Although the essential character of Africa's dependence on the world system changes very slowly, if at all, particular aspects of it are always in flux. For whilst dependence continues to generate underdevelopment, some growth has occurred in several countries at particular periods with important implications for certain classes. The incorporation of the continent into the world system is an ongoing process that reflects shifts in (i) the nature of the world system, and (ii) the nature of Africa's political economies. The sub-structure of the periphery – the capitalist and extractive modes and relations of production – evolves slowly, but the super-structure – the politics and ideology of the state – are considerably more volatile. Given the organic links between the sub- and super-structure, the instability of the latter affects the continuity of the former.