The many forms of animal intelligence
I have an abiding sense of shame about what initially seemed like an exciting culinary adventure: I ate a small octopus right after it had been dismembered. The fish market food stalls in Seoul offer the ultimate in freshness: they pull a fish out of a tank, and then it becomes sushi right in front of you. I’d had charbroiled octopus before, and as a regular sushi eater I couldn’t quite imagine why eating octopus sushi was problematic. But after the Seoul fishmonger chopped up the octopus, it didn’t stop moving. Its arms crawled off the plate. My friend didn’t want to eat it, but I insisted that we not let its death go to waste.
I haven’t eaten an octopus since, less because I was disgusted by the roving meal than because I learned that octopuses are smart—very smart—and that ⅔ of its neurons are in its arms. Octopus arms have decision-making abilities that they coordinate with the octopus’s central brain. As Kara Rosania notes in Nature, “These arms can use tools, twist off lids and even childproof caps, withdraw from a noxious stimulus, and keep from entangling one another. Many of these feats have been observed in amputated octopus arms, demonstrating how little input from the central brain is needed.” I wondered whether the arms trying to climb off my plate knew they were in danger, even after being cut off.
Non-mammalian brains can be hard to decipher, not only because they are structured differently, but also because it’s difficult to conceive of intelligence that doesn’t look like our own. Indeed, a New York Times article, in acknowledging how smart octopuses appear to be, also asked “but why?” Normally, large brains and complex cognitive behaviors are coupled with an animal’s longevity, since it takes a long time to develop and hone the skills that these brains are capable of. Octopuses, though, only live for 2-3 years, deteriorating after they reproduce. Their remarkable adaptivity to new environments—they can decide to change color—and their problem solving abilities, evidenced by their ability to escape captive environments, just don’t seem to scale to their lifespans.
Other animals whose cognitive abilities are not always appreciated include birds, but especially the corvid family, to which crows, ravens, jays, and magpies belong. While African Gray parrots doing mental feats might not shock us—after all, they can imitate human speech—corvid intelligence may be less obvious. Like octopuses’, bird brains do not map neatly onto human brain structures. Bird brains lack a cortex, which in humans consists of the gray matter forming the frontal lobe, parietal lobe, temporal lobe, and occipital lobe. These are responsible for perception, memory, decision making, and personality, among other things. Nevertheless, corvids display primate levels of cognition: crows recognize themselves in the mirror, plan for the future, and even show an understanding of water displacement—they’ll drop stones into a glass to raise the water level. How do they do this without a cortex? One theory lies in the discovery that corvid and parrot brains have twice the neuron density of similarly sized brains in primates, with most of the work of the cortex being done in the neuron-packed bird forebrain.
In contrast to crows whose collective name is “a murder”, we are emotionally connected to dogs, so we may be primed to think the best of them and their brainpower. But even for the most dog-loving humans, the findings of a recent study might be unexpected: it concluded that dogs have an understanding of numerosity—that is, the concept of quantity—even if they don’t understand numbers per se. If offered a few treats versus one treat, dogs chose a few. But, they also show an understanding of how many treats there should be if a person places first one, then two treats behind a screen, then secretly removes one. The dogs display confusion when the expected two treats aren’t there.
But this is nothing compared to an insight into ape psychology. Not only were bonobos, orangutans, and chimpanzees confounded by the disappearance of objects like dogs were, but they appeared to have a theory of mind that anticipated whether humans would also be confused. That is, when one person hid an object from another, the apes knew whether a barrier blocked the humans from seeing the object being moved, based on the barrier’s transparency. They seemed to understand that an opaque barrier prevented the human from knowing an object had been moved from its expected location. Apes’ theory of mind is still controversial, but whatever consensus the scientific community ends up with, something we can take away from the experiment is a reminder that we can’t and don’t always know what other animals know. Which is a good reason not to underestimate them.
By Aimee Fountain
References:
https://www.pnas.org/content/116/42/20904 & https://science.sciencemag.org/content/354/6308/110/tab-e-letters (rebuttal)
https://www.sciencedirect.com/science/article/abs/pii/S0376635715300814
https://link.springer.com/article/10.1007/s10071-002-0140-0
https://royalsocietypublishing.org/doi/10.1098/rsbl.2019.0666
https://www.nature.com/articles/laban.615.pdf?origin=ppub
https://www.ncbi.nlm.nih.gov/books/NBK538496/
https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0092895