Darwin, Wallace, and evolution

150 years ago, Charles Darwin was born in England. 100 years ago, his famous Origin of Species was published.

To commemorate those events, this year is “Darwin year”. As part of that, there is an exhibition about Darwin and evolution in the natural history museum. It is called “Expeditie Darwin”.

The central theme of the exhibition is Darwin‘s journey around the world, and the contribution of especially his visit to the Galapagos islands then, to his theory of evolution. Islands, the exhibition says, make for peculiar twists in the evolution of animal (and plant) species. Animals, eg, may evolve into bigger, or smaller species, than their original continental ancestors, depending on presence of predators, food, etc. Today still, scientists, including employees of the museum, discover new facts on evolution, including on islands.

According to the exhibition, the major contribution to evolution theory were the various species of buntings, which Darwin collected on the Galapagos islands. Darwin at first thought they were finches, and they are still known as Darwin’s finches.

Well, the exhibition says that Darwin’s finches are really buntings. Wikipedia claims that they are really tanagers (thraupidae).

This mistake by Darwin was not really unexpected, as Darwin’s major subject at university had been theology, not biology. In fact, then it was hardly possible to major in biology at any university. Some recent authors say that Darwin’s discoveries on Galapagos mockingbirds, or in Argentina, really were more of an influence on evolution theory than the buntings. This view is not discussed in the exhibition.

Darwin’s view that natural selection was the mechanism propelling evolution forward was influenced by another theologian, Thomas Malthus, who had not majored in the subject in which he would become best known; political economy in Malthus‘ case.

Darwin found out that the main differences between the various Galapagos “finch” species were their beaks, adapted to different kinds of food in the island environment. From that, he concluded that the divergence from one continental ancestral species which had arrived on the islands to the present different species had been rather recent. 12 of the 14 Darwin’s finch species are present in the museum collection.

After traveling around the world on the ship Beagle as a twen, and forming the basic principles of his evolution theory during and soon after that journey, Darwin waited until he was fifty with publishing his ideas. Perhaps there was something of another theologian-scholar in him, a literary fictional theologian-scholar: Edward Casaubon from George Eliot’s novel Middlemarch. Casaubon does not want to publish his complex sweeping theories until he would be totally sure that no critic would have a chance of successfully attacking them. Which means defering and defering publication, maybe until the Greek kalends.

In Darwin’s nineteenth century reality, however, there was an additional reason for delaying publication on especially the evolution theory: it could be foreseen that Christian believers in creation (about 6,000 years ago, according to Bishop Usher‘s addition of numbers in the Bible) of immutable species would sharply attack Darwin. Charles Darwin was an irenic person, who did not want trouble, also not with what later would become known as “creationists“, some of which he knew well personally. Eg, his wife, and Captain Fitzroy of the Beagle were very devout.

However, in 1858 Darwin got a letter, all the way from Asia, from Welsh born Alfred Russel Wallace. Like Darwin, Wallace had not studied biology as major university subject; contrary to Darwin, he had no university education at all. He also “pioneered the theory of the Ice Ages and equal wages for women“.

Like Darwin, Wallace had studied birds on various (Indonesian in his case) islands. He studied especially imperial pigeons: various species, similar to each other, like Darwin’s finches; yet differing according to environment, also like Darwin’s finches. Wallace was from a much poorer family than Darwin. He had less cause than Darwin to be afraid of criticisms from Christian “polite society” if he would publish.

Darwin understood that soon, maybe someone else would get the credit for theories on which he had been working for decades. A potential conflict between Darwin and Wallace was prevented by the presentation of a paper, written jointly by them. Darwin now started working much faster toward publishing the Origin of Species, which came out next year.

At the exhibition are three imperial pigeon species studied by Wallace: the elegant imperial pigeon; the pink-headed imperial pigeon; and the purple-tailed imperial pigeon.

At the exhibition are also many other animal species, mainly from islands. Living or extinct (eg, the dodo). There are explanations how scientists of this museum study those animals. One example of that research is the discovery of the jellyfish eating sea anemone (or lake anemone, as it lives in a salt lake) Entacmaea medusivora. It was already known from Palau. Later, a museum researcher found out that it lives in Borneo island as well.

Darwin Killed Off The Werewolf: here.

Darwin and the Silurian, here.

Timeline: The evolution of life, here.

Mangrove finches: here.

Newly Goat-Free, a Galapagos Island Awaits a Finch Renaissance: here.

A new species of finch may have arisen in the Galapagos: here.

Adaptation and function of the bills of Darwin’s finches: divergence by feeding type and sex: here.

Race, sex and the ‘earthly paradise’: Wallace versus Darwin on human evolution and prospects: here.

A global model for the origin of species independent of geographical isolation: here.

Linnaean taxonomy is still a cornerstone of biology, but modern DNA techniques have erased many of the established boundaries between species. This has made identifying species difficult in practice, which can cause problems, as shown by a researcher from the University of Gothenburg, Sweden: here.

Charles Darwin’s theory of gradual evolution is not supported by geological history, New York University Geologist Michael Rampino concludes in an essay in the journal Historical Biology. In fact, Rampino notes that a more accurate theory of gradual evolution, positing that long periods of evolutionary stability are disrupted by catastrophic mass extinctions of life, was put forth by Scottish horticulturalist Patrick Matthew prior to Darwin’s published work on the topic: here.