Africa : THE PEOPLE AND POLITICS OF AN EMERGING CONTINENT by Sanford J. Ungar (Simon & Schuster: $19.95; 466 pp.)

“Our ancient continent is now on the brink of disaster,” Sanford J. Ungar quotes a former secretary-general of the Organization of African Unity as saying. “Gone are the smiles, the joys of life.”

Rather along the lines of John Gunther’s 1955 best seller “Inside Africa,” Ungar has written a nation-by-nation account of Africa and its contemporary dilemmas. He focuses in depth on U.S. policy toward Africa and on four countries regarded as of special interest and importance to Americans: Kenya, Liberia, Nigeria and South Africa. A former host of National Public Radio’s evening news program, “All Things Considered,” Ungar brings an admirable professionalism to this vast and daunting task. A few minor factual inaccuracies aside, the result is a necessary, highly readable book. Unavoidably, however, it is also a somewhat depressing one.

Most of sub-Saharan Africa’s 46 nations flounder in a swamp of corruption, crime and incompetence. Economic failure is made inevitable by imported ideology; millions starve; forests are cut down; the land erodes; wildlife is exterminated. At least 20% of Africa is desert now, and that proportion may rise to 45% within the next half century. The population is growing faster than anywhere else on Earth, and is likely to double by the year 2005. Between 1980 and 1983, Africa’s average per capita income actually fell by 18%. Individual statistics are startling: For example, Guinea produced 100,000 tons of bananas in 1960 but only 162 tons in 1982.

The most important reason for this mysterious climate of disaster is that the great powers of the West and East have systematically promoted what Ungar aptly dubs kleptocracy-- government by thieves--throughout Africa. Thieves and worse. The Russians propped up Idi Amin and back the current Ethiopian dictator Mengistu. We are the main support and comfort of Mobutu in Zaire and of Siad Barre in Somalia, who combines “scientific socialism” with “a classically corrupt autocracy.”

Take the immense and potentially rich land in Zaire. Per capita income is only $127 a year. Perhaps half of all children die before their fifth birthdays. Agricultural products used to be a major export. Now food has to be imported. “The Zairian economy has been declared bankrupt so many times now that the term has lost its meaning,” Ungar observes.

Mobutu, however, has become one of the richest men in the world, and is reputedly worth more than $3 billion. He rules by methods that would have embarrassed Mussolini, but is a cunning manipulator of American support. “Angry congressmen . . . routinely vote to cut the authorization for aid to Zaire, only to see it restored by House-Senate conference committees or Executive Branch maneuvers,” Ungar notes. The argument is, needless to say, that if Mobutu were to fall, Zaire would pass into the “Soviet sphere.”

Ungar himself believes that our friendship with the likes of Mobutu and Siad Barre are “understandable and probably inevitable.” More aid, better administered; greater efforts to persuade such rough diamonds to respect their subjects’ human rights; and a reasonably tough line with South Africa are his main policy recommendations.

This does not, however, go to the roots of the African emergency. More of the same is not the answer. It is precisely “aid,” especially military aid, that has so largely rendered Africans impotent in the face of the terrible difficulties that they and their continent face. Many countries have become almost entirely dependent on foreign assistance. Aid is literally their main economic activity. Entire classes have sprung up to take advantage of it--and rule by means of it.

Governed by such myopic oligarchies, or by the dictators they periodically generate, few Africans have any real hope of influencing their future. The best are often terrorized into silence. Or they despair, give up and emigrate, if they can.

Under both Republican and Democratic administrations, the United States has been prepared to trade aid and approbation for economic access, military facilities and, above all, token anti-Russianism. Shared ideals of justice, democracy and human rights count for less, it seems, than votes at the United Nations (almost a third of which are now cast by African countries). Not even a commitment to the capitalist way is required of our “friends”-- vide “socialist” Somalia.

Under the spell of a foreign policy that is almost wholely opportunistic, we are bush “aiding” Africa into the grave. The irony is that even in the short term we suffer too. Surely experience has shown that our truest allies are free peoples?