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Abstract
Water is arguably the most important resource for successful crop production in the Southwest. In this dissertation, I examine the economic tradeoffs involved in dry farming maize vs. maize farming using simple surface irrigation for the Fremont farmers who occupied Range Creek Canyon, east-central Utah from AD 900 to 1200. To understand t...
Citations
... The range of latitude, variation in elevation, distribution of water sources, and general aridity of prehistoric Utah creates a range of unique and challenging environments (Boomgarden, 2015;Burnett et al., 2008;Hart et al., 2021;Spangler, 2000;Thomson and MacDonald, 2020). These environments range from high elevation, high moisture, low growing season mountains, to low elevation, low moisture, long growing season deserts (Fig. 2). ...
... These environments range from high elevation, high moisture, low growing season mountains, to low elevation, low moisture, long growing season deserts (Fig. 2). A thin slice of these environments has the correct combination of ecological variables suitable for maize agriculture (Boomgarden, 2015;Burnett et al., 2008;Thomson and MacDonald, 2020). Modern maize, requires a minimum growing season length, measured in growing degree days Fahrenheit (GDD), of between 2400 and 3200 GDD (Adams, 2015;Muenchrath et al., 2017), imposing a constraint on habitats in which maize can be reliably grown. ...
... Modern maize, requires a minimum growing season length, measured in growing degree days Fahrenheit (GDD), of between 2400 and 3200 GDD (Adams, 2015;Muenchrath et al., 2017), imposing a constraint on habitats in which maize can be reliably grown. While we do not know specific growing season requirements of the varieties of maize grown by prehistoric farmers in Utah Boomgarden, 2015), we can assume that the native varieties of maize also had a minimum requirement of growing season length, at which productivity suffered from the lack of an adequate growing season length. Additionally, with Utah being such an arid region, moisture abundance, both in the form of precipitation, accumulation in the environment, and perennial streams, is likely an important factor. ...
Between 2100 and 500 BP, maize farming spread throughout the American Southwest, driving changes in land use patterns and relative increases in the number of archaeological sites, which is commonly interpreted as increases in population. In the context of the Southwest, with its variable topography and limited water sources, the locations suitable for productive maize agriculture are limited. Higher elevation locations often have a greater abundance of water, both in the form of precipitation and perennial water sources but lack the growing season lengths required for maize farming. Lower elevation locations have the long growing seasons required for maize, but often have higher evaporation rates corresponding with higher temperatures, and thus decreased soil moisture retention. The relationship between elevation and maize agriculture is well recognized, and locations where both growing season length and moisture requirements can be met serve as a Goldilocks Zone in which maize farming is possible. Here, we use a regional approach to model the Goldilocks Zone for maize farming in Utah, and then contextualize patterns of settlement and abandonment on the West Tavaputs Plateau (WTP) in east-central Utah. We use archaeological sites with direct evidence of maize cultivation, modern growing degree days estimates, and modern estimates of moisture abundance to bracket the prehistoric maize farming niche in Utah. Then, we apply the model to archaeological data from the WTP to test hypotheses derived from the Ideal Free Distribution model about the effects population and precipitation changes had on prehistoric land use patterns of settlement and abandonment, and whether the patterns of settlement and abandonment differ from one another. We find that a) population drives land use patterns in the WTP, but not in the way we originally hypothesized, suggesting there is an important decision variable missing from our model, which may pertain to the specific topographic setting of the WTP and the distribution of its water sources, b) precipitation has no effect on land use patterns suggesting that maize agriculture on the WTP was dependent on irrigation, and c) that patterns of settlement and abandonment seem to mirror each other.
... Farmers using irrigation systems take on related capital and maintenance costs, decisions which reflect upon the environmental constraints under which they operated. The present phytolith research supports ongoing projects in Range Creek Canyon evaluating the opportunities and constraints faced by Fremont farmers and how they influence settlement patterns and subsistence decisions (Boomgarden, 2015, Boomgarden et al., 2019. The Fremont occupied the canyon most heavily from 800 to 1100 BP. ...
... The Fremont occupied the canyon most heavily from 800 to 1100 BP. Over 100 storage structures, many of which are difficult-to-access granaries, have been recorded throughout the canyon, as have numerous maize cobs (sometimes in the granaries), digging sticks, and ground stone manos and metates with evidence of maize starch (Boomgarden, 2015, Simons et al., 2017. ...
... The proportions of long-cell and short-cell phytoliths have previously proven effective for studies using wheat, barley, and sorghum (Madella et al., 2009, Jenkins et al., 2016, Jenkins et al., 2020. The ongoing maize irrigation studies in Range Creek Canyon include an experiment involving adjacent maize plots grown with differential water amounts along a spectrum from zero water input (dry farming) to water amounts exceeding those resulting in optimal crop production (Boomgarden, 2015, Boomgarden et al., 2019. Comparing the proportions of short-cell and long-cell maize phytoliths from these plants provides a controlled study from which to generate patterns which may be compared with archaeological contexts. ...
In arid and semi-arid regions, systems of water management and irrigation are crucial for successful crop production, and therefore provide valuable information regarding human behavior and the environmental constraints under which they operated. Unfortunately, structural evidence of irrigation can be difficult to locate, prompting various studies to evaluate the utility of phytolith analysis as a means of identifying past water availability. Evidence suggests the ratio of long-cell to short-cell phytoliths is an effective measure of relative water availability in some important economic crops such as wheat, barley, and sorghum. Expanding on this, the present research applies a similar method of analysis to determine the utility of maize (Zea mays) phytoliths for understanding past water availability. Experimental maize crops receiving different amounts of irrigation were grown in Range Creek Canyon, Utah, a canyon in the northern Colorado Plateau occupied by Fremont populations most heavily from around 800-1100BP. The production of long-cell and short-cell phytoliths from maize leaves, husks, and tassels is analyzed using statistical modeling. Results suggest the ratio of long-cell to short-cell phytoliths in maize increases as a function of increased water availability. The statistical models indicate maize phytoliths are an effective tool for inferring past water availability. By examining maize phytolith assemblages from archaeological contexts, analyzing the inferred available water, and comparing to relative climate and precipitation records, systems of irrigation can be identified and better understood.
... While maize agriculture is typically conceived of as rain-fed dry farming in the Four Corners region (e.g. Bocinsky and Kohler, 2014), it may be optimal (Boomgarden et al., 2019) if not altogether necessary (Boomgarden, 2015) to irrigate maize in the study region. While less costly subirrigation may have been possible in a few limited locations in the study area, such as wetland meadows in the arid uplands around Kanab (Roberts 2018;Roberts et al. in press), irrigating in the majority of the study area would dramatically increase the costs of farming and would likely delay the point at which individuals would find it profitable to adopt agricultural subsistence strategies. ...
The spread of agriculture is a major driver of social and environmental change throughout the Holocene, yet experimental and ethnographic data indicate that farming is less profitable than foraging, so why would individuals choose to adopt agriculture leading to its expansion? Ideal distribution models offer one framework to answer this question: Individuals should adopt less profitable subsistence strategies and occupy more marginal environments when local population density increases competition to the point where the suitability of the best strategies and habitats becomes equal to what can be gained in poorer strategies and habitats. Coupling radiocarbon-dated archaeological sites with a validated measure of agricultural suitability, we evaluate the emergence of farming in the Basin-Plateau region of North America. Our results show that farming first occurs in the more suitable Colorado Plateau physiographic region, and only spreads into the less suitable Great Basin after population density on the Plateau increases. This produces an approximate 300- to 400-year lag between the onset of farming on the Plateau and in the Basin. These findings support the ideal distribution hypothesis for the spread of farming, and suggest a general socioecological process that may help explain global patterns in the timing and tempo of agricultural expansions.
... The key pollen taxa marking the occupation of the Fremont was the identification of a Zea mays pollen grain at 900 cal yr BP. Zea mays (corn) is a type of Poaceae that cannot grow without cultivation and has been found in several granaries throughout the canyon (Boomgarden, 2015;Metcalfe, 2008). The presence of Zea mays at NGB supports the use of this location in the canyon for agriculture which had not been established until this study. ...
A 3300 year-long reconstruction of paleoenvironmental moisture conditions was constructed from a sediment core from North Gate Bog (NGB) in the northern section of Range Creek Canyon within the Colorado Plateau. The methods used to analyze the record include loss on ignition (LOI), magnetic susceptibility (MS), elemental analysis with X-ray fluorescence (XRF), charcoal influx, isotopic analysis, elemental ratios and pollen percentages, influx, and ratios. This study adds two new insights to the paleoenvironmental record of the northern section of the Colorado Plateau. First, four climatic zones were established. Zone 1 (3300–2750 cal yr BP) had 100-year wet to dry variations with droughts recorded from 3300–3200, 3000–2900, and 2800–2700 cal yr BP. Zone 2 (2750–1600 cal yr BP) had an overall dry period with an 800-year transition to increased warmth and winter moisture. Zone 3 (1600–850 cal yr BP) had an overall warm, wet, summer precipitation climate conducive to the establishment of Zea Mays and Pinus edulis, two staple foods of the Fremont culture. The Medieval Climate Anomaly (MCA) registered warm and wet in this part of the Colorado Plateau. Zone 4 (850–0 cal yr BP) had a sharp transition to a drier climate from 850 to 400 cal yr BP. During the Little Ice Age (LIA), wetter climate taxon increases such as Artemisia, Cyperaceae, and Pinus edulis. The second overall finding in this study was that NGB was a place of human activity including Fremont farming. The identification of a Zea mays pollen grain confirms the archeological presumptions that this higher elevation site was used to farm corn along with other sites in Range Creek Canyon (RCC). The post Fremont occupation period was marked by a sharp increase in organic material and a return of pinyon-juniper woodlands.
... The stimulus for this study is to better understand the opportunities and constraints faced by prehistoric farmers in Range Creek Canyon ( Figure 1) and how they influence prehistoric settlement patterns (Boomgarden 2015). We focus on simple diversion irrigation from Range Creek, an obvious source of irrigation water in this canyon that was intensively occupied by Fremont farmers from around AD 900 to 1200. ...
... Two sets of maize farming experiments using simple diversion irrigation from a perennial creek were conducted in Range Creek Canyon between 2013 and 2017 ( Figure 1). The first set, conducted over a five-year period, was designed to investigate the relationship between edible grain yields and the amount of supplemental water supplied to multiple maize plots (Boomgarden 2015). These experiments determined the water-crop production function (benefits for irrigation). ...
... This means that for 87% of the Fremont occupation, precipitation was the same or below the reconstructed 38 cm annual precipitation average. This low moisture availability and low predictability means some form of irrigation would have been a key factor in the prehistoric settlement and land use of Range Creek Canyon much like it is today (Boomgarden 2015). ...
A series of farming experiments was conducted between 2013 and 2017 in Range Creek Canyon, Utah, to better understand the opportunities and constraints faced by prehistoric farmers in the Southwest. The experiments were designed to collect data on the optimal amount of supplemental water that should be applied to maize fields given the costs in labor and benefits in greater yield. We investigate expected variation in water management strategies using an optimal irrigation model (OIM). The model makes clear that the payoff for farming is best understood as a continuum of relative success and that irrigation is one activity (probably of many) that may improve farming efficiency as well as increase harvest yields. The optimal harvest will always be less than the maximum harvest when there are significant operating costs associated with irrigation. Estimating the costs and benefits of irrigation in a specific area allows for an assessment of whether irrigation is expected, and if so, how much effort should be devoted to water management. A local dendroclimatological study is used to provide the prehistoric context for the Fremont who occupied Range Creek Canyon, and irrigation is expected even in periods of greater precipitation.
https://www.cambridge.org/core/journals/american-antiquity/article/an-optimal-irrigation-model-theory-experimental-results-and-implications-for-future-research/DF0CBBF86DF131028AA44DFA154DC4F8/share/7ccaff6cb4d6ef5e49110dadb518d6933946da73
... Except for abnormally wet years, Utah was considered marginal for maize cropping (Harris et al., 1920;Walker, 1883;Wenda and Hanks, 1981). Moreover, Fremont irrigation was rudimentary, likely not more than rough channels and weirs to redirect low-energy water flows (Boomgarden, 2015;Metcalfe and Larrabee, 1985;Simms, 2016). Benson (2011) gives a detailed review of the physical and chemical barriers to maize production in the Southwest, as well as Puebloan Native American maize farming practices which likely follow, at least in part, from their AP forebears. ...
... As with other sites situated within canyons on the Colorado Plateau, higher elevation correlates strongly with increasingly mesic conditions. We did not have precise provenience information for dated RC Fremont artifacts from to make our own determination, but archaeologists have previously stated that they observe an early to late-occupation progression of high to low elevation, or more mesic to more xeric, sites in Range Creek (Boomgarden, 2015). However, evidence of increased flood frequency in the late-stage RC occupation suggests that relocating to lower elevation occupation sites would carry increased flood risk (Rittenour et al., 2015). ...
... Along Range Creek, our model shows that it was then, as it is now, simply too dry to grow maize without irrigation, which accords with field-experimental plotting (Boomgarden, 2015). Furthermore, doing so would also rapidly deplete the soil of nutrients, particularly if pursuing a mono-cropping and/or residue burning strategy. ...
The Fremont were members of an expansive maize-based Ancestral Puebloan (AP) cultural complex who disappeared from Utah between the 12th and 13th centuries CE. This period brackets that of a climatic transition in the Southwest from the warm, dry Medieval Climate Anomaly (MCA, ca. 850–1350 CE) to the cool, hydro-climatically variable Little Ice Age (LIA, ca. 1350–1850 CE). We simulated maize (Zea mays) crop productivity for Fremont AP archaeological sites in Utah between 850 and 1449 CE using a process-based crop model driven by climatologies from a statistically downscaled a climate model. We compared the model-simulated crop yields to time-series of archaeological site occupations given by spatially discrete, chronologically summed probability distributions (SPDs) of radiocarbon-dated Fremont artifacts. We found that the anomalous abandonment of different sites throughout Utah may be explained by site-specific combinations of reduced mean yield due to volatile year-to-year yields caused by increasing temperature variability, increasing hydro-climatic variability, and loss of soil quality, which depended on crop management strategy. In other words, we model the elimination of the Fremont AP ecological niche by exogenous influences of temperature and precipitation variability at the MCA-LIA transition and endogenous degradation of soil from organic carbon and nitrogen loss. Our method has broad applicability to contexts of low-technology, dryland farming human-environmental interactions.
During Basketmaker II (∼800 BC to AD 400), Kiowa-speaking Eastern Basketmaker (EBM) farmers who migrated north shared threads of common heritage with Fremont peoples [Ortman and McNeil, 2017. The Kiowa Odyssey: Evidence of Historical Relationships among Pueblo, Fremont, and North Plains Peoples. Plains Anthropologist 63(246):152-174]. But were EBM farmers alone on their migration north? In this paper, we draw upon linguistic, archaeological, and rock art evidence to argue that: (1) during BM II, Central Mesa Verde served as a “interaction zone” between Hopi foragers (or forager-farmers) and Kiowa farmers; (2) affiliated Hopi and Kiowa groups migrated through west-central Colorado and the Tavaputs Plateaus to the Uintah Basin; (3) both groups shared threads of common heritage with Eastern Fremont people; and (4) while Kiowa-Fremont farmers remained in the Uintah Basin until approximately AD 1300 [Finley et al. 2019. Multidecadal Climate Variability and Florescence of Fremont Societies in Eastern Utah. American Antiquity, in press]. Hopi-Fremont who became farmers left earlier (∼AD 1050), embarking on a return migration south to join Hopi-speaking kinsmen in the south.
Humans modify their environments in ways that significantly transform the earth's ecosystems.[1-3] Recent research suggests that such niche-constructing behaviors are not passive human responses to environmental variation, but instead should be seen as active and intentional management of the environment.[4-10] Although such research is useful in highlighting the interactive dynamics between humans and their natural world, the niche-construction framework, as currently applied, fails to explain why people would decide to modify their environments in the first place.[11-13] To help resolve this problem, we use a model of technological intensification[14, 15] to analyze the cost-benefit trade-offs associated with niche construction as a form of patch investment. We use this model to assess the costs and benefits of three paradigmatic cases of intentional niche construction in Western North America: the application of fire in acorn groves, the manufacture of fishing weirs, and the adoption of maize agriculture. Intensification models predict that investing in patch modification (niche construction) only provides a net benefit when the amount of resources needed crosses a critical threshold that makes the initial investment worthwhile. From this, it follows that low-cost investments, such as burning in oak groves, should be quite common, while more costly investments, such as maize agriculture, should be less common and depend on the alternatives available in the local environment. We examine how patterns of mobility,[16] risk management,[17] territoriality,[12] and private property[18] also co-evolve with the costs and benefits of niche construction. This approach illustrates that explaining niche-constructing behavior requires understanding the economic trade-offs involved in patch investment. Integrating concepts from niche construction and technological intensification models within a behavioral ecological framework provides insights into the coevolution and active feedback between adaptive behaviors and environmental change across human history.
