The Great Rift Valley can be seen from space. It shears down the eastern shoulder of Africa, a vast geological gash, one of the mysteries of the continent’s power. Human life began in the Rift, as if it were gleaming up through a crack in the world. Africa has a genius for extremes, for the beginning and the end. It seems simultaneously connected to some memory of Eden and to some foretaste of apocalypse. Nowhere is day more vivid or night darker. Nowhere are forests more luxuriant. Nowhere is there a continent more miserable. Africa — sub-Saharan Africa, at least — has begun to look like an immense illustration of chaos theory, although some hope is forming on the margins. Much of the continent has turned into a battleground of contending dooms: AIDS and overpopulation, poverty, starvation, illiteracy, corruption, social breakdown, vanishing resources, overcrowded cities, drought, war and the homelessness of war’s refugees. Africa has become the basket case of the planet, the “Third World of the Third World,” a vast continent in free fall. In the face of political instability and disintegrating roads, airports and telephone networks, and other disincentives, investors from Europe, America and Japan are withdrawing from sub-Saharan Africa and looking elsewhere; Africans too are pulling out their money. Why risk expropriation or failure in a continent with a weakness for one-party kleptocracy, where drainage by corruption often equals or exceeds the legitimate intake? Cynics in Kenya refer to President Daniel arap Moi’s mining interests as “That’s mine! That’s mine! And that’s mine! . . .” Expatriate businessmen estimate that wealthy Nigerians have enough money in personal deposits abroad to pay off the country’s entire foreign debt, more than $36 billion. Zaire’s President Mobutu Sese Seko has a personal fortune that has been estimated from $4 billion to $6 billion, not far below the level of the country’s external debt. He has isolated himself from his people — and from gathering political unrest — aboard a luxury yacht that cruises the Zaire River. If it is to recover, Africa in the coming years will need all its mystical powers of resilience. AIDS is devastating the continent’s population. It has hit as hard among the cosmopolitan, educated elite as among the villagers, a fact that threatens continuing development. If the rate of infection continues to increase, the effect could be like that of World War I upon the youth of Britain, France and Germany. Yet in the strange arithmetic of apocalypse, aids will not serve as an ultimate check on over-population. According to World Bank projections, sub-Saharan Africa’s population will rise from 548 million today to 2.9 billion by the year 2050. The huge increase in mouths to be fed threatens to swamp any foreseeable economic growth and force living standards ever downward. There are 160 countries on the United Nations’ annual development index, a measure of comparative economic and political progress: 32 of the lowest 40 are in Africa. Between 1960 and 1989, Africa’s share of the world’s gross national product dropped from 1.9% to 1.2%. Since 1980, sub-Saharan Africa’s external debt has tripled to about $174 billion.