Saharan Climate and Human Migration Prehistoric North Africa

human habitation in north africa has been influenced climate of sahara, has undergone enormous variations between wet , dry on last few hundred thousand years. due 41000-year cycle in tilt of earth changes between 22° , 24.5°. @ present (2000 ad), in dry period, expected sahara become green again in 15000 years (17000 ad).

during last glacial period, sahara larger today, extending south beyond current boundaries. end of glacial period brought more rain sahara, 8000 bc 6000 bc, perhaps because of low pressure areas on collapsing ice sheets north. once ice sheets gone, northern sahara dried out. in southern sahara, drying trend counteracted monsoon, brought rain further north today. around 4200 bc, however, monsoon retreated south approximately today, leading gradual desertification of sahara. sahara dry 13,000 years ago.

these conditions responsible has been called sahara pump theory. during periods of wet or green sahara , sahara becomes savanna grassland , various flora , fauna become more common. following inter-pluvial arid periods, sahara area reverts desert conditions , flora , fauna forced retreat northwards atlas mountains, southwards west africa, or eastwards nile valley. separates populations of of species in areas different climates, forcing them adapt, possibly giving rise allopatric speciation.

in terms of human evolution, saharan pump has been used date 4 waves of human migration africa, namely:

homo erectus (ssp. ergaster) southeast , east asia
homo heidelbergensis middle east , western europe
homo sapiens sapiens out of africa theory
the spread of afro-asiatic languages (berber , egyptian north africa , semitic arabian peninsula , middle east).




^ kevin white; david j. mattingly (2006). ancient lakes of sahara . 94 (1). american scientist: 58–65. 
^ orbit: earth s extraordinary journey documentary
^ christopher ehret. civilizations of africa. university press of virginia, 2002.
^ fezzan project — palaeoclimate , environment. retrieved march 15, 2006. archived june 7, 2009, @ wayback machine.
^ sahara s abrupt desertification started changes in earth s orbit, accelerated atmospheric , vegetation feedbacks.
^ kröpelin, stefan; et al. (2008). climate-driven ecosystem succession in sahara: past 6000 years (pdf). science. 320 (5877): 765–768. doi:10.1126/science.1154913. pmid 18467583. 
^ stephen, stokes. chronology, adaptation , environment of middle palaeolithic in northern africa . human evolution, cambridge university.