Another subject that posed a quandary for Darwin's
theory was inheritance. At the time when Darwin developed
his theory, the question of how living beings transmitted
their traits to other generations-that is, how inheritance
took place-was not completely understood. That is why the
naive belief that inheritance was transmitted through blood
was commonly accepted.
Vague beliefs about inheritance led Darwin
to base his theory on completely false grounds. Darwin assumed
that natural selection was the "mechanism of evolution."
Yet one question remained unanswered: How would these "useful
traits" be selected and transmitted from one generation
to the next? At this point, Darwin embraced the Lamarckian
theory, that is, "the inheritance of acquired traits." In
his book The Great Evolution Mystery, Gordon R. Taylor,
a researcher advocating the theory of evolution, expresses
the view that Darwin was heavily influenced by Lamarck:
is known as the inheritance of acquired characteristics...
Darwin himself, as a matter of fact, was inclined to believe
that such inheritance occurred and cited the reported case
of a man who had lost his fingers and bred sons without
fingers... [Darwin] had not, he said, gained a single idea
from Lamarck. This was doubly ironical, for Darwin repeatedly
toyed with the idea of the inheritance of acquired characteristics
and, if it is so dreadful, it is Darwin who should be denigrated
rather than Lamarck... In the 1859 edition of his work,
Darwin refers to 'changes of external conditions' causing
variation but subsequently these conditions are described
as directing variation and cooperating with natural selection
in directing it... Every year he attributed more and more
to the agency of use or disuse... By 1868 when he published
Varieties of Animals and Plants under Domestication he gave
a whole series of examples of supposed Lamarckian inheritance:
such as a man losing part of his little finger and all his
sons being born with deformed little fingers, and boys born
with foreskins much reduced in length as a result of generations
However, Lamarck's thesis, as we have seen
above, was disproved by the laws of genetic inheritance
discovered by the Austrian monk and botanist, Gregor Mendel.
The concept of "useful traits" was therefore left unsupported.
Genetic laws showed that acquired traits are not passed
on, and that genetic inheritance takes place according to
certain unchanging laws. These laws supported the view that
species remain unchanged. No matter how much the cows that
Darwin saw in England's animal fairs bred, the species itself
would never change: cows would always remain cows.
The genetic laws discovered
by Mendel proved very damaging to the theory of
Gregor Mendel announced the laws of genetic
inheritance that he discovered as a result of long experiment
and observation in a scientific paper published in 1865.
But this paper only attracted the attention of the scientific
world towards the end of the century. By the beginning of
the twentieth century, the truth of these laws had been
accepted by the whole scientific community. This was a serious
dead-end for Darwin's theory, which tried to base the concept
of "useful traits" on Lamarck.
Here we must correct a general
misapprehension: Mendel opposed not only Lamarck's model
of evolution, but also Darwin's. As the article "Mendel's
Opposition to Evolution and to Darwin," published in the
Journal of Heredity, makes clear, "he [Mendel] was familiar
with The Origin of Species ...and he was opposed to Darwin's
theory; Darwin was arguing for descent with modification
through natural selection, Mendel was in favor of the orthodox
doctrine of special creation."4
The laws discovered by Mendel put Darwinism
in a very difficult position. For these reasons, scientists
who supported Darwinism tried to develop a different model
of evolution in the first quarter of the twentieth century.
Thus was born "neo-Darwinism."
3 Gordon Rattray Taylor,
The Great Evolution Mystery, London: Abacus, 1984, s. 36-
4 B.E. Bishop, "Mendel's
Opposition to Evolution and to Darwin," Journal of Heredity
87 (1996): s. 205-213; ayrýca bkz. L.A. Callender, "Gregor
Mendel: An Opponent of Descent with Modification," History
of Science 26 (1988): s. 41-75.