Judging animal intelligence not easy

By Dr. Beth Leermakers

“My golden retriever is smarter than your honor student.” Is that bumper sticker proclamation really true? Since you can’t administer a standard IQ test to animals, it’s difficult to determine and compare their intelligence. Furthermore, it’s tough to distinguish between general intelligence — the ability to perform well on multiple cognitive tasks, from math to problem solving — and specific skills such as a chimpanzee’s fine motor skills, which allow them to make tools. How do scientists evaluate animal intelligence, and what are some of the brainiest animals? 

Scientists have developed a variety of tests that measure these cognitive abilities and attributes in animals.

Self-recognition. Animals’ ability to recognize themselves is tested using a mirror. Researchers apply a mark (usually red paint or makeup) to the animal’s face and then show them their reflection. If the animals touch the mark on the mirror, they don’t recognize themselves. If they touch the mark on their own face, they have some sense of self-identity. People develop self-identity at 18 months of age.

Problem solving. To determine animals’ ability to solve new problems, researchers usually measure animals’ success at opening some kind of container to access food. I bought a puzzle toy that requires my dogs to find treats hidden in covered compartments. Some of my dogs, smelling the food, just pick up the entire puzzle and turn it over to dump out all the treats. I’m not sure that counts as logical problem solving. 

Tool use. Many animals use various objects as tools to gather food, with different levels of creativity and success. Creating a new tool by modifying an object the animal found requires greater intelligence than merely using a rock to smash open a shell. 

Memory and facial recognition. Memory is crucial for survival. Animals have to remember where they hid their food stashes, and they need to know that some berries are poisonous. Social animals need to be able to distinguish other animals in their pack by sight, sound or smell and understand how to interact with each other to survive.

Brain size. Although there are a few exceptions, in most cases, the bigger the brain, the smarter the animal. 

Here are a few animals that belong on the list of “smartest animals”:

Apes. Our closest genetic relatives (our genomes are 98 percent identical!) share our intelligence. Apes, particularly chimpanzees, are excellent problem solvers and tool makers/users, and they can use sign language to communicate with people. 

In fact, apes actually perform better than people at short term memory tasks, memorizing short number sequences and patterns in a fraction of a second. A chimpanzee may very well be smarter than your honor student. 

Dolphins. Dolphins are creative tool users. Indo-Pacific bottlenose dolphins, found in Australia, carry sponges in their beaks to protect their snouts from sharp rocks, stingrays and urchins, particularly as they forage for food along the seafloor. Another sign of intelligence is their communication system.  Their distinct whistles and clicks may serve as dolphin names, perhaps used in a type of language. 

Elephants. Elephants certainly have brain size on their side. Although it’s not true that elephants never forget, they do have excellent long-term memory and can recognize people and other elephants after being separated for years. Elephants are also one of the few animals that recognize themselves in the mirror. Apes and dolphins also pass the mirror test. 

Octopuses. Although they have relatively small brains, these invertebrates are excellent problem solvers and can escape from elaborate prisons (including unscrewing jar lids from the inside!). 

Octopuses have brain cells distributed throughout their entire body, including in all eight tentacles, allowing them to navigate and survive in constantly changing ocean ecosystems.
Photo courtesy of Science Alert

They use objects as tools, recognize faces, have a seemingly irrepressible curiosity and dislike boredom. Octopuses have brain cells distributed throughout their entire body, including in all eight tentacles, allowing them to navigate and survive in constantly changing ocean ecosystems. 

What about cats and dogs?

Although neither species belongs on the list of smartest animals, some dogs have impressive memories. One border collie remembered 1,022 nouns — the largest tested vocabulary of any dog. That dog probably was smarter than your honor student, too. 

The research doesn’t clearly indicate whether cats or dogs are smarter. A 2017 study concluded that dogs are smarter than cats, based on dogs having significantly more cortical brain cells (530 million) — responsible for thinking, planning and complex behavior — than cats (250 million). People have about 12 billion. 

However, in 2018 another study concluded that dogs aren’t geniuses after all. Researchers may consider dogs smarter than cats because dogs have been studied more often. Cats are rarely studied because — cat people already know this — they are uncooperative test subjects. Perhaps they really are the smarter species.