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The Origins of Agriculture
An International Perspective
By C. Wesley Cowan, Patty Jo Watson
The University of Alabama Press Copyright © 2006 The University of Alabama Press
All rights reserved.
C. WESLEY COWAN AND PATTY JO WATSON
The transformation of human foragers into agriculturally based societies remains an enduring problem for scientists studying the human condition. Questions revolving around these transformations have been enough to launch entire expeditions to isolated valleys in the Near East and northern Mexico and to less remote places, such as the Green River valley of western Kentucky. Archaeologists, botanists, and crop scientists have collaborated to develop shadowy pictures of developmental processes that took place on every continent of the earth. This volume brings into focus these disparate pictures by presenting recent syntheses of agricultural beginnings at several places around the world.
Although worldwide in scope, this volume should not be considered an encyclopedic treatment describing all such transformations known (see Harris and Hillman 1989 for a more comprehensive and more technical set of papers). Rather, our intent is to make available a set of case studies from a variety of world regions, both tropical and temperate, to illustrate the diversity of specific details, as well as the processual similarities and differences, among several cases of shifts to horticultural and agricultural economies. We emphasize the New World evidence because it is less well-known internationally than such Old World cases as Europe and the Near East. It is also clear that the evidence for those transformations we associate with agricultural beginnings is most detailed and abundant in the New World.
This volume originated in a symposium we organized for the American Association for the Advancement of Science (AAAS) meetings in Los Angeles in 1985. The original versions of papers by Crawford, Dennell, Harlan, Miller, Minnis, and Pearsall were read at the symposium; those of McClung de Tapia and Smith were solicited later. We considered the AAAS meetings an appropriate forum for our symposium because few scholars outside the anthropological and botanical communities are familiar with the empirical data for agricultural origins, and because recent advances have made new information available that might prove of interest to other scholars. Indeed, our audience in Los Angeles consisted almost exclusively of scholars outside the disciplines that usually study agricultural origins.
With the exception of Harlan (a crop scientist), all of the authors in this volume are anthropologists. Without exception, all of the authors work with primary data bearing on the issue of early plant cultivation and are experts in the areas they represent here. Each chapter is as authoritative and up-to-date as possible, but also as clear and non-technical as possible. Each author summarizes the current archaeobotanical evidence for his or her area and offers interpretations of it.
Most chapters follow a relatively standardized outline. The history of investigations of plant domestication, the current archaeobotanical record, important sites, and current models treating the domestication process are discussed for each region. Although similar in basic format, the chapters vary considerably. This is, in part, a reflection of the writing style of the individual authors, but, more importantly, it is a reflection of the kinds and quality of available data. Harlan's chapter on African domestication, for example, does not contain the quantity of detail that Dennell is able to provide for the introduction and spread of domesticates in Europe. It was necessary for Dennell to sift a veritable mountain of information, gleaned from dozens of archaeological field projects, whereas Africa's archaeobotanical record is virtually unknown. In spite of these differences, the chapters provide accurate reflections of the current state of knowledge about early plant domestication in a series of different world areas. Although it was not a conscious goal of the authors or editors, we hope the inadequacies of the data from several areas will spur some much-needed research there.
Because the student and casual reader may not be familiar with all of the concepts and terms found in this volume, we devote the remainder of this first chapter to a summary of background information relevant to the data-oriented chapters that follow. It is not our primary purpose to review the history of intellectual thought surrounding agricultural origins or to provide a model of agricultural beginnings, but we believe the reader may find some historical perspective useful. We also include a brief discussion of the techniques used for obtaining data relevant to agricultural origins, as well as some consideration of the major problems in interpreting those data.
A Historical Perspective on the Origins of Agriculture
The Swiss botanist Alphonse de Candolle (1885) was the first to recognize that information from botany, philology, geography, and archaeology must be integrated and brought to bear if scholars were to understand agricultural origins. Using such data as were then available, de Candolle attempted to define the regions where most of the world's important crops were first domesticated.
The early- to mid-twentieth-century Russian botanist Nicolai Vavilov followed de Candolle's tradition of combining information from a variety of sources, including the rapidly developing field of genetics. Vavilov's work, supported by the Russian state, led him to many different parts of the world and enabled him to create formulations that are still influential.
Vavilov proposed that areas where both genetic and species diversity were highest were probably "centers" of domestication, and he identified several such centers or "hearths." Although many of his ideas are not in favor today, his search for regions where agriculture began provided the impetus for further investigations. The initial searches for the origins of both Near Eastern and Mexican crop plants, for example, were heavily influenced by Vavilov's early ideas.
As archaeobotanical data began to be accumulated from various continental regions, it quickly became apparent that the concept of a "center" of domestication was difficult to apply. When sites producing evidence of early domestication are spread out over an area that encompasses hundreds or thousands of square kilometers, how does one define a "center" (see also Harlan 1971)?
As the science of archaeology grew in the twentieth century, prehistorians discovered that they could contribute directly to the study of agricultural beginnings. Not only tools and architectural features could be brought to bear on the topic, but also the charred or, in some cases, desiccated remains of early cultivated plants could be recovered and studied to provide direct evidence of the domestication process.
In the years after World War II, two projects explicitly designed to gather information about early agriculture were fielded: Braidwood's Iraq-Jarmo Project in the Near East from 1948 to 1955 (Braidwood and Howe 1960; Braidwood et al. 1983) and MacNeish's search for the origins of corn in Mexico (MacNeish 1964). Both scholars were influenced by Vavilov's concept of domestication "centers" and de Candolle's multidisciplinary approach. In addition, Braidwood was seeking specific archaeological evidence of the "Neolithic revolution" hypothesized by V. Gordon Childe (1936).
Interest in agricultural origins—and in "environmental archaeology" in general—received tremendous impetus in the 1960s from growing global awareness of the human impact on the physical environment. This was particularly true in the United States where the 1960s saw the emergence of many subdisciplines of archaeology, most of which had an environmental and ecological emphasis. Paleoethnobotany was one of these and, thanks to the techniques routinely applied by today's generation of archaeologists to recover plant remains, more information related to the origins of agriculture has become available in the past decade than in the previous ten.
Paleoethnobotany is a word given currency in the 1960s by Hans Helbaek (1960), Richard Yarnell (1963), and others who perceived themselves as scholars applying ethnobotanical perspectives to the archaeological record of ancient plant use. That is, just as ethnobotany is the study of botanical knowledge and plant use cross-culturally (e.g., see Harshberger 1896; King 1984; Smith 1923, 1928, 1932, 1933; Stevenson 1915; Teit 1930), paleoethnobotany is the cross-cultural study of the interrelationships between prehistoric plant and human populations.
Until relatively recently, most plant remains recovered from archaeological contexts were the results of happenstance. If a large quantity of charred seeds, corn cobs, etc., was encountered during excavation, this material would be gathered up and saved; if something caught the eye of an excavator, it might be retained. These sorts of macrobotanical remains are obviously biased toward those plant tissues that are large and durable; in the field, small charred seeds and plant parts are not easily detected by the naked eye, and, as a consequence, specialized means are necessary to obtain such remains. The most common method by which these smaller macrobotanical plant fragments are concentrated and recovered is through the technique known as flotation.
Many different flotation systems have been devised in the past twenty years, but all of them depend upon the following basic principle: if archaeological sediment is released into a container filled with water, then the sediment sinks and the charred plant remains float. There is a considerable literature on flotation/water-separation (e.g., Dye and Moore 1978; Hastorf and Popper 1988; Minnis and LeBlanc 1976; Pearsall 1989; Schock 1971; Struever 1968; Wagner 1982; Watson 1976; Wiant 1983). Some techniques are multiple-operator, machine-assisted assembly lines, whereas others are simple, one-person bucket or barrel operations. It is sufficient to note here, however, that all of these systems are aimed at retrieving charred macrobotanical plant remains, and that the basic purpose is the same for all: to concentrate and collect charcoal that is dispersed throughout archaeological deposits.
The development of flotation as a technique to recover microbotanical remains has revolutionized our ability to collect data that are directly relevant to the study of agricultural origins. Although the use of flotation has found worldwide acceptance, not all archaeologists employ it as a technique to retrieve plant remains. In some areas archaeological sediments may not be amenable to flotation. Even in cases where flotation is not physically possible, however, attempts are often made to recover plant remains. Dry or water sieving of sediments, for example, is routinely used in some European countries to obtain plant remains. Another reason for this circumstance is doubtless that the recovery and study of paleoethnobotanical data is time-consuming and expensive; many archaeological projects simply do not have the necessary time and money. On the other hand, it is commonly noted by paleoethnobotanists that many archaeologists have been slow to recognize the value of studying plant remains, and for this reason do not collect "float" samples or include archaeobotany in their research designs. Fortunately, this attitude seems to be disappearing.
When charred plant remains arrive at the paleoethnobotanist's laboratory, they are sorted, identified, weighed, counted, and described. Paleoethnobotanists use a variety of instruments to aid in these tasks, but most important is a high-powered binocular dissecting microscope; access to a scanning electron microscope, or SEM, is also frequently necessary. In addition, an accurate balance or scale and an adequate comparative collection, together with a set of key reference books specific to the region under investigation, are needed.
So far we have been referring to charred archaeobotanical remains, but in many parts of the world very old plant remains may be preserved in an uncharred, dry, or saturated state. In very arid and desert climates, like ancient Egypt or coastal Peru, dried plant parts may last indefinitely. Even in temperate climates, plants may be beautifully preserved in dry caves and rockshelters. Saturated sites (bogs, swamps, lakes, etc.) may also preserve fragile plant materials indefinitely. Obviously, identification and quantification of uncharred remains differs somewhat from work with charred, often distorted, flotation-derived fragments from an open archaeological site. Identification and dating problems are similar for both types of remains, however. There has been considerable success recently in the application of direct, accelerator mass spectrometer (AMS) dating techniques to small plant fragments, both charred and uncharred (e.g., Conard et al. 1984; Fritz and Smith 1988; Harris 1986; Smith and Cowan 1987).
Although considerable progress has been made in interpreting ancient plant remains, many serious problems have yet to be solved. There is still insufficient standardization in recovery techniques and in quantification procedures. This means that the results of paleoethnobotanical analyses are often difficult to compare directly.
There are also many problems in basic identification of charred remains because of the often seemingly unpredictable distortion and size alteration caused by the original charring process, and then the further fragmentation and wear and tear before the charcoal is retrieved from its archaeological context. However, paleoethnobotanists in one geographic area or those focusing on a specific archaeobotanical question often form very effective working groups to trade information, provide access to comparative collections, share new techniques, etc., as they seek to reach the same interpretive goals. These working groups have made substantial progress toward solving a number of common problems.
One such archaeobotanical question is that addressed in this volume: the evolution of domestic plants. Obviously the paleoethnobotanist must be able to differentiate between wild and domestic forms of the same species. This is sometimes possible on the basis of size, shape, or other morphological attributes (e.g., see chapters by Miller and Smith in this volume), or sometimes the plant is found outside its area of natural distribution, or it may be found in such abundance and in such contexts (storage pits or containers, for instance) as to indicate that it was domesticated, or at least cultivated. Most paleoethnobotanists distinguish between a species that is simply tolerated or encouraged and one whose reproduction is carefully controlled or managed. Ultimately, the distinction between the two—cultigens versus domesticates—is based upon a single important factor. Whereas cultivated plants might continue to exist as a breeding population without the interference of humans, domesticated plants are so different genetically from their wild ancestors that their very existence depends upon human intervention in their life cycles. Ford (1985:6) has justifiably referred to domesticated plants as "cultural artifacts" resulting from human selection.
The careful reader will note in the following papers that the appearance of a domesticate in the archaeological record is the end result of generations of cumulative genetic transformations. Hence, the discovery of early domesticates defines only the end point of a process that might have taken hundreds or even thousands of years.
Thus, it is impossible to delineate a single point in the past for any continent or geographic region that marks the "beginnings" of agricultural economies there. Agriculturally based societies did not spring up overnight as the result of an idea proposed by some prehistoric genius. As will be seen in the chapters that follow, early agriculture is a process preceded by thousands of years of cultural and biological evolution.
Each of the following chapters summarizes the evidential base for a different part of the globe. We begin in the Old World with East Asia, then turn to the Near East, Africa, and Europe before moving to the New World where the Eastern Woodlands and the Southwest of North America, Mesoamerica, and South America are addressed. Although there is considerable variation in the quality and quantity of data for these eight regions, the authors have followed the same presentation format to enhance ease of comparison by readers not familiar with all eight. They also make frequent use of maps and tables to display relevant information in an efficient and readily accessible manner.CHAPTER 2
Prehistoric Plant Domestication in East Asia
GARY W. CRAWFORD
In earlier syntheses on the origins of agriculture, China was a necessary subject of some deliberation, but Korean and Japanese agricultural origins were largely ignored (e.g., Harris 1977; Ho 1969, 1977). Discussions on Korea and Japan were of interest only to small circles of local archaeologists; few others seemed to think it worthwhile to pay attention to these two subareas of East Asia. After all, in neither Korea nor Japan were there apparent indigenous agricultural origins. At present, archaeologists are still debating the existence of food production in pre-Bronze and Iron Age Korea and Japan. The prevailing view is that agriculture began in Korea and Japan in the third millennium B.P. with the initiation of rice-based agrarian societies by both the diffusion of crops and ideas and the migration of people. Evidence is mounting, however, for earlier agricultural origins in these two areas.
Excerpted from The Origins of Agriculture by C. Wesley Cowan, Patty Jo Watson. Copyright © 2006 The University of Alabama Press. Excerpted by permission of The University of Alabama Press.
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