History and Origins of Wheat Domestication

History and Origins of Wheat Domestication Wheat is a grain crop with some 25,000 different cultivars in the world today. It was domesticated at least 12,000 years ago, created from a still-living ancestor plant known as emmer. Wild emmer (reported variously as T. araraticum, T. turgidum ssp. dicoccoides, or T. dicocoides), is a predominantly self-pollinating, winter annual grass of the Poaceae family and Triticeae tribe. It is distributed throughout the Near Eastern Fertile Crescent, including the modern countries of Israel, Jordan, Syria, Lebanon, eastern Turkey, western Iran, and northern Iraq. It grows in sporadic and semi-isolated patches and does best in regions with long, hot dry summers and short mild, wet winters with fluctuating rainfall. Emmer grows in diverse habitats from 100 m (330 ft) below sea level to 1700 m (5,500 ft) above, and can survive on between 200–1,300 mm (7.8–66 in) of annual precipitation. Wheat Varieties Most of the 25,000 different forms of modern wheat are varieties of two broad groups, called common wheat and durum wheat. Common or bread wheat Triticum aestivum accounts for some 95 percent of all the consumed wheat in the world today; the other five percent is made up of durum or hard wheat T. turgidum ssp. durum, used in pasta and semolina products. Bread and durum wheat are both domesticated forms of wild emmer wheat. Spelt (T. spelta) and Timopheevs wheat (T. timopheevii) were also developed from emmer wheats by the late Neolithic period, but neither has much of a market today. Another early form of wheat called einkorn (T. monococcum) was domesticated at about the same time but has limited distribution today. Origins of Wheat The origins of our modern wheat, according to genetics and archaeological studies, are found in the Karacadag mountain region of what is today southeastern Turkey- emmer and einkorn wheats are two of the classic eight founder crops of the origins of agriculture. The earliest known use of emmer was gathered from wild patches by the people who lived at the Ohalo II archaeological site in Israel, about 23,000 years ago. The earliest cultivated emmer has been found in the southern Levant (Netiv Hagdud, Tell Aswad, other Pre-Pottery Neolithic A sites); while einkorn is found in the northern Levant (Abu Hureyra, Mureybet, Jerf el Ahmar, Gà ¶bekli Tepe). Changes During Domestication The main differences between the wild forms and domesticated wheat are that domesticated forms have larger seeds with hulls and a non-shattering rachis. When wild wheat is ripe, the rachis- the stem that keeps the wheat shafts together- shatters so that the seeds can disperse themselves. Without hulls, they germinate rapidly. But that naturally useful brittleness doesnt suit humans, who prefer to harvest wheat from the plant rather than off the surrounding earth. One possible way that might have occurred is that farmers harvested wheat after it was ripe, but before it self-dispersed, thereby collecting only the wheat that was still attached to the plant. By planting those seeds the next season, the farmers were perpetuating plants that had later-breaking rachises. Other traits apparently selected for include spike size, growing season, plant height, and grain size. According to French botanist Agathe Roucou and colleagues, the domestication process also caused multiple changes in the plant that were generated indirectly. Compared to emmer wheat, modern wheat has shorter leaf longevity, and a higher net rate of photosynthesis, leaf production rate, and nitrogen content. Modern wheat cultivars also have a shallower root system, with a larger proportion of fine roots, investing biomass above rather than below ground. Ancient forms have built-in coordination between above and below ground functioning, but the human selection of other traits has forced the plant to reconfigure and build new networks. How Long Did Domestication Take? One of the ongoing arguments about wheat is the length of time it took for the domestication process to complete. Some scholars argue for a fairly rapid process, of a few centuries; while others argue that the process from cultivation to domestication took up to 5,000 years. The evidence is abundant that by about 10,400 years ago, domesticated wheat was in widespread use throughout the Levant region; but when that started is up for debate. The earliest evidence for both domesticated einkorn and emmer wheat found to date was at the Syrian site of Abu Hureyra, in occupation layers dated to the Late Epi-paleolithic period, the beginning of the Younger Dryas, ca 13,000–12,000 cal BP; some scholars have argued, however, that the evidence does not show deliberate cultivation at this time, although it does indicate a broadening of the diet base to include a reliance on wild grains including the wheat. Spread Around the Globe: Bouldnor Cliff The distribution of wheat outside of its place of origin is part of the process known as Neolithicization. The culture generally associated with the introduction of wheat and other crops from Asia to Europe is generally the Lindearbandkeramik (LBK) culture, which may have been made up of part immigrant farmers and part local hunter-gatherers adapting new technologies. LBK is typically dated in Europe between 5400–4900 BCE. However, recent DNA studies at Bouldnor Cliff peat bog off the northern coast of mainland England have identified ancient DNA from what was apparently domesticated wheat. Wheat seeds, fragments, and pollen were not found at Bouldnor Cliff, but the DNA sequences from the sediment match Near Eastern wheat, genetically different from LBK forms. Further tests at Bouldnor Cliff have identified a submerged Mesolithic site, 16 m (52 ft) below sea level. The sediments were laid down about 8,000 years ago, several centuries earlier than the European LBK sites. Scholars suggest that the wheat got to Britain by boat. Other scholars have questioned the date, and the aDNA identification, saying it was in too good a condition to be that old. But additional experiments run by British evolutionary geneticist Robin Allaby and preliminarily reported in Watson (2018) have shown that ancient DNA from undersea sediments is more pristine than that from other contexts.   Sources Avni, Raz, et al. Wild Emmer Genome Architecture and Diversity Elucidate Wheat Evolution and Domestication. Science, vol. 357, no. 6346, 2017, pp. 93–97. Print.International Wheat Genome Sequencing Consortium. A Chromosome-Based Draft Sequence of the Hexaploid Bread Wheat (Triticum Aestivum) Genome. Science, vol. 345, no. 6194, 2014. Print.Fuller, Dorian Q, and Leilani Lucas. Adapting Crops, Landscapes, and Food Choices: Patterns in the Dispersal of Domesticated Plants across Eurasia. Human Dispersal and Species Movement: From Prehistory to the Present. Eds. Boivin, Nicole, Rà ©my Crassard and Michael D. Petraglia. Cambridge: Cambridge University Press, 2017. 304–31. Print.Huang, Lin, et al. Evolution and Adaptation of Wild Emmer Wheat Populations to Biotic and Abiotic Stresses. Annual Review of Phytopathology, vol. 54, no. 1, 2016, pp. 279–301. Print.Kirleis, Wiebke, and Elske Fischer. Neolithic Cultivation of Tetraploid Free Threshing Wheat in Denmark and Nort hern Germany: Implications for Crop Diversity and Societal Dynamics of the Funnel Beaker Culture. Vegetation History and Archaeobotany, vol. 23, no.1, 2014, pp. 81–96. Print. Larson, Greger. How Wheat Came to Britain. Science, vol. 347, no.6225, 2015. Print.Marcussen, Thomas, et al. Ancient Hybridizations among the Ancestral Genomes of Bread Wheat. Science, vol. 345, no. 6194, 2014. Print.Martin, Lucie. Plant Economy and Territory Exploitation in the Alps During the Neolithic (5000–4200  cal Bc): First Results of Archaeobotanical Studies in the Valais (Switzerland). Vegetation History and Archaeobotany, vol. 24, no. 1, 2015, pp. 63–73. Print.Roucou, Agathe, et al. Shifts in Plant Functional Strategies over the Course of Wheat Domestication. Journal of Applied Ecology, vol. 55, no. 1, 2017, pp. 25–37. Print. Smith, Oliver, et al. Sedimentary DNA from a Submerged Site Reveals Wheat in the British Isles 8000 Years Ago. Science, vol. 347, no. 6225, 2015, pp. 998–1001. Print.Watson, Traci. Inner Workings: Fishing for Artifacts beneath the Waves. Proceedings of the National Academy of Sciences, vol. 115, no. 2, 2018, pp. 231-33. Pr int.

GED Overview - Prep, Online Help, Courses, Practice

GED Overview - Prep, Online Help, Courses, Practice Once youve decided to get your GED, it can be difficult to figure out how to prepare. Our poll shows that most people searching for GED info are either looking for classes and study programs, or are taking practice tests and looking for a testing center. It sounds easy, but it isnt always. State Requirements In the U.S., every state has its own GED or high school equivalency requirements that can be difficult to locate on the states government pages. Adult education is sometimes handled by the Department of Education, sometimes by the Department of Labor, and often by departments with names like Public Instruction or Workforce Education. Find your states requirements in GED/High School Equivalency Programs in the United States. Finding a Class or Program Now that you know whats required by your state, how do you go about finding a class, either online or on campus, or some other kind of study program? Many of the state sites offer learning programs, sometimes called Adult Basic Education, or ABE. If your state’s classes werent obvious on the GED/High School Equivalency page, search the site for ABE or adult education. State directories of schools offering adult education are often included on these pages. If your state GED/High School Equivalency or ABE websites dont provide a directory of classes, try finding a school near you on Americas Literacy Directory. This directory provides addresses, phone numbers, contacts, hours, maps, and other useful information. Contact the school that matches your needs and ask about GED/High School Equivalency prep courses. Theyll take it from there and help you achieve your goals. Online Classes If you cant find a convenient or appropriate school near you, what next? If you do well with self-study, an online course may work for you. Some, such as GED Board and gedforfree.com, are free. These sites offer free study guides and practice tests that are very comprehensive. Check out the math and English courses at GED Board: Free Math Videos and QuizzesFree Help with English Others, such as the GED Academy and GED Online, charge tuition. Do your homework and make sure you understand what youre buying. Remember that you cannot take the GED/High School Equivalency test online. This is very important. The new 2014 tests are computer-based, but not online. There is a difference. Do not let anyone charge you for taking the test online. The diploma they offer you is not valid. You must take your test at a certified testing center. These should be listed on your states adult education website. Study Guides There are many GED/High School Equivalency study guides available at national book stores and in your local libraries, and some of these are probably available at your local independent book store as well. Ask at the counter if youre not sure where to find them. You can also order them online. Compare prices and how each book is laid out. People learn in different ways. Choose the books that make you feel comfortable using them. This is your education. Adult Learning Principles Adults learn differently than children. Your study experience is going to be different from your memory of school as a child. Understanding adult learning principles will help you make the most of this new adventure you’re beginning. Introduction to Adult Learning and Continuing Education Practice Tests When youre ready to take the GED/High School Equivalency test, there are practice tests available to help you find out how ready you really are. Some are available in book form from the same companies that publish the study guides. You may have seen them when you shopped for guides. Others are available online. Following are just a few. Search for GED/High School Equivalency practice tests and choose a site that is easy for you to navigate. Some are free, and some have a small fee. Again, be sure you know what youre buying. Test Prep ReviewGED Practice.com from Steck-VaughnPeterson’s Registering for the Real Test If you need to, refer back to your state’s adult education website to locate the testing center closest to you. Tests are usually offered on certain days at specific times, and youll need to contact the center to register in advance. Effective January 1, 2014, states have three testing choices: GED Testing Service (partner in the past)HiSET Program, developed by ETS (Educational Testing Service)Test Assessing Secondary Completion (TASC, developed by McGraw Hill) Info about the 2014 GED Test from GED Testing Service is below. Watch for info about the other two tests coming soon. The GED Test from GED Testing Service The new 2014 computer-based GED test from GED Testing Service has four parts: Reasoning Through Language Arts (RLA) (150 minutes)Mathematical Reasoning (90 minutes)Science (90 minutes)Social Studies (90 minutes) Sample questions are available on the GED Testing Service site. The test is available in English and Spanish, and you can take each part up to three times in a one-year period. Calming Test Stress No matter how hard youve studied, tests can be stressful. There are lots of ways to manage your anxiety, assuming youre prepared, of course, which is the first way to reduce test stress. Resist the urge to cram right up to test time. Your brain will function more clearly if you: Arrive early and relaxedTrust yourselfTake your timeRead the instructions carefullyAnswer the questions you know easily first, and thenGo back and work on the harder ones Remember to breathe! Breathing deeply will keep you calm and relaxed. Relieve study stress with 10 Ways to Relax. Good Luck Getting your GED/High School Equivalency certificate will be one of the most satisfying accomplishments of your life. Good luck to you. Enjoy the process, and let us know in the Continuing Education forum how youre doing.