The History of Darwin’s Theory of Evolution

Nothing in biology makes sense except in the light of evolution.

(Dobzhanski, 1973)

It was during his journey on board the Beagle that Darwin developed his theory of evolution. “On the Origin of Species” (Darwin, 1859) proposed two main principles: evolution really occurs and natural selection is its mechanism. This work published on 24th November 1859 traces a coherent portrait of life bringing together in an orderly manner an astonishing variety of apparently independent facts. It led biologists to concentrate on the diversity of organisms, their origins and their relation, their similarities and their differences, their geographical distribution and their adaptation to various environments.

Darwin (1859) arrived at two main conclusions.

• All species on earth descend from ancestral species and he presents a mechanism explaining evolution called natural selection.

• Natural selection results in adaptive evolution (prevalence of hereditary characteristics favouring the survival and the reproduction of organisms in different environments).

Evolution: Historical Controversy

In order to fully understand Darwin’s vision, it is important to understand the historical context and compare it to the previous ideas on Earth and life on Earth. “On the Origin of Species” (Darwin, 1859) revolutionized the ideas of the time: not only did it question the scientific ideas but it also questioned the basis of occidental culture. Darwin’s vision opposed the vision of a world made of immutable species created in a week by a Creator who modelled the whole universe. Philosophers such as Plato (428-348 BC) and Aristotle (384-322 BC), who had a major influence on occidental culture, would have opposed to the idea of evolution. Plato cou...

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...ptation and the emergence of new species were linked. If two groups of individuals from the same species were separated, finches for example, and placed in different environments, then after many generations, the two groups will have accumulated differences making it possible to differentiate two distinct species. The Galapagos finches can be differentiated by the size of their beak, which is adapted to the food available on the islands. Darwin had an intuition of the importance of these mechanisms to explain evolution.

In the early 1840s, the main principles of Darwin’s theory of evolution were formulated by the mechanism of natural selection; however, he did not publish it. Although evolutionary theory sprouted in many places, Darwin rejected the publication of his theory, and it was not until 1859 that he published “On the Origin of Species” (Darwin, 1859).