4 SCIENCE IN AFRICA 



THE CHANGING ENVIRONMENT 



As an aid to the appreciation of the interdependence of scientific 

 studies in Africa, some description may be given of the main 

 aspects of the African environment with the changes which they 

 are undergoing at the present time. 



Under natural conditions, the forms of plant and animal life 

 which survive in a particular regime represent a kind of 'balance 

 of nature' in which constructive and destructive factors are in 

 general equilibrium. The balance involves both the vitality of 

 organisms and their surroundings. Environmental changes can 

 be classed in the same categories as are used in the diagram on 

 page 2. In a mechanical sense the balance of nature is not a simple 

 balance, but a complex system of levers and links all balanced with 

 each other, so that extra weight placed on any part of the system 

 may cause the whole to change its equilibrium. First, the structure 

 of the surface and of the underlying rocks may be taken together. 

 These parts of the environment typically exhibit very slow change, 

 such as steady erosion, which carves out valleys, leaving mountains 

 between, the rending of the surface to produce rifts, and the build- 

 ing-up of volcanoes. Such changes have undoubtedly had great 

 effect on the evolution of early man, but they can be disregarded 

 when considering the present and the immediate future, except 

 in so far as the acceleration of erosive processes can, under certain 

 circumstances, lead to the direct loss of soil. 



Measurement of the surface configuration leads to the produc- 

 tion of accurate maps. At first sight this again cannot have much 

 effect on the African, but on it depend many of the developments 

 of civilization which are already causing most drastic changes to 

 his environment, for example, railways and roads. Furthermore, 

 the study of the physiography of rivers from precise levelling and 

 the measurement of their flow is leading to the development of 

 irrigation, and of all changes to the environment the irrigation 

 project, coupled with settlement schemes, calls upon the most 

 extreme adaptability of the African. Thus the Gezira irrigation 

 scheme in the Sudan has produced great changes in the social 

 structure of the agriculturalists involved. As another example, the 

 great irrigation projects of the French in the region of the Middle 



