The Darwinian Revolution

Charles Darwin (1809–1882)Charles Darwin (1809–1882)

The Darwinian revolution is generally taken to be one of the key events in the history of Western science. In recent years, however, the very notion of a scientific revolution has come under attack, and in the specific case of Charles Darwin and his Origin of Species there are serious questions about the nature of the change (if there was such) and the specifically Darwinian input. 

This article considers these issues by addressing these questions: 

• Was there a Darwinian revolution? 

• That is, was there a revolution at all? 

• Was there a Darwinian revolution? 

• That is, what was the specific contribution of Charles Darwin? 

• Was there a Darwinian revolution? 

• That is, what was the conceptual nature of what occurred on and around the publication of the Origin? 

I argue that there was a major change, both scientifically and in a broader metaphysical sense; that Charles Darwin was the major player in the change, although one must qualify the nature and the extent of the change, looking particularly at things in a broader historical context than just as an immediate event; and that the revolution was complex and we need the insights of rather different philosophies of scientific change to capture the whole phenomenon. In some respects, indeed, the process of analysis is still ongoing and unresolved. 

Darwin’s fervent interest in the natural world began as a young boy and continued unabated throughout his remarkable career.

What influenced Darwin's ideas about species?

• During the 5-year surveying mission in which Darwin served aboard the Royal Navy Brig HMS Beagle as a naturalist, he became intrigued by Charles Lyell's Principles of Geology.

• In Principles of Geology, Lyell presents arguments in support of uniformitarianism, the theory that observable processes occurring in the present are sufficient to explain the formation of all geological features over great time periods.

• Darwin eventually applied the idea that ongoing, observable processes can account for the variety of features in the natural world to living systems.

• Departing the coast of South America, the Beagle arrived at the Galapagos Islands, where Darwin would make his most famous observations of species, including the 14 or so closely related species of finches now commonly referred to as Darwin's finches.

Just four of the Galapagos Islands finch species that Darwin observed, described and drew. He pondered the great range in bill type among these species.



Darwin's publications came amid academic discussion on the matter of evolution.

• In 1844, Darwin wrote an essay covering the main ideas about how species change slowly over time, a process he called descent with modification, and the mechanism that drives these changes, which he called natural selection.

• Instead of immediately publishing his scientific explanation of origins-which did not mention a divine creator-he spent years gathering more supporting evidence.

• In 1858, English naturalist Alfred Russel Wallace sent Darwin a manuscript, requesting that he review it and pass it along to Lyell.

• Darwin was shocked to read Wallace's hypothesis about natural selection, which was nearly identical to his own.

• After receiving Wallace's hypothesis about natural selection, Darwin quickly completed work on his book, On the Origin of Species by Means of Natural Selection, and published it in 1859.

• Lyell presented Wallace's paper together with excerpts from Darwin's unpublished 1844 essay to a scientific society in London.

• Wallace admired Darwin and respected his work. Recognizing that Darwin had more fully developed the hypothesis, Wallace wanted Darwin to receive primary credit.

• Wallace went on to devote himself to research in bio-geography, the study of the geographical distribution of species.

Darwin's hypothesis described the evolutionary relationships between taxonomic groups.  

• Darwin's idea of descent with modification explained how species change slowly over time as they adapt to environments.

• Darwin proposed that all species descended step by step from a single common ancestor by adapting to changing environments or to new environments arrived at by migration.

• Darwin's work explained taxonomic relationships between groups of organisms, which were related by common ancestry and not necessarily by outward form.

• Gaps between forms signalled the importance of extinction. Before Darwin's work, most scientists had not appreciated the phenomenon's relevance, in part because it was not supported by theology.

Phylogenetic tree showing evolutionary relationships.
Extinct species represent gaps in body forms of extant species. Fossil discoveries help fill in the gaps and reconstruct the evolutionary trajectory of the group.