How do species evolve? Richard Dawkins, one of the world's most eminent zoologists, likens the process to scaling a huge, Himalaya-size peak, the Mount Improbable of his title. An alpinist does not leap from sea level to the summit; neither does a species utterly change forms overnight, but instead follows a course of "slow, cumulative, one-step-at-a-time, non-random survival of random variants"--a course that Charles Darwin, Dawkins's great hero, called natural selection. Illustrating his arguments with case studies from the natural world, such as the evolution of the eye and the lung, and the coevolution of certain kinds of figs and wasps, Dawkins provides a vigorous, entertaining defense of key Darwinian ideas.
The fig grows at the top of Mountain Improbable- the peak of evolution as we know it, and to get there we are led through the models of evolution of spider webs, gradual evolution of wings and eyes, variety of shell design and body design. For example, a seemingly infinite number of shell variations can be accounted for by the relationships among three variants only: flare (expansion rate), verm (how wide the shell is) and spire(how tall it is).
Mount Improbable itself is a peak, or many peaks of the development of various very complex, and seemingly too complex, elements and forms life takes to develop on its own just through the natural selection and survival pressure. Dawkins, though, takes each element he discusses: spiders and their webs, wings, etc., and shows (sometimes involving computer models into his demonstrations) how it is all possible and feasible, and not really that difficult if done step by step.
Dawkins frustrated me from time to time, even though I agree with him all along. He is such a hard core fundamentalist, that he has lost the ability to derive pleasure from seeing the world through non-Darwinian eyes. Figs and paradises exist surely to provide esthetic pleasure for us, and flowers definitely are there to make our world more beautiful :o)