By Fekri Hassan, Institute of Archaeology, University College London
I saw at one time
a leaflet that asked people to come together in stopping climate change. It seems that many are not aware that the climate changes all the time and that the change is not stoppable. Climate changes, however, differ in their timing and magnitude and are a result of many factors, such as the distance between the sun and the equator, which contributes to the heat budget of the Earth, and the difference in the temperature of the equator from that of the cooler poles due to deviations in Earth’s orbit, or variations in solar radiation.
The differences in temperature lead to air currents which in turn influence rainfall. On the scale of tens of thousands of years, the Earth experienced numerous episodes of glacial cooling, alternating with warmer intervals. Following the last major glaciation which began 110,000 years ago, a transition to warmer conditions from 16,000 to 11,500 years ago was characterized by frequent climatic oscillations. Bands of foragers in climatically sensitive habitats, such as semi-desert regions in Southwest Asia, North Africa and China responded with a variety of social and food-extractive technologies. These included intensive utilization of wild grasses and managing animal games, the manufacture and use of grinding stones, trapping, the use of bows and arrows, as well as food preservation. While some continued to elaborate their hunting gear, others settled down to maximize the gain from wild grain resources. The most successful groups lived in the Eastern Mediterranean where wild wheat and barley were abundant.
The Invention of Agriculture
From 11,600 to 8,200 years ago, the climate became warmer and in the Eastern Mediterranean, wetter. It was during this period that successive generations of foragers, who took advantage of the well-watered habitats, adopted farming as their dominant mode of obtaining food. This marked the most remarkable revolutionary achievement of humankind—the invention of agriculture.
Life has never been the same since. Villages coalesced to form corporate village communities governed by councils or chiefs. Afterwards, conglomerates of farming communities merged into kingdoms, while those who managed cattle, sheep and goats became herders and roamed the rain-fed grasslands outside the river valleys preferred by farmers.
The effect of climate change on humanity under this new agrarian regime with its politically more complex organization assumed a new turn. This has been mostly due, in part, to the nature of the agrarian ecology and economic growth potential. Agricultural yields fluctuated annually, in part because of interannual variability in rainfall, but more importantly, they also varied responding to decadal and centennial changes in climatic conditions, which influenced both the flow of rivers and rainfall in the grasslands. These problems were tackled by digging irrigation canals to parched lands, drains to dispose of excess water and building dykes to protect fields and settlements from the ravages of floods.
Great Civilizations
As agrarian communities expanded, they developed into complex political States with a hierarchical management. State officials, clerks, and priests who deployed rituals and myths to promote and buttress the policies of the State led to an increase in the demand for greater food production. These demands were met by extracting tributes from the farmers who had to work harder and expand their fields to meet the growing demands of the State functionaries.
By the 5000 B.C. the early agrarian States had developed into the world’s first great civilizations in Egypt, Mesopotamia, and India. But by around 4200 B.C., an abrupt turn of climate led to dramatic changes all over the world. On the banks of the Nile, the Egyptians had established a centralized State. Successive dynasties constructed imposing pyramids for four hundred years from 4600 to 4200 B.C., before a sudden, unanticipated series of reduced Nile flood discharge spelled disaster. The government collapsed. Famines ravaged the rural population, violence erupted and the whole country slipped into a state of chaos.
