Dawn Of Agriculture Research Articles

KTT in a Digital Age (poster)

Since the dawn of agriculture there has been a need to communicate in order to optimize production and yields. Extension and Knowledge Technology and Transfer (KTT) has seen a lot of changes over the past 100 years. None of these were as great as in the introduction of the Internet and computer technology. With this rapid change in technology, KTT workers and consultants have to adapt how information is getting to producers. Though majority of farms still prefer hard copies of publications and research, we are seeing an increase in the amount of material found online. We have also seen a shift away from demo days and on farm consultations, in order to use webinars, podcasts and social media. Farmers have a been labelled as 'slow to adapt', but this is not just a generational gap anymore. Herd size, producer personalities and delivery methods all effect how the producer wants to receive information. Though the industry is good at producing information, it is important to get it into the producers hands. Until the digital space becomes the norm for all producers there is a need to view the trends in KTT and combine traditional and new age communication methods in order to reach all farmers. As technology continues to change there will be a constant need to change how we are reaching producers while continuing with the KTT methods that have worked in the past.

KTT in a Digital Age

Since the dawn of agriculture there has been a need to communicate in order to optimize production and yields. Extension and Knowledge Technology and Transfer (KTT) has seen a lot of changes over the past 100 years. None of these were as great as in the introduction of the Internet and computer technology. With this rapid change in technology, KTT workers and consultants have to adapt how information is getting to producers.
 Though majority of farms still prefer hard copies of publications and research, we are seeing an increase in the amount of material found online. We have also seen a shift away from demo days and on farm consultations, in order to use webinars, podcasts and social media. Farmers have a been labelled as 'slow to adapt', but this is not just a generational gap anymore. Herd size, producer personalities and delivery methods all effect how the producer wants to receive information. 
 Though the industry is good at producing information, it is important to get it into the producers hands. Until the digital space becomes the norm for all producers there is a need to view the trends in KTT and combine traditional and new age communication methods in order to reach all farmers. As technology continues to change there will be a constant need to change how we are reaching producers while continuing with the KTT methods that have worked in the past.

Landscape transformations at the dawn of agriculture in southern Syria (10.7–9.9 ka cal. BP): Plant-specific responses to the impact of human activities and climate change

In southwest Asia, the accelerated impact of human activities on the landscape has often been linked to the development of fully agricultural societies during the middle and late Pre-Pottery Neolithic B (PPNB) period (around 10.2–7.9 ka cal. BP). This work contributes to the debate on the environmental impact of the so-called Neolitisation process by identifying the climatic and anthropogenic factors that contributed to change local and regional vegetation at the time when domesticated plants appeared and developed in southern Syria (around 10.7–9.9 ka cal. BP). In this work a multidisciplinary analysis of plant microremains (pollen and phytoliths) and macroremains (wood charcoal) is carried out along with stable carbon isotope discrimination of wood charcoals in an early PPNB site (Tell Qarassa North, west of the Jabal al-Arab area). Prior to 10.5 ka cal. BP, the results indicate a dynamic equilibrium in the local and regional vegetation, which comprised woodland-steppe, Mediterranean evergreen oak-woodlands, wetland vegetation and coniferous forests. Around 10.5–9.9 ka cal. BP, the elements that regulated the vegetation system changed, resulting in reduced proportions of arboreal cover and the spread of cold-tolerant and wetlands species. Our data show that reinforcing interaction between the elements of the anthropogenic (e.g. herding, fire-related activities) and climatic systems (e.g. temperature, rainfall) contributed to the transformation of early Holocene vegetation during the emergence of fully agricultural societies in southern Syria.

Preface

Preface Stephanie LeMenager Resilience welcomes this innovative special issue, edited by Johan Gärdebo, Anna Svensson, and Ma Isabel Pérez-Ramos of the Division of History of Science, Technology, and Environment at KTH Royal Institute of Technology and by Tom Buurman of the Department of Media Studies at Stockholm University. The topic of “Social Media in the Anthropocene” immediately presents its ambition. The large concepts of social media and the Anthropocene each have spawned volumes of critical thought. Taken together, they present a provocation large enough for a multivolume collection. Our special editors neatly sum up where they see the point of intersection between their primary objects, and that is in temporal practice. In their introduction to the issue, they write, “Social media are perceived as providing nearly instant information, and the Anthropocene is the transformation of our previous perennial nature toward the unstable, (con)temporary environment.” This special issue unfolds as a query into how the times of social media and the Anthropocene at once emphasize immediacy—the lightning-flash Twitter response, the focus on methane levels NOW— and depth. Depth more readily inheres to Anthropocene thought, where the necessity of locating a start date for the new geologic era in the stratigraphic record forces a material constraint on scholars, making it necessary to choose a moment when ecological modernity begins, be it the dawn of agriculture, the era of colonialist genocide in the Americas, or the detonation of the atomic bomb. Of course it can be argued that no such originary date exists— all are, to an extent, fictional origin stories born within the contemporary crisis of climate change. So the Anthropocene lives between the time zones of historical imagination (social time), geological imagination (deep time), and crisis (the immediate). So, too, social media, if defined capaciously, lives in multiple time zones. One of the unique gifts of this special issue is its insistence that social media cannot be recognized as only a product of digital culture. In fact, social media may be slow media, such as letters sent by post. Social media may be live performance, played out by multiple actors on a Welsh beach— actors including water and stone, [End Page vii] whose movements generate a contemporary social surround yet hearken back to millennia of nonhuman practice. While our special editors utilize the most up-to-date social media fora, such as blogging, Tumblr archiving, and open-source review, they also engage in a McCluhanite expansion of the meanings of social media to include multiple ways of mediating sociality. In the process, they implicitly and explicitly ask us, their readers, to develop an ethics of social praxis (always mediated!) for the Anthropocene. The ethical questions at the core of this special issue touch on structural problems at the core of academic life, such as the necessity of travel for academic career building, the importance of expertise versus amateurism, and the complexity of incorporating community voices into academic publications. “Social Media in the Anthropocene” leaves us thinking, and thinking hard, about what it means to be a mediated, mediating animal— in other words, human— in this unprecedented ecological era. [End Page viii] Copyright © 2018 University of Nebraska Press

European derived Saccharomyces cerevisiae colonisation of New Zealand vineyards aided by humans.

Humans have acted as vectors for species and expanded their ranges since at least the dawn of agriculture. While relatively well characterised for macrofauna and macroflora, the extent and dynamics of human-aided microbial dispersal is poorly described. We studied the role which humans have played in manipulating the distribution of Saccharomyces cerevisiae, one of the world's most important microbes, using whole genome sequencing. We include 52 strains representative of the diversity in New Zealand to the global set of genomes for this species. Phylogenomic approaches show an exclusively European origin of the New Zealand population, with a minimum of 10 founder events mostly taking place over the last 1000 years. Our results show that humans have expanded the range of S. cerevisiae and transported it to New Zealand where it was not previously present, where it has now become established in vineyards, but radiation to native forests appears limited.

Uso de imagens digitais obtidas com câmeras para analisar plantas

Plant visual analysis is performed empirically by man since the dawn of agriculture. Currently, the advent of digital cameras (RGB, multispectral, hyperspectral and thermal) using images gains momentum as an evaluation tool. The use of digital cameras for plant analysis is a non-destructive, rapid and reproducible method, with the possibility of stock images in a database for future evaluations. Visual diagnoses of images may have limited scope for extraction of information so it becomes important to use software’s to discuss issues of interest in a image. When there is no specific software for the analysis of certain larger image, manipulation is required, usually involving format transformation, editing, analysis on common software and data entry, thus the specific software is necessary to facilitate the acquisition and data analysis. The analysis of plants through images has been held in all plant organs, on scales ranging from micro to macroscopic and in diverse environments. Thus, this literature review aims to get the science state of plant analysis by digital images.

Healthy Ground, Healthy Atmosphere: Recarbonizing the Earth's Soils.

On a bright October morning Dave Brandt tromps through the middle of his central Ohio wheat field. The grain was harvested months ago, but there isn’t an inch of bare dirt anywhere. Instead, more than 10 varieties of plants, including crimson clover, pearl millet, and Austrian winter peas, form a “cover crop cocktail” that stretches all the way to the road bordering his property. “This will be here all winter,” Brandt says. “And in the spring, we’ll plant corn right into this.” Brandt hasn’t tilled his soil since 1972, when he rented his first 600 acres of farmland to grow wheat, corn, and soybeans. And by keeping plants on his land in various stages of growth and decomposition, Brandt appears to have increased the amount of carbon in his soil over the years. One study estimated that total organic carbon in the top foot of Brandt’s soil increased by 10% after six years of no-till, 35% after 20 years, and 61% after 35 years.1 (The data on which this estimate was based were not peer reviewed.) Overall, Brandt’s soil stored, or sequestered, an estimated average 960 kg of carbon per hectare per year.1 Since the dawn of agriculture, the world’s soils are estimated to have lost billions of metric tons of carbon to the atmosphere. Researchers are now looking at ways to recarbonize the global soil pool using methods such as cover cropping, no-till ... With figures like those, soil scientists and climate researchers believe that returning carbon to the soil on a large scale could help mitigate climate change. The world’s terrestrial carbon stores—the combined amount of carbon in soil and in plant matter—are much greater than the amount of carbon in the atmosphere: 3.12 trillion metric tons in the top meter of soil versus 780 billion metric tons in the atmosphere, by one estimate.2 Before the dawn of agriculture, there was even more carbon in the global soil pool—an estimated 55–78 billion additional metric tons,3 and the world’s plant biomass held still more, much of it lost to land use changes.2 That’s why Rattan Lal, one of world’s preeminent soil scientists and director of the Carbon Management and Sequestration Center (C-MASC) at The Ohio State University, has called for recarbonizing the world’s soils.2 Doing so, Lal says, “would be a truly win–win–win situation.” In addition to carbon sequestration, increasing carbon in soil has many other co-benefits: increased water storage in soil, increased length of the growing season, cooling of the ground via evapotranspiration, recharging groundwater aquifers, keeping springs and rivers flowing in the dry season. Soil itself filters water, reduces flooding, and provides a water reserve for plants in times of drought Dave Brandt has been practicing soil conservation measures on his Ohio farm since 1972. By one estimate, these measures sequestered an average 960 kg of carbon per hectare of his farmland per year. Lal believes food security is an especially important co-benefit. By one estimate, about 24% of total global land area shows evidence of impaired productivity,4 and each year some 1–2.9 million hectares is degraded so badly that it becomes unsuitable for farming.5 Increasing population levels, predicted to reach 9.2 billion by 2050, will place more pressure on the world’s farmlands to produce enough food.6 Lal has calculated that increasing organic carbon in the soil surrounding plant roots by 1 ton per hectare per year can increase grain production by 32 million tons per year.7,8 “This is especially important for small landholders of sub-Saharan Africa, South Asia, and the Caribbean,” he says.

Reciprocal sign epistasis and truncation selection: When is recombination favorable in a pre-breeding program with a selfing species?

Since the dawn of agriculture, humans have applied artificial selection on traits of interest, regardless of their genetic architecture. Yet, still today, most models used to study and streamline this process overlook genetic interactions. In this study, we determined the conditions in which a target genotype can be fixed when truncation selection is applied on an epistatic trait. Previous studies have shown that reciprocal sign epistasis with two fitness peaks of unequal height involves multiple equilibrium states, i.e. below one critical parameter value, such as a critical recombination rate, one genotype may be fixed, and above it, another one may be fixed. Using a haploid bi-locus model, we identified which genotype would be fixed, and how quickly, in an infinite population selected for a phenotypic trait subject to reciprocal sign epistasis with unequal peak heights, depending on two criteria: the recombination rate and percentage of selected individuals. The critical parameter values at which bistability sets in, were also calculated. These results were complemented by stochastic simulations in finite populations. Our results confirmed that, in the case of fitness under reciprocal sign epistasis, high recombination rates induce blockage at the local optimum or attainment of an equilibrium state between the two peaks. However, if linkage disequilibrium is negative in the initial population, recombination is necessary to create the most favorable genotype. Therefore, in this case, reciprocal sign epistasis favors non-null recombination rates, particularly if selection is intense.

Novel quantitative trait loci underlying major domestication traits in tetraploid wheat

Wheat domestication and subsequent evolution under domestication occurred since the dawn of agriculture and caused significant genetic changes that affected plant morphology, physiology and phenology. The majority of these traits are quantitative traits controlled by many genes. Correspondingly, the main goal of the current study is genetic dissection of the key domestication trait (brittle rachis) and traits evolved under domestication, based on quantitative phenotyping. Genetic mapping of quantitative trait loci (QTL) affecting brittle rachis, threshability, threshing efficiency, spike harvest index and kernel weight was conducted using a recombinant inbred lines population derived from a cross between Triticum durum and wild emmer wheat. Using a new quantitative phenotyping approach, we discovered novel QTLs underlying rachis fragility, spike threshability and other domestication-related traits and confirmed some of the known putative locations for QTLs affecting these traits. Overall, the number of domestication-related QTLs mapped to the A genome was twofold higher than those found on the B genome, in accordance with the concept of ‘genome asymmetry’, implying that the A genome is dedicated to the control of morphological traits, house-keeping metabolic reactions and yield components. Our results add a new dimension to this important concept and contribute to a better understanding of the initial steps of domestication evolution of cereals.

The potential of transcription factor-based genetic engineering in improving crop tolerance to drought.

Drought is one of the major constraints in crop production and has an effect on a global scale. In order to improve crop production, it is necessary to understand how plants respond to stress. A good understanding of regulatory mechanisms involved in plant responses during drought will enable researchers to explore and manipulate key regulatory points in order to enhance stress tolerance in crops. Transcription factors (TFs) have played an important role in crop improvement from the dawn of agriculture. TFs are therefore good candidates for genetic engineering to improve crop tolerance to drought because of their role as master regulators of clusters of genes. Many families of TFs, such as CCAAT, homeodomain, bHLH, NAC, AP2/ERF, bZIP, and WRKY have members that may have the potential to be tools for improving crop tolerance to drought. In this review, the roles of TFs as tools to improve drought tolerance in crops are discussed. The review also focuses on current strategies in the use of TFs, with emphasis on several major TF families in improving drought tolerance of major crops. Finally, many promising transgenic lines that may have improved drought responses have been poorly characterized and consequently their usefulness in the field is uncertain. New advances in high-throughput phenotyping, both greenhouse and field based, should facilitate improved phenomics of transgenic lines. Systems biology approaches should then define the underlying changes that result in higher yields under water stress conditions. These new technologies should help show whether manipulating TFs can have effects on yield under field conditions.

Plant science. Making hunger yield.

A combination of approaches to develop crops with improved yields is needed to address the demands of a growing population.

Mining herbaria for plant pathogen genomes: back to the future.

Since the dawn of agriculture, plant pathogens and pests have been a scourge of humanity. Yet we have come a long way since the Romans attempted to mitigate the effects of plant disease by worshipping and honoring the god Robigus [1]. Books in the Middle Ages by Islamic and European scholars described various plant diseases and even proposed particular disease management strategies [1]. Surprisingly, the causes of plant diseases remained a matter of debate over a long period. It took Henri-Louis Duhamel du Monceau's elegant demonstration in his 1728 “Explication Physique” paper that a “contagious” fungus was responsible for a saffron crocus disease to usher in an era of documented scientific inquiry [2]. Confusion and debate about the exact nature of the causal agents of plant diseases continued until the 19th century, which not only saw the first detailed analyses of plant pathogens but also provided much-needed insight into the mechanisms of plant disease. An example of this is Anton de Bary's demonstration that a “fungus” is a cause, not a consequence, of plant disease [3]. This coming of age of plant pathology was timely. In the 19th century, severe plant disease epidemics hit Europe and caused economic and social upheaval. These epidemics were not only widely covered in the press but also recognized as serious political issues by governments [1], [4]–[6]. Many of the diseases, including late blight of potato, powdery and downy mildew of grapevine, as well as phylloxera, were due to exotic introductions from the Americas and elsewhere. These and subsequent epidemics motivated scientific investigations into crop breeding and plant disease management that developed into modern plant pathology science over the 20th century. Nowadays, our understanding of plant pathogens and the diseases they cause greatly benefits from molecular genetics and genomics. All aspects of plant pathology, from population biology and epidemiology to mechanistic research, are impacted. The polymerase chain reaction (PCR) first enabled access to plant pathogen DNA sequences from historical specimens deposited in herbaria [7]–[9]. Historical records in combination with herbarium specimens have turned out to provide powerful tools for understanding the course of past plant epidemics. Recently, thanks to new developments in DNA sequencing technology, it has become possible to reconstruct the genomes of plant pathogens in herbaria [10], [11]. In this article, we first summarize how whole genome analysis of ancient DNA has been recently used to reconstruct the 19th-century potato-blight epidemic that rapidly spread throughout Europe and triggered the Irish potato famine. We then discuss the exciting prospects offered by the emergence of the discipline of ancient plant pathogen genomics.

The Legacy of Extraction

The Legacy of Extraction

Cereal landraces genetic resources in worldwide GeneBanks. A review

Since the dawn of agriculture, cereal landraces have been the staples for food production worldwide, but their use dramatically declined in the 2nd half of the last century, replaced by modern cultivars. In most parts of the world, landraces are one of the most threatened components of agrobiodiversity, facing the risk of genetic erosion and extinction. Since landraces have a tremendous potential in the development of new cultivars adapted to changing environmental conditions, GeneBanks holding their genetic resources potentially play an important role in supporting sustainable agriculture. This work reviews the current knowledge on cereal landraces maintained in GeneBanks and highlights the strengths and weaknesses of existing information about their taxonomy, origin, structure, threats, sampling methodologies and conservation and GeneBanks’ documentation and management. An overview of major collections of cereal landraces is presented, using the information available in global metadatabase systems. This review on winter cereal landrace conservation focuses on: (1) traditional role of GeneBanks is evolving beyond their original purpose to conserve plant materials for breeding programmes. Today’s GeneBank users are interested in landraces’ history, agro-ecology and traditional knowledge associated with their use, in addition to germplasm traits. (2) GeneBanks therefore need to actively share their germplasm collections’ information using different channels, to promote unlimited and effective use of these materials for the further development of sustainable agriculture. (3) Access to information on the 7.4 million accessions conserved in GeneBanks worldwide, of which cereal accessions account for nearly 45 %, particularly information on cereal landraces (24 % of wheat, 23 % of barley, 14 % of oats and 29 % of rye accessions), is often not easily available to potential users, mainly due to the lack of consistent or compatible documentation systems, their structure and registration. (4) Enhancing the sustainable use of landraces maintained in germplasm collections through the effective application of recent advances in landrace knowledge (origin, structure and traits) and documentation using the internet tools and data providing networks, including the use of molecular and biotechnological tools for the material screening and detection of agronomic traits. (5) Cereal landraces cannot be exclusively conserved as seed samples maintained under ex situ conditions in GeneBanks. The enormous contribution of farmers in maintaining the crop and landraces diversity is recognised. Sharing of benefits and raising awareness of the value of cereal landraces are the most effective ways to promote their conservation and to ensure their continued availability and sustainable use. (6) Evaluation of costs and economic benefits attributed to sustainable use of cereal landraces conserved in the GeneBanks requires comprehensive studies conducted on a case-by-case basis, that take into consideration species/crop resources, conservation conditions and quality and GeneBank location and functions.

The legume manifesto: (Net)workers on Fabaceae, unite!

Legumes have been an important part of cropping systems since the dawn of agriculture. The shift in Europe from draught animals to meat animals coincided with the increasing availability of soybean meal from North and South America, and the Common Agricultural Policy of the European Union promoted the growing of cereals and oilseeds at the expense of other crops so legumes fell out of favour with farmers and decision-makers. Continental concerns about food and feed security, high prices of oil and soybean meal and advances in the application of fundamental molecular genetics to crop species, all mean that now is a good opportunity to promote the return of legumes to European cropping systems by enhancing the efficiency of research and development on this family. Hence we propose the establishment of a Legume Society that will promote information exchange and scientific productivity by uniting the various legume research communities.

Daily Practice and the Organization of Space at the Dawn of Agriculture: A Case Study from the near East

Drawing upon the lithic remains from the Late Natufian and Pre-Pottery Neolithic A occupations of "Iraq ed-Dubb, Jordan, we utilize a quantifiable statistical approach with Geographic Information Systems analysis to interpret shifting practices that influenced site structure. This study indicates that the highly mobile Late Natufian population who inhabited the site had fairly nondelineated use of space compared to a more delineated use of space during the Pre-Pottery Neolithic A. It appears that intensified intra-community organization of space was a byproduct of decreased residential mobility. Moreover, the emergence of more formal intra-community organization likely aided in the development of much more complex human societies that evolved several millennia after the onset of Holocene conditions.

A sterile‐female technique proposed for control of Striga hermonthica and other intractable weeds: advantages, shortcomings and risk management

Weeds have posed intractable challenges to farmers since the dawn of agriculture. This article describes in detail a proposed control strategy based on the introduction of genes conferring female sterility into the genome of an intractable target weed. Spread of these genes through target populations via pollen would be facilitated by their incorporation within active transposable elements. Advantages (e.g. self-dissemination, self-proliferation, target specificity) and shortcomings (e.g. high cost, long project incubation period, limited range of possible targets) of this strategy are discussed in depth, as are assessment and management of its attendant biological and ecological risks, such as the risk of introduced genes spreading to non-target species. The parasitic weed Striga hermonthica (Del.) Benth. is examined as a potential target.

What is the Future for Wild, Large Herbivores in Human‐Modified Agricultural Landscapes?

Since the dawn of agriculture, people and wild animals have been in conflict because agricultural crops generally offer a rich food source for wild animals as well as for people. Large, wild herbivores compete for pasture resources with livestock and can act as reservoirs of livestock diseases. Furthermore, livestock form a concentrated and vulnerable food source for predators. As a result, humans have extirpated many native animal species from agricultural areas, either directly, or indirectly through modifications in habitat availability or structure resulting from land use changes. As human populations have expanded in developing countries they have caused loss in biodiversity and species extinctions, and will continue to do so. I review attempts to change the interaction between people and large herbivores from one that is primarily negative to one that is positive by increasing the benefits which individuals, communities and society derive from wild, large herbivores. My proposition is that, in developing countries, it is only by using this approach that wild, large herbivores have a chance of surviving outside areas specifically set aside for their protection. In the developed world the opposite trend will occur as people move into the cities causing human populations to decline in rural regions. As a consequence, wildlife habitat will increase and wild, large herbivores will come into conflict with humans, particularly in peri‐urban areas rather than in rural areas as happens at present. This will lead to a change in public attitude from one that supports wildlife conservation to one that sees wild, large herbivores as a threat; again, with potential negative consequences for wildlife conservation.

A Flash of the Spirit

As a young student of anthropology at Harvard, I was fortunate to fall into the orbit of David Maybury-Lewis, who became my undergraduate tutor. A man of searing intelligence, whose formal eloquence masked a deeply humane spirit, Maybury-Lewis was one of the great Americanists, a brilliant scholar who had lived for years among the Akwe-Xavante and Xerente Indians in central Brazil. A student of Rodney Needham at Oxford, he had come to anthropology after earning a degree at Cambridge in romance languages, and his fluidity in every tongue was astonishing. His German, Russian, Danish, Spanish, and Portuguese were flawless, but it was the way he spoke English that fired the senses. His accent implied erudition. Combined with the precision of his thoughts, the effect was mesmerizing. David had traveled to central Brazil in the mid-1950s to investigate and, in a sense, celebrate the so-called Ge anomaly. Throughout the nineteenth century and well into the first decades of the twentieth, anthropologists had maintained that technological sophistication and material well-being were a direct measure of the complexity of a culture-a convenient concept that invariably placed Victorian England at the top of a Darwinian ladder to success. Modern ethnographers rejected the notion out of hand, arguing that every human culture had by biological definition the same mental acuity. Whether this potential was realized through technological prowess or by the elaboration of intensely complex threads of memory inherent in a myth was a matter of cultural choice and historical circumstance. Nowhere was this modern notion more perfectly displayed than among the peoples of eastern Brazil, the complex of fierce tribes known as the Central Ge. Living in the forests of Mato Grosso and on the arid savannas and uplands that separate the southern Amazon basin from the Atlantic coast, the Akwe-Xavante and Xerente, Kayapo, Timbira, and a host of other tribes all spoke dialects of the Ge language family. Semi-nomadic hunters and gatherers, they ranged across vast territories, hunting peccaries for meat, and birds for brilliant plumage to be woven into ceremonial coronas that shone like the sun. Their material culture was exceedingly rudimentary. They knew nothing of canoes, though rivers dissected their lands, and as late as the 1950s were still dependent on the bow and arrow. They cleared the savanna, but their harvests were meager-their sparse plantings reminiscent of the dawn of agriculture. Yet beneath the primitive veneer lay an astonishingly rich and complex worldview-a tangle of religious beliefs and myths that informed all of life and gave rise to patterns of social organization Byzantine in their sophistication, yet perfectly elegant in their elaboration. This apparent contradiction-a marginal people, technologically backward yet mentally and intellectually afire-confounded many early ethnographers. Hence, the notion of the Ge anomaly. But the great French anthropologist Claude Levi-Strauss saw the situation quite differently. For him-a scholar of immense vision capable of embracing all of the Americas in a single thought-the cultures of the Central Ge represented nothing more than a simple triumph of the human spirit and imagination. Having lived briefly among the Bororo-a people whose social structure was very closely related to that of the Ge tribes-Levi-Strauss had come to see their world as a universe of oppositions: man and woman, light and darkness, good and evil, the sun and the moon, the raw and the cooked, the wild and the tame. Every facet of their society-every ritual and institution, every concept of kinship and procreation, the very cycles of life and death, the transitions of birth and initiation, even the architecture and settlement pattern of the seasonal encampments-reflected a subconscious and indeed conscious attempt to resolve in harmony these opposing elements. Thus, there were two moieties and two exogamous patrilineages, entwined by cross-cousin marriages. …

The Prehistory of Potyviruses: Their Initial Radiation Was during the Dawn of Agriculture

BackgroundPotyviruses are found world wide, are spread by probing aphids and cause considerable crop damage. Potyvirus is one of the two largest plant virus genera and contains about 15% of all named plant virus species. When and why did the potyviruses become so numerous? Here we answer the first question and discuss the other.Methods and FindingsWe have inferred the phylogenies of the partial coat protein gene sequences of about 50 potyviruses, and studied in detail the phylogenies of some using various methods and evolutionary models. Their phylogenies have been calibrated using historical isolation and outbreak events: the plum pox virus epidemic which swept through Europe in the 20th century, incursions of potyviruses into Australia after agriculture was established by European colonists, the likely transport of cowpea aphid-borne mosaic virus in cowpea seed from Africa to the Americas with the 16th century slave trade and the similar transport of papaya ringspot virus from India to the Americas.Conclusions/SignificanceOur studies indicate that the partial coat protein genes of potyviruses have an evolutionary rate of about 1.15×10−4 nucleotide substitutions/site/year, and the initial radiation of the potyviruses occurred only about 6,600 years ago, and hence coincided with the dawn of agriculture. We discuss the ways in which agriculture may have triggered the prehistoric emergence of potyviruses and fostered their speciation.