate taxa identified from chronometrically dated archaeological contexts in the Ohio River valley to examine the procurement of animal species and their response to changes in climate during the Holocene. The Ohio River valley includes the tributary streams of the Scioto, Little Miami, Licking, Great Miami, and Kentucky rivers (Figure 1). For almost 300 years, faunal remains have been collected from archaeological sites in this region (Willey and Sabloff, 1980).
Geographic location of Holocene age archaeological sites in the Ohio River valley.
In order to examine species response to climate changes during the Holocene, we obtained data on the location, age, and taxa of vertebrate and invertebrate remains from archaeological sites. While there are many thousands of sites documented in this region, the quality of data vary greatly from the types of data reported to the ways they are reported. Although synchronic cultural summaries have been written for the region, there has been no attempt to examine faunal data diachronically in terms of human procurement and species response to Holocene climate change.
Following the standard set by Graham and Lundelius (1994), archaeological site criteria for this study include (1) a known geographic location; (2) chronological controls including radiocarbon dates, stratigraphy, and known cultural affiliation; (3) species-level animal taxa; (4) data that can be found in published peer-reviewed scientific literature, theses, or accessible cultural resource management reports; and (5) faunal remains that are curated in public institutions. Using these parameters, we filtered the data into standardized taxonomic classifications and established temporal periods, eliminated mixed assemblages, and calibrated radiocarbon dates.
Because this study focuses on the procurement of species and their response to Holocene climate change, the data have been specifically collected from sites with precise temporal control (Table 1). For this reason, many sites were excluded. Chronometric dating is one of the most important aspects of any archaeological investigation. In order to accurately interpret species response to climate change, it is crucial to document faunal taxa within a temporal framework. The most precise and trustworthy chronologies in the Ohio River valley are those developed from calibrated radiocarbon dates using samples of known composition from well-documented archaeological, geological, and environmental contexts.
Radiocarbon ages for Holocene age archaeological sites in the Ohio River valley.
An accurate chronology and the ability to demonstrate synchroneity, or lack thereof, between climatic periods is crucial to the accuracy of identifying past species responses. For this reason, data from the same stratum, cultural horizon, excavation level, or other interpretive level have been lumped together. Rather than using individual counts of specimens for each taxon, site-specific summary data were joined into a database summarized chronologically by cultural periods in Tables 2–5. Faunal data were collected from six Archaic sites, six Woodland sites, three Prehistoric Fort Ancient sites, and six Proto to Historic Fort Ancient sites (Table 6).
Faunal species recovered from Archaic sites in the Ohio River valley.
Note: 0 = absent; 1 = present.
Faunal species recovered from Woodland sites in the Ohio River valley.
Note: 0 = absent; 1 = present.
Faunal species recovered from Prehistoric Fort Ancient sites in the Ohio River valley.
Note: 0 = absent; 1 = present.
Faunal species recovered from Proto and Historic Fort Ancient sites in the Ohio River valley.
Note: 0 = absent; 1 = present.
Summary table of faunal species recovered from Holocene age sites in the Ohio River valley.
All of the species examined in this study were recovered from well-dated, stratified, cultural strata with robust well-preserved faunal assemblages. In other words, the species included in this study were recovered from sealed midden deposits or features. None of the species included in this study were intrusive bones, tools made from bones, or bone artifacts that were potentially curated from earlier occupations. However, species, which were modified during butchering and burning, were included.
Temporal distributions
Statistically significant differences were found between distinct taxa recovered from Holocene age archaeological sites in the Ohio River valley. Indeed, statistically significant differences were found between all of the faunal groups with the exception of birds and fish and mammals and mollusks (Table 7). These statistical differences may be the result of the adaptability and sustainability of these species throughout the climatic and environmental changes of the Holocene.
A summary of t tests used to determine significant difference between groups of fauna recovered from Holocene age archaeological sites in the Ohio River valley.
Note. Boldface relationships are not statistically significant.
With the exception of the Woodland cultural period, mollusks are the predominate taxa in the Ohio River valley throughout the Holocene (Table 6). The greatest diversity of mollusk procurement occurred during the Prehistoric Fort Ancient cultural period, which likely resulted because their soft tissue provided a cost-effective source of protein and their shells provided a much needed raw material for ceramic temper. Mammals and bird species were the second and third most diverse taxa recovered from Holocene age archaeological sites, respectively. The greatest diversity of mammal species procurement occurred during the Archaic cultural period and the greatest diversity of bird procurement occurred during the Prehistoric Fort Ancient cultural period (Table 6).
During the Holocene Climatic Optimum, Archaic populations procured a greater number of aquatic vertebrates such as amphibians and reptiles (e.g., frogs, salamanders, and aquatic turtles) than other cultural periods as well as a greater diversity of mammals. This emphasis on aquatic species is likely a result of the warm and moist conditions of the Holocene Climatic Optimum. A similar procurement pattern occurs during the Medieval Warming. Fort Ancient populations procured a greater number of fish, migratory water fowl, and mollusks than other cultural periods (Table 6).
The occurrence of extralimital bird and mammal species from well-dated archaeological contexts may be the best indicator of climate change during the Holocene. Extralimital species from Archaic archaeological sites include both southern species such as rice rat (Oryzomys palustris) and swamp rabbit (Sylviagus aquaticus) as well as northern species such as snow goose (Anser caerulescens) and porcupine (Erethizon dorsatum). The occurrence of northern extralimital species are also present on Woodland archaeological sites, which date to the post-Holocene Climatic Optimum including snow goose, common loon (Gavia immer), hooded merganser (Lophodytes cucullatus), and pine martin (Martes Americana), as well as the western badger (Taxadea taxus), long-billed curlew (Numenius americanus), prairie vole (Microtus ochrogaster), and Trumpeter swan (Olor buccinator). Similarly, northern extralimital species dominate on Fort Ancient archaeological sites, which date to the Medieval Warming including snow goose, common loon, hooded merganser, and pied-billed grebe (Podilymbus podiceps) as well as the western trumpeter swan and prairie vole, and the southern raven (Corvus corax) and rice rat. The greatest biogeographic diversity of extralimital species occur on Proto to Historic Fort Ancient sites, which date to the Little Ice Age including the western modern bison (Bison bison), trumpeter swan, and badger, the northern porcupine and pine martin, as well as the southern rice rat.
Discussion
The core data set used in this study is a compilation of 163 distinct species from 21 archaeological sites in the Ohio River valley, which span the Holocene. Faunal remains from archaeological sites result from the procurement of animal resources, which were available to ancient human populations and ultimately reflect the composition of ancient ecosystems. Climate change causes changes to occur in the ecosystem, which changes the composition of available animal resources.
The decisions people made concerning what animal resources were procured and processed and how they were used directly affected their adaptability. These decisions are archaeologically preserved as patterns in the exploitation of animal resources. An important economic dimension of human adaptability to climate change is the availability of species required to sustain or maintain human livelihood.
Subsistence proxies
Theoretically, if Primary Forest Efficiency was a viable subsistence strategy throughout the Holocene in the Ohio River valley, then there would have been a suite of animal food and raw material resources that were highly adaptable and resilient to long-term climatic and environmental changes. In other words, in a Primary Forest Efficiency economy, we would expect to find sustainable animal resources that were procured throughout the Holocene.
This study found that a large suite of terrestrial vertebrates was procured all the way through the Holocene including the white-tailed deer (Odocoileus virginianus), eastern cotton-tail (Sylvilagus floridanus), elk (Cervus canadensis), gray and fox squirrels (Sciurus carolinensis and Sciurus niger), opossum (Didelphis virginianus), raccoon (Procyon lotor), timber rattlesnake (Crotalus horridus), woodchuck (Marmota monax), and dog (Canis familiarus). In this regard, dogs are considered a stored food resource, which can be exploited as the need arises. A variety of avian species were also procured during all cultural periods including the blue-wing teal (Anas discors), Canada goose (Branta canadensis), and turkey (Meleagris gallopavo). In addition to mollusks (i.e., mussels and snails), aquatic food resources procured during all cultural periods included the buffalo (Ictiobus bubalus), channel catfish (Ictaluridae punctalus), freshwater drum (Aplodinotus grunniens), gar (Lepisosteus sp.), snapping turtle (Chelydra serpentina), spiny softshell turtle (Trionyx spinferus), river redhorse sucker (Moxostoma carinatum), and bass (Centrarchidae). These aquatic, avian, and terrestrial species would have provided a secure source of protein in the Ohio River valley regardless of the climatic and environmental changes of the Holocene. Despite the fact Caldwell’s Primary Forest Efficiency is more than 60 years old, it remains a valid theoretical subsistence strategy for Holocene age archaeological sites in the Ohio River valley.
Climate proxies
Species found on Holocene age archaeological sites in the Ohio River valley north, south, and west of their modern biogeographic range may be used as proxies of climate change. Temporal shifts in a species biogeographic range may be associated with changes in the mean annual temperature, an increase or decrease in mean annual precipitation, and milder or more harsh winters (Vickery et al., 2016). There are, however, certain caveats, which must be taken when interpreting the Holocene faunal record, especially concerning avian species. For example, short-term downturns in weather such as extremely harsh winters from one or more catastrophic volcanic events may have caused the common loon, hooded merganser, pied-billed grebe, raven, snow goose, and trumpeter swan to migrate into the Ohio River valley during the Holocene (Tankersley et al., 2018).
A change in a species biogeographic distribution also may be anthropogenic rather than climatic. While the rice rat is found today south of the Ohio River valley, it has been recovered from Archaic, Woodland, and Fort Ancient archaeological sites. Its appearance in the Ohio River valley co-occurs with the origins of agriculture during the Archaic cultural period. The presence of the rice rat co-occurs with oily and starchy seed-bearing cultigens such as erect knotweed, little barley, marsh elder, maygrass, and sunflower. While climatic conditions may have favored a change in the biogeographic distribution of the rice rat (Vickery et al., 2016), the expansion of its range during the Archaic and continued presence through the Fort Ancient cultural period is likely associated with the domestication of seed-bearing cultigens. In addition to the rice rat’s natural diet of fungus and green vegetation, it would have found stored starchy and oily seeds desirable, especially during the winter months.
Despite these caveats, there are unquestionable species, which occur in the middens of Holocene age archaeological sites in the Ohio River valley, which can be considered climatic proxies. These species include the bison, long-billed curlew, pine marten, porcupine, prairie vole, and swamp rabbit. The most profound examples of a climatic proxy are the bison, which was absent in the Ohio River valley for approximately 10,000 years (i.e., since the late Pleistocene). Their skeletal remains appear in massive Proto-historic Fort Ancient kill sites, which date to the Little Ice Age (e.g., Big Bone Lick, Kentucky) and in midden deposits (e.g., Madisonville and Wynema sites, Ohio).
Footnotes
Declaration of Conflicting Interests
The author(s) declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.
Funding
The author(s) disclosed receipt of the following financial support for the research, authorship, and/or publication of this article: This research was supported by the Charles Phelps Taft Foundation and the Court Archaeological Research Foundation. No Grant Numbers issued.