Contrasting Patterns in Crop Domestication and Domestication Rates: Recent Archaeobotanical Insights from the Old World

Background Archaeobotany, the study of plant remains from sites of ancient human activity, provides data for studying the initial evolution of domesticated plants. An important background to this is defining the domestication syndrome, those traits by which domesticated plants differ from wild relatives. These traits include features that have been selected under the conditions of cultivation. From archaeological remains the easiest traits to study are seed size and in cereal crops the loss of natural seed dispersal. Scope The rate at which these features evolved and the ordering in which they evolved can now be documented for a few crops of Asia and Africa. This paper explores this in einkorn wheat (Triticum monococcum) and barley (Hordeum vulgare) from the Near East, rice (Oryza sativa) from China, mung (Vigna radiata) and urd (Vigna mungo) beans from India, and pearl millet (Pennisetum glaucum) from west Africa. Brief reference is made to similar data on lentils (Lens culinaris), peas (Pisum sativum), soybean (Glycine max) and adzuki bean (Vigna angularis). Available quantitative data from archaeological finds are compiled to explore changes with domestication. The disjunction in cereals between seed size increase and dispersal is explored, and rates at which these features evolved are estimated from archaeobotanical data. Contrasts between crops, especially between cereals and pulses, are examined. Conclusions These data suggest that in domesticated grasses, changes in grain size and shape evolved prior to non-shattering ears or panicles. Initial grain size increases may have evolved during the first centuries of cultivation, within perhaps 500–1000 years. Non-shattering infructescences were much slower, becoming fixed about 1000–2000 years later. This suggests a need to reconsider the role of sickle harvesting in domestication. Pulses, by contrast, do not show evidence for seed size increase in relation to the earliest cultivation, and seed size increase may be delayed by 2000–4000 years. This implies that conditions that were sufficient to select for larger seed size in Poaceae were not sufficient in Fabaceae. It is proposed that animal-drawn ploughs (or ards) provided the selection pressure for larger seeds in legumes. This implies different thresholds of selective pressure, for example in relation to differing seed ontogenetics and underlying genetic architecture in these families. Pearl millet (Pennisetum glaucum) may show some similarities to the pulses in terms of a lag-time before truly larger-grained forms evolved. </p

Surprisingly low limits of selection in plant domestication

Current debate concerns the pace at which domesticated plants emerged from cultivated wild populations and how many genes were involved. Using an individual-based model, based on the assumptions of Haldane and Maynard Smith, respectively, we estimate that a surprisingly low number of 50–100 loci are the most that could be under selection in a cultivation regime at the selection strengths observed in the archaeological record. This finding is robust to attempts to rescue populations from extinction through selection from high standing genetic variation, gene flow, and the Maynard Smith-based model of threshold selection. Selective sweeps come at a cost, reducing the capacity of plants to adapt to new environments, which may contribute to the explanation of why selective sweeps have not been detected more frequently and why expansion of the agrarian package during the Neolithic was so frequently associated with collapse

Refuge or Reservoir? The Potential Impacts of the Biofuel Crop Miscanthus x giganteus on a Major Pest of Maize

BACKGROUND: Interest in the cultivation of biomass crops like the C4 grass Miscanthus x giganteus (Miscanthus) is increasing as global demand for biofuel grows. In the US, Miscanthus is promoted as a crop well-suited to the Corn Belt where it could be cultivated on marginal land interposed with maize and soybean. Interactions (direct and indirect) of Miscanthus, maize, and the major Corn Belt pest of maize, the western corn rootworm, (Diabrotica virgifera virgifera LeConte, WCR) are unknown. Adding a perennial grass/biomass crop to this system is concerning since WCR is adapted to the continuous availability of its grass host, maize (Zea mays). METHODOLOGY/PRINCIPAL FINDINGS: In a greenhouse and field study, we investigated WCR development and oviposition on Miscanthus. The suitability of Miscanthus for WCR development varied across different WCR populations. Data trends indicate that WCR populations that express behavioural resistance to crop rotation performed as well on Miscanthus as on maize. Over the entire study, total adult WCR emergence from Miscanthus (212 WCR) was 29.6% of that from maize (717 WCR). Adult dry weight was 75-80% that of WCR from maize; female emergence patterns on Miscanthus were similar to females developing on maize. There was no difference in the mean no. of WCR eggs laid at the base of Miscanthus and maize in the field. CONCLUSIONS/SIGNIFICANCE: Field oviposition and significant WCR emergence from Miscanthus raises many questions about the nature of likely interactions between Miscanthus, maize and WCR and the potential for Miscanthus to act as a refuge or reservoir for Corn Belt WCR. Responsible consideration of the benefits and risks associated with Corn Belt Miscanthus are critical to protecting an agroecosystem that we depend on for food, feed, and increasingly, fuel. Implications for European agroecosystems in which Miscanthus is being proposed are also discussed in light of the WCR's recent invasion into Europe

Moudre ou faire bouillir ?

Moudre ou faire bouillir ? Nourrir les corps et les esprits dans des traditions culinaires et sacrificielles en Asie de l’Ouest, de l’Est et du Sud. Les techniques de préparation alimentaire révélées par l’archéologie pour les différentes régions d’Eurasie, incluant l’utilisation des céramiques, des meules et des plantes domestiques, mettent en évidence des situations contrastées. En Asie de l’Ouest, la mouture, la fabrication du pain et les soles de cuisson en aires ouvertes pour le rôtissage de la viande constituent les modes de préparation de la nourriture, tandis qu’en Asie de l’Est, l’accent porte depuis longtemps sur les techniques de cuisson à l’eau ou à la vapeur développées beaucoup plus tôt qu’à l’ouest. Ces différentes traditions précèdent l’origine de l’agriculture et se sont amplifiées et améliorées avec les avancées de celle-ci. Elles ont aussi des manières très différentes d’approcher le surnaturel. À l’ouest, les dieux, distants, sont nourris par la fumée sacrificielle tandis que le partage des nourritures rituelles promeut une solidarité communautaire ; à l’est, le partage commensal de nourritures s’effectue en vue de conserver un lien entre des esprits ancestraux et des vivants. Cette dernière tradition, en privilégiant les nourritures « gluantes », a influé sur l’évolution du riz glutineux et les millets. Les traditions d’Asie du Sud, spécialement celles de la vallée de l’Indus, suggèrent des liens avec celles du Proche-Orient. L’archéologie révèle que ces traditions ont pénétré graduellement une tradition différente de l’Inde du Sud, laquelle est à relier avec la mouture des haricots et la cuisson à l’eau. Ces observations comparées suggèrent que les systèmes rituels et les modes de préparation de la nourriture sont liés et servent à contraindre et à maintenir des continuités culturelles régionales.To grind or to boil ? Nourishing bodies and spirits in the divergent traditions of food and sacrifice in West, East, and South Asia. Long-term sequences of the development of food technology revealed by archaeology, including use of ceramics, grinding stones, and domesticated crops, in different regions of Eurasia indicate contrasting emphases. In West Asia, food processing focused on grinding stones, preparation of bread and open roasting of meat, whereas in East Asia there has been a long focus on boiling and steaming technologies which developed much earlier there than in the West. These differing food processing traditions precede the origin of agriculture and gain increasing emphasis and elaboration as agriculture advances. These traditions also have very different approaches to the supernatural, with a western emphasis on sacrificial smoke feeding distant gods and ritual food sharing promoting community solidarity, and an eastern emphasis on ancestral spirits kept close to the living through the commensal sharing of foods ; this has promoted « sticky foods » including the evolution of glutinous rice and millets. South Asian traditions, especially from the greater Indus Valley, can be seen as linked to those of West Asia, whereas archaeology reveals their gradual penetration of a different South Indian tradition, which had been more focused on grinding of beans and boiling. These comparative observations suggest that long-term systems of ritual and food-processing are linked and help to constrain and maintain regional cultural continuities

Studying the relationship between past people and their environments

AGU Chapman Conference on Climates, Past Landscapes, and Civilizations; Santa Fe, New Mexico, 21–25 March 2011; The fortunes of human societies are intimately linked to the environments that sustain them. This has been true from the first emergence of human ancestors through to the present day. An AGU Chapman Conference was held to discuss the relationship between past people and their environments. Participants examined the state of the field, debated issues of contention, and formulated ways that such cross-disciplinary research can progress. Scientists' increasing ability to generate high-resolution climate records has proliferated studies that link the rise and fall of cultures to climate change. This meeting brought together scholars from across the divide between Earth sciences and archaeology to derive a deeper understanding of how humans have reacted to and shaped the changing environment.Anthropolog

Plants to textiles: Local bast fiber textiles at Pre-Pottery Neolithic Çatalhöyük

Textiles from Neolithic Çatalhöyük are among the earliest and best-preserved woven plant artifacts from ancient Southwest Asia. Recent examinations of textiles from Çatalhöyük’s East Mound middle habitation phase (6700–6500 cal. B. C.) provide surprising evidence that instead of being made from flax (linen, Linum usitatissimum), as previously thought, the fibers are from the inner bark of trees (tree bast), some samples identified as bast from locally growing oak (Quercus sp.). The present paper reports on a separate analysis of five woven textile and two cordage fragments, also from the middle habitation phase. Our aims were to identify their raw material origins, distinguish the thread-making technology present, and to situate them within the broader chaîne opératoire of thread and textile making in the prehistory of the region. We observed that the thread-making technology was based on an end-to-end splicing method, and while agreeing with the earlier published study, that tree bast, not flax, was the source of the fiber, our results further suggest that elm (Ulmus sp.) and willow/poplar (Salicaceae) were also among the bast raw materials used in textile manufacture at the site. From these results we can infer that the textile makers possessed complex understandings of the biology, physiology, and seasonality of local wild tree genera throughout the surrounding environment

The early adoption of East Asian crops in West Asia: rice and broomcorn millet in northern Iran

Following their early domestication, broomcorn millet and rice (in East Asia) and wheat and barley (in South-west Asia) were subsequently adopted across Eurasia during the Bronze Age/early historic period. The precise timing and dispersal routes for this trans-Eurasian exchange, however, remain unclear. Here, the authors present archaeobotanical evidence from sites on the Caspian Sea's southern coast, demonstrating that broomcorn millet reached West Asia by c. 2050 BC and rice by c. 120 BC. These dispersals relate to two waves of globalisation and were based on two different mechanisms: an ‘infiltration’ model (broomcorn millet) and a ‘leapfrog’ model (rice). The results contribute to our understanding of the continental-scale connectivity of the late prehistoric/early historic periods

Short communication: Massive erosion in monsoonal central India linked to late Holocene land cover degradation

Soil erosion plays a crucial role in transferring sediment and carbon from land to sea, yet little is known about the rhythm and rates of soil erosion prior to the most recent few centuries. Here we reconstruct a Holocene erosional history from central India, as integrated by the Godavari River in a sediment core from the Bay of Bengal. We quantify terrigenous fluxes, fingerprint sources for the lithogenic fraction and assess the age of the exported terrigenous carbon. Taken together, our data show that the monsoon decline in the late Holocene significantly increased soil erosion and the age of exported organic carbon. This acceleration of natural erosion was later exacerbated by the Neolithic adoption and Iron Age extensification of agriculture on the Deccan Plateau. Despite a constantly elevated sea level since the middle Holocene, this erosion acceleration led to a rapid growth of the continental margin. We conclude that in monsoon conditions aridity boosts rather than suppresses sediment and carbon export, acting as a monsoon erosional pump modulated by land cover conditions