"My training was basically as an ecologist—for is largely applied ecology—and, since serving in Ghana for 14 years in the 1930s and 1940s. I have been back 14 times to East, South and West Africa. Even when I started work, it was already clear that the arid land such as the could not be safely occupied other than by s, who with their flocks and herds of grazers and browsers can use small patches of mixed vegetation scattered over a wide area, seldom causing anything more than limited short-term degradation, for the nomads had worked out a '."