What Is the Smartest Animal? The 10 Most Intelligent Animals, Ranked

Ask ten people what the smartest animal is and you will hear dolphins, chimps, crows and probably somebody’s dog. Each answer has a real experiment behind it, and each animal shines at something different. So, what is the smartest animal? Below you’ll find the 10 animals with the strongest evidence, the studies behind every claim and an honest look at how scientists compare minds that can’t sit a written test.

Is there an animal IQ scale? How scientists compare species

There is no animal IQ scale, and any “chimp IQ” number you see online is invented. An IQ score is built for humans: your answers are compared with a large sample of people your own age and placed on the human IQ scale, which has a mean of 100 and a standard deviation of 15 (our guide to what IQ is and how it’s calculated walks through the math). A dolphin can’t take that test, and even if it could, there is no group of dolphins to norm it against.

So researchers test abilities one at a time, with tasks built around each species’ body and senses:

• Mirror self-recognition: a mark is placed where the animal can only see it in a mirror. Does it use the mirror to inspect the mark?
• Tool use and causal reasoning: can it figure out which object will get the food, and why?
• Memory: how much can it hold in mind, and for how long?
• Planning and self-control: will it give up a small treat now for a bigger payoff later?
• Social cognition: does it understand what another individual knows or wants?
• Neuron counts: how many neurons sit in the parts of the brain that handle complex thinking?

The closest thing to an animal IQ scale comes from primates. Duke University researchers ran a meta-analysis of hundreds of published primate studies in 2006 and found that great apes (orangutans, chimpanzees and gorillas) consistently outperformed monkeys and prosimians across many kinds of tests, a hint of general, not just narrow, intelligence.

Lead author Robert Deaner added a caution that applies to every ranking in this article: one species may score higher “not because it’s smarter, but because one species is poorly suited to that particular testing situation.” A 2017 review in Behavioral and Brain Sciences (Burkart, Schubiger and van Schaik) found that studies of rodents and primates are consistent with a general intelligence factor, while stressing that the idea still needs validation.

Head-to-head comparisons with children are revealing, too. In a 2007 study published in Science, about 100 chimpanzees, 30 orangutans and 100 human children aged 2.5 took the same battery of tests. According to ScienceDaily’s summary, all three groups did about equally well on physical problems (space, quantities, cause and effect). On social tasks such as learning by imitation or reading intentions, the toddlers were right about 74% of the time and the apes about 33%.

The 10 most intelligent animals, ranked by evidence

This is not a score table. We weighed how flexible each species’ behavior is, how many abilities it has shown and how solid the studies are.

1. Chimpanzees: the numbers whiz named Ayumu

In a 2007 study in Current Biology (Inoue and Matsuzawa), a young chimpanzee named Ayumu watched numbers flash on a touchscreen, turn into white squares and then touched the squares in ascending order from memory. As National Geographic reported, when the numbers stayed visible for two thirds of a second, Ayumu and a group of university students were all about 80% accurate. When the display time dropped to one fifth of a second, the students fell to 40%, while Ayumu kept his high scores. Practice narrows the gap, though: humans who trained on the same task matched Ayumu (Silberberg and Kearns, 2009), and two practiced university students later outperformed him (Cook and Wilson, 2010).

Chimps also rewrote the definition of tool use. On November 4, 1960, at Gombe in Tanzania, Jane Goodall watched a chimpanzee she called David Greybeard strip the leaves from a stem and poke it into a termite mound to fish out insects. History.com recounts Louis Leakey’s famous reply: “Now we must redefine ‘tool,’ redefine ‘man’ or accept chimpanzees as human.”

2. Bonobos and orangutans: mind readers and self-medicators

Bonobos seem to grasp what others don’t know. In a preregistered 2025 study in PNAS (Townrow and Krupenye), three male bonobos, including the well-known Kanzi, watched food being hidden under one of several cups and could get it only if a human partner found it. They pointed more often and more quickly when the partner had not seen where the food went, which suggests they can track someone else’s ignorance and act on it.

Orangutans stand out for innovation. A 2024 paper in Scientific Reports (Laumer and colleagues) describes Rakus, a wild male Sumatran orangutan with a fresh facial wound, first seen on June 22, 2022. He chewed the leaves of a liana known for its painkilling and anti-inflammatory compounds, applied the juice to the wound again and again, then covered it with the chewed leaves. The wound had closed by June 30. The authors call it the first systematic documentation of active wound treatment with a biologically active plant in a wild animal.

3. Dolphins: they know who’s in the mirror and remember old friends for 20 years

In 2001, Diana Reiss and Lori Marino exposed two bottlenose dolphins to mirrors after marking their bodies. Both used the mirror to inspect the marked spots, at a time when convincing evidence of mirror self-recognition existed only for humans and great apes.

Their social memory is even more striking. Jason Bruck tested 43 dolphins across six facilities in a breeding consortium, including Brookfield Zoo and The Seas at Walt Disney World, by playing recordings of signature whistles, the dolphin equivalent of a name. In his 2013 study, the dolphins reacted far more strongly to former tank mates than to strangers, even after up to 20 years apart. It was the first evidence that social recognition can last at least 20 years in a nonhuman species.

4. Elephants: Happy passes the mirror test

At New York’s Bronx Zoo, researchers placed a jumbo mirror in front of three Asian elephants and marked each one’s head with a visible mark and an invisible sham mark. In a 2006 PNAS study (Plotnik, de Waal and Reiss), an elephant named Happy passed on the first day of marking, touching the visible mark with her trunk again and again while ignoring the sham. The other two did not pass. That sounds weak until you learn, via National Geographic, that only about half of chimpanzees pass it.

Elephants also understand teamwork. In a 2011 PNAS experiment (Plotnik and colleagues), pairs of elephants had to pull both ends of the same rope at once to get food. They waited up to 45 seconds for a late partner and didn’t bother pulling when the partner couldn’t reach the rope.

5. Crows, ravens and magpies: the feathered apes

Corvids put the old “bird brain” insult to rest. In a 2007 Current Biology study (Taylor and colleagues), New Caledonian crows faced meat they could only reach with a long stick, which they could only fetch with a short one. Six of seven crows tried using the short stick to get the long one, and four got the meat on the very first trial.

The same species solved real-life versions of Aesop’s fable. In a 2014 PLOS ONE study (Jelbert and colleagues), crows dropped stones into water-filled tubes rather than sand-filled ones and picked sinking objects over floating ones to raise the water level. They failed harder versions, but the authors rated their understanding of water displacement as rivaling that of 5- to 7-year-old children.

Ravens can plan. In a 2017 Science study from Lund University, five ravens learned to use a stone to open a puzzle box and to trade a bottle cap for food. Scientific American reported that the birds then chose the tool or token over a smaller immediate treat even when they could only use it 17 hours later, matching or beating great apes and 4-year-old children in some tasks. And magpies became the first non-mammal to show mirror self-recognition in a 2008 PLOS Biology study (Prior, Schwarz and Güntürkün).

6. African grey parrots: Alex and the idea of zero

Psychologist Irene Pepperberg worked with an African grey parrot named Alex for about 30 years. According to the Associated Press, Alex could identify 50 objects, seven colors and five shapes and count up to six. In a 2005 study, he answered “how many” questions about mixed groups of objects with over 80% accuracy, without training on those questions, and used the word “none” in a way the authors described as a zero-like concept.

7. Octopuses: the smartest invertebrate

Octopuses have more than 500 million neurons, according to the Okinawa Institute of Science and Technology, which puts them in the same range as a dog’s cerebral cortex (see the neuron table below), and over two thirds of them sit in the arms and body rather than the brain. In Indonesia, researchers watched veined octopuses carry coconut shell halves across the seafloor and assemble them into shelters when needed (Finn and colleagues, 2009). Because the shells pay off only later, it counts as tool use, and National Geographic described it as the first known case of tool use in an invertebrate.

8. Dogs: Chaser and her 1,022 words

A border collie named Chaser learned and remembered the names of 1,022 objects over three years of training (Pilley and Reid, 2011). She could also work out the name of a new toy by exclusion: if the word was unfamiliar, it probably meant the one toy she didn’t know yet, a learning strategy usually credited to young children. Breed differences are a story of their own, covered in our ranking of the smartest dog breeds.

9. Pigs: gamers with hooves

In a 2021 study in Frontiers in Psychology (Croney and Boysen), two Yorkshire pigs and two micro pigs learned to operate a joystick that steered a cursor into targets on a computer screen. All four scored significantly above chance on their first attempts at one-walled targets, despite the visual and dexterity limits the authors noted.

10. Rats: helpers and hide-and-seek players

Rats are easy to underrate. In a 2011 Science study (Ben-Ami Bartal and colleagues), rats learned to open a restrainer to free a trapped cagemate. They ignored empty restrainers, and when a second restrainer held chocolate, they usually freed their companion and shared the chocolate.

In 2019, researchers in Berlin even taught rats to play hide-and-seek, rewarding them with tickling instead of food. The rats learned to switch between hiding and seeking, stayed quiet while hiding and, according to the Science paper, preferred opaque boxes when it was their turn to hide.

Brain size or neuron count: which animal has the most brainpower?

If big brains meant big intelligence, elephants and whales would top every list. Neuroscientist Suzana Herculano-Houzel’s lab showed why that logic fails: brain size is not a reliable proxy for neuron count, because different animal groups pack neurons at very different densities. Her team proposes that the absolute number of neurons in the cortex (or its bird equivalent, the pallium) is a better guide to cognitive capacity.

The table holds two surprises. First, the elephant brain has three times as many neurons as ours, yet 97.5% of them sit in the cerebellum, leaving its cortex with about a third of the human count. Second, birds punch far above their brain weight: parrots and songbirds pack about twice as many neurons as primate brains of the same mass, which helps explain how a raven’s small brain can plan ahead.

The pilot whale is the twist that keeps scientists humble. A 2014 count found about 37.2 billion neocortical neurons, more than any mammal studied up to then, humans included. The authors concluded that neuron numbers alone can’t explain the cognitive gap between humans and cetaceans. (The dog and cat counts come from a 2017 study whose authors cautioned that claims about the two species’ actual abilities remain largely a matter of opinion.)

The mirror test: useful, but not an intelligence score

The mirror mark test, made famous by psychologist Gordon Gallup’s 1970 study of chimpanzees, became the most famous yardstick in animal cognition. Great apes, dolphins, an elephant and magpies have passed it. Then a fish did.

In a 2019 PLOS Biology study (Kohda and colleagues), cleaner wrasse, small reef fish that pick parasites off larger fish, tried to scrape off a colored mark by rubbing their bodies against surfaces, but only when a mirror let them see it. Reviewers were split, and the journal published the paper with an editor’s note. A 2022 follow-up found that all 14 new fish scraped their throats when given a brown, parasite-like mark, but only in front of a mirror.

So either a small reef fish is self-aware, or the mirror test measures something narrower than we thought. Either way, passing or failing says little on its own, especially since plenty of individual chimpanzees fail.

So, what is the smartest animal? It depends on the skill

Line up the smartest animals by ability and the winner keeps changing:

• Working memory: chimpanzees, thanks to Ayumu’s number test.
• Planning ahead: ravens and great apes.
• Social memory: dolphins, with whistle recognition after up to 20 years.
• Cooperation: elephants, who wait for a partner who hasn’t arrived yet.
• Causal reasoning and tool use: New Caledonian crows and chimpanzees.
• Words and labels: African grey parrots and the occasional prodigy dog.
• Breadth across all of these: great apes, which is why they top most evidence-based lists.

Which animal is the most intelligent?

If you want a single answer for the most intelligent animal after humans, the evidence points to the chimpanzee, with bonobos and orangutans close behind. No animal wins every test, but on our reading of the studies above, no other group shows strong results across as many abilities as the great apes.

This patchwork is not unique to animals. Psychologists split human intelligence into abilities too, such as fluid reasoning, verbal knowledge, spatial skill and memory, as explained in our guide to the types of intelligence. The difference is that humans can all take the same test, so their abilities can be measured on one scale.

From the smartest animals to your own IQ

No chimp, crow or dolphin will ever get an IQ score, because there is no species-wide test to compare them on. You, on the other hand, can be measured against other test takers on the standard mean-100 scale, across several of the same abilities scientists probe in animals: pattern recognition, spatial reasoning, numbers, logic and memory.

The IQtonics IQ test has 40 progressively harder questions across those five areas, with a 20-minute time limit. Your result is placed on the standard IQ scale (mean 100, standard deviation 15) with a percentile, plus a cognitive profile that shows your strongest area. Starting the test is free; your full results unlock with a trial membership, which renews automatically unless you cancel it. It is an online test, not a clinical assessment. Want to warm up first? See what to expect in our guide to IQ test questions, then see what counts as a good IQ score to read your result.