Periodic Reporting for period 2 - FEDD (Fruits of Eurasia: Domestication and Dispersal)
Periodo di rendicontazione: 2021-07-01 al 2022-12-31
The plants in your kitchen have complex and poorly understood histories; they each followed unique paths through their domestication and dispersal across the ancient world. In many cases these plants crossed entire continents long before the invention of the combustion engine and they evolved elaborate domestication traits long before humans understood breeding or heredity. The Fruits of Eurasia: Domestication and Dispersal (FEDD) project grapples with the most impressive chapter in the history of the plants in your kitchen: the movement of crops along the routes of the ancient Silk Road. The trans-Eurasian trade routes are responsible for bringing economically important plants from East Asia to Europe in prehistory and vice versa, representing one of the main factors in shaping the cuisines of the modern world. Additionally, it is becoming increasingly clear that the movement of these plants over two continents changed their genetic makeup on a population scale, this occurred through a number of different processes, including the hybridization of distantly related species that would not have crossed in the wild and the formation of genetically isolated populations after experiencing genetic bottlenecks. In this way, ancient trade on the Silk Road is responsible for both the domestication and dispersal of many of the most economically significant plants in the world today. Understanding how this process unfolded, what routes of exchange the plants followed, and the timing of this process will all feed into a clearer understanding of the formatting of cuisines and the evolution of the foods we all rely on.
The FEDD team is composed of an international group of top research specialists, with areas of specialty covering archaeobotany, history, art history, linguistics, ancient genetics, and molecular methods (ancient proteomics and metabolites). Collectively, these specialists are pooling their knowledge and data to answer linked questions about the movement of crops on these ancient trade routes. The team has collected archaeobotanical samples for 13 archaeological sites over the past 2.5 years and plans to work at another 10 sites (covering 6 countries). These studies have already revealed earlier evidence for cultivation and consumption of plants across this region than was previously thought. The archaeobotanical assemblage consists of hundreds of thousands of individually identified and quantified ancient seeds or plant parts. In some cases, these ancient remains are desiccated and are therefore suitable for further analysis via ancient genetics, which will further illustrate the processes of domestication for certain crops and the paths of their dispersals.
The FEDD team is composed of an international group of top research specialists, with areas of specialty covering archaeobotany, history, art history, linguistics, ancient genetics, and molecular methods (ancient proteomics and metabolites). Collectively, these specialists are pooling their knowledge and data to answer linked questions about the movement of crops on these ancient trade routes. The team has collected archaeobotanical samples for 13 archaeological sites over the past 2.5 years and plans to work at another 10 sites (covering 6 countries). These studies have already revealed earlier evidence for cultivation and consumption of plants across this region than was previously thought. The archaeobotanical assemblage consists of hundreds of thousands of individually identified and quantified ancient seeds or plant parts. In some cases, these ancient remains are desiccated and are therefore suitable for further analysis via ancient genetics, which will further illustrate the processes of domestication for certain crops and the paths of their dispersals.
The main data collection and processing portion of this project is based on archaeobotanical studies. The methods of archaeobotany have been well represented in East Asia and Europe, but have traditionally been absent in the archaeology of Central Asia. By introducing these methods to this vast area of the world, we are linking the routes of dispersal of cross across two continents. In order to achieve these goals we are engaging in data collection campaigns tied to ongoing excavation projects in Kazakhstan, Kyrgyzstan, Uzbekistan, Tajikistan, Turkmenistan, and Mongolia. We are also collaborating with archaeobotanical colleagues working in China to fill in the spaces in between, notably in Xinjiang, Qinghai, and Tibet. We are collecting sediment samples for processing for macrobotanical remains from archaeological contexts that span from the Terminal Pleistocene to the Mongolian Expansions. We have already collected sediment samples from more than 200 archaeological contexts across 13 sites, representing more than 3,000 liters of sediment, and almost a quarter of a million individually identified archaeological remains of plant seeds and other floral parts. Collectively, this represents that largest single endeavor to clarify the spread of crops across the ancient world ever undertaken in Central Asia.
While archaeobotany provides the central dataset in this study, we are careful not to neglect other complementary lines of data and historians that we are collaborating with have linked the plants we are finding in these archaeological sites to Sogdian, Turkic, Arabic, Chinese, and Classical texts. Likewise, artistic depictions of plants in wall paintings at sites, such as Panjikent, and on ceramic vessels are key to understanding the timing and spread of certain crops, notably melons, pomegranates, and grapes. The words used to name plants also provide important clues towards understanding their origins, and linguists are assisting us in fitting these data into the broader interpretations. Additionally, we have collaborations with an ancient genomics specialists and a postdoc on the project, who will help process these data. Given that it would be unfeasible to run ancient genomics samples for all of the crops that we are working with on this study, we are focusing on the large-fruiting members of the Prunus genus – plums, peaches, and apricots. We are focusing on this economically significant group because their origins and processes of dispersal remain poorly understood, but also because they are far more likely to preserve in a desiccated state in archaeological sites, leaving viable genetic material. This project represents a collaborative international endeavor, spanning halves of two continents and top research experts from around the globe.
While archaeobotany provides the central dataset in this study, we are careful not to neglect other complementary lines of data and historians that we are collaborating with have linked the plants we are finding in these archaeological sites to Sogdian, Turkic, Arabic, Chinese, and Classical texts. Likewise, artistic depictions of plants in wall paintings at sites, such as Panjikent, and on ceramic vessels are key to understanding the timing and spread of certain crops, notably melons, pomegranates, and grapes. The words used to name plants also provide important clues towards understanding their origins, and linguists are assisting us in fitting these data into the broader interpretations. Additionally, we have collaborations with an ancient genomics specialists and a postdoc on the project, who will help process these data. Given that it would be unfeasible to run ancient genomics samples for all of the crops that we are working with on this study, we are focusing on the large-fruiting members of the Prunus genus – plums, peaches, and apricots. We are focusing on this economically significant group because their origins and processes of dispersal remain poorly understood, but also because they are far more likely to preserve in a desiccated state in archaeological sites, leaving viable genetic material. This project represents a collaborative international endeavor, spanning halves of two continents and top research experts from around the globe.
Given the dearth of archaeobotanical data from across most of Central Asia before this project, the large-scale investment in this method that the FEDD project represents has already produced important results. We have pushed back the earliest known dates in this part of the world for a number of crops, including rice, cotton, apricots, plums, broomcorn millet, melons, watermelons, and almonds. Some of these crops represent long-distance movements of plants millennia ago. Notably, the identification of watermelon seeds at medieval sites in Central Asia represents the first evidence for an African domesticated crop this far north. We have also published detailed studies of the ancient dispersal and mapped out routes for spread for rice, cotton, apples, and pistachios. These studies remain the most up-to-date multidisciplinary studies of each of these economically important crops, allowing agronomists to better understand their processes of domestication and the origin regions where, in most cases, the greatest genetic diversity resides today. Arguably even more interestingly, we have further explored Central Asia as a center of crop domestication, a topic that had almost completely been ignored previously. There are several important long-generation-perennial crops that were first brought under cultivation and evolved domestication traits in Central Asia, these include apples and pistachios, which the FEDD team has already published detailed studies on, as well as Russian olives and part of the domestication process for walnuts, which we intend to study in more detail over the next few years. While data are limited, it is likely that both species of quince, medlar, and part of the process for one of the plum and one of the pear lineages originated in Central Asia as well.
Given the complexities of the domestication process for plums, and the number of continual hybridization events that clearly led to the modern plum, there is only so much that can be done in studying domestication in this group from an archaeobotanical perspective. The FEDD team is using multivariate statistics and geometric morphometric analyses to better parse out morphological differences between populations of ancient plums, as recovered from archaeological sites across Europe and West Asia. However, even with these advanced methods, the continual hybridization of populations lead to a melding of measurable traits. Therefore, members of the FEDD team have been collecting desiccated and waterlogged plum pits to use for an ancient genomics analysis. The resulting data will fit into an existing database on modern population genetics in Prunus, as assembled through herbarium and germplasm facilities. Ultimately, we expect these results to further clarify the domestication and dispersal process for this important set of tree crops.
Given the complexities of the domestication process for plums, and the number of continual hybridization events that clearly led to the modern plum, there is only so much that can be done in studying domestication in this group from an archaeobotanical perspective. The FEDD team is using multivariate statistics and geometric morphometric analyses to better parse out morphological differences between populations of ancient plums, as recovered from archaeological sites across Europe and West Asia. However, even with these advanced methods, the continual hybridization of populations lead to a melding of measurable traits. Therefore, members of the FEDD team have been collecting desiccated and waterlogged plum pits to use for an ancient genomics analysis. The resulting data will fit into an existing database on modern population genetics in Prunus, as assembled through herbarium and germplasm facilities. Ultimately, we expect these results to further clarify the domestication and dispersal process for this important set of tree crops.