Scientists have found that the first farmers on Earth used fertilizers, irrigation systems and other crop management methods to grow peas and wheat, which disproves the notion of primitive agriculture, according to an article published in the journal Nature Plants.
“The emergence of the first cities is considered a turning point in human history, and almost all research in this area focuses on the political, social and economic changes associated with them. Using isotopes, we tried to figure out how this agrarian economy worked and how it supported the growth of new cities in Mesopotamia,”write Amy Bogaard of the University of Oxford (UK) and her colleagues.
Intensity and extensiveness
The first farmers and the beginnings of civilization, as anthropologists and archaeologists today believe, appeared about 11-10 thousand years ago on the territory of the so-called "fertile crescent" - a narrow strip of land in the Middle East, where the wild ancestors of modern cultivated cereals grew.
Traditionally, it was believed that agriculture developed in a very progressive way - at first, the ancient people simply collected the seeds of wild plants and did not grow them, and then cultivated them practically in the wild. Complex agricultural practices such as irrigation, the use of fertilizers and rotation of fields, as historians believed, appeared much later, during the times of Ancient Egypt, the powers of Mesopotamia and the Roman Empire.
On the other hand, recent genetic studies of ancient samples of barley and other agricultural crops show that they acquired their current appearance a very long time ago, about 6-7 thousand years ago, which contradicts theories about the slow development of agriculture. Bogaard and her colleagues have discovered another argument against this idea, finding an unusual way to "extract" important information about how ancient people grew their food supplies.
As the scientists noted, the proportions of the two isotopes of the "elements of life" - carbon-13 and nitrogen-15 - will differ markedly in plants that grow on their own and in crops that people constantly care for.
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Differences in the concentration of the first isotope will be associated with the fact that its share will be higher in the stems and seeds of those plants that are constantly watered and do not experience a lack of moisture that prevents them from absorbing CO2, including molecules with "heavy" carbon atoms. Similarly, the proportion of nitrogen-15 in plant tissues will be unusually high if fertilized with manure, where there is much more heavy nitrogen than in the soil.
Secrets of Mesopotamia
Focusing on both of these patterns, scientists analyzed the isotopic composition of wheat grains, its stalks and pea straw found at different sites of ancient people in northern Syria and southern Turkey, as well as in Israel, where people lived 8500-4000 thousand years ago.
Much to the surprise of scientists, ancient farmers began to use fertilizers and irrigation systems almost immediately after the invention of agriculture, about 8-6.5 thousand years ago. Interestingly, the inhabitants of Mesopotamia, apparently well understood which crops loved water more and which needed it less, and planted wheat and peas in the “wettest” or most irrigated fields, and barley in drier areas of the soil.
In turn, the remains of the people themselves who lived in these regions of Mesopotamia indicate that agriculture played an important role in their life after the transition to a sedentary life. Carbon-13 levels in their bones gradually increased and nitrogen-15 levels decreased, suggesting their gradual transition from a meat-based diet to a plant-based diet.
All this, according to the researchers, suggests that agriculture began to develop very early, in fact, immediately after its inception, and that ancient people used almost all of the same agricultural practices that are used by farmers today. The transition to extensive agriculture in later eras, according to scientists, was associated with the emergence of property stratification and land ownership.
This casts doubt on the "demographic" theories of the development of civilization, postulating that humanity began to use fertilizers and other agricultural innovations only when high population growth required the invention of more effective farming practices, the authors conclude.