The Genesis - Volume Three of The Evolution River Series by R. L. Clayton

In The Genesis, the final volume in the Evolution River Series, humans and their descendants, the Homakuwans, struggle to rebuild after a string of meteorites destroy the ecology of the Earth causing massive extinctions. Using genetic technology, they accomplish in a century what nature does in millennia, and civilization is preserved, but almost 90% of the human population dies. They create machines to assist them that become a race of mechanical beings, Mechs. Conflict breaks out between the civilization of the United World Government and those outside of that control. The Homakuwans, learn that humanity must continue along the path that evolution has set them on, but they incorporate a novel solution to preserve the race that created them. The descendants of the descendants of humans expand their civilization into the Universe, where they grow and join the Universal Mind. New dimensions open up to them as they move beyond the physical, and they evolve again. The flow of evolution reaches its destination, and begins anew.