How Smart Are Dolphins?

Dolphins jumping out of the water
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Besides humans, dolphins are said to be the smartest animals on Earth — smarter, even, than any other primate. They have extraordinarily large brains in comparison to body size and exhibit exceptional levels of emotional and social intelligence. They have the capacity to communicate through language, solve complex problems, use tools, and remember a great number of pod members for long periods of time, just like humans.

Dolphins are highly social and have been proven to deeply care for and learn from one another. However, they're also acutely self-aware. They are one of the only known animals that can recognize themselves in a mirror.

Find out more about what makes these cetaceans so clever and how, exactly, their smarts stack up against human intelligence.

Dolphin Brain Size

Dolphins are second only to humans in brain-to-body size ratio, beating out all other highly intelligent members of the primate family. In terms of mass, a bottlenose dolphin's brain typically weighs 1,500 to 1,700 grams, which is slightly more than a human's and four times the weight of a chimpanzee's. Although brain size doesn't alone determine intelligence, having a big brain, compared to body size, can certainly help free up space for more complex cognitive tasks, scientists say.

Dolphin Cognition

dolphin
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Renowned dolphin researcher Louis Herman referred to dolphins as humans' "cognitive cousins" on account of the many characteristics they share with humans and great apes, even though cetaceans and primates are only slightly related. Cognition is an umbrella term used to describe high level brain functions like thinking, knowing, remembering, judging, and problem-solving. These functions allow us to use language, imagination, perception, and to plan.

Problem-Solving

An experiment conducted in 2010 at the Dolphin Research Center in Grassy Key, Florida, found that a bottlenose dolphin named Tanner tapped into his problem-solving capabilities to imitate the actions of other dolphins and humans while blindfolded. With his eyes covered by latex suction cups, Tanner resorted to another sense — his hearing — to determine the proximity and position of other dolphins and his trainer (in a follow-up study). Even though the sound of a human in the water differs from the sound of another dolphin in the water, Tanner was still able to mimic his trainer's changing swimming styles without being able to see him.

Future Planning

Dolphin catching fish in sea
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Many other dolphins have risen to fame with their various feats of sophistication. Consider Kelly, a resident of the Institute for Marine Mammal Studies in Mississippi, who earned a reputation in the early 2000s for gull baiting. Her cheeky tricks started after the staff began rewarding the dolphins with fish every time they cleaned up a piece of litter. Kelly resolved to hide a piece of paper under a rock at the bottom of the pool so that she could tear off one small sliver at a time, knowing that she would earn more treats with more pieces of paper. 

Then, once Kelly discovered that a seagull would earn her even more fish than a piece of paper, she began hiding fish where she hid the paper, and baiting gulls with her own treats. This case of the trainer being trained by the trainee showed that Kelly was, in fact, capable of planning for the future and understood the concept of delayed gratification.

Communication

School in Formation
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Dolphins have an extensive and complex communication system that allows them to decipher exactly which member of the pod is "talking." Although those in captivity have been trained to respond to certain hand motions, they naturally communicate through pulses, clicks, and whistles rather than vision.

In 2000, behavioral ecologist Peter Tyack proposed the idea that the pitch of a dolphin's whistle functions as a means of individual identification — like a name. They use their "signature whistles" to announce their presence or let others in the pod know where they are. They'll even emit their unique whistles especially loudly when they're in distress.

There are other similarities, in addition to these name-like whistles, between dolphin and human communication. One study published in 2016 found that some Black Sea bottlenose dolphin vocalizations were "signals of a highly advanced spoken language." They're capable of carrying on conversations and stringing together "sentences" with their various-pitched pulses taking the place of words.

What's more, they follow a very humanlike trajectory of language development, starting out as babblers and learning the laws of language over time. And, of course, the many dolphins that have been taught tricks in captivity prove that they, too, are capable of learning human words and grammar (even the difference between "take the hoop to the ball" and "take the ball to the hoop").

Echolocation 

Like toothed whales, bats, shrews, and some birds, dolphins use a physiological process called echolocation, also known as bio sonar. This allows certain animals to locate distant, sometimes invisible objects using only sound waves, which travel four and a half times faster in water than on land. Whereas most other species (even whales) create these sounds with their larynxes, dolphins force air through their nasal passages to produce sequences of short, broad-spectrum burst-pulses known as "click trains."

These clicks then travel through water at a speed of nearly 1,500 meters (1,640 yards) per second, bouncing off any nearby objects and returning to the dolphin via its lower jaw bones, ultimately letting it know what's nearby. The process is sensitive enough to even reveal the size, shape, and speed of an object that is hundreds of yards away. 

It was through echolocation that Tanner was able to detect his trainer's location and mimic his exact movements without being able to use sight. Dolphins use echolocation to find both food sources and potentially threatening things in the water.

Self-Recognition

Bottlenose dolphin sees reflection in a mirror.

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One of the most prominent testaments to dolphin intelligence is their ability to recognize themselves in a mirror. The mirror test — also called the mark test or MSR, for "mirror self recognition" test — is a technique designed to measure self-awareness. The only animals to have passed the test so far are dolphins, great apes, orcas, a single elephant, the Eurasian magpie, and cleaner wrasse.

The mirror test usually involves anesthetizing an animal and marking a part of its body that it can't normally see, then, when it wakes up, putting it in front of a mirror to see whether it investigates the mark. If it does, there's evidence that it recognizes itself in the reflective surface. Two male bottlenose dolphins were tested using this method in 2001, and researchers determined that they not only recognized themselves, but provided a "striking example of evolutionary convergence with great apes and humans."

The study mentioned such exploratory behaviors as "repetitious head circling" and "close viewing of the eye or genital region reflected in the mirror." More recent tests have revealed that dolphins actually recognize themselves in a mirror earlier in life than humans do — about seven months versus 15 to 18 months.

Memory

Long-term memory (scientifically known as LTSR, "long-term social recognition") is another indicator of cognitive capacity, and a 2013 study revealed that dolphins have the longest known memory other than that of humans. The experiment, led by University of Chicago animal behaviorist Jason Bruck, included 43 bottlenose dolphins that had been part of a breeding consortium between the U.S. and Bermuda for decades. First, the researchers played whistles of unfamiliar dolphins over a speaker until the dolphins got bored of them. Then, they played the whistles of old social partners from which they had been separated for 20 years, and the dolphins perked up, some of them whistling their own "names" and listening for a response.

Dolphins Use Tools

Dolphins, like primates, crows, and sea otters, also use tools, a skill once thought to be possessed by only humans. In the '90s, an Indo-Pacific bottlenose dolphin population that had been the center of long-term research was observed on several occasions carrying around sponges through deep water channels. The phenomenon mostly occurred among females.

While the study noted that they could be playing with the sponges or using them for medicinal purposes, researchers determined that they were most likely using them as a foraging tool, perhaps to protect their snouts from sharp objects, stinging sea urchins, and the like.

Are Dolphins Smarter Than Humans?

Despite the running joke that Kelly the dolphin "trained her own trainer," intelligence tests indicate that dolphins do not actually surpass humans in cognition. One measure to take into account, considering intelligence has been repeatedly linked to brain size, is the encephalization quotient — or EQ — which considers an animal's brain mass compared to the brain mass predicted for an animal of its size. Other than humans, who possess an EQ of around 7.5, dolphins have the highest EQ of any animal, about 5.3. This means their brains are more than five times the mass they're expected to be. 

Emotional Intelligence

The many cetaceans witnessed pushing deceased pod mates in the water for days have provided substantial anecdotal evidence that dolphins feel grief, a complex emotion experienced only by social creatures with large, complex brains. But a 2018 study published in Zoology quantified the occurrence, saying that of all surveyed cetacean species, dolphins attended to dead conspecifics most often (92% of the time).

Adult and two baby spotted dolphins swim in the Caribbean ocean. Stenella spp. Bahama Islands.
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As demonstrated by their friendly countenances, dolphins are also brimming with personality. Data shows there are both bold and shy types, and that dolphins' individual personalities determine the structure of their social networks. For instance, bold dolphins play a central role in group cohesion and the spreading of information.

Their emotional capacity has even led some researchers to draft and lobby for a cetacean-specific Declaration of Rights. Lori Marino of Emory University, Thomas I. White of Loyola Marymount University, and Chris Butler-Stroud of the Whale and Dolphin Conservation Society, who proposed the document during the world's largest science conference (the American Association for the Advancement of Science in Vancouver, Canada) in 2012, said dolphins should be perceived as "nonhuman persons" because they exhibit individuality, consciousness, and self-awareness. The Declaration of Rights aims to prevent the killing of these clever marine mammals by commercial whaling.

Social Intelligence

Group of Atlantic spotted dolphins (Stenella frontalis), underwater view, Santa Cruz de Tenerife, Canary Islands, Spain
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Dolphins live in complex groups and exhibit strong bonds with their pod mates, with whom they swim and hunt. Pods can contain anywhere between two and 15 dolphins. Like humans, their social networks are composed of close family members and acquaintances. They are thought to have a "collective consciousness" that sometimes results in mass stranding. One dolphin's distress calls will cause others to follow it ashore. When being herded together, they huddle instead of trying to jump the net. These acts provide proof that dolphins are compassionate.

Within their social systems, they also form long-term cooperative partnerships and alliances, exhibit conformity (as is the case with the tool-using population), and learn from their pod members.

Dolphins Have Spindle Neurons

Studies show that dolphins have special, spindle-shaped neurons called Von Economo neurons, or VENs, that aid in the intuitive assessment of complex situations, like social interplay. VENs are housed in the anterior cingulate cortex, the part of the brain responsible for emotion, decision-making, and autonomic functions, and are found only in a handful of social species outside of the great ape category. Dolphins have three times as many VENs as humans.

Social Learning

Dolphins learn to forage, play, and even perform tricks simply by observing their pod members. This phenomenon is evident in the conformity demonstrated by the Indo-Pacific pod of tool-using dolphins, and also in Wave, the wild bottlenose dolphin that left researcher and conservationist Mike Bossley in shock when it leapt from the water of Australia's Port River and began "tail-walking." This trick, in which the dolphin uses its tail flukes to "walk" on the water's surface while remaining in a vertical position, is often taught to dolphins in captivity. It was discovered that Wave had learned the behavior from another, once-captive dolphin, and that other members of the pod had picked up on the stunt as well.

This kind of social learning happens frequently among wild species, but most often, the techniques that permeate animal populations involve essential tasks, such as feeding and mating. Tail-walking, however, seemed to have no adaptive function. It isn't clear why the wild dolphins picked up on such a trivial trick — or why they performed it more frequently after Billie, the once-captive dolphin that sparked the behavior, had died — but this phenomenon remains one of the best examples of dolphin social learning decades after it was first discovered.