The Problem of Genetics

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:

Lamarckism... 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 of circumcision.3

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.

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- 41
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.