30TH JULY 2021
Dear Friend of Darwin,
On this day in 1837, nine months after returning to Britain at the end of the Beagle voyage, Charles Darwin wrote to his inspiration and new friend, the geologist Charles Lyell:
I believe there are 27 [species of] land birds from the Galapagos, all new except one, (a species of very wide range) yet all of an American form, some north, some south, Now as the Galapos is on the Equator is not this curious— […] I have been attending a very little to species of birds, & the passages of forms, do appear frightful—every thing is arbitrary; no two naturalists agree on any fundamental idea [of what defines a species] that I can see.
Contrary to popular myth, Darwin had not immediately realised the various finches he had collected on the Galápagos Islands comprised different members of a group of closely allied species—although he had been intrigued by the different mockingbird species found on the islands. It wasn’t until Darwin’s and his Beagle shipmates’ collections were later examined by the ornithologist John Gould that their true diversity was appreciated.
In the same month Darwin was writing to Lyell, he had just begun his first notebook on the ‘Transmutation of Species’. He wasn’t to publish his discoveries for another two decades.
Experts still disagree over what precisely defines a species. But one thing Darwin made clear is that there’s a non-arbitrary, natural way to group them: by genealogical descent. In other words, the best way to classify species is by how closely they’re related to each other.
As insights go, that’s pretty profound.
Some Darwin- and evolution-related stories that caught my eye recently:
- Ban imposed on overseas sale of John Gould’s landmark ornithological studies
The UK government has put a temporary export ban on a collection of ‘exquisite’ works by the celebrated 19th-century ornithologist John Gould, in an attempt to save them for the nation. (That would be the same John Gould who analysed the birds collected on the Beagle voyage—see above.)
- Scientists discover the first known algae species with three distinct sexes
Researchers from a number of Japanese universities have discovered that a type of green algae has three distinct sexes. Other closely related algae have different sex systems, meaning the discovery might provide clues as to how these sexual changes evolve.
- Rise of marine predators reshaped ocean life as dramatically as sudden mass extinctions
Evolutionary arms races between marine animals overhauled ocean ecosystems on scales similar to the mass extinctions triggered by global disasters, a new study shows.
- Massive human head in Chinese well forces scientists to rethink evolution
The ‘Dragon Man’ skull has revealed a new branch of our family tree, which is more closely related to modern humans than to the Neanderthals.
- ‘Big-brained’ mammals may just have small bodies, study suggests
Large-brained mammals are typically considered intelligent. But a new study suggests body size could have become smaller to adapt to environmental changes, making the brain appear proportionally larger. In other words, relatively large brain size might have nothing to do with being clever. And, on a related topic…
- Human body size shaped by climate, evolutionary study shows
New research combining data from 300-million fossils and climate models has given clues as to the effect of temperature on body size.
- Origins of flowers traced back to fossilised plants from 126 million years ago - study finds
Darwin described it as an ‘abominable mystery’ as to when flowers first appeared on Earth. Now their origins have been traced back to fossilised plants from 126 million years ago.
- One incredible ocean crossing may have made human evolution possible
Humans evolved in Africa, along with chimpanzees, gorillas and monkeys. But primates themselves appear to have evolved elsewhere—most likely in Asia—before colonising Africa. At the time, around 50 million years ago, Africa was an island isolated from the rest of the world by ocean. So how did primates get there?
- Mammals in the time of dinosaurs held each other back
A new study analysing the variability of mammal fossils suggests it was not dinosaurs, but other mammals, that were the main competitors of modern mammals before and after the mass extinction of dinosaurs.
- How did blue whales get so big? (video)
Body size is one of the most important factors in determining how an organism functions and interacts with its environment. Scientists are studying the blue whale to understand how it evolved to such a large size, and what lessons it might hold for protecting the species in the future.
- Galápagos tortoise found alive is from a species thought extinct since 1906 (video)
Tests carried out on a giant tortoise found in 2019 confirm it belongs to a species believed extinct.
- True Facts: Deception in the rainforest (video)
Plenty of good science in this humorous Ze Frank video.
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Some book recommendations for you:
Darwin: a companion
by Paul van Helvert & John van Wyhe
A monumental new reference work, and a must-have for all Darwin scholars.
The Development of Darwin’s Theory
by Dov Ospovat
Natural History, Natural Theology, and Natural Selection, 1838–1859. An important scholarly work that has been much occupying my mind in recent months. Not for the faint-hearted.
by Barry Lopez
Deservedly seen as a science- and nature-writing classic. I loved it.
Journal of Researches
Work on my Darwin book took a major unplanned detour in recent months. During my routine trawling of blog posts, podcasts, YouTube videos, and what-have-you, I came across several references to a wonderful system (and associated app) for making and organising research notes. It turned out to be just the sort of system I’d been looking for all these years.
So I disappeared down a major research rabbit-hole, rearranging and refactoring my existing notes for the book—including some for the chapters I’d already written. This might sound like an unnecessary distraction, but it turned out to be an extremely useful exercise: I now have a much better idea of how the book will hang together, and several new ideas for future chapters. Earlier this week, I began work on the latest chapter, which is about Darwin taking 20 years to publish his theory of evolution by means of natural selection. Next to that, a few months detour to rearrange research notes sound a lot more reasonable.
Expression of Emotions
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