Humans delayed by 500 years the appearance of the Sahara Desert

The study conducted by a team of geographers and archaeologists from UCL and King's College London, published in Nature Communicationssuggests that the first pastoralists in North Africa combined in-depth knowledge of the environment with newly domesticated species to cope with the long-term drought trend.

The first pastoralists in North Africa are thought to have developed complex methods for efficiently managing sparse vegetation and relatively dry, low fertility soils.

Dr. Chris Brierley (UCL Geography), lead author, said, "The potential for humans to have a stabilizing influence on the environment has important implications." We dispute the current narrative that past interactions man and the environment must always be excessive, exploitation and degradation.

"The fact that societies practicing" pastoralism "have persisted in this region for so long and have invested both economically and ideologically in the local landscape does not support the over-exploitation scenario. Increasing human population and sustainable pastoralism have not accelerated – and perhaps even delayed – the decline of the "Green Sahara."

About 8,000 years ago, the Sahara was not a desert, but a vibrant ecosystem that supported hunter-gatherers and fishermen. The "Green Sahara" – a familiar term from the humid African period – was the period during which North Africa became much wetter than today thanks to a series of monsoons.

As the Earth's orbit slowly changed, the rain began to decrease and vegetation began to die. About 5,500 years ago, the Sahara ecosystem is in permanent decline towards the desert that we know today.

Pastoralism (nomadic or semi-nomadic cattle herders) developed in the Sahara about 1000 years before this collapse. Previous studies have blamed the collapse of the "green Sahara" for these nomads who have often been marginalized in history, but these latest studies refute this myth.

The study uses a new climate-vegetation model to determine if the end of the African humid period has occurred earlier than expected. The model records variables such as vegetation and rainfall, as well as other processes such as the amount of energy coming from the sun and the amount of carbon dioxide in the atmosphere.

The model concluded that the "Green Sahara" should have collapsed earlier than expected. This suggests that pastoralists have lasted longer than expected and that the techniques they have used have helped them adapt to environmental changes.

Dr. Brierley added, "The places where pastoralists last longer are those where there are the most resources.This is a good adaptation to climate change underway at the time.We are now working on what we can learn from nomadic pastoralists, such as selective grazing strategies, applicable to sustainable adaptation to desertification that we expect from future climate change. "

Dr. Katie Manning (King's College London) concluded: "Despite the largely inhospitable conditions of the Sahara, it is not difficult to find evidence of human occupation over the past 11,000 years. Thousands of rock art sites illustrate a lush environment, The Hunting of Pets and Livestock The Spread of Domestic Animals Across the Sahara Has Occurred at an Increasingly Unstable Time, While These Populations pastoral prospered.

"It is likely that the early pastoralists used the strategies used by traditional pastoralists such as seasonal movements and selective grazing to maintain a deteriorating ecosystem."

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