Nothing in biology makes sense except in the light of evolution.
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 couldn’t have accepted the idea of evolution as such a mechanism was against the vision of a universe populated by perfect organisms created by God and perfectly adapted to their environment (Plato, ca. 360 BC). For Aristotle, all forms of life could be classified on a scale of increasing complexity. All the levels of this scale are occupied by perfect and permanent species which do not evolve (Aristotle, ca. 350 BC).
In Judaeo-Christian culture, the account of the creation in the Old Testament reinforces the idea that all species are independent from one another and cannot evolve.
It is only in the light of this occidental history hostile to the Darwin’s vision on life that we can fully understand the importance and the turmoil provoked by the publication of this master piece (Darwin, 1859). Over the last 150 years, scientists, geologists, philosophers, sociologists and theologists have devoted their lives to confirm or invalidate Darwin’s theory.
Although the theory of evolution is mainly attributed to Darwin, it is important to look at the different scientists who have contributed to the theory.
Georges-Louis Leclerc, Count de Buffon
In the eighteenth century, Georges-Louis Leclerc, had...