Friedel Weinert
Contrary to common belief, Charles Darwin (1809–1882) (fig. 1) is not the father of evolutionary theory. The fact of evolution was recognized by earlier researchers, who also searched for explanations. But it was Charles Darwin who proposed a viable explanation of evolution in his book On the Origin of Species by Means of Natural Selection, or the Preservation of Favoured Races in the Struggle for Life, which was published in 1859. The full title of the book is quite revealing because it expresses in a nutshell the gist of Darwin’s ideas.
To a certain extent, however, this title is misleading. Darwin did not attempt to show how organic life arose on Earth at the dawn of time. Nor is this work concerned with races, human or non-human. It deals with evolutionary descent by the mechanism of natural selection. Although Darwin’s book is quite long, it was originally only meant to be an abstract to a fuller work on evolution that Darwin intended to write later. But Darwin was rushed into publishing his work in order to secure his priority because he had received a paper from Alfred Wallace (1823–1913), “On the Tendency of Varieties to Depart Indefinitely from the Original Type” (1858) in which Wallace presented roughly the same ideas. Receiving a copy of this paper alarmed Darwin because he had already developed his ideas about evolution by 1838, after a five-year voyage on the Beagle, which lasted from 1831–1836.There are differences between Darwin’s and Wallace’s approach: Wallace doubted Darwin’s inference from domestic to wild animals; he was more concerned with species than individuals; and, most importantly, he excluded humans from the impact of natural selection.
We should distinguish Darwin’s theory of branching evolution from earlier attempts, such as Jean Baptiste Lamarck’s (1744–1829) theory of linear, progressive evolution (1809). So, what is Darwin’s theory of branching evolution?
A rough sketch of the theory says that evolution is the survival of the fittest. It is interesting to note that in the first editions of Origin Darwin neither used the term “evolution” nor the phrase “survival of the fittest.” It was actually the British biologist, philosopher, and sociologist Herbert Spencer (1820–1903) who popularized Darwin’s idea of the preservation of favorable variations by the expression “survival of the fittest.”
Darwin approved of this and began to use the phrase “natural selection or survival of the fittest” from the fifth edition onward (it appears in the introduction to chapter four). The association has survived in the popular mind: many think of evolution as some progress toward higher forms of life, but his thinking is more Lamarckian than Darwinian (fig. 2).
What did Darwin really say? First, instead of evolution Darwin speaks of his theory of descent with modification. At the end of the nineteenth century “evolution” had a technical meaning in embryology: it was thought that embryos grew from preformed homunculi (