6TH SEPTEMBER 2024
Dear Friend of Darwin,
In the months and years immediately following the publication of On the Origin of Species, you can sense Darwin’s frustration at the number of clever people who simply didn’t seem to get it. In his correspondence, he repeatedly, politely encouraged sceptics to put aside any religious or philosophical objections they might have had and just look at all the phenomena his theory explained:
The fair way to view the argument of my book, I think, is to look at Natural Selection as a mere hypothesis […] & then to judge whether the mere hypothesis explains a large body of facts in Geographical Distribution, Geological Succession, & more especially in Classification, Homology, Embryology, Rudimentary Organs[.] The hypothesis to me does seem to explain several independent large classes of facts; & this being so, I view the hypothesis as a theory having a high degree of probability of truth.
—Charles Darwin to Samuel Pickworth Woodward, 6 March 1860
In terms of Classification, for example, Darwin’s theory brilliantly explained how the taxonomists of his and earlier generations had been able to sort extinct and living species into logical groups and sub-groups based on anatomical similarities: the groupings simply reflected genealogical/evolutionary descent.
In the book I’m currently writing, I make the point that, so well did Darwin’s theory explain how taxonomists were able to group species, it eventually came to define how they do so. Modern taxonomists consciously try to group species by evolutionary descent. But this, ironically, creates a problem in our continuing to use Classification as evidence in support of evolution. We end up making something of a circular argument: we classify species according to perceived evolutionary descent, so is it any wonder our species classifications seem to lend support to the idea of evolutionary descent? Fortunately, modern DNA analysis removes much of the subjectivity of classification, allowing us to group living (and some extinct) species according to mathematical analyses of the similarities of their genetic material. And, whaddya know?, the groupings identified through impartial DNA analysis totally back up the idea of evolutionary descent.
Natural selection
A book you might enjoy:
Sexual Selection by Marlene Zuk & Leigh W. Simmons
A very useful introduction to Darwin’s other great idea. As well as explaining Darwin’s original thinking, the book explores our current understanding of sexual selection, which has been greatly expanded since Darwin’s day.
Missing links
Some Darwin-related articles you might find of interest:
John Tyndall: how a lecture in Belfast 150 years ago supercharged the modern debate on consciousness
On a controversial lecture given by Darwin’s friend the physicist John Tyndall which attempted to define boundaries between scientific investigation and religious belief.Halesworth to the Himalayas: the adventures of Britain’s greatest botanist
A potted biography of Darwin’s best friend, the botanist Joseph Dalton Hooker.Professor Megalow’s Dinosaur Bones: Richard Owen and Victorian Literature
On how Darwin’s erstwhile friend and later enemy the brilliant anatomist Richard Owen inspired literary works by the likes of William Makepeace Thackeray, Charles Kingsley, and Charles Dickens.What a 100-Year-Old Trial Reveals About America
A new book on the famous 1925 American Scopes Trial traces a long-simmering culture war—and the fear that often drives both sides.Biologist Rosemary Grant: ‘Evolution happens much quicker than Darwin thought’
The evolutionary expert discusses the triumphs and challenges of the groundbreaking research on Galápagos Islands finches she undertook with her husband, Peter,Darwin’s fear was unjustified: study suggests fossil record gaps not a major issue
A new study has examined how the incompleteness of the fossil record influences the reconstruction of evolutionary history. Surprisingly, it’s not such a big issue.
Original paper: Identification of the mode of evolution in incomplete carbonate successionsHow animals are changing to cope with stronger heatwaves
How some animal species are responding to global heating.Mass extinction 66 million years ago triggered rapid evolution of bird genomes, study finds
How early birds evolved in the aftermath of the asteroid strike that devastated the earth 66 million years ago.
Original paper: Genome and life-history evolution link bird diversification to the end-Cretaceous mass extinctionFemale giraffes drove the evolution of long giraffe necks in order to feed on the most nutritious leaves, new research suggests
It’s been a much debated topic: was it natural selection or sexual selection that drove the evolution of giraffes’ long necks? A new study suggests the former—but I predict this one will continue to run and run.
Original paper: Sexual dimorphisms in body proportions of Masai giraffes and the evolution of the giraffe’s neckBeetles conquered Earth by evolving their own biochemical laboratory, new study finds
Beetles represent about a quarter of all described lifeforms. What’s the key to their success? A new study of rove beetles, the largest family of beetles, suggests it might be their chemical defence glands.
Journal of researches
At the start of this newsletter, I explained how, thanks to evolutionary theory, taxonomists have changed how they look at the world. They now take evolution as a given, using the idea to define how they classify species.
It’s not just taxonomists. In addition to Classification, one of the other phenomena Darwin frequently cited as being explained by his theory was that of Geological Succession. In other words, fossil sequences. When the geologists of his and earlier generations worked out the relative ages of different layers of rocks by considering their stratigraphy—how they were ordered one on top of the next, and how they intersected—the fossil sequences within those rocks, when arranged in chronological order, reflected the sequences we would expect to see as species evolved over time.
I recently came across a letter from Darwin to an Austrian geologist named Edmund Mojsisovics von Mojsvár. In his latest book, The Dolomite Reefs of South Tyrol and Veneto (1878–9), Mojsisovics von Mojsvár took Darwin’s theory of evolution as a given, and argued that rocks should be assigned relative dates according to the fossils they contained, rather than relying solely on stratigraphic analysis.
A delighted Darwin wrote:
What a wonderful change in the future of geological chronology you indicate, by assuming the descent-theory to be established, & then taking the graduated changes of the same group of organisms as the true standard! I never hoped to live to see such a step even proposed by anyone.
Nowadays, rocks are routinely dated according to the fossils they contain. But fortunately, this doesn’t create a problem in our continuing to use Geological Succession as evidence in support of evolution, as there are other ways to independently date rocks, including traditional stratigraphy, and more modern methods such as radiometric and thermoluminescent dating. And, whaddya know?, the fossil sequences revealed within the rocks, when arranged in chronological order, once again totally back up the idea of evolutionary descent.
Expression of Emotions
Thanks as always for reading this newsletter. If you enjoyed it, please share it with your friends—and, if you didn’t, please share it with your enemies.
See you next time!
Richard Carter, FCD
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