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Determining short-term dietary change in the American Southwest : seasonality using isotopic analysis… Cooper, Catherine Grace 2013

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     DETERMINING SHORT-TERM DIETARY CHANGE IN THE AMERICAN SOUTHWEST: SEASONALITY USING ISOTOPIC ANALYSIS OF HUMAN HAIR     by  Catherine Grace Cooper  B.S. (Hons.), Beloit College, Wisconsin, 2011     A THESIS SUBMITTED IN PARTIAL FULFILMENT OF THE REQUIREMENTS FOR THE DEGREE OF    MASTER OF ARTS   in   The Faculty of Graduate and Postdoctoral Studies  (Anthropology)   THE UNIVERSITY OF BRITISH COLUMBIA (Vancouver)    October 2013     ? Catherine Grace Cooper, 2013 ii ABSTRACT   This study examines short-term dietary change in a Basketmaker II population from the American Southwest using stable isotope analysis of human hairs from a midden excavated at the site of Turkey Pen Ruins.  Each individual hair was segmented and each section analyzed for ?13C and ?15N on an Elementar-Isoprime EA-IRMS to explore changes in both plant and meat protein intake across a period of months.  The data show that there is some variation along the length of individual hairs, and even though the magnitude of the ?13C and ?15N shifts are not the same across all hair strands, there is enough evidence of semi-sinusoidal curvature in all hairs suggesting seasonal variation in the diet.  The isotope values of these individuals, when compared to previously-published ?13C and ?15N data from archaeological American Southwest turkey remains, suggests that both Basketmaker II humans from Turkey Pen Ruins and turkeys recovered from nearby sites had a similar, mostly herbivorous, diet.  iii PREFACE   The research presented here was conducted as part of a greater, collaborative study of the Turkey Pen site.  The samples were originally excavated by R.G. Matson of University of British Columbia (UBC) and William Lipe of Washington State University (WSU), both of whom provided archaeological background information for the present study.  The samples themselves were provided by Karen Lupo of Southern Methodist University (SMU).  Supervision and guidance on sample preparation and data analysis was provided by my supervisor, Professor Michael Richards of UBC.  Technical assistance with sample preparation and analysis was given by the UBC Archaeological Chemistry Lab Manager, Liz Jarvis.  iv TABLE OF CONTENTS Abstract......................................................................................................................... ii Preface..........................................................................................................................iii Table of Contents......................................................................................................... iv List of Tables................................................................................................................. v List of Figures .............................................................................................................. vi List of Symbols and Abbreviations ............................................................................vii Acknowledgements ....................................................................................................viii Dedication .................................................................................................................... ix  Introduction .................................................................................................................. 1 Significance .............................................................................................................. 2 Background............................................................................................................... 3 Basketmaker II and Turkey Pen Ruins ................................................................. 3 Overview of Carbon and Nitrogen Isotope Analyses ............................................ 7 Isotopes at Basketmaker II sites......................................................................... 13 Materials, Methods, and Considerations: Human Hair...................................... 14 The Hypotheses....................................................................................................... 17 Methods....................................................................................................................... 18 Data and Results ......................................................................................................... 21 Segmental Analysis................................................................................................. 21 Trophic Level Analysis ........................................................................................... 29 Discussion.................................................................................................................... 34 Future Directions........................................................................................................ 36 Conclusions ................................................................................................................. 37  References Cited ......................................................................................................... 38   v LIST OF TABLES  Table 1: Occupational periods in the American Southwest ..............................................3 Table 2: Segmental Stable Isotope Data for Turkey Pen Ruins Human Hairs.................22 Table 3: Bulk Stable Isotope Data for Humans and Turkeys..........................................30  vi LIST OF FIGURES  Figure 1. Map of American Southwest Sites around the Four Corners .............................5 Figure 2. Hair TP 1 ?13C and ?15N values Across Segments...........................................24 Figure 3. Hair TP 3 Isotope Data Across Segments/Time ..............................................25 Figure 4. Hair TP 7 Isotope Data Across Segments/Time ..............................................26 Figure 5. Hair TP 8 Isotope Data Across Segments/Time ..............................................27 Figure 6. Hair TP 9 Isotope Data Across Segments/Time ..............................................28 Figure 7. Human Hair and Turkey Bone Collagen Isotope Data.....................................33  vii LIST OF SYMBOLS AND ABBREVIATIONS  ? ? ?per mil? refers to 1/1000. ?13C ? difference between 13C and 12C, units in ? ?15N ? difference between 15N and 14N, units in ? BMII ? Basketmaker II UBC ? University of British Columbia WSU ? Washington State University SMU ? Southern Methodist University CMP ? Cedar Mesa Project   viii ACKNOWLEDGMENTS   This project would not have been possible without the generous assistance of my supervisors Professor Michael Richards and Professor Michael Blake, and the Archaeological Chemistry Lab Manager Liz Jarvis.  I would also like to thank Professor Karen Lupo for providing the archaeological samples, and Professors R.G. Matson and William Lipe for answering innumerable questions as I dove into the literature.   The writing process would not have gone nearly as smoothly without my friends and family, who read many drafts and told me when I wasn?t making sense.  Many thanks for their tactful critiques and calm assurances that I would actually finish.  ix           To Hope and Anne  For your unfailing support as we all struggle with this thing called ?scholarship?.  Forward Momentum   1 INTRODUCTION  In 1972, a Basketmaker II midden was excavated at Turkey Pen Ruins in Utah by R.G. Matson (UBC) and William Lipe (WSU) (Matson 1991).  This site was, and still is, considered to be a fascinating example of multiple-period occupation through which archaeologists can study change in the American Southwest, focusing on interests such as domestication, technology, and subsistence (Lipe et al. 2011).  Many different methods have been applied to studying the diet of ancient peoples in the American Southwest (Spangler et al. 2010).  Coprolite, stratigraphic, and isotopic studies are just a few methods that have thus far been used, and each provides a different perspective on what these people may have consumed (Matson and Chisholm 1991).  However, questions still remain concerning the resolution of the data it is known that: (1) there was variability across the Basketmaker II (BMII) populations in the American Southwest so each site must be considered by itself as well as regionally (Charles and Cole 2006; Matson 1991; Matson 2006), and (2) scientific methods have continued to improve since the first studies were conducted (Lee-Thorp 2008; Lipe et al. 2011).  The presence of archaeological human hair from the BMII midden presents a unique opportunity to explore a different aspect of ancient human diet at this site.  Previous isotopic studies conducted on samples from Turkey Pen Ruins have focused on bone (Matson and Chisholm 1991), which reflects diet over a period of decades (Webb et al. 2013) whereas hair, in contrast, captures diet over a period of months (LeBeau et al. 2011).  The significant time difference between hair and bone turn-over in the body means that analyzing small amounts of hair changes the focus of inquiry from long-term average diet to short-term diet variability (Webb et al. 2013).  2  This is a pilot study with the goal of using new, high-resolution technologies to serially examine six human hair samples excavated from the Turkey Pen Ruins BMII midden in 1972 to address two questions about BMII diet in this region.  First, did the diet change over short periods of time, e.g., seasonally, or was their diet constant across the seasons?  Second, it is known that there were domesticated turkeys present as early as BMII (Lipe et al. 2011), but were they being regularly used for food or were they raised for some other purpose?  Significance  Alongside addressing the questions above, this research is presented as a proof of concept study on multiple fronts.  First, because stable isotope analysis is destructive, it is important to minimize the amount of sample destroyed while maximizing both the amount of information gained and our confidence in these data.  Prior to analyzing the archaeological hair samples, I used modern hair samples to determine the minimal sample size (0.8 mg) for our Elementar-Isoprime EA-IRMS that would still yield accurate data.  Second, this research provides additional isotopic dietary data for individuals from Turkey Pen Ruins that complements the bone collagen data already presented (eg. Matson and Chisholm 1991; Chisholm and Matson 1994).  Though the relationship between turkeys and humans has been examined using isotopic evidence at other sites in the American Southwest, this is the first study that shows that turkeys were likely raised for uses other than food at Turkey Pen Ruins (Rawlings and Driver 2010).  Third, this study examines the first data showing diet seasonality at Turkey Pen Ruins and suggests that further examination of this variability would be of interest.  3 Background Basketmaker II and Turkey Pen Ruins  Occupational periods in the American Southwest were originally defined by the technology present at the site?especially ceramics and architecture?in order to delineate a chronology for the area?s early inhabitants (Table 1).  Table 1. Occupational periods in the American Southwest with their (approximate) associated dates (Spangler et al. 2010:81).  Period Date Ranges Major Characteristics Pueblo IV 1350-1600 AD -Agriculture (maize, beans, squash) -Large pueblos and fewer kivas -Black and white pottery declines in proportion to red pottery. Pueblo III 1150-1350 AD -Agriculture (maize, beans, squash) -High kiva to room ratios in large pueblos and cliff dwellings -Black and white pottery Pueblo II 900-1150 AD -Agriculture (maize, beans, squash) -Great Houses and ?Chacoan florescence? -Black and white pottery Pueblo I 750-900 AD -Agriculture (maize, beans, squash) -?Proto-kiva? pueblos -Grey plain and neck-banded pottery, black and white pottery begins Basketmaker III 500-750 AD -Beginning of bean cultivation -Deep pithouses -Beginning of pottery Basketmaker II (late) 50-500 AD -Maize and squash agriculture -Shallow pithouses -Baskets, no pottery Basketmaker II (early) 1500 BCE -50 AD -Maize and squash agriculture -Cave sites -Baskets, no pottery Archaic 6500-1500 BCE -Wild foods -Temporary sites: very mobile, small groups    4  The samples examined in this study came from a BMII midden that dated between approximately 200 BCE and 400 AD (Lipe et al. 2011).  As the name implies, Basketmaker II sites were categorized at the Pecos Convention of 1927 by the presence of baskets and the near absence of pottery, along with other normally perishable remains such as atlatls and the evidence of maize agriculture (Spangler et al. 2010).  This technological definition has since been shifted and refined?baskets and maize remain diagnostically important, but temporal, regional and technological variants of BMII across the American Southwest still cause some confusion (Spangler et al. 2010).  There is some geographic relationships between variants, including those that split BMII into Western and Eastern groups (Figure 1).  For further discussion of BMII regional variations, including the differences between Western and Eastern BMII, see Spangler et al. 2010, Matson 2006, and Charles and Cole 2006.             5 Figure 1. Map of American Southwest Sites around the Four Corners with information on which sites are classified as Eastern and Western after Charles and Cole 2006.  Sites are numbered: (1) Glen Canyon?Western BMII, (2) Black Mesa?Western BMII, (3) Cedar Mesa?Western BMII, (4) Chuska?Eastern BMII, (5) La Sal Maountains?Eastern BMII, (6) Durango?Eastern BMII, and (7) Navajo Reservoir?Eastern BMII.  Turkey Pen Ruins is on Cedar Mesa (3) (Charles and Cole 2006:168).                   Turkey Pen Ruins is a multi-period archaeological cave site on Cedar Mesa in southeastern Utah and was named for the wattle and daub structure of sticks and mud that many speculate may have been used to pen turkeys (Lipe et al. 2011).  Though the turkey Washington Oregon California Nevada Utah Colorado Arizona New Mexico Kansas Oklahoma Texas 150 km 0 km 0 mi 100 mi Colorado New Mexico Arizona Utah Durango Farmington  6 pen likely dates to either Pueblo II (PII) or Pueblo III (PIII), Turkey Pen Ruins was also occupied during BMII, which is sometimes called the Grand Gulch Phase in this region (Lipe et al. 2011; Matson et al. 1988).  The site has a history of excavation and illegal looting since its last occupation, both of which shape the context of this study.  Though the first excavations were conducted in the early 1890s by Charles McLoyd and Charles Graham, most archaeological data from the site were collected during the early 1970s Cedar Mesa Project (CMP) headed by William Lipe and R.G. Matson (Spangler et al. 2010).  In 1972, a midden noted in the 1890s was excavated by the Cedar Mesa Project to examine the local BMII and PIII periods and ?the intervening periods as well? (Matson and Chisholm 1991:448-449).  During the excavation, it became clear that the midden only contained BMII material (Matson and Chisholm 1991).  The excavation focused on removing a column of the midden for stratigraphic analysis and the artifacts collected therein have been used for further examination of the Turkey Pen Ruins BMII occupation (Lipe et al. 2011).  These samples are of particular interest, even now, due to looting of the site in the late 1970s, which overturned much of the remaining context of the site (Spangler et al. 2010).  Examination of BMII diet at Turkey Pen Ruins has focused mainly on coprolites, remainders of foodstuffs, and isotopic analysis of biological remains in the midden.  The human and turkey coprolites analyzed thus far have shown high proportions of maize present, and (in decreasing quantities) pi?on pine nut hulls, chenopod leaves, and seeds from Indian rice grass, prickly pear cactus and squash (Matson and Chisholm 1991).  It is important to compare these food remains to those remaining in the midden because some plant materials, such as squash seeds, do not survive in coprolites (Matson and Chisholm  7 1991).  Indeed, bulk samples from the midden excavation show high proportions of domesticated maize and squash, with rice grass, yucca, and pine nuts following in relative quantities (Matson and Chisholm 1991).  The third line of evidence used to examine diet at Turkey Pen Ruins is isotopic analysis of biological remains (Matson and Chisholm 1991).  The theory behind this type of analysis is that body tissues are, in part, built from components of the diet; chemical analysis of biological remains can ideally be used to work backward to better understand what compounds contributed to the tissues (Lee-Thorp 2008).  The following section reviews both classic and recent papers about carbon and nitrogen isotope analysis, their uses in archaeology, and applications for exploring BMII diet in particular.  Overview of Carbon and Nitrogen Isotope Analyses  This method is extensively reviewed in Lee-Thorp 2008 and Hoefs 2006.  Isotopes are atoms of the same element that have different masses.  Each atom has a particular number of protons (positively charged particles), electrons (negatively charged particles) and neutrons (particles with no charge).  Each element is defined by the number of protons and electrons; for example, carbon has six protons, six electrons and six neutrons in its charge neutral state.  The isotopes of an element are defined by number of neutrons, which contribute mass to the atom but not charge.  There are three isotopes of carbon named for their relative masses (protons plus neutrons): carbon 12 (12C), carbon 13 (13C) and carbon 14 (14C).  The first two isotopes, 12C and 13C, are stable while 14C is unstable due to the greater imbalance of protons and neutrons and decays over time.  All three of these elements have a natural relative abundance in the  8 atmosphere and are incorporated into organisms through various metabolic pathways such as respiration and consumption of food (Hedges et al. 2004).  Examination of stable isotopes is dependant on changes between quantities of different isotopes of the same element from their natural abundance ratios.  If all biological tissues reflected the same ratio of 13C to 12C as is found in the atmosphere (currently 1.07% 13C to 98.93% 12C), then it would not be possible to differentiate types of food (Hoefs 2006).  Chemical pathways such as photosynthesis or the body?s manufacture of protein, however, preferentially utilize the most energetically favorable option.  ?Favorable? means that in some cases the small differences in mass between isotopes change the amount of energy needed for a reaction to go to completion and one isotope, the one that requires less energy, is used more than another.  This preferential use of one isotope, called fractionation, changes the ratio of stable isotopes to each other from their natural abundances.  Isotope data tracks this fractionation and is presented as the ratio of the rarer form to the more common form.  Stable carbon isotope signatures, for example, show the ratio of 13C to 12C and are expressed as ? ?13C.  The value of per-thousand is used to manage the very small quantities of the less common isotopes.  Though the differences in isotope ratios incorporated into an organism are very small, there are patterns between how biological tissues manage and utilize elements such that the fractionation is predictable.   Stable carbon isotopes in the food chain are fractionated from atmospheric CO2 as it is incorporated into plants during photosynthesis.  There are three types of plants, categorized by their photosynthetic pathway and the length of carbon chain created, which handle atmospheric CO2 differently: C3, C4, and CAM plants.  C3 plants create  9 chains three carbons in length and generally have isotope ratio values (expressed as ?13C) of -26?; C4 plants create a four carbon chain with average ?13C values of -12? (van der Merwe and Vogel 1978).  CAM plants are succulents that mimic the carbon isotope signature of the most dominant type of plant in that region because their fractionation of stable carbon is dependant on climatic response (Ambrose and Norr 1993).  There is also a difference between stable carbon isotope signatures of marine and terrestrial C3 plants; this is due to the water CO2 source used during photosynthesis of marine plants having a different natural abundance ratio than air.  The difference in marine and terrestrial C3 plant carbon isotopic fractionation has been shown by Tauber (1981) and confirmed by Chisholm et al. (1982): the carbon isotope ratio of marine plants overlaps with C4 plants at -10? to -18?, but is different enough to separate from terrestrial C3 plants.  Climatic and temporal variation between plants of the same photosynthetic pathway is of concern in archaeology when interpreting carbon isotope data.  Regionally collected ?13C data shows a general trend of less fractionation in plants growing in warmer climates (Van Klinken et al. 1994).  Though the reasons behind climatic variation are still being examined, current studies suggest that the difference in the isotopic signatures between plants is the length of time the plant stomata are open and taking in air (Hedges et al. 2004).  A plant?s stomatic response is thought to be directly related to local temperature and moisture and will vary across climates and with climate change (Hedges et al. 2004).  Temporality is also a concern as changes in ?13C values mirror global changes in CO2 concentrations over the last 40000 years (Richards and Hedges 2003).  Regional and temporal variation in carbon isotopes means that a local, contemporaneous baseline is needed for comparison in archaeological interpretation.  10  Even though the ?13C values of the plants are not identical to animal tissues, a direct relationship exits because consumed plant proteins are directly routed to protein construction (e.g., collagen) in the animal?s body (Ambrose and Norr 1993).  These traceable differences in stable carbon have been applied to many archaeological studies of human diet.  Most studies that used only carbon isotope analysis focused on two separations: first, discriminating marine and terrestrial diets in humans who lived in C3 plant dominated areas and had access to both marine and terrestrial foodstuffs (eg. Tauber 1981 and Chisholm et al. 1982) and, second, determining whether the diet contained C3 or C4 plants.  The overlap in carbon signatures between animal and plant proteins from marine and C4 dominated geographies makes the separation of these two subsistence strategies impossible using only carbon isotope values (Ambrose and Norr 1993).  Examining the introduction of maize agriculture in North America using isotopes focuses on the difference between C3 and C4 plant proteins.  Two papers showing the use of this difference were published by van der Merwe and Vogel in 1977 and 1978 where they were able to show the adoption of maize in prehistoric Eastern Woodland North America through carbon isotope analysis (Vogel and van der Merwe 1977; van der Merwe and Vogel 1978).  Maize, a C4 plant, has a significantly higher signature (approximately -10.1?) than the wild C3 plants (-26?) dominating the Eastern Woodlands of North America (Vogel and van der Merwe 1977); their hypothesis being that adoption of maize agriculture would change the isotope signature of the humans in a C3 plant region (van der Merwe and Vogel 1978).  The data published shows a definite shift in human carbon isotope values (listed in order of oldest to most recent samples) from -21.4? in the Archaic and Middle Woodland Periods to -18.1? in the Late  11 Woodland Period and   -14? in the Mississippian Periods (van der Merwe and Vogel 1978).  The -14? values imply the introduction of C4 plants into the diet, for which the only likely candidate was maize based on archaeological and ethnohistoric data (van der Merwe and Vogel 1978).  Though carbon isotopes are useful for determining the plant protein sources at the base of the food chain, the data do not help with understanding if humans were eating the plant material directly, or eating herbivores that grazed on the plants.  Nitrogen isotope analysis is frequently used to complement carbon isotope analysis because nitrogen fractionation is related to trophic level and nitrogen isotope ratios change between who eats and who is being eaten, leaving carnivores with higher ?15N values than herbivores (Schoeninger et al. 1983).  It is important to note that nitrogen isotope enrichment (an increase in the rarer stable isotope) varies depending on the animal tissue analyzed (DeNiro and Epstein 1981).  Bone collagen, the protein component of bone, evidences a 3? ?15N shift between trophic levels, no matter which food web is being studied (Schoeninger and DeNiro 1984).  One of the first applications of nitrogen isotope analysis was the separation of marine and terrestrial diets.  Schoeninger and DeNiro (1984) were able to show that the difference in the marine animal nitrogen isotope signatures were enriched compared to terrestrial animal isotope signatures.  This difference is due to a combination of: 1) a slightly higher nitrogen fractionation in water plants compared to terrestrial plants, and 2) at least one more trophic level in the marine food chain (Schoeninger and DeNiro 1984).  This dietary separation was also shown by analyzing human bone collagen gathered from archaeological and historical populations with well-documented subsistence  12 (Schoeninger et al. 1983).  The marine populations they examined were Alaskan Eskimos, and Haida and Tlingit Native Americans from the Alaskan Coast and had nitrogen signatures between 17? to 20?, which were significantly higher than the 6? to 12? signatures from the agricultural populations from New Mexico (maize) and Colombia (manioc) (Schoeninger et al. 1983).  This data supports the conclusion that the trophic level shift noted in animals and birds continues in humans and upper levels of the food chain (Schoeninger et al. 1983)  In 1986, Heaton et al. noted a complication in using nitrogen signatures to differentiate trophic levels: elephants across South Africa and Namibia had very different nitrogen signatures, even though they are herbivorous animals that should not be shifting trophic level (Heaton et al. 1986).  The trend found in these elephant populations was that the elephants in more arid regions had distinctly higher nitrogen isotope signatures.  The explanation for this shift was suggested to be either due to the animal?s metabolism recycling nitrogen (or urea) in the body or the result of differences in soil composition changing the nitrogen isotope baseline of the area (Heaton et al. 1986).  Ambrose conducted an experiment on laboratory rats to examine the hypothesis that nitrogen shifts in arid conditions are due to the animal?s metabolism and the recycling of urea under drought conditions (Ambrose 2000).  The diet was completely controlled for isotope composition (both carbon and nitrogen) and the rats were raised under varying conditions of water access and temperature.  Analysis of the rats? bone collagen showed a consistent 3? shift from their feed, with no variation due to drought or heat conditioning (Ambrose 2000).  This data suggests that metabolic changes or stress during drought does not affect the fractionation of nitrogen by the animal recycling urea  13 because all of the rats had the same nitrogen signature.  With the data not supporting metabolism as the reason for nitrogen shifting in arid regions, it is more likely that there is some variation in soil composition (geologic or microbial) that results in the higher nitrogen fractionation of these desert areas (Hedges et al. 2004).  The nitrogen aridity shift is very important to the current study on BMII short term dietary change because of the consistent arid conditions in the American Southwest.  Though the amount of rainfall in the American Southwest fluctuated and resulted in many periods of severe drought, even the times when there was ?enough? rainfall were likely still within ?arid? parameters (defined as <400mm of rain per year) (Corr et al. 2005:321; Matson and Brand 1995).  The likelihood of an aridity shift in the nitrogen isotope data in this area means local baseline data for comparison are necessary.  More recently, it has also been suggested that not all animals fractionate nitrogen at +3? for each trophic level.  A paper published in 2012 proposed that humans fractionate nitrogen at ~6? (O?Connell et al. 2012).  The conclusion presented in this paper, though, relied on data collected from 13 individuals and converting ?15N values from red blood cells into ?15N values for keratin and collagen without addressing the compounding of error (O?Connell et al. 2012).  At this time, ~6? is not fully defensible, and trophic level shifts here will be interpreted using the +3? model.  Isotopes at Basketmaker II Sites  As mentioned above, a number of diet studies focusing on BMII sites in the American Southwest have used stable isotope analyses.  One of the earliest studies published on BMII subsistence used stable carbon isotope analysis as one line of  14 evidence to show the dependence of the population on maize horticulture rather than hunting and gathering (Matson and Chishom 1991).  This study was further extended by Chishom and Matson in 1994 with the publication of a second paper including nitrogen isotope data alongside the carbon isotopes.  Their results, while not conclusive, showed a small range of ?15N signatures, with smaller differences between individuals during the BMII period.  Old Man Cave, an ?archaic baseline? for the area, had two individuals with ?15N values of 12.2? and 7.5?, while the two BMII values were 9.5? and 10.4?  (Chisholm and Matson 1994, 247; Lipe et al. 2011).  Materials, Methods, and Considerations: Human Hair  Biological materials that are examined for diet markers using stable isotope analysis must have two things: a component, such as protein, which will have incorporated the individuals? food through metabolism, and good preservation such that the component is intact (Ambrose 1990).  Two major types of material used for these analyses are hair and bone (O?Connell and Hedges 1999).  The most commonly analyzed component of human remains is bone collagen because bone often survives in archaeological sites (Ambrose 1990).  Bone collagen is the protein component of bone and is continuously built and destroyed over the course of an individual?s life (Hedges et al. 2004).  The turn-over rate for bone collagen in humans is variable, but is generally considered to be about 20 years; the data gathered from bone isotope analysis, therefore, reflects the last couple of decades of the individual?s life (Webb et al. 2013).  The preservation of human bone is gauged by the ratio of carbon atoms to nitrogen atoms present in the sample (DeNiro 1985).  The importance of this  15 ratio is that it shows whether or not diagenesis has occurred.  During diagenesis, the atoms of the bone exchange with the soil, contaminating the sample and making any isotope signature invalid when discussing an individual?s diet.  In bone collagen, the accepted C/N ratio range that indicates collagen is deemed to be sufficiently well preserved, is 2.9-3.6 (DeNiro 1985).  Human hair is another biological material that can survive in archaeological contexts.  Human hair is made of keratin, which is pure protein, and thus does not need to have the protein component extracted as bone does  (O?Connell and Hedges 1999). The preservation of archaeological hair and its use in analysis can be determined similarly to bone collagen: the C/N ratio of modern human hair, which has not undergone any diagenic process, is between 3.0 and 3.8 (O?Connell and Hedges 1999).  O?Connell and Hedges were able to use an archaeological population with no seasonal variability of the diet to look at any systematic shifts in isotope composition between bone collagen and hair keratin, which are constructed of different proteins (O?Connell and Hedges 1999).  The data they collected shows a slight enrichment of collagen over keratin, but the difference was not quantifiable without more data and smaller standard deviations (O?Connell and Hedges 1999).  With a very close relationship between isotopic fractionation in diet, bone collagen and hair keratin, the difference in turn-over rate between the two tissues means that it is possible to examine two varying aspects of an individual?s life.  In contrast to the decades averaged in bone collagen, hair reflects just the last months of an individual?s life (O?Connell and Hedges 1999).  Bulk analysis of human hair averages the last few months of an individual?s life,  16 but it is also possible to conduct segmental analysis of hair to narrow the time window being examined.  One example of using archaeological human hair to examine short-term diet was published by Webb et al. (2013).  In this paper, the authors show the use of segmental isotope analysis of archaeological human hair to address questions of mobility and seasonality in Peruvian individuals.  The samples were chosen because the individuals came from a region with diverse topography and one would expect to be able to see isotopic shifts if individuals moved about the variable landscape (Webb et al. 2013).  The authors were able to separate out individuals from their sample with stable diets, seasonally varying diets, and ?single, discrete changes in diet? (Webb et al. 2013:137).  The reason that studies, such as the one conducted by Webb et al., can address seasonality is that hair grows at roughly a rate of 1 cm per month (LeBeau et al. 2011; Webb et al. 2013).  This value, however, is an estimate because hair growth rates can vary due to a number of factors including, but not limited to, genetics, age, hormones and nutrition (LeBeau et al. 2011).  Other considerations when conducting a segmental analysis of hair is that the growth rates between a single individual?s hairs can differ as well as there being variation in average hair growth rate between individuals (LeBeau et al. 2011).  The growth of human hair has three stages, only one of which is active growth (LeBeau et al. 2011).  These growth patterns must be taken into consideration as a limitation when analyzing seasonal or segmental variation along human hairs.     17 The Hypotheses  If the individuals at Turkey Pen Ruins had seasonal variation in their diet, then stable isotope ratios should differ along the length of the hair.  If turkey meat contributed significantly to the diet of the site?s residents, then they should have higher stable nitrogen isotope ratios than domesticated turkeys, signifying a higher trophic level.  18 METHODS  The six human hairs analyzed and discussed in this paper were excavated from the Turkey Pen Ruins BMII midden by R.G. Matson and William Lipe in 1972.  They were found when sifting the dirt taken from the sidewall of the excavation and therefore lack more specific context with other associated materials.  They are, however, useful for conducting this pilot study and determining whether or not analysis of other hair samples from this site would be of interest.  Each strand of human hair (designated TP 1, TP 2, TP 3, TP 7, TP 8 and TP 9) was handled and cleaned separately using a modified version of the method published by O?Connell and Hedges (1999).  One aspect of this method used consistently between this study and others is cleaning the hair using a chloroform methanol mixture such that dirt, oils, and other contaminants are removed from the sample (O?Connell and Hedges 1999).  The cleaning process used a series of de-ionized (DI) water and chloroform:methanol rinses.  Each hair was placed in a labeled beaker, filled with approximately 175 mL of DI H2O and put in an ultrasonic bath for ten minutes.  After ten minutes, the liquid was drained off and the rinse repeated.  The second rinse was emptied, and the beaker refilled with 150 mL of chloroform:methanol (2:1 v:v).  The hair was left to soak in the chloroform:methanol for five minutes.  This third rinse was emptied out, and the beaker was refilled with 150mL of chloroform methanol, covered, and left for 12 hours.  After 12 hours, the chloroform:methanol rinse was decanted off the top and the hair left in the beaker was rinsed four times with small amounts of DI H2O.  The hair was allowed to air dry for 12hrs in the same beaker.  19  Once dry, the strand of hair was prepared for analysis on the elemental analyzer-isotope ratio mass spectrometer (EA-IRMS).  The segmenting part of the method presented by O?Connell and Hedges (1999) varies between laboratories conducting similar experiments because it requires compromise between sample size, segment length, and time resolution.  In order for a sample to be analyzed chemically, there must be enough material present to be detectable.  O?Connell and Hedges (1999) used multiple strands of hair from one individual taken in a small bundle of 20-30 hairs.  This bundle was then wrapped in aluminum foil and cut in half such that each sample was approximately 0.75 cm to 1 cm long and the multiple hair strands ensured a large enough sample for analysis (O?Connell and Hedges 1999).  Due to the nature of hair growth and the variation between individual hairs, one cannot be sure that each hair in a segment bundle will represent the same period of time, so the data reflects an average of the diet across the range of growth represented.  The other end of the compromise is to section a single strand of hair and have longer segment lengths to reach the required sample mass.  This study used a single strand of hair for analysis.  To determine if the follicle end was present, each hair was examined with an eye-loop.  When identified, the follicle end became part of segment one.  To cut the hair, it was weighed down and placed on a clean-aluminum foil covered cutting board.  The distant end of the hair was weighted down and the hair was pulled straight using tweezers.  To ensure the minimum mass, 0.5 cm length segments were cut one at a time using a ruler and scalpel and put into a pre-weighed tin boat until the mass of hair in the boat reached at least 0.8mg.  The total length of hair required to reach this mass (usually  20 four to five segments totaling between 2 and 2.5 cm) was recorded.  The tin boat was then folded/crushed, reweighed, and set aside for analysis.  Each sample was analyzed with the Elementar-Isoprime EA-IRMS in the UBC Archaeological Chemistry Lab for carbon and nitrogen isotope ratios relative to standards vPDB (Vienna Pee Dee Belemite) for carbon and AIR (ambient inhalable reservoir) for nitrogen.  21 DATA AND RESULTS  The two questions asked in this study focus on two related but different data sets.  In order to address dietary seasonality, the data was analyzed serially, comparing the stable isotope ratios of each segment of hair to the segment that came before and after.  To address trophic level, however, it was necessary to introduce another data set, published by Rawlings and Driver in 2010, that include isotopic data for turkeys from other Puebloan sites.  It is the comparison between the humans and the turkeys that shows whether or not a trophic level shift may have occurred due to the humans at Turkey Pen Ruins eating more animal protein than the turkeys, or the turkeys themselves.  Segmental Analysis  The stable carbon and nitrogen measurements for each segment of each hair are presented in Table 2.  The first consideration when examining this data is the quality of the archaeological samples and whether or not they may have been affected by diagenesis.  For hair, it is important that the C/N ratio be between 3.0 and 3.8 (O?Connell and Hedges 1999:663).  There is only one strand of hair that did not have a C/N ratio within this range: TP 2.  Though the data for strand 2 is presented in the table, it will not be discussed further.  The rest of the strands, however, all fall within the 3.0-3.8 C/N range suggesting good preservation of the hair protein.        22 Table 2. Segmental Stable Isotope Data for Turkey Pen Ruins Human Hairs shows isotope ratio data for each hair, broken down into segments and listed sequentially.  Hair Segment Length (cm) mass (mg) C/N ?13C ?15N 1 2.5 0.090 3.7 -10.1 6.9 2 2.5 0.095 3.7 -13.1 6.8 TP 1 3 2.5 0.108 3.7 -14.1 7.1 1 2 0.077 3.9 -11.3 6.9 TP 2 2 2 0.092 4.3 -12.9 7.9 1 2 0.107 3.6 -10.6 7.2 2 2 0.115 3.5 -12.1 7.5 3 2 0.120 3.5 -10.2 7.5 TP 3 4 ? 2 0.115 3.6 -11.2 7.0 1 2 0.137 3.4 -11.4 7.3 2 2 0.153 3.5 -8.6 6.8 3 2 0.153 3.5 -8.7 6.2 4 ? 2 0.133 3.6 -8.6 6.4 TP 7 5 2 0.146 3.5 -8.8 6.1 1 2.25 0.089 3.6 -10.8 6.0 2 2.25 0.086 3.6 -9.9 6.2 TP 8 3 2.5 0.105 3.6 -9.6 6.9 1 2.5 0.104 3.7 -9.9 7.2 2 2.5 0.123 3.6 -9.9 6.1 3 2.5 0.127 3.5 -14.3 6.9 4 2.5 0.130 3.6 -11.5 4.8 5 2.5 0.132 3.4 -10.0 5.1 TP 9 6 2.5 0.134 3.4 -10.4 5.9    To better illuminate patterns along the lengths of the hairs, the data are shown graphically in Figures 2-6 below.  These graphs relate ?13C and ?15N (the y axes) to time (the x axis).  The solid squares show the ?13C data and are scaled to the y axis on the left of the graph while ?15N data is graphed with open diamonds scaled to the y axis on the right.  The x axis is the same for both ?13C and ?15N and is only labeled ?time unit? due to the uncertainty of growth rates for human hair, and the inter-individual and intra- 23 individual differences therein.  A number of studies have been published on the growth rate of human hair and a summary in LeBeau et al. (2011) shows that the minimum growth rate between these studies ranged between 0.65-0.95 cm/month and the maximum ranged between 0.96-2.2 cm/month (LeBeau et al. 2011).  The averages of these studies ranged from 0.86 cm/month to 1.4 cm/month; the average of these average growth rates was determined to be 1.06 cm/month, and it was still deemed acceptable to use 1 cm/month as an average growth rate (LeBeau et al. 2011).  Using the accepted average of 1 cm/month, each 2-2.5 cm hair segment represents roughly 2 to 2.5 months of an individual?s life, and the growth of his or her hair over the course of that time (LeBeau et al. 2011).  Scales are consistent across all graphs for easier comparison between the human hairs.  Unfortunately, the follicle end of the majority of these hairs was not identifiable, so the newest growth of hair was indeterminable and the direction of the time scale (most recent to earliest growth) is uncertain.            24 Figure 2. Hair TP 1 ?13C and ?15N values Across Segments/Time shows the ?13C and ?15N values for each segment of hair sample TP 1.  This individual?s hair captures approximately 7.5 months of his or her life.  There is no repeatable pattern, but ?13C has an overall shift of 4?.             25 Figure 3. Hair TP 3 ?13C and ?15N values Across Segments/Time shows the ?13C and ?15N values for each segment of hair sample TP 3.  This individual?s hair captures approximately 8 months of his or her life.  There is a semi-repeatable pattern in the ?13C signature along the length of the hair with a maximum ?13C shift of 1.9?.             26  Figure 4. Hair TP 7 ?13C and ?15N values Across Segments/Time shows the ?13C and ?15N values for each segment of hair sample TP 7.  This individual?s hair captures approximately 10 months of his or her life.  While there is no repeatable pattern, both ?13C and ?15N shift in opposite directions suggesting an inverse relationship.   27 Figure 5. Hair TP 8 ?13C and ?15N values Across Segments/Time shows the ?13C and ?15N values for each segment of hair sample TP 8.  This individual?s hair captures approximately 7 months of his or her life.  There is very little change in ?13C and ?15N over the three segments of this hair.   28 Figure 6. Hair TP 9 ?13C and ?15N values Across Segments/Time shows the ?13C and ?15N values for each segment of hair sample TP 9.  This individual?s hair captures approximately 15 months of his or her life.  This hair shows the most variation and inverse relationship between ?13C and ?15N values.   The graphs of the stable carbon and nitrogen values for samples TP 3, TP 7 and TP 9 have a semi-sinusoidal curvature to them suggesting regular variation in diet over time (Figures 3, 4 and 6).  A purely sinusoidal curve would exhibit a regular rise and fall where the amplitudes of the ups and downs are repeatable across the pattern.  Unfortunately, none of the hairs were long enough (the longest being 15 cm) to capture more than one year of growth and most captured less than that.  The largest shifts in both ?13C and ?15N values along a single strand of hair occurred in hair TP 9: ~ 4? for carbon and 2.5? for nitrogen (Figure 6).  Shifts along the lengths of the hairs is not so apparent in the other samples, indeed, there are some hairs that evidence little to no change across their length (Figures 4 and 5).  29  There are two overall trends that can be seen in the hair segment values.  First, there is evidence of variation along the lengths of most of the hair samples.  This can be seen both in the graphs, and in the ranges listed in Table 3 below.  Second, the changes in isotope ratio for ?13C and ?15N show a tendency, in 3 out of 5 samples, to be inversely related to each other.  This trend is particularly apparent in Figures 3 and 5 where the shifts in isotope signature are the greatest.  Trophic Level Analysis  In order to address the question of whether or not the individuals from Turkey Pen Ruins were eating a substantial amount of meat, the average isotope ratio for each hair was determined to look at what, generally speaking, these individuals were eating.  The second advantage to examining the overall isotope values for each hair is that it is easier to compare the data from the Turkey Pen Ruins individuals to the available isotopic data from turkeys from Shields Pueblo (approx. 100 km east of Turkey Pen Ruins) and other sites in the San Juan Region as presented by Rawlings and Driver (2010) (Table 3).  The data presented by Rawlings and Driver (2010) is currently the only turkey dietary data published and encompasses a number of sites from the Northern San Juan Region and a range of occupations from BMII thru late PIII.  Rawlings and Driver (2010) were able to show that compared to other local herbivores, such as jackrabbits and cottontails, the turkeys found at Shields Pueblo had enriched ?13C values corresponding to a C4 diet component.  This trend held true for the turkeys sampled from other sites as well, even though the range of ?13C values of the other sites was greater than that at Shields Pueblo (Rawlings and Driver 2010).  The carbon isotope ratios also did not vary  30 temporally from Basketmaker III (BMIII) through PIII occupations (Rawlings and Driver 2010).  They concluded that the C4 signatures compared to human ?13C values from the region suggest that the turkeys were being intentionally fed maize rather than leaving them to graze off of wild plants (Rawlings and Driver 2010).  Table 3. Stable Isotope Data for Humans and Turkeys shows average human isotope values for the Turkey Pen Ruins hair samples as well as the isotope signatures of turkeys as published by Rawlings and Driver 2010.  The ranges (segmental max and min) for the human isotope values are also shown.  Sample Site/Period Sample Type ?13C Bulk Value ?13C Segment Average ?13C Segment Range ?15N Bulk Value ?15N Segment Average ?15N Segment Range TP 1 Turkey Pen Ruins/BMII Human Hair  -12.4 -10.1 to -14.1  6.9 6.8 to 7.1 TP 3 Turkey Pen Ruins/BMII Human Hair  -11.0 -10.2 to -12.1  7.3 7.0 to 7.5 TP 7 Turkey Pen Ruins/BMII Human Hair  -9.2 -8.6 to -11.4  6.5 6.1 to 7.3 TP 8 Turkey Pen Ruins/BMII Human Hair  -10.1 -9.6 to -10.8  6.4 6.0 to 6.9 TP 9 Turkey Pen Ruins/BMII Human Hair  -11.0 -9.9 to -14.3  6.0 4.8 to 7.2 MEG-1 Shields Pueblo/LPII Turkey Bone Collagen -8.4   7.1   MEG-3 Shields Pueblo/EPIII Turkey Bone Collagen -7.7   7.5   MEG-4 Shields Pueblo/LPIII Turkey Bone Collagen -9.1   6.1   MEG-6 Shields Pueblo/LPIII Turkey Bone Collagen -10.1   6.5   MEG-8 Shields Pueblo/LPIII Turkey Bone Collagen -9.3   8.2   MEG-10 Shields Pueblo/LPII Turkey Bone Collagen -8.8   7.7    31 Table 3. Stable Isotope Data for Humans and Turkeys Cont. Sample Site/Period Sample Type ?13C Bulk Value ?13C Segment Average ?13C Segment Range ?15N Bulk Value ?15N Segment Average ?15N Segment Range MEG-11 Shields Pueblo/MPII Turkey Bone Collagen -9.1   7.6   MEG-14 Shields Pueblo/EPIII Turkey Bone Collagen -9.5   8.1   MEG-17 Shields Pueblo/EPIII Turkey Bone Collagen -9.9   7.9   MEG-18 Shields Pueblo/MPII Turkey Bone Collagen -9.3   8.0   TU-1 Hedley Ruin/PII Turkey Bone Collagen -9.1   7.1   TU-2 Hedley Ruin/PII Turkey Bone Collagen -8.5   7.2   TU-12 Grass Mesa/BMIII Turkey Bone Collagen -9.0   5.2   TU-13 Aldea Sierritas/PI Turkey Bone Collagen -9.4   7.9   TU-15 Le Moc Shelter/PI Turkey Bone Collagen -9.0   7.0   TU-19 House Creek Villiage/PI Turkey Bone Collagen -10.0   8.2   TU-20 Mc Phee Village/PI Turkey Bone Collagen -8.4   7.1   TU-21 Mc Phee Village/PI Turkey Bone Collagen -11.4   6.9   TU-23 Masa Negra Pueblo/PI Turkey Bone Collagen -9.0   9.3     32 Table 3. Stable Isotope Data for Humans and Turkeys Cont. Sample Site/Period Sample Type ?13C Bulk Value ?13C Segment Average ?13C Segment Range ?15N Bulk Value ?15N Segment Average ?15N Segment Range TU-26 Escalante Pueblo/PII Turkey Bone Collagen -9.3   7.4   TU-40 Castle Rock Pueblo/PIII Turkey Bone Collagen -6.7   6.8   TU-42 Castle Rock Pueblo/PIII Turkey Bone Collagen -9.3   8.1   TU-44 Mockingbird Mesa/PI-PII Turkey Bone Collagen -7.2   9.8   TU-47 Mockingbird Mesa/PIII Turkey Bone Collagen -8.9   7.5   TU-51 Mockingbird Mesa/PIII Turkey Bone Collagen -10.2   9.0   TU-66 Sand Canyon Pueblo/PIII Turkey Bone Collagen -11.3   9.0   TU-77 Sand Canyon Pueblo/PIII Turkey Bone Collagen -8.1   7.6   TU-82 Sand Canyon Pueblo/PIII Turkey Bone Collagen -8.8   7.1   TU-88 Los Alamos/PIII Turkey Bone Collagen -6.9   10.8   TU-90 Los Alamos/PIII Turkey Bone Collagen -8.3   8.2        33 Figure 7: Human Hair and Turkey Bone Collagen Isotope Data, showing the similarity between the turkey isotopes averaged by time period and the average human isotope values for the Turkey Pen Ruins individuals.  The error bars around each data point shows the standard deviation.    The average ?13C and ?15N isotope ratio of the individuals from Turkey Pen Ruins indicate that they were reliant on a C4 plant protein source and maintained a mostly herbivorous diet (Table 3).  The stable carbon isotope signatures of these individuals range from around -9.2 ?13C to -12.4 ?13C, which is similar to other C4 based diets and closer to the C4 plant signature of -14 ?13C.  Though there are other plants in the American Southwest that have C4 signatures or can mimic the signature of a C4 plant, agricultural maize remains the most likely contributor to the high C4 signature (Matson and Chisholm 1991).  These human isotope ratio signatures are very similar to those of the turkeys, as noted by Rawlings and Driver (2010).  The slightly lower ?13C values in  34 the humans suggest that they may even have been eating a less maize rich diet than the turkeys.  The similarity between the human ?15N isotope ratios and the turkey signatures suggests that they were eating at approximately the same herbivorous trophic level as well as taking in similar plant proteins (Figure 7).  35 DISCUSSION  The data collected in this study shows very similar stable isotope values to those presented in other research focusing on BMII subsistence (e.g. Matson and Chisholm 1991; Chisholm and Matson 1994).  The ?13C data in this study are in complete agreement with earlier isotope diet studies conducted on samples from Turkey Pen Ruins.  The ?15N values, however, are lower than the BMII isotope values presented in Chisholm and Matson (1994) by almost an entire trophic level.  This difference may be due to the samples coming from different sites or changes in instrumentation between when the two data sets were collected.  The data from this study does show strong indications of diet seasonality at Turkey Pen Ruins during the BMII period.  Though not all of the hairs exhibit equally strong variations, the semi-sinusoidal trends seen in Figures 3, 4 and 6 suggest that seasonality was likely in this population and more study is warranted.  The ?15N values in this study make it apparent that the humans from BMII Turkey Pen Ruins were not eating large quantities of meat or subsisting on domesticated turkeys with any regularity.  The most important evidence for this is the comparison between the human stable isotope data and the data collected by Rawlings and Driver (2010) on domesticated turkeys in the American Southwest.  The stable nitrogen isotope values for the humans are not one or more trophic levels shifts higher than the turkey isotope values.  Indeed, the turkeys appear to have slightly higher nitrogen isotope values than the humans.  The trophic level similarity is parallel to those discussed by Rawlings and Driver (2010) when they compared their turkey data to human isotope ratios published on ancient American Southwest populations.  36  There are several problems with the comparison between the Turkey Pen Ruins individuals and the turkeys examined in Rawlings and Driver?s (2010) paper that all stem from relative context.  First, the turkeys examined did not date to BMII, so while probably similar to the BMIII turkey data shown above (Table 3), the diet of BMII turkeys is not known.  Second, the human and turkey data came from different sites and, arguably, distinctly different regions (Charles and Cole 2006).  The relationship between turkeys and humans at Turkey Pen Ruins could be better understood if all of the biological samples were gathered from the same site.  37 FUTURE WORK  More information on seasonality could be gleaned from refining and narrowing the periods of time being examined.  This would be done by conducting the analysis of hair samples on an instrument that can handle even smaller sample masses.  Being able to analyze smaller, shorter lengths of hair would permit us to examine change across shorter periods of time.  Lastly, research concerning the separation and stable isotope analysis of protein component amino acids continues to improve.  Of particular interest here is to determine how the humans from Turkey Pen Ruins balanced their diet when a maize only diet cannot provide the complete proteins necessary for survival.  Looking particularly at the essential amino acids which maize lacks, it should be possible to determine whether or not the supplementary source was C3 or C4 based.  If these essential amino acids are C4 based, then it must be determined whether there was a secondary C4 plant source of protein or the individuals were eating a C4 fed animal such as turkey.  The current data available suggests that we would expect a C3 signature for the essential amino acids that maize lacks.  38 CONCLUSIONS  This preliminary study indicates that the individuals from BMII period Turkey Pen Ruins had seasonal variation in their diet though the overall basis of their diet was maize with little meat protein.  These trends are similar to results of other research conducted on this time period, though the relationship between diet variation and seasonality needs to be better understood.  The fact that the data from this and other studies show semi-sinusoidal curvature over the short term, suggests that further examination of short-term diet in the American Southwest would be of interest.  It would be interesting to explore the regularity of the variation, focusing on both the amplitude and the frequency of the curvature.  In order to do this, expansion of the study is necessary, with more samples from known individuals, and multiple strands of hair from each person to enlarge the dataset.  The increased dataset could be examined a number of different ways, from regional to inter-site comparison of seasonality and variability.  39 REFERENCES CITED Ambrose, S.H. 2000 Controlled diet and climate experiments on nitrogen isotope ratios of Rats.  In Biogeochemical Approaches to Paleodietary Analysis, S.H. Ambrose and A.M. Katzenberg eds.  Kluwer Academic/Plenum, New York. p. 243-259.  Ambrose, S.H. 1990 Preparation and Characterization of Bone and Tooth Collagen for Isotopic Analysis.  Journal of Archaeological Science 17:431-451.  Ambrose, S.H. and L. Norr. 1993 Experimental evidence for the relationship of the carbon isotope ratios of whole diet and dietary protein to those of bone collagen and carbonate.  In Prehistoric Human Bone: Archaeology at the Molecular Level. J. Lambert and G. Grupe, eds. Sprinter-Verlag, New York. p. 1-37.  Charles, Mona C. and Sally J. Cole 2006 Chronology and Cultural Variation in Basketmaker II.  Kiva 72(2):167-216  Chisholm, B.S., Nelson, D.E., and H.P. Schwartz. 1982 Stable carbon ratios as a measure of marine versus terrestrial protein in ancient diets.  Science 216: 1131-1132.  Chisholm, Brian, and R.G. Matson. 1994. Carbon and Nitrogen Isotopic Evidence on Basketmaker II Diet at Cedar Mesa, Utah. Kiva 60(2):239-255.  Corr, Lorna T., Judith C. Sealy, Mark C. Horton, and Richard P. Evershed. 2005 A novel marine dietary indicator utilizing compound-specific bone collagen amino acid ?13C values of ancient humans.  Journal of Archaeological Science 32:321?330.  DeNiro, Michael J. and Samuel Epstein. 1981 Influence of diet on the distribution of nitrogen isotopes in animals.  Geochemica et Cosmochimica Acta 45:341-351.  DeNiro, Michael J. 1985 Postmortem preservation and alteration of in vivo bone collagen isotope ratios in relation to paiaeodietary reconstruction.  Nature 317:806-809.  Heaton, Tim H. E., John C. Vogel, Gertrud von la Chevallerie & Gill Collett. 1986  Climatic influence on the isotopic composition of bone nitrogen. Nature 322(28):822-823.  40 Hedges, Robert E.M., Rhiannon E. Stevens and Michael P. Richards. 2004 Bone as a stable isotope archive for local climatic information. Quaternary Science Reviews 23:959?965.  Hoefs, Jochen. 2006 Stable Isotope Geochemistry, 6th ed.  Springer-Verlag, Berlin.  LeBeau, Marc A, Madeline A. Montgomery, and Jason D. Brewer. 2011 The role of variations in growth rate and sample collection on interpreting results of segmental analyses of hair. Forensic Science International 210:110?116.  Lee-Thorpe, J. A. 2008 On Isotopes and Old Bones.  Archaeometry 50(6):925?950.  Lipe, William D., R.G. Matson, and Brian M. Kemp. 2011 New Insights from Old Collections: Cedar Mesa, Utah, Revisited.  Southwestern Lore 77(2):103-111.  Longin, R. 1971 New Method of Collagen Extraction for Radiocarbon Dating.  Nature 230:241-242.  Matson, R.G. 1991 The Origins of Southwestern Agriculture.  University of Arizona Press, Tuscon, AZ.  Matson, R.G. 2006 What Is Basketmaker II?  Kiva 72(2):149-165.  Matson, R.G., and Michael Brand, Eds. 1995 Exploring Anasazi Origins; The Cedar Mesa Basketmaker II: Report on the 1991/2 Fieldwork.  Laboratory of Archaeology, University of British Columbia, Vancouver, BC.  Matson, R.G. and Brian Chisholm 1991 Basketmaker II Subsistence: Carbon Isotopes and Other Dietary Indicators from Cedar Mesa,Utah.  American Antiquity 56(3):444-459.  Matson, R.G., William Lipe, and William R. Haase. 1988 Adaptational Continuities and Occupational Discontinuities: The Cedar Mesa Anasazi.  Journal of Field Archaeology 15:245?264.  O?Connell, T.C., C.J. Kneale, N. Tasevska, and G.G.C. Kuhnle. 2012 The Diet-Body Offset in Human Nitrogen Isotopic Values: A Controlled Dietary Study.  American Journal of Physical Anthropology 149:426?434.  41 O?Connell, T. C. and R. E. M. Hedges. 1999  Isotopic Comparison of Hair and Bone: Archaeological Analyses. Journal of Archaeological Science 26:661?665.  Rawlings, Tiffany A. and Jonathan C. Driver. 2010 Paleodiet of domestic turkey, Shields Pueblo (5MT3807), Colorado: isotopic analysis and its implications for care of a household domesticate. Journal of Archaeological Science 37:2433-2441.  Richards, M.P. and R.E.M. Hedges. 2003 Variations in bone collagen N13C and N15N values of fauna from Northwest Europe over the last 40 000 years. Palaeogeography, Palaeoclimatology, Palaeoecology 193:261-267.  Schoeninger, M., DeNiro, M., and H. Tauber. 1983 Stable nitrogen isotope ratios of bone collagen reflect marine and terrestrial components of prehistoric human diet.  Science 220:1381-1383.  Schoeninger, Margaret J. and Michael J. DeNiro  1984 Nitrogen and carbon isotopic composition of bone collagen from marine and terrestrial animals. Geochemica et Cosmochimica Acta 48:625-639.  Smith, Colin I., Benjamin T. Fuller, Kyungcheol Choy, and Michael P. Richards. 2009 A three-phase liquid chromatographic method for the ?13C analysis of amino acids from biological protein hydrolysates using liquid chromatography-isotope ratio mass spectrometry.  Analytical Biochemistry 390:165-172.  Spangler, Jerry D., Andrew T. Yentsch and Rachelle Green. 2010 Farming and Foraging on the Southwestern Frontier: An Overview of Previous Research of the Archaeological and Historical Resources of the Greater Cedar Mesa Area. Antiquities Section Selected Papers 9(18).  Tauber, H. 1981 13C evidence for dietary habits of prehistoric man in Denmark.  Nature 292:332-333.  Van der Merwe, N.J. and J.C. Vogel. 1978 13C Content of human collagen as a measure of prehistoric diet in Woodland North America.  Nature 276, 815-816.  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