Charles Darwin's theory of evolution has inspired science fiction writers from H. G. Wells to the present author, Dougal Dixon, to speculate on how humankind in the distant future will adapt, physically and mentally, to an ever-changing world.

These fictions tend toward either hope or despair. Wells' "The Time Machine," a Victorian-era "Blade Runner" dramatizing technological progress decaying into human viciousness, had already established the grimmer category by the turn of the century.

The stunningly illustrated, starkly written "Man After Man" falls squarely into the "Blade Runner" genre.

Dixon, a British university-trained paleontologist and geologist, has written extensively, for children as well as adults, on dinosaurs, geology and climate. His dark vision of the future reached many American readers in his 1984 book "After Man," a beautifully illustrated bestiary of imaginary creatures the author proposes will populate the Earth in the absence of humans.

Now, in "Man After Man," we learn that the humans in Dixon's cosmos manage to hang on after all. With the help of natural selection aided by genetic engineering, artificial organs, luck and pluck, humans not only repopulate the Earth but move underwater and into space as well. But they manage to foul their nest all over again, in a future 5-million-year cycle that eerily recapitulates humankind's first 5 million years.

As Dixon puts it, in a particularly epigrammatic passage, "Dig a shelter today. Build a house tomorrow. Clear a forest for a city the day after. Choke the landscape with the waste materials the next."

In "Man After Man," Dixon begins his prophecy with a highly compressed but readable recap of human evolution. He also teaches the reader the mechanisms of evolution, including an easy-to-grasp and clearly illustrated lesson on molecular genetics.

To keep the reader oriented through the prophesied future, Dixon provides a flowchart. There the reader can see when, in Dixon's fictional future, humans help out natural evolution with genetic engineering and technological enhancement, producing a zoo of truly wondrous human creatures.

Most of the book is devoted to telling the story of the future of the human race. Instead of a conventional narrative, however, the story unfolds as a sequence of isolated, dramatic moments in the lives of individuals representing the 40-odd species of humans that evolve--or are engineered--to fill the various niches of the future.