Kew’s connection with Charles Darwin: an evolutionary relationship
On 11 January 1844, a long letter on cream paper was sent by Penny Post to the home of William Hooker, the director of Kew. Addressed to Hooker’s son Joseph, and written in black India ink in a scrawling hand, it looked much the same as any other letter arriving at the Botanic Gardens.
But this letter wasn’t like any other, for its contents were the first expression of an idea that would change the world. "It is like confessing a murder," wrote the letter’s author, the naturalist Charles Darwin, for he had just taken an extraordinary step.
He had confided in Joseph Hooker, a friend of just a few months, explaining his suspicions that species of plants and animals were not fixed as created by God, but had come into being by a process of slow evolution, by a mechanism that would come to be known as natural selection. "You will now groan," wrote Darwin, apologising for his radical confession, "and think to yourself 'on what a man have I been wasting my time in writing to'," but Joseph Hooker repaid Darwin’s confidence.
Unwilling to trust such radical theories to any of his scientific contemporaries, Darwin recognised in Joseph Hooker a keen mind, a world-class researcher and, most importantly, a loyal and lifelong friend.
Darwin used Hooker as a sounding board for all his new ideas, and scholars are clear on the significance of the relationship. "Without Hooker and Kew, the Origin of Species wouldn’t exist as we now know it," says Jim Endersby, lecturer in the history of science at the University of Sussex and author of Imperial Nature, a new book about Joseph Hooker.
"[He] contributed intellectually, and put Darwin in contact with Kew’s network of possible contributors, but the value of his friendship to Darwin was almost more important."
Darwin and Hooker had first become acquainted in late 1843, after Darwin found himself in need of a good plant taxonomist to work on the specimens he had collected on the voyage of the Beagle. Joseph, son of Kew’s formidable director, was an interesting choice. Eight years younger than Darwin, he was desperate to prove himself as a professional botanist, having returned from an icy voyage on HMS Erebus full of ambition.
Letters criss-crossed from Kew to Darwin’s home at Down House in Kent over the next few months. In their first letters, Darwin addressed Hooker formally, but the two men quickly became warm friends and by spring 1844 Darwin’s letters invariably began "My dear Hooker".
In the course of his studies, Darwin sent queries about whether Hooker knew of any hooked seeds that grab on to fur occurring on islands lacking large quadrupeds. Joseph Hooker quickly replied that he would look into it, and sent as a gift a portrait of the German naturalist Alexander von Humboldt, one of Darwin’s heroes. Sir William Hooker also sent a deodar cedar (Cedrus deodara), which Darwin planted at Down House.
According to Professor David Mabberley of the Herbarium, Kew’s usefulness to Darwin was clear: "Darwin always said he didn’t understand plant systematics, even though he was actually a very good botanist." Darwin saw in Hooker a born classifier who could give Darwin’s plant studies the rigour he was looking for – "for the advantage of Botanical Ignoramuses like myself", Darwin wrote early on in their friendship.
Hooker repaid Darwin’s confidence – he worked rapidly, sorting Darwin’s Southern Hemisphere collections into genus and species. Many of the dried plant specimen sheets collected by Darwin in the Galapagos and elsewhere on his famous voyage eventually ended up in Kew’s Herbarium, annotated in Darwin’s scrawled writing and classified according to Hooker’s system.
But the exchange between Darwin and Kew didn’t stop at taxonomic knowledge. Darwin’s intellectual curiosity was voracious, ranging across different disciplines and topics with extraordinary energy. He was self-deprecating about this part of his character:
"Your interesting letters tempt me to be very unreasonable in asking you questions", Darwin wrote to Hooker in 1844. In response, Hooker used all the resources of Kew to try to answer Darwin’s 'unreasonable questions', in pursuit of answers he thought would change science for ever.
Darwin and Hooker’s interests coincided in one important area – biogeography. Darwin knew that any evolutionary theory would need to explain how plants came to be distributed across the Earth’s surface. However, the two men didn’t always agree – Darwin theorised that plant species colonised new areas of land by floating as seeds across the oceans. Hooker pooh-poohed this idea, arguing that seeds would be killed by saltwater and that long-vanished land bridges were a more likely explanation.
An important test case came in the seeds of the Entada vine. These smooth, flattened beans float across the Atlantic on the Gulf Stream from their Caribbean homeland, occasionally washing up as far away as Britain and Scandinavia. Darwin longed to study these beans and realised that Hooker’s Kew contacts could open many useful doors. Hooker solicited Entada beans from the British consul in Norway and the head of the botanic garden in the Azores, demonstrating the power of Kew’s imperial reach and its usefulness for Darwin’s purposes.
The early relationship between Kew and Darwin had been conducted entirely by post, despite Hooker’s enthusiastic invitations: "I wish you would come to Kew and see the plans for planting 48 acres as an arboretum".
Finally, in June 1844, Darwin asked for details of the steamboats to Kew from London Bridge. In the end, he came by farmer’s cart on Thursday 18 July 1844, with his wife Emma, granddaughter of the renowned potter Josiah Wedgwood. From then, Hooker became a regular visitor to Down House, coming with plants and specimens and spending several hours a day talking through scientific questions with Darwin in his study.
As to the ‘Species Theory’, Hooker kept Darwin’s confidence, just as Darwin had hoped. It wasn’t until 1858’s Linnean Society meeting that the pressure of Alfred Russel Wallace’s similar theory forced Darwin to reveal his hand. Stress kept Darwin himself away from the meeting, but Hooker helped to present the paper, although the audience showed surprisingly little sign of having heard something revolutionary. Afterwards Hooker wrote joyfully that he was "most thankful… that I can now use Darwin’s doctrines – hitherto they have been kept secrets I was bound in honour to know, to keep, to discuss with him in private – but never to allude to in public."
Darwin benefited from Kew in simpler ways, too. He suffered greatly from bad health, and after his doctor forbade him to eat sugar in the late 1870s, Darwin’s sweet tooth drove him to distraction. It was Hooker who directed the resources of the Royal Botanic Gardens to producing bananas for this VIP invalid. The best fruits from the Palm House were sent to Down House by courier – Darwin wrote grateful letters of thanks, and the family always referred to the bananas by a coded nickname, 'Kew gooseberries'.
The long friendship came to an end with Darwin’s death in spring 1882, but Hooker sent his best wishes to Emma and the family, returning all of Darwin’s letters to them as a final tender gesture. In his will Darwin revealed the extent of his gratitude to Kew, leaving essential funds for the Index Kewensis (the formal register of all plant names, still maintained today by Kew in the form of The International Plant Names Index).
And through Joseph Hooker, the relationship between Kew and Charles Darwin was firmly written into history. We can only envy a friendship of such warmth and longevity – as Darwin wrote admiringly, "What a candid honest fellow you are, too candid and too honest. Fighting a battle with you clears my mind wonderfully."
Kew is helping schoolchildren learn about Darwin’s work and the importance of plants through The Great Plant Hunt, supported by The Wellcome Trust.
Author: Emma Townshend