QUANTIFYING CLOVIS DYNAMICS: CONFRONTING THEORY WITH MODELS AND DATA ACROSS SCALES by MARCUS JOHN HAMILTON B.Sc., Institute of Archaeology, University College London, 1998 M.S., Department of Anthropology, University of New Mexico, 2002 DISSERTATION Submitted in Partial Fulfillment of the Requirements for the Degree of DOCTOR OF PHILOSOPHY ANTHROPOLOGY The University of New Mexico Albuquerque, New Mexico August, 2008 Marcus J. Hamilton: Quantifying Clovis Dynamics ©2008, Marcus John Hamilton ii Marcus J. Hamilton: Quantifying Clovis Dynamics DEDICATION I would like to dedicate this dissertation to my wife, Ana Desiree Davidson, and the two halves of my family, the UK Hamilton side and the US Davidson side, for all their love and support. I would also like to dedicate this dissertation to two old friends who were instrumental in getting me interested in archaeology, Briggs Buchanan, and Wayne Warren Kinney, Jr. iii Marcus J. Hamilton: Quantifying Clovis Dynamics ACKNOWLEDGEMENTS I would like to thank my committee for their advice and guidance over the years. They are co-chairs, Bruce Huckell and Jim Boone, 3rd department member Ozzie Pearson, and outside member Vance Holliday. Much of this dissertation would not have been possible without access to the Rio Grande Valley Clovis collections, granted by Dr. Robert H. Weber, of Socorro, New Mexico. Bob sadly died in February, 2008 after leading a long and productive life, very much in the tradition of classic Southwest scientists. Over his 80+ years Bob amassed an encyclopedic knowledge of the geology, geography, archaeology and history of the region, much of it on foot with a canteen and map. I would also like to thank fellow UNM Anthropology graduate students Briggs Buchanan, Rob Walker, David Kilby, Oskar Burger and the 2000 graduate student cohort. I am very grateful to the following funding sources for financial support during the dissertation and my time at graduate school: the Binford Foundation, UNM, the Hibben Foundation, UNM, the Latin American and Iberian Institute, UNM, SRAC/RPT, UNM, the Arizona Archaeological and Historical Society, and the National Science Foundation. I would also like to thank James H. Brown, Distinguished Professor in the Department of Biology, UNM for encouraging and enabling me to explore my wider interests human ecology and evolution. I list acknowledgements more specific to the following papers at the end of Chapters 2 and 3. iv Marcus J. Hamilton: Quantifying Clovis Dynamics QUANTIFYING CLOVIS DYNAMICS: CONFRONTING THEORY WITH MODELS AND DATA ACROSS SCALES by MARCUS JOHN HAMILTON B.Sc., Institute of Archaeology, University College London, 1998 M.S., Department of Anthropology, University of New Mexico, 2002 ABSTRACT OF DISSERTATION Submitted in Partial Fulfillment of the Requirements for the Degree of DOCTOR OF PHILOSOPHY ANTHROPOLOGY The University of New Mexico Albuquerque, New Mexico August, 2008 v Marcus J. Hamilton: Quantifying Clovis Dynamics QUANTIFYING CLOVIS DYNAMICS: CONFRONTING THEORY WITH MODELS AND DATA ACROSS SCALES By MARCUS JOHN HAMILTON B.Sc., Institute of Archaeology, University College London, 1998 M.S., Department of Anthropology, University of New Mexico, 2002 Ph.D., Department Anthropology, University of New Mexico, 2008 ABSTRACT This dissertation examines spatial and temporal variation in the Clovis archaeological across Late Pleistocene North America at multiple scales. This multi-scale approach allows the development of models at a broad continental scale that are then tused to inform processes occurring on more localized, regional scales. In particular this dissertation attempts to understand the nature of the Clovis population expansion across the North American continent, and the interplay between this expansion and cultural transmission processes that combine to generate the spatiotemporal structure of the Clovis archaeological record we see today. First, using the spatial distribution of radiocarbon dates across the continent I show that the Clovis expansion was a population expansion originating from the ice-free corridor, most likely sometime after ca. 11.6k 14C yrs BP. Second, I develop a mathematical model of cultural transmission that is designed to explain the generation of variation in the archaeological record. The model predicts that the average size of projectile points should decrease through time at a predictable rate, due to the accumulation of copying errors. When combined with the expansion model, the combined model predicts that Clovis points should get smaller at a predictable vi Marcus J. Hamilton: Quantifying Clovis Dynamics rate, on average, as the population expanded across the continent. Results show that indeed, the mean size of Clovis points reduces through time at the rate predicted. Third, I analyze the Clovis record of the central Rio Grande Valley and adjacent mountains. Results show that the Clovis occupation of the region was relatively long-term, with evidence of the repeated use of the landscape, most notably evidenced at the Mockingbird Gap Clovis site near Socorro, New Mexico. This long-term occupation is consistent with the predictions of the initial expansion model. Moreover, an analysis of Clovis projectile point size in the central Rio Grande Valley meets the predictions of the cultural transmission model, in that the points, while small, are exactly the predicted size given the linear distance of the central Ro Grande Valley from the mouth of the ice-free corridor. When combined, these results demonstrate that the Clovis archaeological record is the archaeological residue of a population expansion, which is evidenced both by the spatial distribution of radiocarbon dates across the continent, and in the spatiotemporal gradient of projectile point sizes. On a broader scale, this dissertation provides an analytic framework for exploring the cultural dynamics of the archaeological record through time and space, highlighting both the development of mathematical models, and the use of statistical metrics to test the predictions of these models. vii Marcus J. Hamilton: Quantifying Clovis Dynamics TABLE OF CONTENTS LIST OF FIGURES .................................................................................................................. x LIST OF TABLES ................................................................................................................ xv CHAPTER ONE: INTRODUCTION.......................................................................................... 1 Toward an objective approach to Clovis archaeology.................................................. 1 The importance of dynamics and scale in archaeology ................................................ 2 The Chapters ................................................................................................................. 5 CHAPTER TWO: SPATIAL GRADIENTS IN CLOVIS-AGE RADIOCARBON DATES ACROSS NORTH AMERICA SUGGEST RAPID COLONIZATION FROM THE NORTH................................... 9 Abstract......................................................................................................................... 9 Introduction................................................................................................................. 10 Time-delayed wave of advance model ....................................................................... 12 Parameter estimates............................................................................................... 14 Data........................................................................................................................ 15 Statistical Approach ............................................................................................... 15 Results......................................................................................................................... 17 Best-fit model.......................................................................................................... 17 Slope ....................................................................................................................... 18 Intercept.................................................................................................................. 18 Discussion................................................................................................................... 22 Acknowledgements..................................................................................................... 26 Methods ...................................................................................................................... 27 Wavefront/Bin width ............................................................................................... 27 Radiocarbon evidence............................................................................................. 28 CHAPTER THREE: THE ACCUMULATION OF STOCHASTIC COPYING ERRORS CAUSES DRIFT IN CULTURALLY TRANSMITTED TECHNOLOGIES ..................................................................... 33 Abstract....................................................................................................................... 33 Introduction................................................................................................................. 34 The archaeology of cultural transmission................................................................. 35 The accumulated copying error model under vertical and biased transmission......... 38 Unbiased transmission: The ACE model..................................................................