Wright thinks this is exactly what happened. He suggests this may have triggered the end of the humid period more abruptly than can be explained by the orbital changes. These nomadic humans also may have used fire as a land management tool, which would have exacerbated the speed at which the desert took hold. Instead, the culprits might be regular old vegetation feedbacks and changes in the amount of dust.
And then at some point you pass the tipping point where change accelerates. During the last humid period, the Sahara was filled with hunter-gatherers.
As the orbit slowly changed and less rain fell, humans would have needed to domesticate animals, like cattle and goats , for sustenance. If you have not traveled in the Sahara and you are not familiar with the local conventions and standards, you should consult a travel agent, who should provide the information you will need for a rewarding trip.
Saharan woman, traditionally dressed, at communal well. Location Landscape Water Climate. How to Keep Ice Cold in the Desert.
Desert Survival Skills. Get the Best Hotel and Motel Rates. DesertUSA Newsletter -- We send articles on hiking, camping and places to explore, as well as animals, wildflower reports, plant information and much more. Sign up below or read more about the DesertUSA newsletter here. It's Free. Enter E-Mail address:. Enter Email:. But the primary difference between pre-Neolithic and post-Neolithic burning is that the ecology of fear was altered.
Most grazing animals will avoid landscapes that have been burned , not only because the food resources there are relatively low, but also because of exposure to predators.
Scorched landscapes present high risks and low rewards. But with humans guiding them, domesticated animals are not subject to the same dynamics between predator and prey. They can be led into recently burned areas where the grasses will be preferentially selected to eat and the shrubs will be left alone. Over the succeeding period of landscape regeneration, the less palatable scrubland will grow faster than succulent grasslands — and, thus, the landscape has crossed a threshold.
It can be argued that early Saharan pastoralists changed the ecology of fear in the area, which in turn enhanced scrubland at the expense of grasslands in some places, which in turn enhanced albedo and dust production and accelerated the termination of the African Humid Period.
I tested this hypothesis by correlating the occurrences and effects of early livestock introduction across the region, but more detailed paleoecological research is needed. If proven, the theory would explain the patchy nature of the transition from wet to dry conditions across northern Africa.
Although more work remains, the potential of humans to profoundly alter ecosystems should send a powerful message to modern societies.
The end of the African Humid Period is a lesson for modern societies living on drylands: if you strip the vegetation, you alter the land-atmosphere dynamics, and rainfall is likely to diminish. This is precisely what the historic records of rainfall and vegetation in the south-western desert of the United States demonstrates , though the precise causes remain speculative.
In the meantime, we must balance economic development against environmental stewardship. Camels were domesticated about 3, years ago on the Southeast Arabian Peninsula, to be used for transportation in the desert, according to the University of Veterinary Medicine, Vienna.
Camels, also known as the "ships of the desert," are well-adapted for the hot, arid environment, according to the San Diego Zoo. The humps on a camel's back store fat, which can be used for energy and hydration in between meals. Camels store energy so efficiently that they can go more than a week without water and several months without food.
Other residents of the Sahara include a variety of gazelles , addax a type of antelope , cheetahs , caracals, desert foxes and wild dogs, according to the Sahara Conservation Fund.
Many reptile species also thrive in the desert environment, including several species of snakes , lizards , and even crocodiles in places where there is enough water. Several species of arthropods also call the Sahara home, such as the dung beetle, scarab beetle, " deathstalker " scorpions and many types of ants.
Plant species in the Sahara have adapted to the arid conditions, with roots that reach deep underground to find buried water sources and leaves that are shaped into spines that minimize moisture loss. The most arid parts of the desert are completely void of plant life, but oasis areas, such as the Nile Valley, support a large variety of plants, including olive trees, date palms and various shrubs and grasses.
The Sahara alternates from being a dry, inhospitable desert and a lush, green oasis about every 20, years, according to a study published in the journal Science Advances in The study's authors examined marine sediments containing dust deposits from the Sahara from the past , years.
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