It’s almost impossible to come up with a definitive, ranked list of the smartest animals in the world, not least because scientists don’t agree on a single, specific definition of intelligence, or how to measure it.
All animals – including humans – have evolved their cognitive abilities to succeed in their natural habitat. For human beings, we use many indicators of intelligence – self-awareness, creativity, abstract thinking, cooperation, altruism, problem-solving, maths skills, social learning, language and communication skills, and many more.
When measuring animal intelligence scientists tend to look at similar indicators, which possibly underestimates animal intelligence by relying too much on human-centric testing. It’s easy to recognize the traditional human signs of intelligence in great apes with their tool use and communication skills, but a wide range of non-primate species have also been observed to display traits of intelligence.
Measuring animal intelligence can be problematic, and comparing intelligence across the animal kingdom is a tricky task, as tests are usually created for one specific species and hard to reuse reliably across species.
Bearing all of this context in mind we’ve pulled together this list of 15 of the smartest animals (excluding humans) ranked by their relative intelligence in reverse order:
Often overlooked when thinking about the smartest animals, raccoons are renowned for their lock picking skills, and are able to remember the solutions to problems for years.
Researchers at the University of Wyoming performed a test, giving raccoons some pebbles and a jug of water containing marshmallows. Half of the raccoons figured out that they could add the pebbles to the jug to raise the water level and get the marshmallows. That’s some pretty sophisticated problem solving that would stretch a young human.
Parrots are well known for puzzle-solving and reproducing human words, but tests have shown that in some cases parrots actually understand the meaning of the words they speak.
An African grey parrot named Alex was trained by a Harvard psychologist to recognize colours, shapes, and more than 100 English words. The video below shows that Alex the African parrot has a true understanding of these concepts, rather than simply memorizing objects:
Much like domesticated dogs, some cats have been trained to follow instructions and sit, roll, or perform other tricks on demand. Along with being trickier to train, cats are harder to study, as their famed indifference to things means they’re less likely to participate in experiments.
It’s this disinterest that may actually be a sign of their smarts. Some sociologists believe that the cats’ combination of curiosity and cautious behaviour, along with their complete independence are evidence of high intelligence.
Numerous in most major cities around the world, these birds considered by many as pests are actually pretty smart. Their ubiquity has led to them being involved in plenty of intelligence tests over the years, in which they perform surprisingly well.
Pigeons have been shown to recognize the correspondence between objects and pictures, recognize individual human faces, and identify themselves in a mirror. It may be that the pigeon is a super-intelligent bird, or simply one of average intelligence that has been over-studied. Either way, they clearly demonstrate many abilities that we would class as intelligence in any other species.
The squirrels’ persistence, memory, and cunning have made it the arch-enemy of gardeners worldwide. Essentially woodland animals, they have adapted to live alongside humans, and use an array of strategies to feed from bird-feeders and any food they can figure out how to access.
Some squirrels in California have been observed covering their fur in rattlesnake scent to mask their own scent from predators. And when storing their food for the winter months squirrels sometimes make an elaborate pretense of hiding food to confuse would-be thieves, another sign of advanced intellect.
The much-maligned rat is widely used in research labs, and has been the subject of countless intelligence tests. These highly intelligent rodents are natural students who excel at learning and understanding concepts. Although considerably smaller than dogs, they seem to be at least as capable of solving problems.
Even though rats have poor eyesight, they excel at solving mazes, and once they learn a navigation route they never forget it. And as with many other intelligent animals, rats are highly empathetic. One study showed that the vast majority of rats tested chose to help another rat which was being forced to tread water, even when offered the opportunity of a treat instead.
All the other species on this smartest animals list are vertebrates (i.e. have backbones), but there are some extremely clever invertebrates. Not only does the octopus have the largest brain of any invertebrate and share complex human brain features such as folded lobes, but 60% of their neurons are actually in their arms!
Octopi are known to use tools, such as one kept in an aquarium that threw rocks and sprays water at the overhead lights to break them, and another filmed scooping up halved coconut shells to use as protection. Other signs of intelligence include the smarts to screw the lid off a jar, and quickly navigate their way through mazes.
Domesticated dogs use their intelligence to relate to humans. They are able to understand emotions and symbolic language, and show empathy.
In some ways, dogs have more human-like behaviour that primates, and are able to follow and respond to human gestures, like pointing and eye movements without training.
The average dog understands around 165 human words, but are able to learn many more. One border collie named Chaser was able to recall over 1,000 object names and had the ability to understand basic elements of English grammar in the form of short sentences (e.g. “to ball take frisbee”).
Probably the smartest domesticated animals in the animal kingdom, pigs display a large number of intelligence traits. They are able to solve mazes, display and understand emotions, and grasp the concept of reflection at a younger age than humans.
Pigs can also understand abstract representations, and apply this skill to such tasks as playing computer games. In fact, in some tests using video screens pigs performed as quickly as chimpanzees. One other pointer to their intelligence is the pigs’ ability to out-compete native species wherever they have been taken.
The crow is part of the super-intelligent Corvid bird family, which includes magpies, ravens, jays, and crows. Crows are the only birds (or indeed, non-primate vertebrates) known to invent tools – forming probes and hooks from sticks and leaf stems to poke into the crowns of the palm trees. Young birds are able to make tools, but improve their skills by watching and imitating their elders, a sure sign of a high animal IQ. Scientists believe that New Caledonian crows specifically are the smartest birds, in part because they stay in the nest as fledglings – rather than heading off on their own – giving them more time to develop their cognitive abilities.
Understanding cause and effect – some say to the ability of a 5 to 7 year old human – leads them to master their environment, for example by dropping nuts on to roads to allow cars to crack the nutshells for them to eat the nuts. Combine this with the ability to recognize human faces and communicate complex concepts, and it’s easy to see why crows are considered the most intelligent birds.
One way to measure intelligence is by comparing the brain to body size, and the elephant has the largest brain of any land animal, with as many neurons as a human brain.
Elephants are known to have excellent memories, seem to be capable of extreme empathy, and are self-aware, recognizing themselves in a mirror. They’re also capable of working cooperatively to solve puzzles, with one experiment set up requiring two elephants to drag different ropes in unison to access two food bowls.
Dolphins (and whales) are at least as smart as birds and primates, with large brains relative to their bodies. Not only that, but the dolphin brain has more folds than a human brain, suggesting potentially higher intelligence.
Dolphins and whales are the only marine animals that pass the mirror test of self-awareness, and are extremely sociable animals with a clear sense of social identity. And as with other highly intelligent species they use tools – for example using sponges to protect their snouts when foraging on the seafloor.
Many scientists believe that dolphins clicks and whistles may actually be a sophisticated language, with some sounds serving as dolphin names. Like many of the most intelligent animals on earth, young dolphins stay close to their mothers for several years to gain schooling in many life lessons.
One of the smartest animals after humans, orangutans are especially gifted in terms of intellect. Like chimpanzees, they have their own cultures, and have been observed using a variety of sophisticated tools in the wild. Like gorillas, each night they construct elaborate sleeping nests from branches and foliage.
Orangutans live primarily solitary lives in widely scattered communities and form strong but distant social bonds. One study showed that they use ‘calculated reciprocity’ to weigh the costs and benefits of gift exchanges and keep track of these over time – the first nonhuman species seen exhibiting this behaviour.
Our closest living relatives with a 99% gene overlap with humans, it’s hardly surprising that top of this list of smartest animals is the chimpanzee. Their intelligence is displayed in so many ways that overlap with human abilities – they can make and use tools, hunt as a group, use sign language, exhibit altruism, empathy, and self-awareness.
Groups of chimpanzees develop their own cultures – unique tendencies and behaviours that are learned or imitated in contrast to other groups, and are capable of sophisticated communication. They use over 60 distinct gestures to communicate with each other in the wild, and can learn human sign language when in captivity.
And if that weren’t enough, there have been some memory tests where chimps actually outperformed humans… so what is the smartest animal in the world – a human or a chimpanzee?
And that’s your lot for our pick of the world’s smartest animals. What do you think – did any of the smartest animals on the list surprise you? Or perhaps we’ve left out an obvious pick to add to the intelligent animals list. Let us know your thoughts in the comments section below!