Excerpts from "The Emergence of a Food-Producing Economy in the Sahara" by A. Muzzolini from The Archaeology of Africa edited by Thurston Shaw, Paul Sinclair, Bassey Andah and Alex Okpoko (Link)
"In the arid zone, the semi-sedentism resulting from periodic return to the same water sources cannot be considered as a 'revolutionary' innovation - it is a necessity, common to all periods; however, building with durable materials around water sources shows a greater degree of sedentism. This condition is evident in the Egyptian Western Desert, not only in seasonal encampments of the eighth millennium BC (the El-Adam facies around 9500 bp) but also during the seventh, in which the first traces of stone-built houses and of underground granaries are found (starting with the remains of El-Kortein c. 8750 bp and El-Ghorab c. 8450 bp). At Nabta Playa, from c. 8000 bp onwards, encampments appear to be in almost continuous occupation, and fourteen circular houses are arranged in two rows to make a 'street'. At El-Ghorab pits or houses are laid out along the arc of a circle. Associated with these houses are various underground storage chambers and wells, some of which have sunken access ramps (Wendorf, Schild & Close 1984, pp. 1, 414, 415; Wendorf, Close & Schild 1985)."
"These first developments show that in Africa, as elsewhere, human groups were becoming larger, and that henceforth they concentrated their dwellings, if not their activities, within relatively small 'territories'. This major turning point sowed the seeds from which neolithic and later societies grew. Sedentism and demographic increase, at one and the same time, make possible and necessitate division of labour, storage of food and more complex organization of social relations within the group and between groups."
Wendorf, F., R. Schild & A. E. Close (eds) 1984. In Cattle-keepers of the Eastern Sahara: the Neolithic of Bir Kiseiba. Dallas: Southern Methodist University Press.
Wendorf, F., A. E. Close, R. Schild 1985. Prehistoric settlements in the Nubian desert. American Scientist 173, 132-41.