Steps towards an ecology of landscape

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Steps towards an ecology of landscape

  1. 1. University of Cambridge Department of Archaeology Steps towards an Ecology of Landscape: a Geoarchaeological Approach to the Study of Anthropogenic Dark Earths in the central Amazon region, Brazil Manuel Arroyo-Kalin Girton College This dissertation is submitted for the degree of Doctor of Philosophy 2008
  2. 2. i DECLARATION This dissertation is the result of my own work and includes nothing which is the outcome of work done in collaboration except where specifically indicated in the text. Excluding cited references, the main text of the dissertation consists of 79,890 words. Manuel Arroyo-Kalin Cambridge, October 2008 ABSTRACT Steps towards an ecology of landscape: a geoarchaeological approach to the study of anthropogenic dark earths in the central Amazon region, Brazil Amazonian anthropogenic dark earths constitute an increasingly more important dimension of the archaeological record of the Amazon basin. These anthropogenic soils mark the location of large, abandoned pre-Columbian settlements that were inhabited from around 500 BC until AD 1500. The dissertation examines the archaeological record of the Amazon basin looking for clues about their proximate and ultimate causes. In order to examine proximate causes, a suite of geoarchaeological techniques is used to analyse exemplars from the central Amazon region, the research area of the Central Amazon Project. Among others, the study discusses the contribution of pre-Columbian ash, charcoal, bone and pottery to their composition. It also establishes empirically that the distinction between darker-coloured artefact-laden dark soils (terras pretas) and lighter-coloured, artefact-poor, and less nutrient-enriched brown soils (terras mulatas) reflects a contrast between areas of settlements where houses and refuse middens decomposed vis-à-vis surrounding or adjacent areas in which spatially-restricted, fire-intensive, and amendment-reliant agricultural practices took place. Finally, inter-site variability is related to overall effects of landscape evolutionary dynamics on the soil mantle. As regards the ultimate causes for the widespread appearance of Amazonian anthropogenic dark earths, the dissertation advances a series of arguments that link incipient processes of tree domestication in the early Holocene, the domestication of Manihot esculenta as a two-phase process involving preceramic and ceramic groups, and the intensification of bitter manioc by expanding horticulturists. The dissertation thus offers an archaeological understanding of the Amazonian landscape as a historical ecology modified by the enduring effects of human practices, one in which specific processes of plant domestication over trans-generational time scales have left their enduring marks. In memoriam Jim Petersen (2005)
  3. 3. ii TABLE OF CONTENTS DECLARATION AND ABSTRACT i LIST OF FIGURES v LIST OF TABLES vii ACKNOWLEDGMENTS viii NOTES ON DATA SOURCES xiii CONVENTIONS xiv CHAPTER 1: INTRODUCTION .................................................................................................1 1. ANTHROPOGENIC LANDSCAPE TRANSFORMATIONS...............................................................1 2. THE LANDSCAPE OF AMAZONIA............................................................................................3 3. ANTHROPOGENIC LANDSCAPE TRANSFORMATIONS IN AMAZONIA........................................6 4. THIS DISSERTATION ..............................................................................................................8 CHAPTER 2: THE DARK EARTHS OF THE AMAZONIAN FORMATIVE.....................11 1. DEFINITION AND MAIN CHARACTERISTICS ..........................................................................11 2. THEORIES ABOUT PROXIMATE ORIGINS...............................................................................13 3. ANTHROPOGENIC DARK EARTHS IN PRE-COLUMBIAN HISTORY...........................................14 3.1 The Amazonian Formative: immigrant or indigenous...................................................15 3.2 Pre-Columbian sedentism, social complexity, and Amazonian dark earths..................20 4. FORMATION PROCESSES OF ANTHROPOGENIC DARK EARTHS ..............................................22 4.1 Pedological and archaeological insights ......................................................................22 4.2 Ethnographic insights ...................................................................................................26 5. SUMMARY...........................................................................................................................30 CHAPTER 3: THE ROOTS OF THE AMAZONIAN FORMATIVE....................................31 1. INTRODUCTION ...................................................................................................................31 2. THE LANDSCAPE IS DYNAMIC: A PALAEO-ENVIRONMENTAL BASELINE ...............................32 3. THE ROOTS OF THE AMAZONIAN FORMATIVE .....................................................................38 3.1 First fruits? Colonisation and arboriculture.................................................................38 3.2 Next roots? Anthrosols and the manioc question ..........................................................41 3.3 The Ceramic Archaic ....................................................................................................49 4. REVISITING THE AMAZONIAN FORMATIVE .........................................................................53 4.1 The Tropical Forest Cultures of Amazonia...................................................................53 4.2 Interaction spheres of the early Formative ...................................................................55 4.3 The Ceramic Formative in the middle and lower Amazon............................................62 5. SUMMARY...........................................................................................................................68
  4. 4. iii CHAPTER 4: THE CENTRAL AMAZON REGION..............................................................69 1. INTRODUCTION ...................................................................................................................69 2. THE LANDSCAPE OF THE CENTRAL AMAZON REGION..........................................................69 3. THE ARCHAEOLOGICAL SEQUENCE OF THE CENTRAL AMAZON REGION..............................73 3.1 Early research in the region..........................................................................................73 3.2 The Central Amazon Project .........................................................................................77 3.2.1 The Archaic in the central Amazon region.........................................................................77 3.2.2 The ceramic sequence in the central Amazon region .........................................................79 3.2.2.1 The Açutuba site............................................................................................................79 3.2.2.2 The Osvaldo site ............................................................................................................83 3.2.2.3 The Hatahara site ...........................................................................................................84 3.2.2.4 The Lago Grande site.....................................................................................................88 3.2.2.5 The Nova Cidade site.....................................................................................................91 3.2.2.6 The Lago do Limão and Antônio Galo sites ..................................................................91 3.2.3 The Negro-Solimões confluence area ................................................................................94 4. SUMMARY...........................................................................................................................97 CHAPTER 5: THE GEOARCHAEOLOGY OF AMAZONIAN DARK EARTHS..............98 1. INTRODUCTION ...................................................................................................................98 2. METHODS .........................................................................................................................100 2.1 Sampling......................................................................................................................100 2.2 Micromorphology........................................................................................................100 2.3 Analysis of bulk samples..............................................................................................102 2.4 Measurement of 13 C/12 C carbon isotopes ....................................................................105 2.5 Radiocarbon dating of microscopic charcoal .............................................................105 3. CASE STUDIES ..................................................................................................................105 4. UNDERSTANDING VARIABILITY: THE MAKE-UP OF ANTHROPOGENIC DARK EARTHS .........109 4.1.1 Horizonation ....................................................................................................................109 4.1.2 Texture and soil mantle evolution....................................................................................111 4.1.3 Anthropogenic inputs.......................................................................................................113 4.1.3.1 Heat treated clay and their physico-chemical signatures..............................................113 4.1.3.2 Microscopic bone.........................................................................................................115 4.1.3.3 Microscopic charcoal and soil melanisation ................................................................115 4.1.3.4 Plant matter, fresh and ashed .......................................................................................117 4.1.4 Summary..........................................................................................................................119 5. EXAMINING SITE FORMATION PROCESSES: THE PEDO-STRATIGRAPHY OF ANTHROPOGENIC DARK EARTHS......................................120 5.1.1 The Hatahara site: settlement soils (Profiles HA-1, HA-3, HA-5, and HA-9) .................121 5.1.1.1 Profile HA-9 (background profile)...............................................................................122
  5. 5. iv 5.1.1.2 Profile HA-5 (Urns’ unit, terra preta) .........................................................................123 5.1.1.3 Profiles HA-1 and HA-3 (Mounds 1 and 2, terras pretas)...........................................126 5.1.1.3.1 The buried land surfaces under Mounds 1 and 2..................................................127 5.1.1.3.2 The overburden of Mounds 1 and 2 .....................................................................129 5.1.1.4 Discussion....................................................................................................................131 5.1.1.4.1 HA-5 (Urns’ unit) ................................................................................................131 5.1.1.4.2 HA-1 and HA-3 (Mounds 1 and 2) ......................................................................132 5.1.1.4.3 New radiocarbon evidence for Mound 2..............................................................135 5.1.2 The Lago Grande site: settlement and hinterland soils (Profiles LG-1, LG-2, LG3 and LG-4) ...................................................................136 5.1.2.1 Profile LG-3 (Mound 1, terras pretas) ........................................................................136 5.1.2.2 Profiles LG-1, LG2 and LG-4 (terras mulatas) ...........................................................139 5.1.2.3 Discussion....................................................................................................................142 5.1.3 The Osvaldo site: settlement soils (Profile OS-1, terras pretas)......................................144 5.1.3.1 Discussion (OS-1)........................................................................................................146 5.1.4 The Açutuba site: settlement and hinterland soils (Profiles AC-1, AC-2, AC-2).............148 5.1.4.1 Profile AC-2 (background profile)...............................................................................148 5.1.4.2 Profile AC-1 (riverfront, sector IA, terra preta)..........................................................150 5.1.4.3 Profile AC-3 (Açutuba phase buried soil, terra mulata)..............................................154 5.1.4.4 Discussion....................................................................................................................156 5.1.4.4.1 AC-1 ....................................................................................................................156 5.1.4.4.2 AC-3 ....................................................................................................................157 5.1.5 The Nova Cidade site: settlement soils (Profile NC-1) ....................................................159 5.1.5.1 Discussion (OS-1)........................................................................................................162 5.1.6 The Dona Stella site (Profile DS-1)..................................................................................163 5.1.6.1 Discussion (DS-1)........................................................................................................165 CHAPTER 6: SYNTHESIS.......................................................................................................167 1. THE GEOARCHAEOLOGICAL STUDY...................................................................................167 2. ANTHROPOGENIC LANDSCAPE TRANSFORMATIONS AND DOMESTICATION IN THE LANDSCAPE OF AMAZONIA.....................................................................................172 3. REFLECTIONS ON THE RESEARCH DESIGN OF THE DISSERTATION ......................................175 4. LANDSCAPE ARCHAEOLOGY, LANDSCAPES LEGACIES AND LANDSCAPE DOMESTICATION ...............................................................................177 GLOSSARY ..................................................................................................................................180 REFERENCES .............................................................................................................................195 FIGURES, TABLES AND CHARTS 233
  6. 6. v LIST OF FIGURES Figure 1. Children playing in a pit at the Hatahara site..........................................................234 Figure 2. The Amazon basin...................................................................................................235 Figure 3. The confluence of the Negro and the Solimões rivers ............................................235 Figure 4. A Yuhupdu family collecting forest fruits. .............................................................236 Figure 5. Bitter manioc growing in terra preta. .....................................................................236 Figure 6. Oxisol profile and monolith of dark earths at Nova Cidade....................................237 Figure 7. Wim Sombroek, terras pretas and terras mulatas..................................................238 Figure 8. Regions or sites discussed in Chapter 2, Section 3.1. .............................................239 Figure 9. Denevan bluff model of riverine settlement............................................................240 Figure 10. Models for the formation of dark earths................................................................241 Figure 11. Interior of longhouses in northwest Amazonia. ....................................................242 Figure 12. Palaeo-environmental records discussed in Chapter 3, Section 2.........................243 Figure 13. Archaeological sites discussed in Chapter 3, Sections 3.1-3.3..............................244 Figure 14. Archaeological sites discussed in Chapter 3, Section 4.2.. ...................................245 Figure 15. Archaeological sites and regions discussed in Chapter 3, 4.3...............................246 Figure 16. The Negro-Solimões confluence area. ..................................................................247 Figure 17. Selected sites from the central Amazon region.....................................................247 Figure 18. Archaeological sites in the Negro-Solimões confluence area...............................248 Figure 19. Calibrated ages and 3D viewshed for the Dona Stella site....................................249 Figure 20. Projectile point from Dona Stella site. ..................................................................250 Figure 21. The Açutuba site and its subdivisions in 3D. ........................................................251 Figure 22. Calibrated age ranges for the Açutuba site............................................................252 Figure 23. 3D viewshed of the Açutuba site...........................................................................253 Figure 24. Calibrated age ranges for the Osvaldo site............................................................254 Figure 25. 3D viewshed of the Osvaldo site...........................................................................255 Figure 26. 3D viewshed of the Hatahara site..........................................................................256 Figure 27. Calibrated age ranges for the Hatahara site...........................................................257 Figure 28. Excavations at the Hatahara site: Mound 1 and Urns’ unit...................................258 Figure 29. 3D viewshed of the Lago Grande site. ..................................................................259 Figure 30. Excavations at the Lago Grande ditch and promontories site...............................260 Figure 31. Calibrated age ranges for the Lago Grande site ....................................................261 Figure 32. 3D viewshed for the Nova Cidade site..................................................................262 Figure 33. 3D viewshe for the Lago do Limão and Antônio Galo sites.................................263 Figure 34. Calibrated age ranges for sites in the Lago do Limão area. ..................................264 Figure 35. Finished excavations at the Lago do Limão site in 2005 ......................................264 Figure 36. Central Amazon Project Late Holocene calibrated age ranges. ............................265 Figure 37. Sites examined in the geoarchaeological study.....................................................266 Figure 38. Three different geoarchaeological sampling contexts...........................................267 Figure 39. Three finished thin sections employed in the study ..............................................268 Figure 40. Image analyses to measure charcoal and soil texture............................................269 Figure 41. The Malvern Laser Particle analyser and Molybdenum blue................................270 Figure 42. Exposures examined in the geoarchaeological study............................................271 Figure 43. Selected clayey soil profiles of the Negro-Solimões area ....................................272 Figure 44. Selected sandy soil profiles of the Negro-Solimões area .....................................273 Figure 45. A “modal” terra preta soil profile: Urns’ unit, Hatahara site ...............................274 Figure 46. B horizon sediments: micromorphological characteristics....................................276 Figure 47. Micromorphology of clayey A horizon of background soil .................................276 Figure 48. Micromorphology pf terra mulata A horizon:......................................................277 Figure 49. Micromoprhology of terra preta A horizon..........................................................277
  7. 7. vi Figure 50. Micromorphology of sandy terra preta A and B horizons....................................278 Figure 51. Micromorphological observations of pottery........................................................280 Figure 52. MS and Fe in terras pretas, terras mulatas and background soils........................281 Figure 53. Micromorphological observations of bone fragments...........................................282 Figure 54. P and Ca from A horizon samples of terras pretas...............................................283 Figure 55. Micromorphology of microscopic charcoal. .........................................................284 Figure 56 Visual estimates of micro charcoal vis-à-vis measured Co.....................................285 Figure 57. Selected chemical properties by depth. HA1, AC-1, OS-1, NC-1. .......................286 Figure 58. Micromorphology of illuvial clays in terras pretas and terras mulatas. ..............287 Figure 59. Micromorphology of auto-fluorescent phytoliths .................................................287 Figure 60. Mn and MS of selected terra preta A horizon samples. .......................................288 Figure 61. The 2006 excavations at the Urns’ Unit, Hatahara................................................289 Figure 62. Location of sampling units at the Hatahara site ....................................................290 Figure 63. Profile HA-9..........................................................................................................291 Figure 64. HA-9. Selected physical and chemical properties by depth..................................291 Figure 65. Profile HA-5..........................................................................................................292 Figure 66. HA-5. Desiccation cracks, illuvial clays B horizon truncation .............................293 Figure 67. HA-5. Selected physical and chemical properties by depth..................................294 Figure 68. Profile HA-1..........................................................................................................295 Figure 69. Profile HA-3..........................................................................................................296 Figure 70. HA-1. Selected physical and chemical properties by depth..................................297 Figure 71. Full stratigraphic profile of Mound 1 (Profile HA-1). ..........................................299 Figure 72. Excavations of Mound 1 in 2002.. ........................................................................300 Figure 73. Calibrated radiocarbon dates from Mound 1 at Hatahara. ....................................301 Figure 74. Mound 2 showing depth of microscopic charcoal dated by 14 C............................302 Figure 75. Comparison of calibrated ages from Mound 2 and Mound 1................................302 Figure 76. The Lago Grande archaeological site....................................................................303 Figure 77. LG-3. Selected physical and chemical properties by depth. .................................304 Figure 78. Unit 1, Lago Grande (Profile LG-3): photo and profile........................................305 Figure 79. Profile drawing for Profiles LG-1, LG-2 and LG-4. .............................................306 Figure 80. LG-1, LG-2, LG-4. Physical and chemical properties by depth ...........................309 Figure 81. Plan of the Osvaldo site and photo of sampled profile OS-1 ................................310 Figure 82. Profile OS-1 ..........................................................................................................311 Figure 83. OS-1. Physical and chemical properties by depth.................................................311 Figure 85. The Açutuba site....................................................................................................312 Figure 86. Profile AC-2..........................................................................................................313 Figure 87. AC-2. Physical and chemical properties by depth ................................................313 Figure 88. Profile AC-1..........................................................................................................314 Figure 89. AC-1. Physical and chemical properties by depth ................................................315 Figure 90. Profile AC-2..........................................................................................................316 Figure 91. AC-3. Physical and chemical properties by depth ................................................317 Figure 92. The sandy banks at the Açutuba site .....................................................................318 Figure 93. The Nova Cidade site............................................................................................319 Figure 94. Profile NC-1..........................................................................................................320 Figure 95.Physical and chemical properties by depth ............................................................321 Figure 96. The Dona Stella archaeological site......................................................................322 Figure 97. Field research at the Dona Stella Site....................................................................323 Figure 98. Profile DS-1 ..........................................................................................................324 Figure 99. Micromorphology of DS-1....................................................................................324 Figure 100. Physical and chemical properties by depth; 13 C isotopes....................................325 Figure 101. A model for the development of soils at the Dona Stella site .............................326
  8. 8. vii List of Tables Table 1. Radiocarbon dates from the Dona Stella site............................................................250 Table 2. Radiocarbon dates from the Açutuba site.................................................................252 Table 3. Radiocarbon dates from the Osvaldo site.................................................................254 Table 4. Radiocarbon dates from the Hatahara site................................................................257 Table 5. 13C isotopes on human bone, Hatahara. ..................................................................257 Table 6. Radiocarbon dates from the Lago Grande site. ........................................................261 Table 7. AMS dates on shards from Lago do Limão and Antônio Galo. ...............................264 Table 8. Soil physical and chemical parameters of selected profiles. ....................................275 Table 9. Micromorphology of selected profiles......................................................................279 Table 10. Hatahara 9. Micromorphological characteristics....................................................291 Table 11. Hatahara 9. Soil physical and chemical parameters. ..............................................291 Table 12. Hatahara 5. Micromorphological characteristics....................................................292 Table 13. Hatahara 5. Soil physical and chemical parameters. ..............................................294 Table 14. Hatahara 1. Micromorphological characteristics....................................................295 Table 15. Hatahara 3. Micromorphological characteristics....................................................296 Table 16. Hatahara 1. Soil physical and chemical parameters. ..............................................298 Table 17. Hatahara 3. Soil physical and chemical parameters. ..............................................298 Table 18. New 14C dates on microscopic charcoal for Mound 2...........................................302 Table 19. Lago Grande 3. Soil physical and chemical parameters.........................................304 Table 20. Lago Grande 3. Summary of micromorphological characteristics.........................304 Table 21. Lago Grande 1. Micromorphological characteristics .............................................307 Table 22. Lago Grande 2. Micromorphological characteristics .............................................307 Table 23. Lago Grande 4. Micromorphological characteristics .............................................307 Table 24. Lago Grande 5. Soil physical and chemical characteristics....................................308 Table 25. Lago Grande 1. Soil physical and chemical parameters.........................................308 Table 26. Lago Grande 2. Soil physical and chemical parameters.........................................308 Table 27. Lago Grande 4. Soil physical and chemical parameters.........................................308 Table 28. Osvaldo 1. Soil physical and chemical parameters. ...............................................311 Table 29. Açutuba 2. Micromorphological characteristics.....................................................313 Table 30. Açutuba 2. Soil physical and chemical parameters. ...............................................313 Table 31. Açutuba 1. Soil physical and chemical parameters. ...............................................314 Table 32. Açutuba 1. Micromorphological characteristics.....................................................314 Table 33. Açutuba 3. Soil physical and chemical parameters. ...............................................316 Table 34. Açutuba 3. Micromorphological characteristics.....................................................316 Table 35. Nova Cidade 1. Soil physical and chemical parameters.........................................320 Table 36. Nova Cidade 1. Micromorphological characteristics .............................................320 Table 37. Dona Stella-1. Micromorphological characteristics ...............................................324 Table 38. DS- 1. Soil physical and chemical parameters .......................................................325
  9. 9. viii ACKNOWLEDGEMENTS Despite obligatory declarations to the contrary (page i) a dissertation about an enormous landscape involves the help of many people – colleagues, family, friends and others – dispersed in a geography that is even wider than the Amazon basin. Now finally at the end of the long road, it is my very great pleasure to hereby greet them and offer many thanks to all of them. At the Department of Archaeology, University of Cambridge, my gratitude goes first to my supervisor, Preston Miracle, and my advisor, Charles French. In different ways both constantly supported this project over the many years it took to reach its completion, offered their good and experienced advice, patiently read over numerous drafts and hundreds of pages of Amazonian archaeology and Dark earths, and even gave me books as presents (thank you). My gratitude is also due to past, present, and affiliated members of the McBurney Geoarchaeology Lab – Helen Lewis, Melissa Goodman, Karen Milek, Federica Sulas, Andrea Balbo, Ann-Maria Hart, Miranda Semple, Heejin Lee, Mary Ownby, Clea Payne, Lawrence Smith, and Judith Bunbury – with whom I have discussed aspects of the geoarchaeological evidence and shared many good moments. Resident or visiting academic staff at the Department – Liz DeMarrais, Chris Chippindale, Ezra Zubrow, Paul Sinclair, Marie-Louise Sørensen, and Robin Boast – are also thanked for different exchanges and overall support over the years. My gratitude also goes to Jane Woods, David Redhouse, Jessica Rippengal, Natasha Martindale, Casey Singe, and Julie Boreham, at the Department of Archaeology, and Steve Boreham and Chris Rolfe, of the Physical Geography Laboratory at the Department of Geography. Julie and Steve, in particular, provided assistance and expertise crucial to conduct some of the laboratory analyses reported in the following pages. At the Department of Social Anthropology, I would like to thank Françoise Barbira-Friedman and Stephen Hugh-Jones, with whom I have enjoyed good exchanges and pondered long silences about what life in the Amazon basin must have been like in the past. Finally, with the Cambridge rite of passage still fresh in my mind, I would like to first thank my colleague and friend Sue Hakenbeck, who proofed much of the final draft of the dissertation before initial submission. Second, I would like to offer a big thank you to the examiners of this thesis, Graeme Barker from Cambridge University and Peter Stahl from Binghamton University. Despite my attempts to make pages and pages about soil accessible to the non-geoarchaeologist, I know that what I have written is not the easiest piece to read. I therefore truly appreciate their attention to detail as well as the sharp and thought-provoking points offered by each at the Viva Voce exam. My next stop is Brazil, where my first and heartfelt gratitude is extended to Eduardo Góes Neves, at the Universidade de São Paulo. Edu was the first person to host me during my initial trip to Brazil, a time (1999) when I knew very little about Amazonia. Apart from good times, Edu let me rummage through his filing cabinet and copy whatever I felt like copying, an openness to sharing knowledge that I have never forgotten. Later, in 2002, he accepted my
  10. 10. ix offer to conduct a geoarchaeological study of anthropogenic dark earths within the Central Amazon Project. He thus provided me with a unique opportunity to take my first step into the vast realm of Amazonian archaeology after a false start working in the upper Negro basin in 2001. Over the years, exchanges of ideas and information with Edu have played an important part in shaping some of the thoughts presented in this dissertation. We have also shared complicated moments, not least the assassination of Jim Petersen in 2005. In earnest, I feel indebted by Edu’s support, generosity, friendship and hospitality (and Dainara’s). I believe that this PhD would not have come into being had it not been for his openness to collaboration, and strongly hope that we will continue to work together at full speed in the years to come. My involvement with the Central Amazon Project, on the other hand, led me to meet, work with, and exchange ideas with a large cohort of archaeologists, researchers and field workers, many of whom today I also count among my good friends. Among others they include the late Jim Petersen, Bob Bartone, Helena Pinto Lima, Fernando Costa, Claide Moraes, Carlos Augusto da Silva, Levemilson Mendonça, Anne Rapp Py-Daniel, Claudio Cunha, Raoni Valle, Carla Carneiro, Valdilene Moraes, Tereza Parente, Marcos Brito, Francisco ‘Pupunha’ Vilaça, Lilian Rebellato, Patrícia Donnati, Juliana Machado, Lucas Bueno, Mauricio da Paiva, and Ricardo Chirinos. Important lessons were learned and great moments were had with many: Jim offered many thought-sparks, many laugh-absurds, and taught me the word Saladoid; Bob showed me the importance of being earnest, made my mind ponder grave questions, and taught me the power of the shovel; Doutora Macuqinho taught me about ceramics, passion and friendship, Fernando shared his white sand madness, his musical acumen, and also his friendship; with Claide, a great archaeologist, let the show roll – lets dig and discuss some more (same goes for Fernando Osorio); Commander Raoni was my buddy on a mighty trip, commands all my respect as a human being and as a scholar, and we ready ourselves for the upper Negro; Carla has offered her friendship and also shown the most exciting way of socializing archaeology; Anne, the mother of Rafael and silent conspirator of the skeletal revolution, has also offered her friendship and hospitality … at this rate I will not finish these acknowledgements. Suffice it to say that over the course of four field seasons in 2002, 2003, 2005 and 2006, the Central Amazon Project provided me with an opportunity to be part of what is, without a shadow of a doubt, the most exciting and intense archaeological project I have ever participated in. Still in Brazil I would like to extend my gratitude to my friend and colleague Renato Kipnis and his family, which have hosted my stays in Brazil on numerous occasions; to Charles Clement, with whom discussion continues and collaboration is perhaps only starting; to Arnaldo Carneiro, who was the first earth scientist in Brazil which heard what the rationale of my research was about; to Fatima Teles, at the Museu Paraense Emílio Goeldi, who went to great lengths to help me find references and make my stay in Belem comfortable; to Fabiola Silva, whose religious fervour no doubt helped the happy arrival of my first samples to the UK
  11. 11. x and who knows what else; to Cristiana Barreto, whom I first met in Cambridge and whose thought-wavelengths I sometimes parallel; to Edithe Pereira, who was among the first to meet me in Brazil, generously shared her personal library with me and, recently, invited me to the incredible Amazonian Archaeology conference in Belém; to Vera Guapindaia, who showed me the Maraca urns before I knew Maraca urns existed. I would also like to acknowledge the support provided in 2001 by Instituto SocioAmbiental colleagues Aloisio Cabalazar, Flora Cabalzar, Beto Ricardo, Geraldo Andrello, the late Jorge Pozzobon, Marta Azevedo, Pieter van der Veld, and Carlão Souza, as well as my ex-girlfriend Ashley Lebner. Despite the many good encounters, this dissertation was written in relative intellectual isolation: no one in Cambridge understood one thing about Amazonian archaeology! No one I could find understood much about tropical soils either. No one, including myself. Over the course of the years, therefore, I was forced to cast the widest net of exchanges and it is these that provided true intellectual lifelines and sources of knowledge. Perhaps the first was a 2002 visit to ISRIC, Wageningen, to study thin sections of antropogenic dark earths. Here I met the very tall and affable Wim Sombroek, who was kind enough to discuss with me what these soils where all about, allowed me to borrow those thin sections for study in Cambridge, and also showed me his collection of orchids. The next was the meeting organised by Johannes Lehmann, Bruno Glaser, Dirse Kern, and Bill Woods in Manaus, also in 2002. This led me to meet other memorable students of the Amazon, including the organisers themselves and Hedinaldo Lima, Laura German, Philip Fearnside, and Charles Mann. Courtesy of this meeting we not only got the most spectacular views of the Negro river and an initial peek of a storm in the Tapajós, but also an amazing opportunity to examine different archaeological sites with anthropogenic dark earths in a variety of different contexts. I particularly cherish discussing a terra preta profile with Wim Sombroek from a boat in the Tapajós, and getting from Bill Woods the first of many good pieces of advice, to key my eye into the landscape. Other settings were equally crucial to expand my horizons in Amazonian archaeology. The meetings organised by Bill Sillar in London put me in touch with the small but bright intellectual community of lowland South Americanist archaeologists in this city, including here especially José Oliver, who once hosted me for a full day of lowland talk and from whom I obtained copies of the most rare pieces of Amazonian literature; Warwick Bray, who graciously provided me with a full set of ProCalimas; Costillita Colin McEwan, who always offered his best wishes for my research; and Liz Graham, who was a great discussant of a paper I presented in London. Similar remarks can be said about meetings in scholarly contexts at Montreal (2004), Puerto Rico (2006), and Dublin (2008), at which I finally came to meet a number of minds interested in the Neotropical lowlands and the Caribbean. Included here are Stéphen Rostain, who has presented me with very nice surprises between book covers and also spiked my curiosity about the Guianas; Mike Heckenberger, who told me to never give up and
  12. 12. xi whom I hope to see in the Xingú some time soon; mad-man-from-Minessota Morgan Schmidt, who is writing another dissertation on dark earths that I am sure will rock the boat; Betty Meggers, who startled me by asking why sedimentation in the Central Amazon was so rapid; Doyle McKey, who at lightning speed provided excellent comments about my manioc domestication hypothesis, and Bill Balée, with whom I know we have much more to talk about. Puerto Rico and Dublin also allowed me to meet others whose scholarship I greatly respect, such as Richard Cooke, Arie Boomert, Arthur Rostoker, Cristóbal Gnecco, and John Walker. Montreal led to a visit to Burlington with Jim, Edu and Bob, during which I met John Crock and Jess Robinson, both good people. Some of the above have been kind enough to send me copies of their own or others’ work to expand my personal library – many thanks. When it comes to dark earths, meetings in Stirling (2004), Cambridge (2007), and Dublin (2008) allowed me to examine at first hand the work that others had done on anthrosols and to present and discuss my own. I have lasting memories of thin sections shown to me by Donald Davidson, of conversations with Paul Adderley about particle-sizing methods and anthrosols, of cross-comparisons and discussion of observations with Yannick Devos, and of inspiring exchanges with Richard Macphail, Hans Huisman, Wendy Matthews and Tim Beach. This trajectory is coronated by the session on Geoarchaeology and Dark Earths that Yannick, our colleague Cristiano Nicosia, and myself recently co-chaired at Dublin: roll on dark anthrosols in geoarchaeology! For varied and altogether good reasons, all of the above encounters are unforgivable. However, it is undoubtedly email which provided the most constant stream of provocation: I have particularly fond memories of discussions about the Central Amazon Project and the archaeology of the lowlands with Edu, Claide, Helena, Bob, and Jim; about soils, anthropogenic or otherwise, with Bill Woods, Hedinaldo Lima, Johannes Lehmann, Bruno Glaser, Hans Huisman, Richard Macphail, Yannick Devos, Wenceslau Texeira, Donald Johnson, Peter Buurmam, Michael Thomas (the latter three which I have never met); about domestication, languages, archaeological distributions, and plants fossils with Charles Clement, Eduardo Neves, Michael Heckenberger, and Glen Sheppard; about slash and burn agriculture with Charles Clement, James Fraser, Eduardo Neves, William Denevan, Robert Carneiro (the latter two whom I have never met). The list could go on but I would just like to acknowledge that many of these exchanges were involved in shaping some of the thoughts I present in this dissertation and also express awe at the fact that so many good thoughts have been formulated in emails! This brief account would be incomplete if I did not mention, first, other scholars like Dolores Piperno, Per Stenborg, Warren DeBoer, Aad Versteeg, Mark Plew, Omar Ortiz-Troncoso, Juan Carlos Berrío, and Clark Erickson – most of which I have never met in person – who sent me copies of their publications and/or responded to my questions about specific points over email. Second, the many important lessons in archaeology and true intellectual collaboration that I have learned from collegues who do not work in the
  13. 13. xii Neotropical lowlands, particularly my friends, some my old professors, Luis Borrero, Donald Jackson, Victoria Castro, Mauricio Massone, Pedro Cárdenas, Teko Prieto, Flavia Morello, and Manuel San Román. The observations presented in this dissertation are the result of doctoral investigations conducted with the support of Wenner Gren Foundation dissertation fieldwork grant no. 6972 and of the McBurney Geoarchaeology Laboratory, Department of Archaeology, University of Cambridge. Additional support was also received from Girton College and the Centre for Latin American Studies, both at the University of Cambridge. Investigations have taken place within the broader framework of the FAPESP-supported Central Amazon Project (grants 02/02953-7 and 05/60604-3), which apart from providing full logistical support, also covered the cost of some air tickets to travel to Brazil. Indeed all of the site plans and some of the profile drawings presented in the dissertation bear the ultimate watermark of Marcos Brito and have been adapted from project research reports. The support of the UK Natural Environment Research Council (NERC), Tom Higham (Oxford Radiocarbon Accelerator Unit), and Preston Miracle (University of Cambridge) to obtain AMS radiocarbon dates on ceramic shards from two sites, Antônio Galo and Lago do Limão, is gratefully acknowledged. Wayne Rasband from the NIH provided prompt responses to all of my questions about the ImageJ software. Gordon Walker, from ALS Chemex, offered helpful responses to question on the ICP-AES data. It would not have been possible to write this dissertation without the unflinching support, strong inspiration, and continuous confidence of both of my parents, Manuel Arroyo and Mary Kalin. Nor would it have been possible to get this far without the love, care and humour of my compañera Özlem Biner, who has been through a few with me and patiently awaited what is undoubtedly a long and difficult coming-into-being. I owe to these three people more than I can convey in words. My good friends and colleagues José Miguel Tagle, Dina Guseynova, Sevil Serbes, Almir Koldzic, Özge Biner, Lucy Delap, Clive Lawson, Sue Hakenbeck, Andrea Balbo, Manuel San Román I, Dave Robinson, Marta Magalhães, Umut Yıldırım, Juanita Baeza, Lennie Charles, Marjorie Marcel, Miguel Castello, Andreas Vlachos, Stefania Merlo, Salam Al-Kuntar, Alex Herrera, Nolwazi Mkenazi, Eisuke Tanaka, David Beresford-Jones, Kevin Lane, Claudia Grimaldo, Daniel Rodríguez, Piotrus Kozak, Valentina Trejo, Harry Loewenfeldt, Clea Chadmal, Sebastian Kohon and Sa’ad Al-Omari know other, different parts of the story: hence many thanks to each and every one of them and toasts for friendship. It is likely that I have forgotten someone that deserves my thank you. It is also possible that I have misunderstood, misread or undeliberately misrepresented somebody’s research or ideas. Advanced apologies in either case. As José Saramago writes in A Jangada de Pedra:
  14. 14. xiii “Thinking carefully there is no beginning to things and persons, everything that started one day had started before, in order to be true and complete the history of this sheet of paper - let us take the example closest at hand - would have to reach back to the beginnings of the world - plural here being purposely used instead of singular; and even then let us doubt, for those beginnings beginnings were not, only points of passage, sliding platforms, poor head is our own, subject to such pulls, admirable head, despite all, that is capable of madness for all reasons but this.” I would like to dedicate this dissertation to the memory of Jim Petersen, so stupidly assassinated in a random day of our lives. I would have wanted Jim to read this dissertation and I am sure that he would have read it already. I know Jim cherished a good discussion as much as I do: Jim, I hope we would have disagreed! NOTES ON DATA SOURCES Unless otherwise credited in figure captions, all photographs presented in this dissertation are of my authorship. All excavations shown in photographs were conducted by the Central Amazon Project. All site plans have been adapted from originals prepared by Marcos Brito for the Central Amazon Project and are used with permission. Profile drawings for HA-3, HA-9, AC-1, AC-2, NC-1, DS-1 prepared by me, all others adapted from originals prepared by Marcos Brito for the Central Amazon Project and used with permission. All 14C dates from Beta Analytic Inc. were obtained by the Central Amazon Project and are used with permission. All 14C dates from the Oxford Radiocarbon Unit and Waikato Labs obtained by me with the support of the Wenner Gren Foundation and NERC. All micromorphological observations compiled by me. All ICP-AES, Co and Ct data produced by ALS Chemex under contract with the McBurney Geoarchaeology Lab, Cambridge, and interpreted by me. All pH, EC, LOI and MS data compiled by me at the Physical Geography Laboratory, Cambridge. The basemap used in maps of the Amazon basin (also inset in satellite images) is based on a USG/WWF Hydrosheds image (hydrosheds.cr.usgs.gov/images/hydrosheds_amazon_large. jpg, accessed 10/04/2008). Vertical satellite imagery are snapshots of the NASA WorldWind 1.4 software or the Google Earth 4.0 software. Tilted viewsheds in Chapter 4 are based on vertically-exaggerated (x10) Landsat satellite images draped onto the digital elevation model used by the NASA WorldWind 1.4 software.
  15. 15. xiv CONVENTIONS USED IN TEXT, FIGURES, TABLES, AND CHARTS Glossary The meaning of specialised terms used in the dissertation has been unpacked in a Glossary (page 180). For the most part these consist on earth-science related terms (including geology, geomorphology, pedology, and micromorphology), terms used in Amazonian scholarship (including a number of concepts used to describe Amazonian geoforms), and terms in Portuguese, Spanish, or Nheengatú used to refer to specific objects or substances. In the main text, the first usage of each term is marked as follows: A horizon. Dates and ages Unless otherwise indicated, all ages quoted in the text are calibrated radiocarbon years (Intcal 04) using a single standard deviation (66.8%). Both cal year BP and cal years BC are used depending on the age of the context under discussion. For the first half of the Holocene ages are discussed in calibrated years before present and rounded to kilo years (kyr), e.g 14 C date 5240 + 40 = cal. 6180-5920 BP = 6.2-5.9 kyr BP. For the next half of the Holocene, evidence is discussed in calibrated years before the Christ era and not generally rounded, e.g. 14 C date 2269 + 42 = cal. 400-220 BC. Site, profile and sample designation Site short-hand names: HA = Hatahara LG = Lago Grande AC = Açutuba OS = Osvaldo DS = Dona Stella NC= Nova Cidade Examples of short-hand name usage: NC = Nova Cidade NC-1 = Profile 1 of the Nova Cidade site NC-1.2 = Profile 1, sample 2 of the Nova Cidade site Conventions for micromorphology tables Porosity = % surface area of thin section. Pores: • = channels/ chambers;   = planar voids. Texture: Based on the US Department of Agriculture standard. The following are used: C= Clay; SC= Sandy clay; LS= Loamy sand; SCL= Sandy clay loam; SL = Sandy loam. Fine fraction, Silt quartz, Sand quartz = % surface area of solids. Microartefacts = % of thin section view. Bone and Charcoal = % of the fine mineral fraction of bone and charcoal fragments. Size classes as described below. Abundance of particulates expressed in relative terms: (•) = marginal; • = rare; •• = common; ••• = frequent; •••• = dominant. Fresh organics: r= roots. n/m = not measured
  16. 16. xv Light sources: OIL=Oblique incident light; XPL=Cross-polarised light; PPL=Plain polarised light; XPO=XPL with OIL beam; OILx=OIL with low XPL beam; UVL=Ultra violet light. The same abbreviations are used in the text. Organic staining: L = limpid, 1 = organic punctuations; 2 = lightly stained; 3; medium stained; 4; strongly stained. B-fabric: u=undifferentiated; s=speckled; S=striated S = strial. Microstructure: Capitals identify the major types: M = matrix-supported fabric (porphyric c/f related distribution) where the fine mineral fraction is made of relatively continuous zones of slightly vughy clayey material; G = grain-supported fabric (enaulic and/or monic c/f related distribution) where the fine mineral fraction is reduced and quartz grains acts as the main skeleton of the soil. Small letters characterise the morphology and organisation of the fine mineral fraction: m = continuous, massive slightly vughy clayey material showing little separation; b = subangular blocks that cannot clearly be associated with faunal action; i = irregular clayey peds that cannot be conclusively interpreted as having a coalesced origin; c = irregular clayey peds that can be interpreted as having an origin in coalesced aggregates; g = granular microstructure made up of <150µm pellets; s = small incipient or relict porphyric clayey peds in a grain-supported matrix; r = grano-oriented clayey braces (<50µm) and small intergrain pellets (<50 µm). Size classes (Texture, bone, charcoal) µm <2 2-20 20-63 63-100 100- 200 200- 500 500- 1000 1000- 2000 >2000 Class fine mineral fraction fine silt coarse silt very fine sand fine sand medium sand coarse sand very coarse sand fine gravel Colours: colours used in tables are approximations of digital photos to Munsell colours. Tiles were sourced from http://www.xrite.com/ (accessed 21/09/2005): 3/4 3/6 4/2 4/3 4/4 4/6 4/8 5/2 5/3 5/4 5/6 5/8 6/3 6/4 6/6 6/8 7/4 7/6 7/8 8/6 8/8 9/8 10YR 7.5 YR 2.5 YR Measurements of soil physical and chemical characteristics Measurements of Aluminium (Al), Barium (Ba), Calcium (Ca), Copper (Cu), Iron (Fe), Potassium (K), Magnesium (Mg), Manganese (Mn), Sodium (Na), Phosphorus (P), Strontium (Sr), and Zinc (Z) are in all cases expressed in ppm. Loss-on-Ignition (LOI), Organic Carbon (Co) and Total Carbon (Ct) are expressed as %w (percentage of weight). Electrical conductivity (EC) is expressed in µs (Microsiemens). Magnetic susceptibility (MS) is expressed in low frequency tesla SI units. Microphotographs Each microphotograph is labelled on the bottom right corner. This label shows profile and sample number and light source. A scale bar has been added to the label.
  17. 17. 1 Chapter 1 INTRODUCTION 1. ANTHROPOGENIC LANDSCAPE TRANSFORMATIONS A shift away from the perception of past environments as self-regulating and equilibrium- seeking systems to which individuals, cultures or populations adapted is now well underway in archaeology (McGlade 1995; Stahl 1996; Erickson 2000; van der Leeuw and Redman 2002; Hayashida 2005; Kirch 2005). This shift can be argued to follow from two complementary understandings. The first is that the nested hierarchies of life and matter that we call environments are historical entities, i.e. that the dynamic relations which articulate the flux between and among their abiotic and biotic components both express and are determined by definitive but non-deterministic trajectories of change, paths whose effects can accumulate over time (Butzer 1982; Delcourt and Delcourt 1988; Phillips 1999a; Thomas 2001; Balée 2006). The second is that the affordances which particular environments offer to human communities, i.e. the way in which such environments constrain, structure and enable particular human lifeways (Figure 1), are not ‘natural givens’ shaped exclusively by broad- scale processes such as climate change, geomorphic evolution, vegetation cover, etc. Instead, these affordances – contingent properties of surrounding worlds as they are interacted with – are in many cases a veritable and enduring effect of specific practices of inhabitation that have characterised past human livelihoods (Denevan 1966a; Denevan 1992a; Balée 1989, 1994; Balée and Erickson 2006; Botkin 1990; Stahl 1996; Cronon 1996; Erickson 1995, 2006; Arroyo-Kalin 2004). The intersection between these two premises in archaeological thinking is perhaps best epitomised by a gradual abandonment of the notion of ‘environment’ and by the increasing popularity of the notion of ‘landscape’ (e.g. Crumley 1994; Tilley 1994; Gosden 1994; Barrett 1999; Layton and Ucko 1999; Ingold 2000; Anschuetz et al. 2001; Stahl 2000; Heckenberger et al. 2003; Balée and Erickson 2006; Erickson 2006; see also Ashmore 2002; Redman and Kinzig 2003; Fisher and Feinman 2005). This abandonment signals the rejection of environment as a kind of external scaffolding for adaptation and its replacement by an understanding of the material world as a dynamic domain that has been inhabited by human communities and changed through human inhabitation. Beyond the step forward that this
  18. 18. Chapter 1 2 formulation represents, however, many would agree that the very diversity of views invoked by the notion of ‘landscape’ makes it difficult to pin down exactly what is meant by the category itself. Rather than attempt here a precise definition, I think it is important to outline how landscapes can fit into archaeological accounts or, more specifically, how they fit into the archaeological account that I attempt in the following pages. I take the perspective that human niche-building (Laland et al. 2000) is a complex process that has implied the continued reproduction of symbiotic relations with other species at least since the early Holocene (Rindos 1984; Lathrap 1984; Harris 1989; Bellwood 2005; Barker 2006; Clement 2006a). In different regions of the planet, this reproduction evolved into ongoing processes of plant and animal domestication and also instigated modifications of the physical environment associated with husbandry practices (e.g. Denevan 1966a; Denevan 1992a, 2001; Pape 1970; Limbrey 1975; Davidson and Carter 1998; Davidson and Simpson 1984; Bray et al. 1987; Bray 1991; Sandor 1992; Woods and McCann 1999; Terrell et al. 2003; French 2003). In many cases, these modifications endured beyond years, decades, or centuries, kick-starting what may be described as divergent – indeed emergent – trajectories of change in the overall characteristics of the physical environment. These modified trajectories may be understood as anthropogenic landscape transformations: a shaping of biotic and abiotic legacies resulting from the intersection between the cumulative effects of human action, often over trans-generational time scales, and broader processes of landscape evolution. Reference to anthropogenic landscape transformations brings together the perspective of Historical Ecology, which highlights how human communities have creatively, sometimes positively transformed the surrounding worlds into which subsequent people are born (Posey 1985; Balée 1989, 1998; Balée and Erickson 2006; Crumley 1994; López-Zent 1998; Clement 1999a), and earth-science and ecological approaches, which chart the dynamic character of landscapes as evolving networks of biotic and abiotic components characterised by self- organisation, spatially-divergent dynamics, and path-dependence (Phillips 1999a; Phillips 1999b; Thomas 2001). As a formulation, the notion of ‘anthropogenic landscape transformation’ evidently adopts the anthropocentric pro-position advanced by Historical Ecology – that the human species is “itself a principal mechanism of change in the natural world, a mechanism qualitatively as significant as natural selection” (Balée and Erickson 2006:5). However, by focusing attention on the intersection between human action and landscape evolution, it argues that the “palimpsest of continuous and discontinuous inhabitation by past and present peoples” (Balée and Erickson 2006:2) has structured bio- physical entities whose continued existence as anthropogenic legacies unfold within
  19. 19. Chapter 1 3 landscapes whose biotic and abiotic components are in path-dependent flux (e.g. Erickson and Balée 2006; Mayle et al. 2007). These remarks provide just enough background to outline the main purpose of this dissertation: to explore how the study of anthropogenic landscape transformations can augment our understanding of the human history of a big landscape, the Amazon basin. 2. THE LANDSCAPE OF AMAZONIA The Amazon basin (Figure 2) comprises the largest tract of land of the tropical lowlands of northern South America, a terrain that drops from an overall elevation just below 200 m asl at the Andean piedmont to sea-level elevation some six thousand kilometres away, at the Atlantic coast. At present it records temperatures that remain above 25°C on a year-round basis, and year-round precipitation gradients that range between <1000 and 8000 mm. These gradients reflect the shifting position of the Inter-Tropical Convergence Zone, the South Atlantic Convergence Zone, and the Atlantic tropical easterlies; the influence of evapotranspiration from the Amazon rainforest itself; and shifts in local air circulation in response to relief, vegetation and differences in albedo (Salati and Marques 1984; van der Hammen and Hooghiemstra 2000; Bush and Silman 2004). Geological research shows that the terrain of Amazonia originated as a Palaeozoic rift- valley that formed on an enormous inter-cratonic basin associated with the Archean age Guiana and Central Brazilian shields. As the Andes emerged, the western half of present-day Amazonia shifted its drainage from the Pacific to the Caribbean, in turn forming depositional basins that became infilled with Andean and Archean sediments and even experienced some marine incursions (Räsänen et al. 1995; Räsänen et al. 1987; Hoorn 1994, 1996; Wesselingh et al. 2002; Roddaz et al. 2005). Depositional basins of the eastern half of Amazonia also became infilled with eroded Archean sediments and may have experienced some estuarine incursions (Rossetti and Netto 2006) but either all Andean sediments were eroded away from the stratigraphic record or they only accumulated in the floodplain of rivers after a single, equatorially-aligned, Andes-to-Atlantic drainage – the precursor of today’s Amazon river – developed at some point between the Miocene and the late Pleistocene (Rossetti et al. 2004a; Irion et al. 2005; Rossetti et al. 2005). A partial sense of the size, geography and ecology of the region is gained if its drainage network is considered. Not only is the Amazon river the biggest river in the world by all possible measures but some of its tributaries can be considered among the five largest as well (Latrubesse et al. 2005). Together they drain about 7.5 million km2 , i.e. about 40% of South
  20. 20. Chapter 1 4 America, and discharge about one sixth of the fluvial freshwater that reaches the oceans on a global basis (Irion et al. 1997). Many Amazonian rivers run in channels that appear as large canyons with respect to the surrounding terrain. Within these channels, the amplitude between flooding highs and lows is expressed in tens of meters and constitutes one form of ‘seasonality’. However, because flooding results from the combined effects of precipitation in upstream regions, it is a seasonality progressively less and less synchronised, from west to east, with dry and wet seasons determined by convective activity. In Amazonian scholarship, rivers are usefully classified into clear, black, and whitewater rivers (Moran 1993). Clearwater rivers are limpid streams that drain the weathered Tertiary plateaus and follow established, often rocky beds with stable banks. Blackwater rivers drain rainforest- or savannah-covered terrain of Tertiary age but are rich in dark-coloured humic compounds deriving from the decomposition of organic matter. Whitewater rivers are those that originate in the Andes, transport copious amounts of suspended sediments of Quaternary age, and - in places - grade an extensive floodplain known, in Amazonian scholarship, as the várzea (Figure 3). The resulting riverscapes are inhabited by a highly diverse and abundant aquatic fauna that includes fish, reptiles and mammals. A broad relation exists between the density and/or size of this fauna and the sediment load of rivers (a higher biomass is found in whitewater rivers), the upstream versus downstream position of the water body (fish become smaller and less abundant upstream), and the flooding regime (there are less fish per volumetric unit of water during flooding highs). The other ‘face’ of the Amazon basin is constituted by the terra firme, the terrain that is never flooded by large rivers. Although an elevation gradient for the most part below 200 m would suggest that this terrain is flat, the terra firme is in reality characterised by rolling hills that have been shaped since the Tertiary by a combination of tectonics, peneplanation, and etchplanation (Bigarella and Ferreira 1985; Clapperton 1993; Thomas 1994). Soils of the terra firme are therefore ancient and characteristically determined by the effects of tropical precipitation and temperature conditions on highly- and deeply-weathered Tertiary rocks. The most common soil types, Oxisols (Sombroek 1966; Richter and Babbar 1991), provide an illustrative case: they show a deep saprolite at many meters below the surface above which develops a kaolinitic horizon with gibbsite and hematite nodules; a thick and permeable B horizon; and a shallow A horizon with low retention of organic matter, acid soil pH, and low soil nutrient status. The collapse of the argillo-ferric structure of these soils as a consequence of lateral subsurface flushing, the latter induced by the very dissection of the terrain effected by rain-fed streamlets or igarapés, shapes a toposequence from clayey Oxisols to sandy Spodosols that contributes to the concave morphology of hillsides and releases humic compounds into the drainage network (Chauvel et al. 1987; Tardy and Roquin 1993; Lucas et
  21. 21. Chapter 1 5 al. 1996; Horbe et al. 2004; do Nascimento et al. 2004). Extensive areas of the basin that are characterised by sandy soils and drained by blackwater rivers are believed to represent an advanced stage of this process (Dubroeucq and Volkoff 1998). The vegetation of the terra firme greatly depends on climatic factors – especially total rainfall, length of the dry season, and temperature (Walsh 1998; Bush et al. 2004a) – as well as edaphic conditions – soil nutrient status, soil texture, and drainage (Rankin-de-Merona et al. 1990; Laurance et al. 1999). Tropical rainforests cover some 4 to 6 million km2 of the basin. They occur mostly in regions exposed to climate regimes that include relatively short dry seasons. It is possible to distinguish between dense aseasonal rainforests, which are associated with high precipitation and well drained clayey soils; open rainforests, which are associated with low water tables, poor drainage and/or drier conditions; semi-deciduous or seasonally dry tropical forests, which are transitional to savannah vegetation; the Amazonian caatinga, an open forest type characteristic of sandy soils; and gallery forests, linear arboreal expanses that flank the rivers running though savannah regions. Savannah covers about 3-4% of the Amazon basin and varies from sedge- and/or grass-dominated treeless landscapes to open parkland vegetation characterised by patches of woodlands with grass-dominated understories. In addition to rainforest and savannahs, flooded vegetation is important throughout the region. It includes flooded forests or igapós, which are highly endemic arboreal formations associated with abandoned channels and inland water bodies of alluvial origin; swamp vegetation, which is often characterised by specific palm taxa that grow well on poorly-drained soils; and mangroves, which occur mostly in tide-sensitive rivers near the mouth of the Amazon. The abundance and diversity of terrestrial fauna in the Amazon basin – insects, birds, mammals, reptiles, and amphibians too numerous to be mentioned – vary according to soils, the standing biomass, and the gradient between open and rainforest vegetation (Prance 1982; Eisenberg 1990; Malcolm 1990). The landscape of the Amazon basin has been anything but static during the late Quaternary. As will be discussed in further detail in this dissertation, palaeoecologists argue that decreases in temperature, atmospheric CO2, and/or precipitation permitted a contraction of the rainforest around its western core towards the Late Glacial Maximum or LGM (Bush et al. 2004b; Anhuf et al. 2006). Thereafter, the rainforest began to expand and continued to do so at least until the early millennia of the Holocene. The picture is more complicated after that, partly because more arid conditions in regions peripheral to the basin during the Holocene accompany a steadfast resilience of the Amazon rainforest (Mayle et al. 2004; Bush et al. 2007), and partly because sea-level rise and potential anthropogenic influence complicate interpretations of many palaeo-ecological records (Behling 2002).
  22. 22. Chapter 1 6 3. ANTHROPOGENIC LANDSCAPE TRANSFORMATIONS IN AMAZONIA The extent to which human communities acted as a significant factor in the evolution of the biotic and abiotic constituents of the Amazonian landscape has been made increasingly clear by scientific research over the last few decades. The archaeological record of the basin evidences a very broad array of forms of pre-Columbian engineering of the landscape. Included here is the construction of different types of earthworks – ditches, shell mounds, earth mounds, roads, raised fields, artificial forest islands – which served to colonise, intensify or develop flooding landscapes rich in aquatic resources; to intensify crop cultivation; and to implant transportation networks and defensive infrastructures that are associated with settlements that range in scale from small villages to proto-urban aggregations (Nimuendajú 1952, 2004; Meggers and Evans 1957; Hilbert 1959; Hilbert 1968; Denevan 1963; Denevan 1966a, 1970a; Denevan 2001; Erickson 1980, 2000, 2006; Simões 1981; Roosevelt 1991; Roosevelt et al. 1991; Perota 1992; Rostain 1994, 1999b; Heckenberger 1998; Heckenberger et al. 1999; Heckenberger et al. 2003; Heckenberger 2005; Heckenberger et al. 2008; Neves 2000, 2003; Neves 2005, 2008; Pärssinen and Siiriänen 2003; Donatti 2003; Schaan 2004; Schaan et al. 2008; Walker 2004; Machado 2005; Moraes 2006). Their size, scale and ubiquity leave little room for doubt that past human communities had an enormous impact on the morphology of the Amazonian landscape (Denevan 1992a; Cleary 2001; Erickson 2006; Mann 2008; see Meggers 2003 for a sceptical view). Different researchers have also identified a very significant number of plant domesticates that most likely originate in the Amazon basin (Lathrap 1977; Piperno and Pearsall 1998; Clement 1999b; Pickersgill 2007) and documented, through studies of the plant fossil record, the time-deep presence of these and others originating beyond the region (Mora 1991; Herrera et al. 1992b; Piperno and Pearsall 1998; Morcote and Bernal 2001; Bush et al. 2007; Bozarth et al. 2008; see also Roosevelt 1989b). In addition, a number of studies of resource management by Amazonian peoples have highlighted practices associated with the manipulation of plant biodiversity (Balée 1989; Politis 1996; Politis 1999; Clement 2006b; Clement et al. 2008) that double as subtle yet effective forms of environmental alteration or disturbance, especially in terms of the spatial distribution of plant stuffs employed by human communities (Balée 2006). Perhaps the most evident is shifting cultivation (Harris 1971; Beckerman 1987), not only the basis of most small scale farming in the Amazon basin today but also a practice entangled with forms of agroforestry and fallow management (Denevan and Paddoch 1987; van der Hammen 1992; Oliver 2001). These practices have a significant impact on the heterogeneity of plant and animal species composition over decadal to centennial scales (Linares 1976; Denevan and Paddoch 1987; Saldarriaga 1994; van der Hammen and Rodríguez 1996; Denevan 2001). Other practices have been elucidated by studies of human groups ranging from tropical rainforest foragers to small-scale
  23. 23. Chapter 1 7 agriculturalists; they include the clearance of vegetation for settlements, the emplacement of doorstep orchards or ‘house gardens,’ the deliberate plantation and transplantation of foodstuffs in natural and human-made forest gaps and old settlements, and the promotion, tending and/or harvesting of clumps of edible and useful plant species (Figure 4), domesticated or otherwise (e.g. Lathrap 1977; Posey 1985; Balée 1989; Anderson and Posey 1989; Denevan and Paddoch 1987; Hecht and Posey 1989; van der Hammen 1992; Balée 1994; Rival 1998; Politis 1999). From an archaeological point of view, perhaps most significant is the fact that forms of landscape transformation associated with the manipulation of plant biodiversity have resulted in enduring or resilient changes to the distribution of biotic constituents of the Amazonian landscape. Balée proposes that well over fifteen percent of the region’s rainforests include plant species that reflect past human disturbance. He offers provocative remarks about their historical significance: “If we consider disturbance indicator trees and liana forests to be archaeological resources, the infrastructures of [ethnographic] Arawete and Asurini societies thrive (…) on the living artefacts of long-extinct cultures” (1989:13). These thoughts not only underscore that part of the vegetation of the Amazon basin is an anthropogenic legacy but also query the extent to which particular locales within the Amazonian landscape were employed for the intensification of yields derived from specific biotic components (Lathrap 1977; Clement 1989, 2006a; Piperno and Pearsall 1998; Morcote and Bernal 2001; Pickersgill 2007), that is, were crucially transformed in ways which enabled the reproduction of symbiotic relations with domesticated plants in the landscape (Balée 1994; Rival 1998; Clement 1999a; Erickson 2000, 2006). This brings us to consider a form of anthropogenic landscape transformation that is at the core of this dissertation: anthropogenic soils or anthrosols. By definition, these are soils whose formation and characteristics have been enduringly influenced by the material effects of human action (Limbrey 1975; Eidt 1984; Woods 2003). In the Amazon basin the best known cases are soils known as terras pretas and terras mulatas. Terras pretas are circumscribed expanses of dark-coloured and chemically-enhanced soils that signal the location of densely- occupied pre-Columbian settlements. They are believed to have formed as a consequence of the concentration of organic inputs – excrements, bone, organic matter, and combustion residues – related to kitchen middens, house gardens, dwelling structures, and pre-Columbian settlements. Decomposed or broken down in the soil, these inputs altered the pedogenetic pathways of parts of the soil mantle by increasing the ubiquity of sorption sites for metals, raising soil pH, and fomenting the formation of stable organo-mineral complexes rich in desirable agricultural nutrients (Sombroek 1966; Smith 1980; Glaser et al. 2000; Lima et al. 2002). Terras mulatas are less chemically-enhanced soils that in some cases surround patches
  24. 24. Chapter 1 8 of terras pretas. They have been interpreted as former outfields associated with the settlements signalled by terras pretas. Collectively, terras pretas and terras mulatas are known as Amazonian anthropogenic dark earths. Amazonian anthropogenic dark earths are prized to this day by farmers (Figure 5) because they achieve higher yields of staple lowlands cultivars such as manioc (Fraser et al. 2008; Fraser and Clement 2008), permit the growth of acid-intolerant crops such as maize (Balée 1989; Miller 1992a; Heckenberger 1998), and concentrate a high diversity of edible/useful fruit trees (Balée 1989; Miller 1992a; Clement et al. 2003). They have also acquired singular importance in Amazonian historical, archaeological and anthropological scholarship because their presence alongside the main waterways of the basin seems to corroborate 16th century AD accounts of sedentary, demographically-dense and organizationally-complex societies (Smith 1980; Denevan 1996; Heckenberger et al. 1999; Myers et al. 2003). As I discuss in further detail in the following chapter, their study also intersects with long-standing discussions about the capacity of Amazonia to sustain large populations (Denevan 1966b; Carneiro 1970; Lathrap 1970b; Meggers 1971; Myers 1973; Gross 1975; Smith 1980; Herrera et al. 1992c; Myers 1992; see Stahl 2002 for a comprehensive review). 4. THIS DISSERTATION The preceding paragraphs touch upon some of the topics that are examined in this dissertation and provide a background to introduce its two main goals. The first is to ascertain the character and time-depth of human practices that have resulted in anthropogenic landscape transformations in the Amazon basin. The second is to examine the formation processes and variability of anthropogenic dark earths in the Negro-Solimões confluence area. Fulfilment of the first goal demonstrates the importance of anthropogenic landscape transformations during the pre-Columbian history of the Amazon basin, especially as they relate to different processes of plant domestication and the formation of anthropogenic dark earths. Fulfilment of the second goal supplements understandings of the archaeological record of the Negro-Solimões region and draws insights that are applicable to a more detailed comprehension of the role and characteristics of these soils in the Amazon basin. Whilst these goals are for the most part pursued independently, they are actually deeply intertwined: the dissertation aims to establish the ultimate and proximate causes for the emergence of anthropogenic dark earths in the Amazon basin. A brief overview of the dissertation is in order: Chapter 2 introduces and defines the object of study: it summarises present knowledge about the variability of anthropogenic dark earths, discusses the changing role which these soils have had in archaeological discussions, and
  25. 25. Chapter 1 9 examines archaeological and ethnographic insights – including here my own ethnographic observations – that elucidate aspects and offer hypotheses about the formation processes of terras pretas and terras mulatas. Chapter 3 offers interpretative reviews of the palaeo-ecological and archaeological literature of the Amazon basin. These reviews examine the antiquity and character of anthropogenic landscape transformations in the region, assess their importance in the context of the Amazonian Formative, and frame a discussion of specific processes of crop domestication and intensification. This review distils how I understand patterns of landscape change and the cultural history of the Amazon basin, provides an essential background for discussions presented in Chapters 4 and 5, and offers a series of arguments that I revisit in Chapter 6. Chapter 4 examines the archaeological record of the central Amazon region. This is the study area of the Central Amazon Project, a research initiative within which I have developed the investigations presented in this dissertation. The Central Amazon Project has produced the most detailed and best studied archaeological sequence for the whole of the Amazon region (Heckenberger et al. 1999; Petersen et al. 2001; Petersen et al. 2004; Neves 2001, 2003; Neves 2005; Neves and Petersen 2006; Costa 2002; Lima 2003; Lima et al. 2006; Donatti 2003; Moraes 2006; Machado 2005; Arroyo-Kalin 2006; Rebellato 2007; Chirinos 2007). Like any archaeological sequence, however, this one deserves to be examined in some detail: the chapter first discusses archaeological understandings of the region as a whole and next examines in some depth present knowledge about specific sites located in the confluence area of the Negro and Solimões rivers. This site-by-site focus reconstructs the inferential routes involved in the interpretation of the regional archaeological sequence and contextualises each of the specific expanses of anthropogenic soils analysed in Chapter 5. Chapter 5 presents the premises, questions, methods, data and interpretations of the geoarchaeological study of archaeological sites from the Negro-Solimões confluence area. The results are divided into two sections. A first section introduces the reader to the primary dataset by discussing the relationship between microscopic remains observed in thin sections and physical and chemical measurements on correlative soil samples. This discussion specifically angles on the modal variability of anthropogenic dark earths, provides a detailed account of their effective makeup, discusses their formation processes, and highlights the effects which broader processes of landscape evolution have had on their measurable characteristics. With this background in place, the second section combines understandings of sedimentary and pedological processes – what I call a pedo-stratigraphic perspective – to discuss field stratigraphic observations, soil physical and chemical data, and existing site
  26. 26. Chapter 1 10 evidence (phases, radiocarbon dates, and broader regional understandings) at each of the soil exposures sampled in the study. The collection of analyses leads to novel archaeological interpretations of specific sites, identifies further insights about the formation processes of these soils, and poses new questions which can be examined by future research. Chapter 6 synthesises the main observations and findings of the dissertation. The chapter is divided into four parts. A first section summarises the main lessons of the geoarchaeological study presented in Chapter 5. A second section retraces steps to some of the arguments developed in Chapter 3 in order to postulate that the historical emergence of anthropogenic dark earths tracks the onset of specific process of plant domestication and intensification in the Amazon basin. A third section briefly discusses how the research design of this dissertation could be improved by considering other types of environmental data and, hence, outlines the need for a broader archaeological approach to the landscape. A fourth section offers a few remarks about wider issues related to landscapes, historical ecology, and domestication. Some readers might miss a separate treatment of the theoretical considerations that underpin the research presented in the following chapters. Not only do I consider that a single chapter or section so devoted would become a laborious transcription of formulations more competently articulated in recent overviews (e.g. Stahl 1996; Balée 2006; Balée and Erickson 2006; Erickson 2006) but the fact that many attractive theoretical propositions are ‘home- grown’, i.e. are endemic to Amazonian scholarship, means that they are important both for their supporting data and theoretical acumen in the context of the dissertation. For this reason I discuss these propositions as necessary, i.e. where and when the dissertation draws upon them as building blocks for specific arguments.
  27. 27. 11 Chapter 2 THE DARK EARTHS OF THE AMAZONIAN FORMATIVE 1. DEFINITION AND MAIN CHARACTERISTICS Amazonian anthropogenic dark earths collectively refer to circumscribed expanses of organically-enriched mineral soils found mostly within the non-flooding terrain of the Amazon basin. They were first described in Brazil as ‘Terra Preta de Índio’ (Indian Black Earth) or simply as ‘Terras pretas’ (Black Earths), the reference to ‘Indians’ reflecting the presence of abundant pottery shards of evident pre-Columbian age on the surface of most known exemplars. Although these remains signal that expanses of anthropogenic dark earths are archaeological sites, many of these patches have been used for cultivation at least since the 19th century (Myers et al. 2003). To this day farmers recognise their enhanced fertility and report both higher yields and longer cropping periods than soils located in the immediate vicinity (Sombroek 1966; Smith 1980; Woods and McCann 1999; McCann et al. 2001; German 2001, 2003; Hiraoka et al. 2003; Fraser et al. 2008). Expanses of dark earths vary in size, shape and location (Smith 1980; Kern et al. 2003; Neves 2005): linear expanses have been reported as patches extending over hundreds to thousands of metres along terra firme bluffs that overlook the major waterways of the basin (e.g. Nimuendajú 1952; Sombroek 1966; Hilbert 1968; Hilbert and Hilbert 1980; Smith 1980; Eden et al. 1984; Mora 1991; Miller 1992a; Miller 1999; Denevan 1996; Heckenberger et al. 1999; Kern et al. 2003; Myers 2004; Heckenberger 2005; Neves and Petersen 2006). However, smaller patches, either oval in shape or draping the horizontal surface of the landform on which they are located, also exist on relict floodplain locations, on terra firme areas adjacent to alluvial lakes and flooding forest, and on terra firme interfluvial terrain away from large rivers (Smith 1980; Simões and Araujo-Costa 1987; Simões and Machado 1987; Miller 1992a; Woods 1995; Kern 1996; Neves and Bartone 1998; Sternberg 1998; Vacher et al. 1998; Woods and McCann 1999; Donatti 2003; Coomes 2004; Zimmerman and Oyuela- Caycedo 2006; Moraes 2006). Soil horizons with at least incipiently similar characteristics are reported to have formed on both shell middens and artificially constructed mounds at flooding landscapes of the Amazon basin and beyond (Hartt 1885; Meggers and Evans 1957; Evans and Meggers 1960; Versteeg 1985; Versteeg 2003b; Roosevelt 1991; Rostain 1994; Schaan 2004; Walker 2004).
  28. 28. Chapter 2. The Dark Earths 12 Anthropogenic dark earths are characterised by a generally darker (grey, brown, or ink black in colour) and deeper (not infrequently reaching down to 60 cm) A horizon that stands in sharp contrast to the more shallow ones observed in neighbouring soils (compare the left and right photographs shown in Figure 6) (Sombroek 1966; Smith 1980; Woods 1995; Kämpf et al. 2003). As pointed out in Chapter 1, studies distinguish between terras pretas, i.e. pottery-rich black soils with a deep A horizon, and terras mulatas, larger surrounding or adjacent expanses of darkened soils whose surface horizon lacks archaeological artefacts but whose nutrient status is intermediate between terras pretas and the broader soilscape (Sombroek 1966). Most scholars consider this contrast to reflect a distinction between sedentary pre-Columbian settlements and associated outfields (Andrade 1986, 1988; Woods and McCann 1999; McCann et al. 2001; Hecht 2003; Denevan 2004) The vast majority of studies of anthropogenic dark earths – in most cases of terras pretas – demonstrate that A horizon sediments show a higher cation exchange capacity, more basic pH, and higher concentrations of organic carbon, calcium, phosphorus, manganese, potassium, barium, copper, manganese, strontium, and zinc than both the sediments that make up the underlying B horizon and comparable adjacent soils (Klinge 1962; Sombroek 1966; Smith 1980; Herrera et al. 1980-1; Eden et al. 1984; Andrade 1986; Mora 1991; Kern and Kämpf 1989; Kern 1996; Kern et al. 2004; Pabst 1985; Pabst 1991; Pabst 1993; Heckenberger 1998; Heckenberger et al. 1999; Glaser 1999; Woods and McCann 1999; McCann et al. 2001; Lima et al. 2002; Schaefer et al. 2004; Ruivo et al. 2003; Lehmann et al. 2004; Liang et al. 2006). Research shows that these soils occlude between four and thirty-five times more pyrogenic carbon than adjacent Oxisols, an observation marshalled to suggest that black carbon is key to high organic matter retention (Glaser et al. 2003). Micromorphological studies also ascertain the ubiquitous presence of microscopic charcoal (i.e. pyrogenic carbon, the most common form of black carbon), bone, and pottery fragments as common particulate inputs in these soils (Lima 2001; Lima et al. 2002; Texeira and Martins 2003; Schaefer et al. 2004; Arroyo-Kalin et al. 2004; Costa et al. 2004b,2004a). Whilst much recent literature has emphasised the unique Amazonian character of these soils (Lehmann et al. 2003; Glaser and Woods 2004), archaeological investigations show that similar anthropogenic modifications are found beyond the Amazon basin, for instance in the north of Colombia (Angulo Valdés; Aceituno and Castillo; Oyuela-Caycedo and Bonzani; Castillo and Aceituno 2006), in the Orinoco basin (Cruxent and Rouse 1958; Barse 1989; Roosevelt 1997b; Zucchi 1999; Oliver 2008), in the Guianas (Vacher et al. 1998), and in subtropical areas south of the Amazon basin proper (Prous 1991a). This has led some to propose the need to reconsider the distribution of anthropically-enriched dark soils of pre-
  29. 29. Chapter 2. The Dark Earths 13 Columbian origin within the broader geographical context of the Neotropics (Graham 2006). Even casual perusal of studies from further afield (e.g. Pape 1970; Macphail 1981; Macphail 1994; Macphail et al. 2003; Davidson and Simpson 1984; Yule 1990; Simpson 1997; Simpson et al. 1998; Blume and Leinweber 2004; Cammas 2004; Galinié 2004; Loveluck 2004; Heimdahl 2005; Nicosia 2006), highlights that darkened anthropogenic horizons have been linked to a very broad variety of situations, i.e. underscores the need to examine dark earth formation processes with attention to historical regional specificities. 2. THEORIES ABOUT PROXIMATE ORIGINS An anthropic origin for Amazonian dark earths was advocated in the first descriptions of these soils by scientific observers of the 19th century: pioneering geologists like Smith (1879) and Hartt (1871; 1885) unhesitatingly related cultivation patches along the lower reaches of the Amazon river (hereinafter referred to as the lower Amazon) to villages of former indigenous peoples (see also Woods 1995; Myers et al. 2003). The results of the first soil chemistry analyses conducted on them allowed Katzer (1903) to argue that their high fertility was the result of unusual concentrations of charcoal and decomposed organics in the fine earth fraction, properties which he argued had also made them attractive to farmers in the past. Based on an archaeological survey of the Santarém area conducted in the early 1920s, ethnologist/archaeologist Nimuendajú (1952; 2004; Palmatary 1960; Neves 2004) suggested that both their geographical distribution and associated archaeological remains, earthworks and roads indicated they had originated in densely-populated, sedentary pre-Columbian settlements. For the first part of the 20th century, however, these opinions remained isolated. The size of farmed expanses in the Brazilian Amazon, the fact that many local farmers did not recognise their human-made origin, a lack of evidence for their contemporary formation, and the scant attention accorded to them by important Amazonian archaeologists (e.g. Meggers and Evans 1957; Evans et al. 1959; Evans and Meggers 1960; Evans and Meggers 1968, see below), led some researchers to advocate a variety of ‘geogenic’ models about their origin. In broad outline these models argue that Amazonian dark earths are patches of fertile soils that have formed as a result of localised, non-anthropogenic accumulations of organic and/or mineral materials. These patches would have attracted people for inhabitation and/or farming purposes during pre-Columbian times, in turn prompting the formation of archaeological sites. Among the main proponents of such views were Camargo (1941), who argued dark earths resulted from the in situ accumulation of volcanic ash; archaeologist Barbosa de Faria (1944), who pointed to the weathering of volcanic rocks as the main source of nutrients; Cunha Franco (1962), who proposed that organic material and habitation debris had accumulated in
  30. 30. Chapter 2. The Dark Earths 14 water-filled depressions that had later dried out; and Falesi (1974), who argued that deep profiles and high phosphorus concentrations were the result of the accumulation of Tertiary alluvial/lacustrian sediments and animal fossil remains. Although Nimuendajú’s archaeological research remained unpublished and, more significantly, beyond the intellectual web of earth scientists until the mid 1960s, Katzer’s (1903; 1944) early suggestion of anthropic inputs prompted further research by Klinge (1962), who argued that the incomparably higher total and soluble phosphoric acid concentrations of dark earths clearly evidenced an anthropogenic origin. In parallel, Hilbert’s (1955; 1968) archaeological research documented the co-occurrence of dark earths and ceramic archaeological remains along the main rivers of the western half of the Brazilian Amazon, noted their formation on both haematite and goethite-rich Oxisols (Red and Yellow Latosols in the Brazilian soil classification), and followed the steps of Nimuendajú in suggesting an origin in long-lasting settlements. However, it was undoubtedly Sombroek’s (1966) interpretation of the physico-chemical characteristics measured in artefact-rich dark earths located on the Belterra plateau, near Santarém, that convincingly refuted geogenic models for their origin. Sombroek pointed out that the overall topography and drainage of the plateau were incompatible with suggestions of that organic material had accumulated in small water bodies. He next noted that instead of the random distribution which would be expected from a natural phenomenon, the position of dark earth expanses in the landscape suggested deliberate selection of areas suitable for the invigilation of navigable waterways. He then reported particle size and x-ray diffraction data which evidenced the same overall texture and kaolinitic parent material in terras pretas and neighbouring soils, effectively overruling a source in volcanic debris. Finally, he enunciated the distinction between terras pretas and terras mulatas and presented distributional evidence that expanses of the former were often associated with much larger surrounding or adjacent areas of the latter (Figure 7). Most scholars who have read Sombroek’s confident arguments would agree that he settled the matter of anthropogenic origins vis-à-vis geogenic origins for good. His research also became a key intellectual referent for the first systematic survey of anthropogenic dark earths in the Brazilian Amazon (Smith 1980) and for pioneering pedo-archaeological investigations in the Colombian Amazon (Herrera et al. 1980-1; Herrera 1981; Eden et al. 1984; Andrade 1986) during the 1970s. 3. ANTHROPOGENIC DARK EARTHS IN PRE-COLUMBIAN HISTORY Whilst Sombroek’s (1966) work inaugurated the modern era of studies about Amazonian anthropogenic dark earths, and even though some archaeological investigations had recorded the presence of these soils in excavations and surveys (see Palmatary 1960; Neves 2004 on
  31. 31. Chapter 2. The Dark Earths 15 Nimuendajú; also Barbosa de Faria 1944; Hilbert 1955; Hilbert 1968), discussions about Amazonian pre-Columbian history did not initially take stock of their presence or ultimate significance. This lack of attention was not trivial: although some researchers argued that the agricultural aptitude of Amazonian terra firme soils was not per se low (Carneiro 1961; Denevan 1966b) nor necessarily unchanging (Carneiro 1983; cf. Roosevelt 1980), the main arguments about the emergence of sedentism in the region were formulated in relative ignorance of (Lathrap 1970a) or militant disregard about (Meggers 1954; Meggers 1971) the possibility that the terra firme soilscape had been transformed during pre-Columbian times. Below I review this intricate intellectual history in order to examine how models of pre- Columbian history were misshaped; I then outline how the recognition of Amazonian anthropogenic dark earths has impacted discussions about sedentary and socially-complex societies in the region. 3.1 The Amazonian Formative: immigrant or indigenous Modern scholarship about pre-Columbian sedentism in Amazonia begins with the publication of the ‘Handbook of South American Indians’ in the late 1940s. Convinced about the hostility of the environment for the development of large and stratified societies, Steward (1948a), the main editor of the Handbook, dismissed a number of 16th century ethnohistorical sources which reported the presence of large indigenous settlements along the Amazon river. Instead Tropical Forest Cultures of the ethnographic record of eastern Amazonia and the Guianas – groups characterised by a laundry list that includes small populations, canoes, shifting cultivation of root-crops, village-based political authority, and hammocks (Lowie 1948) – were considered to be accurate reflections of societies that had existed prior to the European colonisation of the region. These societies contrasted with smaller and more mobile hunter-gatherer groups of the western half of the region, which Metraux (1948) underplayed (Myers 1974) and Steward (1948a) christened as the Marginal groups. The fact that the latter were mostly represented by linguistic isolates of western Amazonia whilst Tropical Forest Cultures generally spoke languages that could be classified into some of its largest linguistic families encouraged an account about their co-existence that emphasised different origins. Steward proposed that the spatial distribution of Tropical Forest Cultures and Marginals was an outcome of the pre-Columbian immigration of horticulturists into a region inhabited by hunter-gatherers since earlier times. This immigration had its place in a broader model for the appearance of sedentary lifestyles in the Americas that contrasted Formative centres at which sedentism, agriculture, and civilisation had emerged with peripheral areas into which budding migrant groups from Formative centres had expanded. When it came to the lowlands of northern South America, his account argued that ‘Formative-level’ groups had expanded from the western half of the continent (the Andes) into the Colombian lowlands and Venezuela,
  32. 32. Chapter 2. The Dark Earths 16 encountering progressively more difficult environmental limitations. These limitations had whittled away techno-economic and socio-political elaboration from the immigrants’ cultures which then had come to resemble the Circum-Caribbean chiefdoms reported in 16th century sources (which, unlike the Amazonian ones, he obviously did credit). As these groups continued to expand into the more hostile conditions of the Guianas and Amazonia, they had simplified further to small village-based societies that relied principally on slash and burn agriculture of root crops, the Tropical Forest Culture. Their distribution within the Amazon basin, therefore, suggested an upstream movement of horticulturists from east to west, one that had successfully colonised riparian areas adjacent to the main waterways, but whose expansion beyond the riverscape had been checked as much by the resistance of ‘Marginal’ hunter-gatherers as by inherent limitations of the environment. Although some aspects of Steward’s account were criticised very early on (Rouse 1953; see also Lévi-Strauss 1952), pioneering Amazonian archaeologists Meggers and Evans staunchly defended and expanded many of its principal arguments. Strongly influenced by Steward, they similarly doubted the veracity of contact-time ethnohistorical accounts for the Amazon basin, regarded the region as a generally hostile environment for human inhabitation, and considered groups who relied on shifting agriculture – the mainstay of Tropical Forest Cultures – as destined to shift residence after a generation or two due to soil exhaustion. These premises were variously formalised as first principles (Meggers 1954); applied to interpret archaeological evidence from Amapá, Marajó Island and what was then British Guiana (Meggers and Evans 1957; Meggers and Evans 1958; Evans and Meggers 1960); and also used to classify into four horizons the ceramic complexes of the Amazon basin that were then known (Meggers and Evans 1961). Three of them, the Zone-Hachured, Incised-Rim, and Incised-and-Punctuate horizons, were interpreted as evidence of root crop horticulturists expanding into the region through the river network; the fourth, the Polychrome horizon, to which were associated lavishly-decorated Marajoara phase pottery and artificial mounds at Marajó Island, was interpreted as evidence for a socially-complex Andean offshoot that had rapidly reached the mouth of the Amazon and then experienced simplification due to harsh environmental conditions (Figure 8 shows the location of sites and regions mentioned in this and the following section). The most evident corollary of these interpretations was that sedentism in the Amazon basin had been strongly arrested by the hostile characteristics of the physical environment, not least its soils, for agricultural production (Meggers 1954). Many shortcomings of the four-horizon model were flagged up by archaeological research over the next 20 years. Evidence for the antiquity of Incised-Rim pottery at the Saladero and Barrancas sites of the lower Orinoco, and the Malambo site of the Colombian Caribbean littoral suggested that the time-depth of root crop horticulture in the Amazon basin needed to

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