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Charles Darwin (1809-1882) published in 1859 a vastly
important work: On The Origin of Species by Means of Natural
Selection, or the Preservation of Favoured Races in the
Struggle for Life. Darwin in 1858 had co-authored (with
Alfred Russel Wallace) the theory of natural selection,
which says that "favourable (biological) variations tend to
be preserved." In the "struggle for existence", the fit are
not those who survive but those who reproduce. Natural selection
also leads to diversification as different organisms
adapt to particular ecological circumstances.
Darwin
said all biological similarities and differences are caused
by "descent with modification." He concluded that all organisms
are descended from at most four or five ancestors, and perhaps
only one. Evolution is the name for this biological process
that (according to modern molecular biology) goes back
to one common ancestor 3-1/2 billion years ago.
The
famous "argument from design" suggests the evolution
of life was planned and ordained by a creator, though Darwin
saw little evidence of "purpose" in the history of life. Some
critics were concerned with the moral implications of Darwinism,
though Darwin never maintained (as in "social Darwinism")
that might makes right.
Acceptance
of the theory of natural selection declined after Darwin's death,
but it was essentially accepted by the 1950s.
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