Growing agricultural addiction had a severe effect on the region’s ecology. As more vegetation was removed by the introduction of livestock, it increased the albedo (the amount of sunlight that reflects off the earth’s surface) of the land, which in turn influenced atmospheric conditions sufficiently to reduce monsoon rainfall. The weakening monsoons caused further desertification and vegetation loss, promoting a feedback loop which eventually spread over the entirety of the modern Sahara. Central to this cycle was the role that fire played in creating the new ecological circumstance. Although there is evidence for the presence of fires throughout all of human history, wild animals will not go onto a newly burned landscape because they would be easy targets for predators. However, pastoralists direct and protect their animals onto the newly regenerating landscape, altering the “ecology of fear.” This encourages scrub growth at the expense of grasses.
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How will we get more accurate answers that enable us to draw a more complete picture?
“There were lakes everywhere in the Sahara at this time, and they will have the records of the changing vegetation. We need to drill down into these former lake beds to get the vegetation records, look at the archaeology, and see what people were doing there.”