Research into the inner lives of animals – their feelings and thought processes – has only just begun. For much of history, biologists and behavioral scientists assumed that animal intelligence could be neatly organized in a hierarchy. Homo sapiens was placed at the very top, followed by our fellow primates. Then came the other mammals, the birds, reptiles and insects.
Then, in the 1960s, a new generation of researchers forced the rest of the academic community to understand animal intelligence in looser terms. They thought the conventional definition of intelligence—something consisting of both consciousness and the capacity for abstract thought—was too specific for our own species; because each animal followed a very different evolutionary trajectory, intelligence must be measured in relative rather than absolute terms.
Over the following decades, a variety of technologies that allow us to observe animals for extended periods of time without disrupting their normal routines revealed behaviors far more sophisticated than many species had previously been attributed. In Melbourne, remote-controlled drones are helping researchers better understand the breeding patterns of southern right whales. Meanwhile, AI is learning to understand, track and predict the movements of organisms.
Regardless of our rapidly changing conception of animal intelligence, it is best recognized when an animal’s behavior resembles ours. Take elephants, for example, who are said to remember and return to the graves of sick members of their herd. A 2019 literature review and study revealed that they also show an unusual interest in the dead bodies of other elephants that persists through the stages of decomposition — indicating their fascination with death and perhaps even hinting at the awareness of their mortality.
Dolphins are a particularly popular test subject for intelligence studies. As far back as 2006, researchers suspected that these aquatic mammals use whistles that act as analogs for human names, assigning a unique frequency to each member of a pod. While many insects communicate via pheromones that always trigger the same predetermined responses, communication with dolphins – like human language – seems more flexible and context dependent; a 2017 study found that dolphins in Laguna in southern Brazil had developed a distinct accent after more than 100 years of sustained interaction with the local fishermen.
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Displays of high intelligence are not limited to mammals. Many birds, including parrots, organize themselves into complex social groups where fellow members of their species are treated differently depending on their relationship to each other, a behavior indicative of a predisposition to associative learning, one of many markers of intelligence. And insects, however tiny their brains, have a whole repertoire of impressive cognitive skills, from tool use and facial recognition to numerical competence and observational learning.
The Evolution of Animal Intelligence
Recognizing intelligence is one thing, understanding where it comes from is another. Until recently, researchers believed that the development of cognitive ability was somewhat unique to our evolutionary line, from mammals to primates and eventually to us. Now research is questioning this hypothesis. For example, newly discovered similarities between the structure of our brains and the brains of cephalopods suggest that intelligence could be the product of convergent evolution — that is, a target that can be reached by any species, as long as they are exposed to the right environmental pressures.
Research suggests that, far from being organized in a hierarchy, intelligence is in fact distributed across the animal kingdom in different ways. In fact, a 2020 study found that most animals “displayed exceptional abilities in some cognitive domains, while performing poorly in others.” Chimpanzees, for their part, have better short-term memory than humans, presumably because short-term memory is more useful in the wild, where life-or-death decisions have to be made on a daily basis and in the blink of an eye.
The study of animal intelligence is heavily based on developments in neuroscience. Many animals are known to have semantic memory – the ability to associate one thing with another, such as the pain of a bee sting with the appearance of a bee. However, recent studies suggest that some animals, such as rats and pigeons, are also capable of episodic memory — the ability to recall past experiences by briefly reliving them in their minds.
Intelligence is connected with other mental qualities that have long been considered distinctly human, including feeling and self-awareness. Most great apes have already shown that they can recognize themselves in a mirror, and so have dolphins and elephants. In the past, rhesus monkeys were successfully taught to recognize their own reflection when they are not naturally inclined to do so, suggesting that self-awareness may be a skill that can be trained.
It turns out that figuring out how an animal feels is even harder than figuring out what’s going on thinks. Studies, driven in part by the increasing appeals of animal rights activists, agree that all vertebrates can in all likelihood experience pain because of the similarities in their nervous systems. However, most of these studies have focused solely on whether animals can experience negative rather than positive emotions, meaning there’s still a lot we don’t know about their inner lives.
As time goes on, we are constantly amazed at the level of cognitive complexity that animals exhibit. Sometimes the method of their madness can be hard to spot, especially when hampered by centuries of evolutionary divergence. Modern technology and theoretical frameworks are finally allowing us to see with some precision, and although the search only began a handful of decades ago, we’ve already discovered more similarities between animals and ourselves than we expected.