Escape from the Planet of the Apes — Jerry Pournelle

The time indicator raced back through the years--from 3955 to 1973. The spacecraft held the Earth's future inhabitants--three survivors of a devastating cataclysm.

The capsule's occupants included Cornelius, his mate Zira, and Dr. Milo--three Apes, the thinking, speaking descendants of the species that had dominated Man and the Earth for centuries.

The world of 1973 welcomed them at first, pampered them when it realized their unusual qualities, threatened them later when it was learned that Zira carried the seed of the future ascendance of Ape over Man.

They had to be killed! But first...