Putting earthworms on the map

Worm man: Darwin’s interest in earthworms led to the publication, in the last year of his life, of a book about them. This is a caricature of Darwin’s theory in the Punch almanac for 1882, published at the end of 1881, just after publication of his book, The Formation of Vegetable Mould through the Action of Worms with Observations of their Habits. (Image: PD-ART(cc PD-old-100)/Wikimedia Commons.) Just six months before he died, Charles Darwin had his last book published, summarising his insights on a topic that had fascinated him for fi ve decades. It sold faster than his more famous opus, On the Origin of Species, and it had a more down-toearth subject matter. The book was called The Formation of Vegetable Mould through the Action of Worms with Observations of their Habits. In his fi nal year, beset by illness and general gloom, Darwin was very keen to get this last book out and was well aware of the irony of obsessing about earthworms when he appeared to be on track to join them in their realm, as Adrian Desmond and James Moore note in their biography of the iconic scientist. Darwin had spent much effort on studying the behaviour of the worms he collected from his garden at Down House. He tested their intelligence by challenging their leaf-pulling behaviour with various materials, and he tested their hearing by shouting at them and by exposing them to the accomplished piano playing of his wife, Emma. Sadly, the musical merits of this entertainment will have been lost on the invertebrate audience, as Darwin established that the worms are stone deaf. While they responded to movements like his breath or the vibrations of the piano when their container was placed on top of the instrument, it became clear that they have no perception of sound waves travelling through the air. After the publication of the worms book, Darwin was left without a scientifi c project and thus with little motivation to keep up the fi ght. He died on April 19th 1882, but he did not rejoin the worms at Downe, as he had anticipated. Instead, the clamour for a state honour — to compensate for the fact that he had remained plain Mr Darwin to his death — led his remains to rest in the sandy foundations of Westminster Abbey.