Last month National Geographic published an article about dolphin intelligence called “It’s time for a conversation”. The article highlighted research about dolphin communication and included an eye-catching graphic that drew parallel evolutionary tracks for human and dolphin brains.

The assertion that some animals have intelligence comparable to humans is not new: it was made by Charles Darwin and his supporters in the late 19th century. One of those supporters, George Romanes, chose his address to the British Association for the Advancement of Science meeting in Dublin in 1878 to make his case. So much of our culture is built around the assumption of a division between human and animal that his subject was a tough sell.

John Lilly’s early research on dolphin language was also dismissed, understandably, when he began giving the animals LSD.

Romanes also crossed an invisible line when he attributed emotions, morality and learning to animals in 1878. Many of Romanes’s ideas now sound familiar and not particularly controversial. The substance of his claims was that the most intelligent animals, such as dogs and horses, could learn from their sensory experience to form abstract ideas. Examples included dogs that associated rumbling sounds with thunder or knew all the signs of a scolding before a word was spoken. When a rumbling noise was produced by other means, the dog hid under a sofa as he did in a thunderstorm. When he was shown the source of the “thunder”, he relaxed. When Romanes made angry faces without so much as opening his mouth, the dog cowered, believing he was accused of wrong.

Romanes claimed that animals could experience “all the human emotions except those which refer to religion and to the sublime”. He thought that interaction with humans helped to endow pets with moral sense. This had important implications for how humans should behave towards animals in their care.

Romanes felt that his lecture was a huge success. He wrote to Charles Darwin the next day that “the applause was also really extraordinary” and remarked that the most sustained applause had been at the mention of Darwin himself, at which there was “loud and long-continued cheering”. The reception of the Dublin public and the press was less enthusiastic, however.

The Dublin satirical magazine Zoz depicted Romanes standing at a podium while a dog sat upon it and remarked “Bow wow”. Mildly disapproving editorials appeared in most of the major papers. The Freeman’s Journal wrote that Romanes’s lecture was ill-suited to an audience in “the Catholic capital of a Catholic country” and took issue with Darwinian ideas about the similarity between humans and animals.

Accused of slipshod science

Religion was not the only stick used to beat Romanes. Letters to the editor accused him of slipshod science as “strong in anecdote as any garrulous old woman”. The general feeling was that Romanes had proposed far too much continuity between human and animal intelligence and that he relied on anecdote. Scientific critics suggested that all Romanes had revealed was the marvellous complexity of instinct rather than intelligence.

Undeterred, Romanes went on to publish a book about animal intelligence – or comparative psychology, as he called it – in 1882. The book was concerned not just with describing the intelligence of animals but ranking it against human intelligence. The book says at least as much about Romanes’s views of human society as it does about his views of animals. “Aristocratic” dogs that have “fallen in pleasant places” were the only dogs “whose feelings may therefore be said to have profited by the refining influences of culture”. Only these aristocratic dogs could exhibit the full range of emotions.

Perhaps it is getting easier for us to imagine we are not in unique possession of intelligence. Jane Goodall’s Nonhuman Rights Project has widespread, if minority, support. Research on animal intelligence, however, may always be dogged by the accusation of getting too close to the subject. Like Romanes using pets to support his argument, the fact that Goodall named the chimpanzees that she worked with suggested an intimacy with her subject that has been interpreted as unscientific. Likewise Lilly’s willingness to share the psychological experience of the 1960s with his dolphin subjects. Our ability to form intimate bonds with animals is, for some, proof of continuity. For others, it is simply bad science.