Robert Louis Stevenson’s adventure story Treasure Island makes, as the question notes, a number of references to animals, and even uses animal names for some of his characters, most notably, Black Dog. The use of animals in the story serves more to provide useful analogies, such as the description in Chapter 21 of the mutinying pirates as swarming “over the fence like monkeys,” than any deeper purpose, although it is easy to suggest that Stevenson is implying that those who live the pirate life are subhuman, more animal than human being. And therein lies the central dichotomy of Treasure Island: the pirates are cruel, murderous heathen, but represent the novel’s ideal of adventure and courage. While the novel’s more admirable figures, Dr. Livesey and Captain Smollett, are good men dedicated to doing right, they are dull and lacking in the kind of bravado and adventure that Jim Hawkins finds most attractive, especially in the person of Long John Silver. The comparison of the pirates to animals, however, is a motif repeated throughout the story, as when, in Chapter Nine, Stevenson has his narrator, Jim, describe the entrance of Silver:
“We were all hard at work, changing the powder and the berths, when the last man or two, and Long John along with them, came off in a shore-boat.
The cook came up the side like a monkey for cleverness, and as soon as he saw what was doing, ‘So ho, mates!’ says he. ‘What’s this?’
‘We’re a-changing of the powder, Jack,’ answers one.”
The animal analogies that occur throughout Treasure Island are not entirely negative. As one of the ship’s crew describes Silver to the young boy, he compares the brave pirate to the king of beasts, suggesting that “a lion’s nothing alongside of Long John!” In the novel’s greatest bit of irony, it is, in fact, an animal that appears to harbor a greater sense of wisdom than any of the human pirates. Having been introduced to Silver’s pet parrot, “Cap’n Flint,” Jim discovers over time that the parrot’s role in this motley crew is entirely aesthetic. In Chapter 27, Jim discovers the source of a series of important developments:
“Silver’s green parrot, Captain Flint! It was she whom I had heard pecking at a piece of bark; it was she, keeping better watch than any human being, who thus announced my arrival with her wearisome refrain.”
Stevenson blurs the line between human and animal because the history of Homo sapiens has all too frequently lent itself to the basest of comparisons. Humans may be at the top of the food chain, but their behavior too often does not compare favorably to members of the so-called “animal kingdom.”
The reader may well wish to reflect that Robert Lewis Stevenson composed his narrative of Treasure Island specifically for his stepson in an effort to provide the boy entertainment with a story of adventure replete with colorful characters. In the era in which this narrative was written, small boys especially were fond of animals and found them interesting and amusing. Certainly, to this day in many a children's book, there is much anthropomorphism, or the attribution of human characters to familiar animals. Curiously, Stevenson reverses the process, as well, attributing animal characteristics to humans. Perhaps, then, the notion that all creatures have similar traits allows the boy who listens to his stepfather to conceptualize easily the personages of the narrative. At any rate, equating the creatures makes the men more familiar to the child. Moreover, as the curmudgeon Andy Rooney, a longtime radio and television commentator, once observed, "The average dog is a nicer person than the average person," so, in this respect, Stevenson lends some of the less reputable characters more dignity by alluding to them in animal terminology.