The Intelligence of Earthworms

A surprising list of villains who reduced animals as mere things with no proof except genesis of bullshit in their own minds - Seneca, Aristotle, Augustine, Cicero, and of course the master villain Descartes. 

Before Darwin came in for rescue, it was David Hume who first inferred all living beings have rational thoughts,  and emotions. Read the whole piece here; a small one but packed with history. 

By the beginning of the 18th century, however, faith in man’s uniqueness had begun to crumble. Now that Aristotle had been rejected, others sought to define thought and reason in broader terms, which eroded the distinction between animals and humans. Leading the charge was David Hume. In A Treatise of Human Nature (1739-40), he argued that thought consisted in ‘images’ arising from sensory data and that reason should be understood as a ‘mere disposition or instinct to form associations among such [images] on the basis of past experience’. Mindful of dogs and horses, he maintained that ‘beasts are endowed with thought and reason as well as men’. A similar argument was put forward by Voltaire in his Dictionnaire philosophique (1764). Yet while it was to enjoy a certain vogue in the early 19th century, some naturalists, such as William Whewell, remained unconvinced. Clinging to the theological wreckage, they refused to grant animals the same status as men; and, in the absence of any decisive proof, showed no signs of changing their minds. An impasse was reached.

Into the fray stepped Darwin. Born slightly over 40 years after Hume’s death, he was immersed in the new thinking. His grandfather, the zoologist Erasmus Darwin, had been a keen reader of Hume’s Treatise and such progressive ideas were a common subject of discussion in the family home. It was almost inevitable that he should take an interest in the question of animal cognition. But when he did, he approached it from a completely different perspective. 

In On the Origin of Species (1859), Darwin demonstrated that, rather than having been created in a singular act by an omnipotent deity, all varieties of animal and plant life had evolved gradually, over many generations, as a result of natural selection. Pursuing the implications of this argument further in The Descent of Man (1871), he went on to contend that man, too, was ‘descended from some pre-existing form’ and had evolved in response to similar processes. As both critics and supporters realised, this confounded any attempt to distinguish between men and beasts – and raised questions about their cognitive abilities.

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Darwin found what he was looking for in worms’ burrows. To prevent air getting in, they have a tendency to block up the entrance to their homes using whatever is at hand. Their preference is, however, for leaves. Whereas, if they lacked reason, they might have been expected to seize them any old how, Darwin observed that they ‘acted in nearly the same manner as would a man’, dragging the leaves down into their burrows by the pointed tip, rather than by the stalk. To his amazement, they did the same thing even when given leaves from trees which are not indigenous to Britain and when presented with several leaves glued together. This could not be mere instinct. It had to be a sign of rational intelligence. 

Needless to say, Darwin would have been the first to admit that worms’ thoughts are probably quite modest. But that they think at all was enough to validate his theory of evolution – and to demonstrate beyond a doubt that all living things share similar cognitive processes. This is more than just a scientific fact, though. It is also a reminder that even the most humble of creatures demand our respect. For if even the worm can think like us, what earthly reason is there not to show them the same consideration as we show one another?