On 23 September 1832 a young naturalist, thousands of miles from home and frequently seasick and homesick, found the fossil of an enormous skull embedded in soft rock. It took Charles Darwin three hours to chip it out of the cliff face at Punta Alta in Argentina, and hours more to lug it back to base. He arrived with it long after dark at the ship which became the most famous in the history of natural science, the Beagle.
Darwin was only 24, a college dropout from his medical degree who had done a crash course in geology in order to join the voyage. He was wild with excitement about the chase, writing in a letter to a friend: “I have just got scent of some fossil bones of a Mammoth, what they may be I do not know, but if gold or galloping will get them, they shall be mine”.
Darwin’s treasures, brought on board after every shore trip to the exasperation of the crew of the small cramped ship, and sent back to England whenever he came upon a vessel making the return journey, were all meticulously recorded in his journals, and labelled according to a four-colour system he devised himself using printed labels he had brought from England.
His fossils, much less famous now in the history of how he came to publish his theory of evolution by natural selection than his observations of wildlife, are among the treasures of the Natural History Museum in London. They are still of interest to scientists all over the world but many of the originals are almost too fragile to handle. The NHM this week launches an ambitious project to scan and digitally recreate the fossils in 3D, in such minute detail that they can be studied by scientists as well as pored over by members of the public. One of the first completed has just been digitally dissected by a scientist in Montpellier in France.
The digitisation also guarantees that a permanent record of the bones will be preserved as scientific tests continue. Carbon dating has recently confirmed a date for one which Darwin could only have guessed at from the rock layer in which he found it – just 12,660 years old, so very close to the extinction of its species – and the NHM will now attempt to extract DNA from it.
The first to go online is the skull of Toxodon platensis, which Darwin found propped up against the fence in a Uruguayan farmer’s yard, where the local children competed to throw stones and knock out its teeth. Darwin bought it for a shilling and sixpence (equivalent to £6.40 today). Its curved teeth led Darwin and fellow scientists to wonder if it was an gigantic rodent, but it was eventually identified as a distant relative of a rhinoceros – and the last member of a group of South American mammals stretching back 60m years.
As they arrived back in England, Darwin’s fossils were already becoming famous and making his reputation, when he still had years of the voyage ahead. One batch contained a missing section of a skeleton which had already been sent back by another collector – the creature whose skull Darwin had chipped out of the cliff face. They were the remains of Megatherium, a ground dwelling relative of modern tree dwelling sloths – but Megatherium was the size of a car, the largest and heaviest land mammal ever to live in South America. After the fossils were displayed at a science event in London, one friend wrote to Darwin: “From sending home the much desired bones of Megatherium your name is likely to be immortalised.” In fact, Megatherium and its relationship to modern animals was one of the observations which would set Darwin’s mind on the course which would make his name immortal, and the publication decades later of his great book.
At the NHM, senior curator Pip Brewer and Adrian Lister, a research leader in the museum’s Earth Sciences department who has written a new book on Darwin’s fossils, share Darwin’s excitement over the hunt, having tracked down a chunk of fossil where it has been missing in plain sight for more than a century.
They launched an international hunt for Darwin fossils as part of the project. Most came to their museum after the second world war from the Royal College of Surgeons – which in the 19th century had the best comparative anatomy collection, while Darwin was scathing about the British Museum’s displays of its natural history specimens. The huge skull remains with the RCS, and others went to Harvard in the 19th century with a Swiss scientist, a correspondent of Darwin’s. The missing slice of the skull which Darwin chipped out of the Argentinian cliff in 1832 turned up in his own home, Down House, now a museum run by English Heritage.
“They told us they had a bit of tooth in the stores but they no idea what it was. When we got there they had had it laid out on a table and we recognised it as the missing piece of Megatherium in seconds,” Lister said. They later brought the fossil to the RCS, and could see instantly how perfectly the cut marks matched with the rest of the skull.
“It wasn’t quite as dramatic as Darwin’s discovery of it – but it was still such a thrill,” Brewer added.