Charles Darwin to J.D. Hooker (11-Jan-1844):

Besides a general interest about the Southern lands, I have been now ever since my return [from the Beagle voyage] engaged in a very presumptuous work & which I know no one individual who w^d not say a very foolish one.— I was so struck with distribution of Galapagos organisms &c &c & with the character of the American fossil mammifers, &c &c that I determined to collect blindly every sort of fact, which c^d bear any way on what are species.— I have read heaps of agricultural & horticultural books, & have never ceased collecting facts— At last gleams of light have come, & I am almost convinced (quite contrary to opinion I started with) that species are not (it is like confessing a murder) immutable.

Joseph Dalton Hooker was one of the first people Darwin confided in regarding his heretical evolutionary views. He chose his friends well. They had only been corresponding with each other for two months, but Hooker was to remain one of Darwin’s most staunch allies for the rest of Darwin’s life.

I received a very interesting query from a student earlier this week: “I was wondering if you had a source that verifies that Owen wrote the anonymous Edinburgh Review article”.

I assumed that a quick flick through the references in a couple of my many Darwin books would soon resolve that one, but not so: that Richard Owen was the author of the scathing review of On the Origin of Species was simply stated as fact in every book I checked. Charles Darwin was certainly in no doubt whatsoever that Owen was behind the review and wrote Owen’s name on the front of his personal copy. But was there a quotable source for this attribution, rather than informed supposition?

I eventually managed to track one down. In a letter to Darwin shortly after the event, Joseph Dalton Hooker wrote:

Bell told me yesterday that Owen avows the Review, I can hardly believe it.

Thomas Bell was president of the Linnean Society. His word reported via Hooker is good enough for me. Guilty as charged, Prof. Owen.

If anyone knows of a document in which Owen admits to being the author of the review first-hand, I’d be interested to hear about it.

But I should like to suggest an alternative scientific field which would be of extreme interest to the resurrected Darwin. I don’t for one second claim that it’s a more appropriate topic than genetics to explain to the great man, but it’s one that would fascinate him: I would tell Mr Darwin about plate tectonics.

Darwin first made his name in the world of science as a geologist. Having received some practical experience geologising with Adam Sedgwick in North Wales shortly before he set off on HMS Beagle, he picked up much of the latest revolutionary geological thinking by devouring Charles Lyell’s recently published Principles of Geology during the voyage. Darwin later wrote that Lyell’s book ‘altered the whole tone of one’s mind & therefore that when seeing a thing never seen by Lyell, one yet saw it partially through his eyes’.

Darwin put his new Lyellian eyes to good use. By the time he returned to Blighty in 1836, he had gathered considerable evidence to show that much of South America is gradually rising, and had come up with what proved to be the correct explanation for the formation of coral reefs. We now know that the underlying mechanism behind both of these phenomena is plate tectonics. Darwin would have been intrigued to hear the modern take on his geological theories.

But it wouldn’t just be Darwin the geologist who would be want to learn about plate tectonics; Darwin the naturalist would be all ears too. Darwin and his friends (most notably Hooker) spent much time thinking about how species came to be distributed in the way that they are. They hypothesised former land-bridges, and Darwin brilliantly suggested how changes in global temperatures associated with the former glacial period (he did not know that there had been more than one ice age) would have allowed temperate species to relocate to tropical areas before being forced into the mountains as warmer temperatures returned. The following extract from a letter Hooker send to Darwin in 1858 is typical of their correspondence on the subject:

[I] want you to [go into] print that I may take up your refrigeration doctrine, to which I think I should have come clumsily at last by myself as the only way of accounting for the spread of European species to Australia.

It is curious—that so many more Europ. sp. should be in Australia than in Fuegia & S. Chili! Especially considering the enormous distance of Europe to Australia & no continuous mountains.

Put end of string on globe on England & other end on V[an] D[ieman's] L[and (i.e. Tasmania)] & it will run through the most continuous masses of Land on globe—it is the greatest stretch of all but [sic, presumably he meant by] dry land that you can find, & I can connect the Botany the whole way by mountains of 1. Borneo; 2, Java & Ceylon & Penins Ind. 3 Khasia; 4 Himal 5 Caucasus, 6 Alps. 7 Scandinavia.— I can thus connect Botanically England with VDL. better than I could Canada with Fuegia!

Had they known about plate tectonics, Darwin and Hooker might have understood better why the flora of Canada and Fuegia (which are nowadays connected by one huge, continuous landmass) are so different. We now know that North and South America were not always joined at the hip, and once formed separate continents with their own distinct species, divided by a wide ocean.

Charles Darwin would have had great fun working out how the modern theory of plate tectonics might be applied to his own theory of evolution. Perhaps he might have realised how it can be used to explain the mysterious Wallace Line which separates the Asian and Australasian zoogeographical regions. No doubt, he would have got many things wrong in his theorising, but knowledge of plate tectonics would have opened up a whole new line of enquiry for Darwin’s species work. It would have been yet more grist to his cerebral mill.

See also: Books – Charles Darwin, Geologist

BBC: Not one but ‘six giraffe species’

The world’s tallest animal, the giraffe, may actually be several species, a study has found. A report in BMC Biology uses genetic evidence to show that there may be at least six species of giraffe in Africa.

Currently giraffes are considered to represent a single species classified into multiple subspecies. The study shows geographic variation in hair coat colour is evident across the giraffe’s range in sub-Saharan Africa, suggesting reproductive isolation.

Note the inverted commas in the headline: the chaps at the BBC don’t sound too sure. It’s the age-old question as to when a sub-species becomes a species. There’s no clear-cut answer (although reproductive isolation is usually seen as an important factor). Where some cladists taxonomists see mere varieties, others see separate species. Those who make a habit of seeing the former are known as lumpers; those who see new species everywhere they look are dubbed splitters.

I had been under the impression that lumper and splitter were relatively modern labels, but not so, as this letter from the botanist Hewett Cottrell Watson to Charles Darwin shows:

The grand difficulty for naturalists or botanists of our turn of thought, is, that the use of the word “species” by technical describers is indefinite & variable. Theoretically, it is supposed to mean objects actually & essentially distinct,—so existing as productions of nature, & reproducing only their own selves or similitudes. Practically, it means only an idea of the mind, with no more real restriction in its application to objects, than have the words “genus” or “order“. Taking J. D. Hooker & Jordan as representative men for the opposite factions in botany,—’lumpers & splitters’, the former would reduce the species of Vascular plants to three score thousand, or perhaps much fewer;—while Jordan would raise them to three hundred thousand.

To his credit, Darwin’s great friend, Joseph Dalton Hooker fully acknowledged his reputation as a lumper, writing:

[George Bentham] has now completed the MSS of his British Flora, having studied every species from all parts of the world, & most of them alive in Britain, France & other parts of Europe—Well—he has turned out as great a lumper as I am! & worse

Not that there’s anything particularly wrong with being a lumper (or a splitter), you understand: it’s just a matter of tending to see things from different perspectives. And having differing perspectives is usually a good thing in science.

• Extensive population genetic structure in the giraffe (BMC Biology, 670kb PDF)
• There Are More Giraffe Species Than You Think (Living the Scientific Life)
• Now We Are Six (A Blog Around the Clock)

Charles Darwin to J.D. Hooker (11-Jan-1844):

Besides a general interest about the Southern lands, I have been now ever since my return [from the Beagle voyage] engaged in a very presumptuous work & which I know no one individual who w^d not say a very foolish one.— I was so struck with distribution of Galapagos organisms &c &c & with the character of the American fossil mammifers, &c &c that I determined to collect blindly every sort of fact, which c^d bear any way on what are species.— I have read heaps of agricultural & horticultural books, & have never ceased collecting facts— At last gleams of light have come, & I am almost convinced (quite contrary to opinion I started with) that species are not (it is like confessing a murder) immutable.

Hooker was one of the first people Darwin confided in regarding his heretical evolutionary views. He chose his friends well. They had only been corresponding with each other for two months, but Hooker was to remain one of Darwin’s most staunch allies for the rest of Darwin’s life.

Wallace’s letter no longer survives (which is wonderful for conspiracy theorists), but we do still have the letter Darwin immediately wrote to his friend and confidante, Charles Lyell:

My dear Lyell

Some year or so ago, you recommended me to read a paper by Wallace in the Annals, which had interested you & as I was writing to him, I knew this would please him much, so I told him. He has to day sent me the enclosed & asked me to forward it to you. It seems to me well worth reading. Your words have come true with a vengeance that I sh^d be forestalled. You said this when I explained to you here very briefly my views of “Natural Selection” depending on the Struggle for existence.— I never saw a more striking coincidence. if Wallace had my M.S.

Charles Darwin to Joseph Dalton Hooker, 27th May, 1855

… You ask about my Photograph; I have been done at the Club; but if I really have as bad an expression, as my photograph gives me, how I can have one single friend is surprising. My Brother has a large drawing of me, by Lawrence, of which he has had some photographs made & no doubt, if anyone really wished, others could be made.—

Hooker had evidently asked for a photograph of Darwin (the letter containing his request, as far as I can tell, does not survive), but Darwin didn’t much like his recent photograph—one of a series of photographs for the Literary and Scientific Portrait Club by Maull and Polyblank, who had also photographed Hooker—preferring a slightly earlier portrait in chalk by Samuel Laurence (not Lawrence).

Charlie ‘No Mates’ Darwin c.1855
by Maull and Polyblank

Darwin in 1853
by Samuel Laurence

I can’t say I blame him. The Maull and Polyblank photograph doesn’t do Darwin any favours: his expression is uptight, bordering on stern. Look at those glowering eyes! There’s a man who isn’t used to having his photograph taken. It’s the sort of photograph he might well have put on the mantelpiece to keep the kids away from the fire.

The Laurence portrait is far kinder to Darwin: although the trademark, ape-like brows are still there, the artist has captured a man deep in thought; a man who has worked out the meaning of life, but has told practically nobody about it yet. What on earth is going on inside that head?

Perhaps it isn’t so surprising that a man so worried about what the world would one day think of him should have cared two hoots about how he looked in a photograph, but I find it amusing that Darwin, like so many other people then and now, should have thought he didn’t photograph well.

Vanity, thy name was Darwin.

Charles Darwin to Joseph Dalton Hooker, 26th July, 1856

… I have let 3 x 4 sq^e feet [*] of old Lawn grow up, & 18 plants in 17 genera have flowered during this summer. Exactly same numbers as in whole Keeling Islands, though so many miles in length!—

I was delighted to learn that an experiment very similar to the one described by Darwin is being carried out by Patrick Roper, a consultant ecologist from Sedlescombe, East Sussex, England. Patrick began his experiment in September, 2003, and is recording developments as they happen on the experiment’s weblog, The square metre at TQ7828618846. Patrick has a number of similar weblogs, including one about his Windowbox Wildlife and his Ramblings of a Naturalist.

Great stuff! If only Darwin had been able to keep a weblog. But he wrote an awful lot of letters, which is pretty close.

[*] Footnote: The dimensions of Darwin’s lawn experiment are given as 3 x 4 square feet in the published (book) version of The Correspondence of Charles Darwin, whereas the online version linked to above gives the area as 34 square feet. I have little doubt the latter is a typo.