Lamarck & Darwin
Many people think that Charles Darwin proposed the theory of evolution. But what Darwin
purposed was the Theory of Natural Selection, the method by which evolution occurs. Long
before Darwin published his ideas, evolution was widely  discussed in scientific circles. Darwin had a predecessor – Lamarck.By examining fossils, Lamarck
realized that some species had remained the same over the millennia while others had
changed. Like Darwin, Lamarck concluded that species change over a period of time, by
adapting to new environments Like Darwin, Lamarck concluded that parents pass on their
traits to their offspring. Where Lamarck’s theory fell short was in his supposition
that parents could pass on acquired characteristics. The idea seems silly, but nobody
understood genetics until after Lamarck’s death.
While the mechanism of
Lamarckian evolution is quite different from that proposed by Darwin, the predicted result
is the same that ; adaptive changes in lineages, ultimately driven by environmental change
over long periods of time.
| |
Lamarck cited in support of his theory of evolution, several similar lines of evidence that Darwin was to use in proffering his theory on Origin of Species. Lamarck’s Philosophie Zoologique mentions the great variety of animal and plant forms produced under human cultivation, the presence of vestigial organs (non-functional structural organs in many animals) and the presence of embryonic structures that have no counterpart in the adult. Like Darwin, Lamarck argued that the Earth was very old. Lamarck even mentioned the possibility of Natural Selection in his writings, although he never seems to have attached much importance to this idea. |
Although Darwin tried to
refute the Lamarckian mechanism of inheritance, he later admitted that the heritable
effects of use and disuse might be important in evolution. In the Origin of Species he
wrote that the vestigial eyes of moles and of cave-dwelling animals are "probably due
to gradual reduction from disuse, but aided perhaps by natural selection." 
Textbooks pit Lamarck against Darwin in a
mythical contest from which Darwin emerges victorious. It is said that Lamarck embraced
the inheritance of acquired characteristics, that Darwin rejected it, and this was the
crucial difference between the two men and their ideas about evolution. None of it is
true. First, Lamarck adopted the inheritance of acquired characteristics as an assumption;
he needed that assumption to make some of his imagined mechanisms work. It was an
assumption about heredity and not about evolution. Second, Darwin accepted the inheritance
of acquired characteristics just as Lamarck did.
Darwin even
thought that there was some experimental evidence to support it. In a book published in
1868, The Variation of Animals and Plants under Domestication, Darwin presented the
‘pangenesis hypothesis’ to explain how the inheritance of acquired
characteristics might operate. All the parts of an organism’s body threw off little
corpuscles that were collected in the organism’s reproductive system and then were
passed on to the organism’s offspring. Darwin was thoroughly familiar with
Lamarck’s views and writings, and explicitly acknowledged them when he composed an
outline of the development of ideas about evolution.  |
