The Sahara Pump Theory is one which is used to explain the various phases by which African flora and African fauna have left that continent to penetrate the Middle East and possibly, thereafter, the rest of the world. African pluvial^[1] periods are associated with a "wet Sahara" phase, in which large lakes and many rivers are found. Image File history File links Size of this preview: 280 × 187 pixelsFull resolution (280 × 187 pixel, file size: 15 KB, MIME type: image/jpeg) Copied by self author I, the creator of this work, hereby release it into the public domain. ... A floristic province is a geographic area with a relatively uniform composition of plant species. ... In Ecology, a biome is a major regional group of distinctive plant and animal communities well adapted to the regions physical environment. ... A map showing countries commonly considered to be part of the Middle East The Middle East is a region comprising the lands around the southern and eastern parts of the Mediterranean Sea, a territory that extends from the eastern Mediterranean Sea to the Persian Gulf. ... A pluvial lake is a lake which experiences significant increase in depth and extent as a result of increased precipitation and reduced evaporation. ...

One example of the Saharan pump has occurred since the Last Glacial Maximum (LGM). During the Last Glacial Maximum, the Sahara desert was, if anything, more extensive than it is now, as tropical forests were of reduced extent. During this period, the lower temperatures reduced the strength of the Hadley Cell where rising tropical air of the Inter-Tropical Convergence Zone (ITCZ) brings rain to the tropics, while dry descending air, at about 20 degrees north, flows back to the equator and brings desert conditions to this region. This phase is associated with high rates of wind-blown mineral dust, found in marine cores that come from the north tropical Atlantic. Around 12,500 BCE, the amount of dust in the cores in the Bølling/Allerød phase suddenly plummets and shows a period of much wetter conditions in the Sahara, indicating a Dansgaard-Oeschger (DO) event (a sudden warming followed by a slower cooling of the climate). The moister Saharan conditions had begun about 12,500 BCE, with the extension of the ITCZ northward in the northern hemisphere summer, bringing moist wet conditions and a savannah climate to the Sahara, which (apart from a short dry spell associated with the Younger Dryas) peaked during the Holocene thermal maximum climatic phase at 4000 BCE when mid-latitude temperatures seem to have been between 2 and 3 degrees warmer than in the recent past. Analysis of Nile River deposited sediments in the delta also shows this period had a higher proportion of sediments coming from the Blue Nile, suggesting higher rainfall also in the Ethiopian Highlands. This was caused principally by a stronger monsoonal circulation throughout the sub-tropical regions, affecting India, Arabia and the Sahara. The sudden subsequent movement of the ITCZ southwards with a Heinrich event (a sudden cooling followed by a slower warming), linked to changes with the El Niño-Southern Oscillation cycle, led to a rapid drying out of the Saharan and Arabian regions, which quickly became desert. This is linked to a marked decline in the scale of the Nile floods between 2700 and 2100 BCE. ^[2] Temperature proxies for the last 40,000 years The Last Glacial Maximum refers to the time of maximum extent of the ice sheets during the last glaciation, approximately 21 thousand years ago. ... The Hadley cell is a circulation pattern that dominates the tropical atmosphere, with rising motion near the equator, poleward flow 10-15 kilometers above the surface, descending motion in the subtropics, and equatorward flow near the surface. ... The thunderstorms of the Intertropical Convergence Zone form a line across the eastern Pacific Ocean. ... Bølling can refer to: Bølling lake, Denmark - a shallow lake in central Jutland, after which the following are named: The Bølling Oscillation or Interstadial - a warm phase during the last phase of the Weichsel glaciation in Europe. ... Allerød is a municipality in eastern Denmark, on the island of Zealand. ... Temperature proxy from three ice cores for the last 140 kyr, showing D-O events in the NH but not the SH Dansgaard-Oeschger events are rapid climate fluctuations during and at the end of the last ice age. ... Three temperature records, the GRIP one clearly showing the Younger Dryas event at around 11 kyr BP The Younger Dryas stadial, named after the alpine / tundra wildflower Dryas octopetala, and also referred to as the Big Freeze [1], was a brief (approximately 1300 ± 70 years [1]) cold climate period following... The Holocene Climate Optimum was a warm period during roughly the interval 9,000 to 5,000 years B.P.. This event has also been known by many other names, including: Hypsithermal, Altithermal, Climatic Optimum, Holocene Optimum, Holocene Thermal Maximum, and Holocene Megathermal. ... There is also Nile, a death metal band from South Carolina, USA. The Nile in Egypt Length 6 695 km Elevation of the source 1 134 m Average discharge 2 830 m³/s Area watershed 3 400 000 km² Origin Africa Mouth the Mediterranean Basin countries Uganda - Sudan - Egypt The... Ethiopian Highlands with Ras Dashan in the background. ... Monsoon in the Vindhya mountain range, central India A monsoon is a rainy season which lasts for several months and has lasting climatic effects. ... An indication of the timing of Heinrich events during the last glacial Heinrich events, named for paleoclimatologist Hartmut Heinrich, are abrupt episodes during the last glacial. ... El Niño-Southern Oscillation (ENSO) is a global coupled ocean-atmosphere phenomenon. ...

During these periods of a wet Sahara, the Sahara and Arabia become a savannah grassland and African flora and fauna become common. During the following inter-pluvial arid period, the Sahara reverts to desert conditions usually as a result of the retreat of the West African Monsoon southwards. Evaporation exceeds precipitation, the level of water in lakes like Lake Chad falls, and rivers become dry wadis. Flora and fauna previously widespread retreat northwards to the Atlas Mountains, southwards into West Africa, or eastwards into the Nile Valley and thence either south-east to the Ethiopian Highlands and Kenya or north-east across the Sinai into Asia. This separates populations of some of the species in areas with different climates, forcing them to adapt, possibly giving rise to allopatric speciation. Savannah may refer to: Four cities in the United States: Savannah, Georgia, a city known for its historic district Savannah River, which flows past the Georgia city Savannah River Site, a nuclear facility near Augusta, Georgia, upriver from Savannah Savannah, Missouri Savannah, New York Savannah, Tennessee sav is so awesome... Monsoon in the Vindhya mountain range, central India A monsoon is a heavy rainy season which lasts for several months and has lasting climatic effects. ... Lake Chad (in French: Lac Tchad) is a large, shallow lake in Africa. ... Wadi alMujib, Jordan A wadi (Arabic: ) is traditionally a valley. ... Map showing the location of the Atlas Mountains (colored red) across North Africa The Atlas Mountains (Arabic: ‎) are a mountain range in northwest Africa extending about 2,400 km (1,500 miles) through Morocco, Algeria, and Tunisia, and including The Rock of Gibraltar. ...  Western Africa (UN subregion)  Maghreb[1] West Africa or Western Africa is the westernmost region of the African continent. ... ... Ethiopian Highlands with Ras Dashan in the background. ... Sinai Peninsula, Gulf of Suez (west), Gulf of Aqaba (east) from Space Shuttle STS-40 The Sinai Peninsula (in Arabic, Shibh Jazirat Sina) is a triangle-shaped peninsula lying between the Mediterranean Sea (to the north) and Red Sea (to the south). ... World map showing the location of Asia. ... A biological adaptation is an anatomical structure, physiological process or behavioral trait of an organism that has evolved over a period of time by the process of natural selection such that it increases the expected long-term reproductive success of the organism. ... Allopatric speciation, also known as geographic speciation, occurs when populations physically isolated by an extrinsic barrier evolve intrinsic (genetic) reproductive isolation such that if the barrier between the populations breaks down, individuals of the two populations can no longer interbreed. ...

The Saharan pump has been used to date four waves of human emigration ^[3] from Africa, namely:

• Homo erectus (ssp. ergaster) into Southeast and East Asia
• Homo heidelbergensis into the Middle East and Western Europe
• Homo sapiens sapiens "Out of Africa theory"
• The spread of Afro-Asiatic languages.

Binomial name †Homo erectus (Dubois, 1892) Synonyms † Pithecanthropus erectus † Sinanthropus pekinensis † Javanthropus soloensis † Meganthropus paleojavanicus Homo erectus (Latin: upright man) is an extinct species of the genus Homo. ... Binomial name †Homo heidelbergensis Schoetensack, 1908 Homo heidelbergensis (Heidelberg Man) is an extinct species of the genus Homo and the direct ancestor of Homo neanderthalensis in Europe. ... Human beings are defined variously in biological, spiritual, and cultural terms, or in combinations thereof. ... Map showing the distribution of Afro-Asiatic languages The Afro-Asiatic languages are a language family of about 240 languages and 285 million people widespread throughout North Africa, East Africa, the Sahel, and Southwest Asia. ...

References

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