ORIGINES DE L'AGRICULTURE
Début de la période holocène 10000 pb. Fusion plus chaude et glaciale avec élévation du niveau de la mer, plus humide avec plus de pluie. Plus de végétation, moins de déserts. Mais pas la même chose partout. Peut-être juste un autre interglaciaire, mais maintenant nous avons une intervention humaine. Effet de serre? La culture dépend de la géologie et de l'évolution physique.
Le mésolithique (européen) et l'archaïque (américains) ont accru l'exploitation de l'environnement et la poursuite des activités de subsistance.
Neolithic- beginning of agriculture 10000bp. Implicit is domestication of plants and animals. Change, via ARTIFICIAL selection, from wild forms to a more useful form, such as wolf to dog, grasses to wheat, etc. In domestication of animals, such as dogs and cattle, more successful if there is a strong dominance hierarchy in the herd. Then humans can become the most dominant and the other animals fall in line. As in artificial selective evolution of wolf to dog. The animals to be domesticated are selectively bred in captivity and thus modified from their wild ancestors. Dog wolf, cattle, auroch, pig wild boar, etc.
First, movements of animals were controlled, then selective breeding and regulation os sex ration and age structure. This changed the gene frequency and anatomical changes resulted. Apparently there were societal shifts back and forth between hunting and pastoralism befor actual herd management occurred. By about 10000 bp goats were being domesticated in the Zagros Mountains.
Why did agriculture originate? 2 groups of theories, environmental and demographic.
Environmental determinism- explanation of cultural behavior that see human action in response to environmental circumstances. Modern differences between societies may be explained because of differences between environments, not because of biological differences between people themselves. People became sedentary because that’s where the food was. "Oasis" theory of V Gordon Childe.
End of Pleistocene 10000BP. Glaciers retreat, warmer, and wetter; food sources changed and people followed the food. With more desertification in a colder, drier periods about 1000 years later, smaller areas, "oases", could support populations as the range of seed crops and animals was reduced. These resources were then so changed by human alteration that they became domesticated and could not survive as untended crops and livestock.
But recent work shows that there may not have been as much of a climate shift as previously thought.
Demographic, or cultural and historical reasons for domestication and agriculture.
1. Population pressure theories. Boserup 1965. Population at end of Pleistocene increased rapidly and people reached the carrying capacity (CC) of the environment, Carrying capacity is the number of people or organisms that a given environment can support. Agriculture was therefore developed. Hunter gatherers (HG) became more sedentary before agri, then with agri they had enough resources so they didn’t have to keep moving.
2. Marginal habitat hypothesis. Binford- Marginal zones. Agriculture in areas in which the CC was reached due to pop pressure. Then pop split and some went where CC not yet reached. Thus, when CC reached it was in the area that previously had the MOST, not the least, resources (opposite to Childe). The new migrants were forced to be nomads or pastoralists. CC being reached caused migration and people took plants and animals with them. In the new areas the stock could only survive with domestication.
In either case pop pressure and environmental pressure are related. In the Near East humans occupied every ecological niche by 10000bp, and population was in equilibrium, so people then had to move to marginal zones if the population was to expand.
3. Readiness hypothesis. Domestication for cultural reasons. There were no specific environmental reasons for it. Braidwoods excavated in the Zagros Mts in Iran and Iraq. Jarmo. They thought that first agri was in areas where plants and animals abundant, also against Childe.. No major stress environmentally, but good environmental conditions led to agriculture as experience of people with the semidomesticates increased. "Hilly flanks" Theory. Culture and history emphasized, domestication occurred because people could do it. There was new knowledge and specialization in subsistence. People became sedentary in places where wild plants and animals amenable to domestication were found. As more knowledge of the animals and plants was obtained, people used this knowledge.
Talk of "Agricultural Revolution," but really a slow process that didn’t happen all at once. Agriculture did not lead to settled towns, because there were settlements before full scale agriculture, and food production and HG were alternate strategies in the same groups. Some sort of cultural revolution before the agricultural one. Still much HG after cereal seeds were used in the Levant at 17000 bp and earliest cultivation at 13000 bp.
"Noah's flood" postulated that at 7500 bp, Med flows into Black Sea, banks overflow. People leave and disseminate agricultural techniques to Europe and Fertile Crescent. Possibly left in myth and cultural history as the Biblical flood.
Another debate is whether people actually moved from the Levant to Europe, or if the technology was spread without human migration. Recent work shows that there is a clinal distribution of a gene on the Y chromosome with only 2% in the Near East but 89% in the Basques and 98% in the West of Ireland, the last outposts of preNeolithic Europe. This implies that there was actually population movement.
Catal Huyuk, Turkey, 9000 bp. A town of 10000 people.. Not quite a city, no division of labor, occupied by farmers, decentralized. Individual residential structures with ovens, benches, storage areas. But had painted murals showing vultures attacking headless men, volcanoes, hunting. A rich symbolic life. Burials under the floors, like Jericho.
The consequence of the rise of agriculture was that more calories meant, ultimately, more people. Selecting the domesticates meant more complex society and a military advantage. So, agriculture not needed to feed more people because the rise of agriculture occurred before there were that many people.
To synthesize the above theories, probably what happened was that there was an ultimate shift to agriculture in these mixed economies.
Decrease wild food at the same time there was an increase in the domesticable wild plants. Extinction? Climate change worked in favor of artificial selection.
Development of technology to make production easier. Natufian suckles, baskets and underground pits for storage, mortars and pestles after 11000 BP.
As there were more agriculturalists, pure HGs became more geographically marginalized.
"Hearths of Domestication"
1. Near East- Fertile Crescent. In SW Asia by 10500 BP there was domestication of wheat, peas, olives,, goats, sheep. Natufian culture of northern Israel, Lebanon and Syria. Golan Heights. Not quite agricultural, but close. Agriculture ultimately developed from attempts to supplement food supply from semidomesticated plants. Had domesticated types of wheat (einkorn and emmer) and barley, sheep goats, later pigs, cattle and finally camels. Had stone mortars, microliths for grinding plant material. Had sickle blades with "Sickle sheen" from cutting grassy semidomesticated plants. Repeated cycles of harvesting and reseeding einkorn and emmer would have selected for mutations for more nutritious grains with less brittle rachis. Natufians were sedentary, but they didn’t have pottery. Jericho had Natufian and agricultural components, including a monumental stone tower and a well.
On other side of fertile crescent, Braidwoods in Iraq and Iran. Preserved pottery and architecture by 8000 BP. Several sites had evidence of emmer and einkorn. These grew wild at end of Pleistocene but were harvested and then selected. Spread across Fertile Crescent, so had agri from Jericho to Jarmo. Original grasses spread out of natural habitat as they became domesticated.
Most recent idea is bases on genetic studies of einkorn. Modern cultivated einkorn is genetically most similar to a distinct variety found in the Karacadag Mountains of SE Turkey, extrapolate back to 11000 bp on basis of DNA differences.
Diamond, "Guns, Germs and Steel" thinks that the rapid spread of agriculture in the Middle East has do with spread along an east-west axis, permitting crops, livestock and people to expand at the same latitude without having to adapt to changes in day length, seasonal variation and disease, as opposed to the Americas, in which agriculture had to spread along a north- south axis with geographic barriers such as mountains, rain forest. Germination time, growth and disease resistance are all related to this. Also, Fertile Crescent had mild wet winters and hot dry summers, along with abundant ancestor plants, especially cereal grains. Biological diversity enables both large mammals and plants to be domesticated.
2. Mexico and SW US. Tehuacan Valley of Central Mexico. Primitive maize at 5600 BP. Also beans, squash, turkeys. Continuous inhabitation 10000 BC to 1500AD. Can follow origins of agriculture. At first, hunter, but by 8700 BP coprolite (Fossilized feces) show undigested beans, avocado, squash differentiated from similar wild plants. Implication- domestication.
Original maize was probably a wild grass that still exists- teosinte. Used as a food source. Seeds fall easily and are dispersed widely because rachis is so brittle. Useful to propagate a wild plant. However, people selected teosinte that had less brittle rachis and naked, larger kernels. Evolved to corn. Keep in mind that the seed size and rachis are mutations, the distribution of which were now controlled by artifical selection. More useful as a domesticated food source.
By 3000 bp, large terraced villages in which the terraces were used as agricultural plots in the SW, Cerro Juanaquena, Northern Mexico.
In SW US maize, squash and beans domesticated by 3000 BP , probably by cultural diffusion from Mexico. Other evidence of diffusion includes ball courts like those of the Maya. Central American macaws at Wupatki.
Hohokam- desert irrigators near Phoenix.
Anasazi pueblos and cliff dwellings at 4 corners.
Chaco Canyon, market and religious center, had radiating roads over 300 sq miles. Dispersed by a.d. 1300. Massive pueblos with hundreds of rooms. Probably began about a.d. 850 as an economic center for food redistribution, followed by political and religious significance. Severe drought 12thcentury.
People of the Mogollon rim. Sinagua.
3. Polynesia. Migrated West to East, on basis of linguistic evidence. Similar peoples may have developed differently because of environment. Chatham Islands were too cold for tropical agriculture, and people were H-Gs. On Tonga and Hawaii there was fertile volcanic soil for agriculture, so social differentiation, political organization and warfare developed because of an excess food supply. Geographical differences may have differentiated societies that had a common starting point.
Problems with agriculture:
1. Plants selected for nutritional return, so big seed and less genetic variation. More prone to failure from disease and climate change such as drought.
2. More work for agriculturalists than HGs. Must prepare land, gather and harvest.
3. Plants in diet reduces variety of nutrients, so more disease. Also more infectious disease as people move permanently closer together in sedentary villages.
- Environmental degradation such as deforestation at Pueblo Bonito, for building material and fuel.
- Changes in culture caused by agriculture. People crowded closer together in villages, infectious disease such as tuberculosis
Evidence? Paleopathology, including porotic hyperostosis, enamel hypoplasia, growth resumption lines.
Now we have CULTURE as prime factor in the relation between people and the environment. Artificial rather than natural selection. Need rules of behavior in living together and in organizing defense, irrigation etc. This will lead to the rise of complex civilization.
L'agriculture est importante car la production alimentaire est essentielle pour créer des excédents pouvant nourrir des spécialistes non producteurs de denrées alimentaires et créer une base de population plus vaste et plus dense. Les moyens de transport de cet aliment impliquent la nécessité d’animaux domestiques. Tout cela est une condition préalable pour que les civilisations vraies, socialement stratifiées et économiquement complexes, suivent. Parallèlement à l'agriculture, la technologie nécessaire à l'innovation et l'écriture nécessaire à la conservation des documents sont développées. Donner à ces sociétés agricoles une longueur d'avance dans le développement d'une civilisation complexe.