It is difficult to overstate the cultural and biological impacts that the domestication of plants and animals has had on our species. Fundamental questions regarding where, when, and how many times domestication took place have been of primary interest within a wide range of academic disciplines. Within the last two decades, the advent of new archaeological and genetic techniques has revolutionized our understanding of the pattern and process of domestication and agricultural origins that led to our modern way of life. In the spring of 2011, 25 scholars with a central interest in domestication representing the fields of genetics, archaeobotany, zooarchaeology, geoarchaeology, and archaeology met at the National Evolutionary Synthesis Center to discuss recent domestication research progress and identify challenges for the future. In this introduction to the resulting Special Feature, we present the state of the art in the field by discussing what is known about the spatial and temporal patterns of domestication, and controversies surrounding the speed, intentionality, and evolutionary aspects of the domestication process. We then highlight three key challenges for future research. We conclude by arguing that although recent progress has been impressive, the next decade will yield even more substantial insights not only into how domestication took place, but also when and where it did, and where and why it did not.The domestication of plants and animals was one of the most significant cultural and evolutionary transitions in the ∼200,000-y history of our species. Investigating when, where, and how domestication took place is therefore crucial for understanding the roots of complex societies. Domestication research is equally important to scholars from a wide range of disciplines, from evolutionary biology to sustainability science (1, 2). Research into both the process and spatiotemporal origins of domestication has accelerated significantly over the past decade through archaeological research, advances in DNA/ RNA sequencing technology, and methods used to recover and formally identify changes in interactions among plants and animals leading to domestication (2-4). In the spring of 2011, 25 scholars with a central interest in domestication and representing the fields of genetics, archaeobotany, zooarchaeology, geoarchaeology, and archaeology met at the National Evolutionary Synthesis Center to discuss recent progress in domestication research and identify challenges for the future. Our goal was to begin reconsidering plant and animal domestication within an integrated evolutionary and cultural framework that takes into account not just new genetic and archaeological data, but also ideas related to epigenetics, plasticity, geneby-environment interactions, gene-culture coevolution, and niche construction. Each of these concepts is relevant to understanding phenotypic change, heritability, and selection, and they are all fundamental components of the New Biology (5) and Expanded Modern Evolutionary Synthesis (6).

The introduction of new analytic methods and expansion of research into previously untapped regions have greatly increased the scale and resolution of data relevant to the origins of agriculture (OA). As a result, the recognition of varied historical pathways to agriculture and the continuum of management strategies have complicated the search for general explanations for the transition to food production. In this environment, higher-level theoretical frameworks are sometimes rejected on the grounds that they force conclusions that are incompatible with real-world variability. Some of those who take this position argue instead that OA should be explained in terms of local and historically contingent factors. This retreat from theory in favor of particularism is based on the faulty beliefs that complex phenomena such as agricultural origins demand equally complex explanations and that explanation is possible in the absence of theoretically based assumptions. The same scholars who are suspicious of generalization are reluctant to embrace evolutionary approaches to human behavior on the grounds that they are ahistorical, overly simplistic, and dismissive of agency and intent. We argue that these criticisms are misplaced and explain why a coherent theory of human behavior that acknowledges its evolutionary history is essential to advancing understanding of OA. Continued progress depends on the integration of human behavior and culture into the emerging synthesis of evolutionary developmental biology that informs contemporary research into plant and animal domestication. evolutionary theory | behavioral ecologyOver the last decade there has been a major expansion of knowledge regarding the timing and socioecological context of plant domestication and emerging agricultural systems. This wealth of data is due in large part to methodological innovations (e.g., in genetics and paleogenomics, in the analysis of plant micro-and macroremains and biological residues, and in the physical and biogeochemical analyses of anthropogenic sediments), reexcavations of some important archaeological sites, and the expansion of archaeological research into regions whose record of agricultural origins has been until recently poorly known [such as New Guinea (1, 2), lowland areas of Mesoamerica and northern South America (3-7), and northern and southern China (8-13)]. These research activities have enriched both the scale and resolution of the data relevant to agricultural origins worldwide. One result of this welcome enhancement of the empirical record is wider acknowledgment of the variability in the historical pathways taken by emerging food production systems across space and time. The dichotomy between foraging and food production has been discarded in favor of a continuum of landscape, plant, and animal management strategies that sometimes resist classification. However, for some scholars (2, 14), the richly detailed records of change seem to have dampened the appeal of general explanations for the transition to agriculture. This tr...

Fossil pollen assemblages from Cliff Palace Pond, Kentucky, characterize changes in forest composition through the past 9,500 years of the Holocene. Early-Holocene spruce and northern white cedar stands were replaced by mixed mesophytic forests after 7300 B.P. Hemlock declined around 4800 B.P., and eastern red cedar became locally important. After 3000 B.P, mixed oak-chestnut and pine forests were dominant. The fossil charcoal record from Cliff Palace Pond demonstrates that Late Archaic and Woodland peoples cleared forest gaps to cultivate native plants in the Eastern Agricultural Complex and that anthropogenic fires served to increase populations of fire-tolerant oaks, chestnut, and pines in upland forests of the northern Cumberland Plateau.

The domestication of plants and animals marks one of the most significant transitions in human, and indeed global, history. Traditionally, study of the domestication process was the exclusive domain of archaeologists and agricultural scientists; today it is an increasingly multidisciplinary enterprise that has come to involve the skills of evolutionary biologists and geneticists. Although the application of new information sources and methodologies has dramatically transformed our ability to study and understand domestication, it has also generated increasingly large and complex datasets, the interpretation of which is not straightforward. In particular, challenges of equifinality, evolutionary variance, and emergence of unexpected or counter-intuitive patterns all face researchers attempting to infer past processes directly from patterns in data. We argue that explicit modeling approaches, drawing upon emerging methodologies in statistics and population genetics, provide a powerful means of addressing these limitations. Modeling also offers an approach to analyzing datasets that avoids conclusions steered by implicit biases, and makes possible the formal integration of different data types. Here we outline some of the modeling approaches most relevant to current problems in domestication research, and demonstrate the ways in which simulation modeling is beginning to reshape our understanding of the domestication process.T he emergence of agriculture beginning some 10,000 y ago marked more than a change in human patterns of subsistence. The beginnings of food production ushered in an era of radically new relationships between humans and other species, dramatic new evolutionary pressures, and fundamental transformations to the earth's biosphere. The evolutionary process of plant and animal domestication by humans led to morphological, physiological, behavioral, and genetic differentiation of a wide range of species from their wild progenitors (1, 2). The selection pressures that were placed on such species continue today, sometimes through direct genetic modification, and both the processes and their outcomes are accordingly of significant broader interest. Domestication is also part of a cultural evolutionary process (3, 4), and some human genes have evolved in response to cultural innovations (5-8), much as the genes of domesticated species have changed under the impact of human artificial selection. The study of domestication today is a multidisciplinary enterprise in which archaeologists and agricultural scientists have been joined by evolutionary biologists and population geneticists (2, 9).At least five major sets of questions tend to reoccur in the domestication literature. The first three are demographic: (i) When, where, and in how many geographic locations was a given species domesticated? (ii) What were the dispersal routes from the original domestication centers? (iii) To what extent did hybridization between domesticates and local wild relatives occur? The remaining questions relate to adaptation: (i...

Analysis of seed morphology in paleoethnobotany typically focuses on identification of domesticates. However, the wild and weed forms that are sometimes recognized in archaeological contexts can provide pertinent information about garden ecology. Morphometric studies of Chenopodium from the eastern United States have revealed patterns of variation compatible with the coexistence and interaction of crop and weed populations. The character of this interaction reflects considerable flexibility and diversity in prehistoric agricultural systems. In addition, the frequency of weed seeds in archaeological collections can be used to assess the nature of selection in managed habitats and the husbandry practices associated with it.