Domestication as innovation : the entanglement of techniques, technology and chance in the domestication of cereal crops

The origins of agriculture involved pathways of domestication in which human behaviours and plant genetic adaptations were entangled. These changes resulted in consequences that were unintended at the start of the process. This paper highlights some of the key innovations in human behaviours, such as soil preparation, harvesting and threshing, and how these were coupled with genetic ‘innovations’ within plant populations. We identify a number of ‘traps’ for early cultivators, including the needs for extra labour expenditure on crop-processing and soil fertility maintenance, but also linked gains in terms of potential crop yields. Compilations of quantitative data across a few different crops for the traits of nonshattering and seed size are discussed in terms of the apparently slow process of domestication, and parallels and differences between different regional pathways are identified. We highlight the need to bridge the gap between a Neolithic archaeobotanical focus on domestication and a focus of later periods on crop-processing activities and labour organization. In addition, archaeobotanical data provide a basis for rethinking previous assumptions about how plant genetic data should be related to the origins of agriculture and we contrast two alternative hypotheses: gradual evolution with low selection pressure versus metastable equilibrium that prolonged the persistence of ‘semi-domesticated’ populations. Our revised understanding of the innovations involved in plant domestication highlight the need for new approaches to collecting, modelling and integrating genetic data and archaeobotanical evidence

Soil domestication by rice cultivation results in plant-soil feedback through shifts in soil microbiota.

BackgroundSoils are a key component of agricultural productivity, and soil microbiota determine the availability of many essential plant nutrients. Agricultural domestication of soils, that is, the conversion of previously uncultivated soils to a cultivated state, is frequently accompanied by intensive monoculture, especially in the developing world. However, there is limited understanding of how continuous cultivation alters the structure of prokaryotic soil microbiota after soil domestication, including to what extent crop plants impact soil microbiota composition, and how changes in microbiota composition arising from cultivation affect crop performance.ResultsWe show here that continuous monoculture (> 8 growing seasons) of the major food crop rice under flooded conditions is associated with a pronounced shift in soil bacterial and archaeal microbiota structure towards a more consistent composition, thereby domesticating microbiota of previously uncultivated sites. Aside from the potential effects of agricultural cultivation practices, we provide evidence that rice plants themselves are important drivers of the domestication process, acting through selective enrichment of specific taxa, including methanogenic archaea, in their rhizosphere that differ from those of native plants growing in the same environment. Furthermore, we find that microbiota from soils domesticated by rice cultivation contribute to plant-soil feedback, by imparting a negative effect on rice seedling vigor.ConclusionsSoil domestication through continuous monoculture cultivation of rice results in compositional changes in the soil microbiota, which are in part driven by the rice plants. The consequences include a negative impact on plant performance and increases in greenhouse gas emitting microbes

From Foraging to Food Production on the Southern Cumberland Plateau of Alabama and Tennessee, U.S.A.

Research involving the origin of plant domestication remains as important today as ever. While early anthropologists viewed plant domestication as a necessary precondition for cultural development, more recent ethnographic studies have shown that agriculture was a much more labor intensive subsistence practice than hunting and gathering, leading many to question the reasons behind the prehistoric transition. Today, research and advances in technology have provided conclusive evidence to include the Eastern Woodlands of North America as one of the eight global centers of indigenous plant domestication. Although the timing of domestication and the plants involved in early horticultural systems are well understood, several questions remain unanswered. Today, most models suggest that initial plant domestication occurred either in the heavily populated river valleys, or in the surrounding uplands that were also frequented by prehistoric groups. To test these models, I analyzed plant assemblages from five sites containing Archaic through Woodland period deposits, the time periods preceding, following, and during which initial plant domestication occurred. The sites were selected for their geographic position and proximity to each other. Found within a 20-mile radius of one another, Michaels Shelter and Uzzelles Shelter are located in the uplands of the southern Cumberland Plateau, Widows Creek and Mussel Beach are located in the Tennessee River Valley, and Russell Cave is situated approximately halfway between the upland and river valley sites. My results from analyzing the plant remains from these five sites show that the conditions that favored early plant domestication in floodplain settings across the region were also present in upland settings. These factors include rich soils, highly disturbed landscapes, and the frequent reoccupation of sites in areas where plant food resources naturally occurred and were encountered on the landscape. All of these factors contributed to initial plant domestication in both the upland and floodplain environments across the Eastern Woodlands. Additionally, through the application of the diet breadth and central place foraging models, I explain how individual decision-making processes in small scale societies, and not geographical location, resulted in the cultivation and domestication of indigenous plants

Evidence for mid-Holocene rice domestication in the Americas

The development of agriculture is one of humankind’s most pivotal achievements. Questions about plant domestication and the origins of agriculture have engaged scholars for well over a century, with implications for understanding its legacy on global subsistence strategies, plant distribution, population health and the global methane budget. Rice is one of the most important crops to be domesticated globally, with both Asia (Oryza sativa L.) and Africa (Oryza glaberrima Steud.) discussed as primary centres of domestication. However, until now the pre-Columbian domestication of rice in the Americas has not been documented. Here we document the domestication of Oryza sp. wild rice by the mid-Holocene residents of the Monte Castelo shell mound starting at approximately 4,000 cal. yr BP, evidenced by increasingly larger rice husk phytoliths. Our data provide evidence for the domestication of wild rice in a region of the Amazon that was also probably the cradle of domestication of other major crops such as cassava (Manihot esculenta), peanut (Arachis hypogaea) and chilli pepper (Capsicum sp.). These results underline the role of wetlands as prime habitats for plant domestication worldwide

The “Bringing into Cultivation” Phase of the Plant Domestication Process and Its Contributions to In Situ Conservation of Genetic Resources in Benin

All over the world, plant domestication is continually being carried out by local communities to support their needs for food, fibre, medicine, building materials, etc. Using participatory rapid appraisal approach, 150 households were surveyed in 5 villages selected in five ethnic groups of Benin, to investigate the local communities' motivations for plant domestication and the contributions of this process to in situ conservation of genetic resources. The results indicated differences in plant domestication between agroecological zones and among ethnic groups. People in the humid zones give priority to herbs mainly for their leaves while those in dry area prefer trees mostly for their fruits. Local communities were motivated to undertake plant domestication for foods (80% of respondents), medicinal use (40% of respondents), income generation (20% of respondents) and cultural reasons (5% of respondents). 45% of the species recorded are still at early stage in domestication and only 2% are fully domesticated. Eleven factors related to the households surveyed and to the head of the household interviewed affect farmers' decision making in domesticating plant species. There is gender influence on the domestication: Women are keen in domesticating herbs while men give priority to trees

How did the domestication of Fertile Crescent grain crops increase their yields?

The origins of agriculture, 10 000 years ago, led to profound changes in the biology of plants exploited as grain crops, through the process of domestication. This special case of evolution under cultivation led to domesticated cereals and pulses requiring humans for their dispersal, but the accompanying mechanisms causing higher productivity in these plants remain unknown. The classical view of crop domestication is narrow, focusing on reproductive and seed traits including the dispersal, dormancy and size of seeds, without considering whole-plant characteristics. However, the effects of initial domestication events can be inferred from consistent differences between traditional landraces and their wild progenitors. We studied how domestication increased the yields of Fertile Crescent cereals and pulses using a greenhouse experiment to compare landraces with wild progenitors. We grew eight crops: barley, einkorn and emmer wheat, oat, rye, chickpea, lentil and pea. In each case, comparison of multiple landraces with their wild progenitors enabled us to quantify the effects of domestication rather than subsequent crop diversification. To reveal the mechanisms underpinning domestication-linked yield increases, we measured traits beyond those classically associated with domestication, including the rate and duration of growth, reproductive allocation, plant size and also seed mass and number. Cereal and pulse crops had on average 50% higher yields than their wild progenitors, resulting from a 40% greater final plant size, 90% greater individual seed mass and 38% less chaff or pod material, although this varied between species. Cereal crops also had a higher seed number per spike compared with their wild ancestors. However, there were no differences in growth rate, total seed number, proportion of reproductive biomass or the duration of growth. The domestication of Fertile Crescent crops resulted in larger seed size leading to a larger plant size, and also a reduction in chaff, with no decrease in seed number per individual, which proved a powerful package of traits for increasing yield. We propose that the important steps in the domestication process should be reconsidered, and the domestication syndrome broadened to include a wider range of traits

Importance and Impact of Ecological Approaches to Crop Domestication

Domestication is the sign of the beginning of agriculture and it is the outcome of a selection process that leads to increased adaptation of crop plants from wild relatives to mitigate the effect of food security problems. Plant breeding primarily based on domestication to facilitate the introgression of adaptive diversity, providing breeders with new tools for crop improvement through drought, insect, and disease-resistant varieties. In the domestication process, significant alteration in phenological, morphological and genetical leads to the increased adaptation and use of the plants under the strategic and modern plant breeding practices. The transformation of wild species into elite cultivars through domestication entails evolutionary responses in which plant populations adapt to selection. Selection and plant breeding has reduced genetic variation in all crop species because limited number of preferred crop plants selected for further improvements for different desirable traits. Therefore, novel variation can be introduced from wild relatives and variation will be useful in crop improvement by either traditional breeding methods or biotechnology. Domestication syndrome is a group of traits that can arise through human preferences for ease of harvest and growth under human management. Domestication focuses on genetic variation, as well as new genetic variation introduced via mutation or introgression. Domestication has been contributing in overcoming the global food challenges and addressing the problem of yield reduction and its links with pest management. Domestication leads to the development of modern cultivars, which have contributed to the dramatic improvement of yield of the crops for the world. It is now believed that plant domestication was much more complex in evolutionary terms and of wider geographical extent than previously believed. Crop plants have been domesticated over vast areas and not in more restricted geographical areas as the center of origin. Generally, the practice of improving crop production through bringing the wild plants to controlled management plays great roles to alleviate poverty and raise the living standards of the peoples. Keywords:  Crop; Domestication; Evolution; Ecology; Center of origin; Environment DOI: 10.7176/JBAH/10-8-04 Publication date: April 30th 202

Anthropogenic seed dispersal: rethinking the origins of plant domestication

It is well documented that ancient sickle harvesting led to tough rachises, but the other seed dispersal properties in crop progenitors are rarely discussed. The first steps toward domestication are evolutionary responses for the recruitment of humans as dispersers. Seed dispersal–based mutualism evolved from heavy human herbivory or seed predation. Plants that evolved traits to support human-mediated seed dispersal express greater fitness in increasingly anthropogenic ecosystems. The loss of dormancy, reduction in seed coat thickness, increased seed size, pericarp density, and sugar concentration all led to more-focused seed dispersal through seed saving and sowing. Some of the earliest plants to evolve domestication traits had weak seed dispersal processes in the wild, often due to the extinction of animal dispersers or short-distance mechanical dispersal

Integrating the processes in the evolutionary system of domestication

Genetics has long been used as a source of evidence to understand domestication origins. A recent shift in the emphasis of archaeological evidence from a rapid transition paradigm of hunter-gatherers to agriculturalists, to a protracted transition paradigm has highlighted how the scientific framework of interpretation of genetic data was quite dependent on archaeological evidence, resulting in a period of discord in which the two evidence types appeared to support different paradigms. Further examination showed that the discriminatory power of the approaches employed in genetics was low, and framed within the rapid paradigm rather than testing it. In order to interpret genetic data under the new protracted paradigm it must be taken into account how that paradigm changes our expectations of genetic diversity. Preliminary examination suggests that a number of features that constituted key evidence in the rapid paradigm are likely to be interpreted very differently in the protracted paradigm. Specifically, in the protracted transition the mode and mechanisms involved in the evolution of the domestication syndrome have become much more influential in the shape of genetic diversity. The result is that numerous factors interacting over several levels of organization in a domestication system need to be taken into account in order to understand the evolution of the process. This presents a complex problem of integration of different data types which is difficult to describe formally. One possible way forward is to use Bayesian approximation approaches that allow complex systems to be measured in a way that does not require such formality