Living Shores by George Branch ; Margo Branch

Author:George Branch ; Margo Branch
Language: eng
Format: epub
Publisher: Struik Nature
Published: 2018-02-02T00:00:00+00:00

South coast: our ancestral birthplace?

John Compton has proposed that modern humans originated in coastal areas, and favours the Cape south coast as the most likely locality. Today, this coast is a narrow plain, cut off from the northern interior by the rugged Cape Fold Mountains, from the western plain by a ridge of mountains extending to the sea at Cape Hangklip (Fig. 17.20), and from the east by dense forest and deep ravines such as the Storms River (Fig. 5.9). However, conditions have not always been like this. During ice ages, at intervals of about 100,000 years, sea levels dropped as much as 140m and the plain widened by 175km. Once sea levels fell 75m or more, the western and eastern barriers would have become open ‘gateways’.

In John’s view, this alternation of habitats between glacial and interglacial periods drove the evolution of modern humans. During warm period with high sea levels, the human population became isolated and crowded on a shrinking coastal plain with few large land animals for food. These hardships could have forced them to switch to seafood and develop cultural innovations, including rational thought. When sea levels dropped again, the previously trapped population could disperse through the opened gateways and expand into other parts of Africa, spreading its new culture and adaptations (Fig. 11.2).

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