In addition to their own value as the finest expressions of Asimov's art,
The Caves of Steel
and
The Naked Sun
stand as touchstones for the way in which they exemplify a basic difference (perhaps
the
basic difference) between science fiction and mainstream fiction the concept of human adaptability. The influence of Darwin's 1859
Origin of Species
has been recognized by many scholars; evolution and natural selection not only shaped H. G. Wells, who, in turn, shaped science fiction; the theory of evolution, whether accepted or rejected, changed forever the way people thought about their place in the universe. In adopting evolution, along with all other scientific concepts of the way things work, however, science-fiction writers also adopted a view of humanity that mainstream fiction rejected: humans, like the rest of the natural world, are not fixed in form or function; people, like whales and elephants, bacteria and viruses, are mutable, not only selected by but shaped by their environments. The human environment, however, increasingly is social, and the fabric of society is woven by science and technology.