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The Uplift War (The Uplift Saga, Book 3) (original 1987; edition 1987)
by David Brin
Amazon.com Amazon.com Review (ISBN 0553279718, Mass Market Paperback)Billions of years ago, an alien race known as the Progenitors began the genetically engineered techniques by which non-intelligent creatures are given intelligence by one of the higher races in the galaxy. Once "Uplifted," these creature must serve their patron race before they, in turn, can Uplift other races. Human intelligence, which developed by itself (and brought about the Uplifting of chimpanzees and dolphins), is an affront to the aliens who plan an attack, threatening a human experiment aimed at producing the next Uplift. Such is the premise of this novel, which won the 1988 Hugo Award.
(retrieved from Amazon Fri, 04 Jan 2013 13:11:18 -0500)
Earth has been allowed to colonize the Planet Garth only because its previous occupants went berserk and wiped out virtually all life there. But now humans, chimps, and their alien allies on Garth are being held hostage in a conflict that could affect the fate of the entire five galaxies.
(summary from another edition)