charles_darwin

64
CHARLES DARWIN AND THE ORIGIN OF SPECIES
widespread acceptance of Darwin’s ideas. Evolution became the explanation
for the origin of life because ignorance about the mechanism
of natural selection and the supposed impact of numerous
small mutations did not undermine Darwin’s basic theory.
In the case of natural selection, scientists, as Alfred Russel Wallace
stated forty years later, accepted Darwin’s argument that mutation
occurred in living organisms even if they disagreed with ‘‘the
particular means’’ that Darwin suggested. 4 Without a knowledge of
chromosomes and genes, Darwin had already made the mental leap
necessary to recognize that all species are related. Dispensing with
the idea of the fixity of species was already a significant contribution
to the discipline of biology. But, no matter how brilliant his ability to
analyze, Darwin could not move too far beyond his fellow scientists.
Darwin was interested in the relationship between species and varieties:
that was his forte. To study the relationship of species to varieties
required expertise in morphology, embryology, and physiology:
these sciences were based on analyzing characteristics visible to the
naked eye, an external view of nature. Because Darwin was not interested
in subcellular biology, there was little chance that he would
investigate mutation at a microscopic level. However, the science of
genetics and the key to explaining why natural selection occurred
was in the nucleus of cells. By the end of the nineteenth century,
many scientists ignored natural selection, the unexplainable process,
and looked for other theories to explain why mutation occurred. 5
As for the plausibility of descent by modification, the major
criticism was that Darwin relied too heavily on the example of
domesticated animals and plants. This was ‘‘a weakness in Darwin’s
work,’’ wrote Alfred Russel Wallace; Darwin should have based his
theory on the measurement of ‘‘variations of organisms in a state of
nature.’’ 6 Darwin began The Origin of Species with practical examples
and derived a theory from them. Wallace and others preferred erecting
a theoretical framework that could be tested empirically. Darwin’s
method was that of a nineteenth-century naturalist; Wallace’s method
came to dominate scientific experimentation in the late-nineteenth
century. Although some scientists complained about Darwin’s
approach, his theory was accepted by scientists, and society, because
it could be tested in a laboratory as well as in the ‘‘wild.’’
Alfred Russel Wallace claimed, correctly, that the criticisms of
The Origin of Species led Darwin to downplay the effect of natural
selection in later editions. 7 Darwin did adopt a more Lamarckian explanation
for mutation in the fourth, fifth, and sixth editions. He
conceded that some mutations did appear spontaneously and others
were transferred wholesale from the parent to the progeny. Darwin’s