Ranking animals by intelligence is always going to be a slippery proposition. Cleverness can be defined in many different ways, with skills and knowledge that are key to the survival of one species entirely irrelevant in the life of another.
There’s also so much we don’t yet understand about the consciousness and behaviour of wild animals – scientists around the world are making breakthroughs on the subject of animal intelligence all the time, with significant implications for our perception of our non-human friends.
This list, therefore, rather than being treated as gospel, should be considered a celebration of some of the animal kingdom’s most impressive problem solving, communication skills and capacity for play.
Cleverest animals
Chimpanzee (Pan troglodytes)
It should come as no surprise that chimpanzees, our nearest relatives, genetically speaking, are considered some of the smartest animals on Earth. They make and use tools in all manner of ways, from poking sticks into trees to extract insects, to wiping their mouths clean with leaves, to cracking nuts open with rocks.
These and other skills and behaviours are passed down from generation to generation. In the wild chimpanzees have a complex system of communication that includes varied calls, gestures and facial expressions, while in captivity some chimpanzees have been able to communicate with scientists using basic human sign language. They can also recognise themselves in mirrors and on video, an ability that suggests self-awareness – human children do not recognise themselves on video until the age of around four.
Komodo dragon (Varanus komodoensis)
The Komodo dragon can boast two superlatives: not only is it the largest lizard on the planet, growing to a length of up to 3m and a weight of 160kg, it’s also considered the most intelligent reptile.
While they’ll eat pretty much anything, including carrion, it’s as ambush hunters that Komodo dragons show off their smarts, lying in wait, well camouflaged, along a known trail for hours until an unsuspecting deer, pig or water buffalo wanders by. In captivity, Komodo dragons appear to recognise their own names and can tell the difference between their keepers.
Dolphin
Dolphins have a brain-to-body ratio – otherwise known as the encephalization quotient – second only to humans, and ahead of non-human primates.
While this ratio alone isn’t enough to make assumptions about animal intelligence, there’s plenty in the behaviour of these marine mammals to support the idea that they’re smart cookies. A group of bottlenose dolphins off the west coast of Australia, for example, has been observed picking up sea sponges and pushing through sand on the sea floor to disturb their small fish prey.
Other bottlenose dolphins, this time off the coasts of the USA, Mexico and Belize, have been recorded hunting by stirring up rings of mud to trap fish. And off Brazil, this species has a long history of working collaboratively with fishers to corral fish into nets – a practise that benefits both dolphins and humans with larger catches.
African grey parrot (Psittacus erithacus)
Labelled as the world's most intelligent bird, the African grey parrot is probably best known for its talent as a mimic, with some individuals able to effectively imitate the sounds of dozens of our words. But the skill of this charismatic species goes beyond mimicry to true understanding – Alex, an African grey studied by animal psychologist Dr. Irene Pepperberg over the course of 30 years, could identify 50 objects, seven colours and five shapes, as well as recognising numbers up to six.
He was also able to perform cognitive tests at a level higher than five-year-old human children, demonstrating reasoning. African grey parrots’ intelligence has unfortunately made them very sought after as pets, fuelling an illegal trade in wild birds that, alongside habitat loss, has led to the species being listed as Endangered on the IUCN Red List.
Rat
Another underappreciated but super smart animal is the rat. They have excellent spatial memories – finding their way through mazes in lab studies – are able to differentiate between numbers – whether or not they can actually ‘count’ is still a matter of scientific debate – and can recognise individual humans. Their whiskers are as sensitive as our fingertips, can hear sounds beyond the range of our hearing, and have eyes that can move independently of each other.
It’s thanks to this intelligence and adaptability (along with short gestation period and large litter sizes) that rats are so successful in the wild. The 56 species of Rattus are found almost everywhere that humans have settled, occupying myriad different habitats on every continent except for Antarctica and enjoying highly varied diets.
Crow
Crows aren’t exactly the best loved of our avian pals. It doesn’t help having ‘murder’ as a collective pronoun (the term came about because of this scavenger’s historic association with battlefields) but it’s high time that we look beyond this unfortunate quirk of grammar and give this amazing species proper credit. That’s because crows, along with their corvid cousins – ravens, jackdaws and jays – possess rather extraordinary intelligence.
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Corvids have been shown to make and use tools to locate prey – stripping twigs to delve into holes in trees, for example – can remember people’s faces, and can work out creative solutions to knotty problems.
Crows will drop nuts onto pedestrian crossings, for instance, waiting until it’s safe to cross collect the kernels once the shells have been opened by passing vehicles. The explanation for this brain power, despite the small size of their brains, is that their neurons are smaller and more tightly packed, giving them computational power akin to that of a gorilla.
Whale
Whales are known to communicate using a wide range of different sounds, with baleen whales such as humpback whales (Megaptera novaeangliae) and fin whales (Balaenoptera physalus) sending out low-pitched songs, and toothed whales such as orca (Orcinus orca) and sperm whales (Physeter macrocephalus) using echolocation.
These vary according to geography, with whales in different areas ‘speaking’ different dialects. Whales are also known to learn new songs from other whales, and to work together when hunting, whether that’s humpbacks creating so-called ‘bubble nets’ to trap and confuse fish, or orcas making waves to push seals off ice floes.
Another intriguing whale behaviour, one that scientists are yet to fully understand, but think is a sign of intelligence, is ‘kelping’. This practise of throwing pieces of seaweed around is thought to be evidence of play, a learning behaviour.
Elephant
They say elephants never forget and it turns out to be true: African elephants (Loxodonta africana) are able to differentiate between groups of humans based on their clothing, smell and voices, and adjust their behaviour according to the level of perceived threat.
They also have excellent memory for migration routes, with herds led by older matriarchs successfully finding their way to water during periods of drought. It is thought that this skill is partly down to elephant brains’ having the largest temporal lobe relative to body size – the temporal lobe is the area responsible for creating memories. Elephants also use tools, with both African and Asian elephants (Elephas maximus) known to break off branches to use as fly swatters.
Octopus
Octopuses – there are around 300 species worldwide – have not one but nine brains: a big central one plus a nerve centre in each of its eight tentacles. It’s brain to body ratio is also the largest of any invertebrate.
This unusual set up means that an octopus can sense and respond to its environment both locally and centrally. In the wild, this is useful for finding prey and hiding from predators, while in the lab, octopuses are able to get through mazes, open jars and untie knots.
Octopuses are also known to use tools: blanket octopuses, for example, will rip off the stinging tentacles of a Portuguese man o’war (to which they are immune) to use as a defence against predators.
Bee
There are more than 25,000 species of bee, each with their own unique adaptations to their particular habitats. What they all have in common, however, is an acute intelligence that makes them arguably the smartest insects in the world.
It used to be the case that bees were only considered intelligent in a purely social sense, but more recent research has proved a whole host of other capabilities.
Bees have been found to be able to count (useful for navigation), observe and learn (enabling them to differentiate between the flowers of different species of plants), use tools (smearing animal poo on their nest as a stinky defense against hornets), and communicate with symbolic language (honeybees waggle dance to tell each other where to find nectar - a talent that lead us to name them one of the best dancers in the animal kingdom).
They’ve even been shown to have emotion-like states, responding to scenarios differently when stressed.
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