Neolithic Subpluvial

The Neolithic Subpluvial, sometimes called the Holocene Wet Phase, was an extended period (from about 7,000 BC to about 3,000 BC) of wet and rainy conditions in the climate history of northern Africa. It was both preceded and followed by much drier periods. The Neolithic Subpluvial was the most recent of a number of periods of "Wet Sahara" or "Green Sahara" during which the region was much moister and supported a richer biota and human population than the present-day desert.

Date ranges

The Neolithic Subpluvial began during the 7th millennium BCE and was strong for about 2000 years; it waned over time and ended in the 4th millennium BCE. Then the drier conditions that prevailed prior to the Neolithic Subpluvial returned; desertification advanced, and the Sahara desert formed (or re-formed). Arid conditions continued through to the present day.

Geography and hydrography

During the Neolithic Subpluvial, large areas of North, Central, and East Africa had hydrographic profiles significantly different from later norms. Existing lakes had surfaces tens of meters higher than today, sometimes with alternative drainages: Lake Turkana, in present-day Kenya, drained into the Nile River basin. Lake Chad reached a maximum extent of some 400,000 square kilometers in surface area, larger than the modern Caspian Sea, with a surface level about 30 meters (100 feet) higher than its twentieth-century average. Some shallower lakes and river systems existed in the subpluvial era that later disappeared entirely, and are detectable today only via radar and satellite imagery.

Ecology

North Africa enjoyed a fertile climate during the subpluvial era; what is now the Sahara supported a savanna type of ecosystem, with elephant, giraffe, and other grassland and woodland animals now typical of the Sahel region south of the desert. Historian and Africanist Roland Oliver has described the scene as follows:

[In] the highlands of the central Sahara beyond the Libyan desert,... in the great massifs of the Tibesti and the Hoggar, the mountaintops, today bare rock, were covered at this period with forests of oak and walnut, lime, alder and elm. The lower slopes, together with those of the supporting bastions — the Tassili and the Acacus to the north, Ennedi and Air to the south — carried olive, juniper and Aleppo pine. In the valleys, perennially flowing rivers teamed with fish and were bordered by seed-bearing grasslands.

Cultures

Main article: Prehistoric Central North Africa

Clement and fertile conditions during the Neolithic Subpluvial supported increased human settlement of the Nile Valley in Egypt, as well as neolithic societies in Sudan and throughout the present-day Sahara. Cultures producing rock art (notably that at Tassili n'Ajjer in southeastern Algeria) flourished during this period.

The practical consequences of these changes took the form of increased abundance of fish, waterfowl, freshwater mollusks, rodents, hippos and crocodiles. The riches of this increased aquatic biomass were exploited by humans with rafts, boats, weirs, traps, harpoons, nets, hooks, lines and sinkers. This "riparian" (river) way of life supported much larger communities than could that of typical hunting bands. These changes, along with the local development of pottery (whereby liquids could be both stored and heated) resulted in a "culinary revolution" consisting of soup, fish stew and porridge. The last mentioned implies the cooking of gathered cereals.

The classic account of the riparian lifestyle of this period comes from investigations in Sudan during World War II by British archeologist Anthony Arkell. Arkell's report described a Late Stone Age settlement on a sandbank of the Blue Nile which was then about 12 feet higher than its present flood stage. The countryside was clearly savanna, not the present-day desert, as evidenced by the bones of the most common species found in the middens — antelope, which require large expanses of seed-bearing grasses. These people probably lived mainly on fish, however, and Arkell concluded, based on the totality of the evidence, that rainfall at the time was at least three times that of today. The physical characteristics derived from skeletal remains suggested that these people were related to modern Nilotic peoples, such as the Nuer and Dinka. Subsequent radiocarbon dating firmly established Arkell's site to between 7,000 BC and 5,000 BC. Based on common patterns at his site and at French-excavated sites already reported from Chad, Mali and Niger (e.g., bone harpoons and a characteristic "wavy line" pottery), Arkell inferred "a common fishing and hunting culture spread by negroid people right across Africa at about the latitude of Khartoum at a time when the climate was so different that it was not desert.

In the 1960s, the archeologist Gabriel Camps investigated the remains of a hunting and fishing community dating from about 6,700 BC in southern Algeria. These pottery-making people (the "wavy line" motif again) were definitely black African rather than Mediterranean in origin and (according to Camps) evidenced definite signs of deliberate cultivation of grain crops as opposed to simply the gathering of wild grains.

Human remains were found by archeologists in 2000 at a site known as Gobero in the Ténéré Desert of northeastern Niger. The Gobero finds represent a uniquely preserved record of human habitation and burials from what is now called the Kiffian (7,700 to 6,200 B.C.) and the Tenerian (5,200 to 2,500 B.C.) cultures.

See also

• Pluvial
• Sahara pump theory
• Abbassia Pluvial
• Mousterian Pluvial
• Older Peron
• Piora Oscillation

References

Citations

Other sources

• Burroughs, William J., ed. Climate: Into the 21st Century. Cambridge, Cambridge University Press, 2003.
• Howell, Francis Clark, and François Bourlière. African Ecology and Human Evolution. London, Routledge, 2004 (reprint of the 1964 edition).

External links

• The green Sahara.