“Tickle, yeah,” Pepperberg counters. “That was some cute little tickle.” Athena redeems herself when Pepperberg quizzes her on the color of a plastic cup. “Ya-yow,” Athena rasps out her version of yellow.

Pepperberg has spent nearly four decades investigating the cognitive abilities of African grays. Athena has big wings to fill; one of her predecessors at the lab was Alex, maybe the world’s smartest parrot until he died unexpectedly a decade ago. Under Pepperberg’s tutelage, Alex identified colors, objects, and shapes and asked for wood, paper, wool, keys, and blocks by name. Another of her parrots picked out shapes obscured by optical illusions. Pepperberg’s work helped show that parrots — once considered natural mimics with no real comprehension — belonged in the ranks of the “smartest” nonhumans.

Pepperberg and her parrots aren’t alone. We knew dogs and cats were bright, but now researchers are finding these favorite pets have much higher levels of cognitive capabilities than was previously understood. Animal studies have also revealed startling mental abilities in tropical fish, crows, even ant lions. “People are much more open to the idea of animal intelligence than they were 40 years ago,” Pepperberg says.


Her parrots are like clever, mischievous preschoolers, Pepperberg says, noting they have done well on many of the same tests — object permanence, delayed gratification, number concepts — that correspond to stages of early childhood. Meanwhile, researchers are delving more deeply into the physiology of the animal brain. For instance, bird brains are physically tiny compared with primate brains, and should not be able to process as much information. Zoologists at Charles University in Prague documented in 2016 that some parrots, along with members of the crow family, average twice as many neurons as a primate brain of similar size, which could explain their better-than-expected cognition.


Even most mammals weren’t thought to be able to relive experiences, until MIT neuroscientist Matt Wilson, in a landmark 2001 study, discovered that lab rats not only dream, they dream about the mazes they ran while awake.

Whether animals can suffer emotional pain was long a source of argument, but now the bigger question is how to tell when animals are in pain, especially ones that don’t make sounds. Concern about what animals feel already affects our daily lives. Many of the 16 million Americans who are vegetarians or vegans say they stopped eating meat, poultry, fish, even crustaceans and shellfish, because they won’t consume creatures that feel physical pain. Massachusetts voters in November overwhelmingly passed a ballot question prohibiting the sale of eggs, veal, or pork from animals confined in conditions considered inhumane.

photograph from associated press

We think of our pets as having personalities of their own, but it’s hard to prove animals think of themselves as unique individuals or can make decisions to advance their own well-being. We know dolphins, primates, and elephants can recognize themselves in mirrors, and chickens can forgo an immediate treat for a later, larger reward. But does that necessarily mean animals feel happy when things go their way and bummed when they don’t? Pepperberg hesitates when I ask. Her parrots “want tickle” — having someone ruffle or scratch their feathers — so often that it suggests enjoyment. At the same time, she knows her parrots say “sorry” because of the reaction it gets from her, not because they experience remorse.


Discoveries about animal cognition are advancing rapidly. In just the last few years, researchers have unearthed mind-boggling abilities in creatures most of us don’t consider even marginally brainy and are finding remarkably advanced abilities in species already known for their smarts. Here are 10 things we now know animals know:

DOODLEBUGS CAN STRATEGIZE

It’s not quite The Art of War, but ant lion larvae — pincered predators known as doodlebugs — can fine-tune their hunting strategy. Mount Holyoke College psychologist Karen Hollis and a student taught the insects to associate different vibrational “signatures” with larger prey. As the educated insects laid in wait for unsuspecting bugs to stumble into their funnel-shaped sand traps, they’d let smaller prey escape. When they captured their desired victims, they buried them more often and more rapidly than untrained ant lions.

PIGS PICK UP ON MOODS

Pigs that got to wallow in a large pen filled with peat, straw, and chocolate raisins were more popular than pigs put in a small compartment and subjected to noises like balloons popping and vacuum cleaners roaring. When scientists at Wageningen University in the Netherlands put the pigs from pig heaven and pig purgatory in a room with a control group of pigs that had been in neither, the new pigs were more likely to act playful and wag their tails around the pampered porkers. The other pigs often got a porcine snub: pinned-back ears. Their behavior demonstrated “emotional contagion” — sharing the emotional response of those nearby.


ORANGUTANS CAN MIX DRINKS

An adult Sumatran orangutan with a fondness for sweet drinks was given varying combinations of cherry, lemon, and rhubarb juices and cider vinegar. Researchers at Lund University compared his ability to predict the sweetest combinations with a group of humans and found the orangutan was almost on par. That ability to apply experiences to new scenarios was previously considered uniquely human, the researchers said in a paper published in August.

TROPICAL FISH RECOGNIZE FACES

Some colorful tropical and subtropical fish called wrasses outperformed chimpanzees and other primates on inductive-learning tests, which measure the ability to make decisions based on evidence. Meanwhile, archerfish, a kind of tropical fish that spit jets of water at airborne prey, learned to spit at photos of human faces in a way that showed they could distinguish among them. You’ll probably never see a frillfin goby in an aquarium, but it can memorize local topography as it swims, and at low tide uses that mental map to leap from one pool to the next.

DOGS KNOW WHEN YOU SPOUT NONSENSE

photograph from associated press

At least, dogs seem to know the difference between words of real praise and just a happy tone of voice. In August, researchers in Hungary published results from using fMRI scanning to show that the reward pathway in dogs’ brains lit up when they heard words of praise in an approving tone, but not when they heard random words in that same praising tone or were praised in a flat tone. They also showed that dogs, like us, process words in the left brain hemisphere and intonation in the right.


HORSES CAN LEARN TO READ, SORT OF

Tricks and jobs aren’t the only things we can teach animals. Norwegian scientists taught horses to request a warm blanket for their backs. The researchers helped 23 horses of different ages, sexes, and breeds learn symbols that meant “blanket on,” “blanket off,” or “no change.” Horse school happened in two to three five-minute chunks daily, over about 10 days. By the end, all the horses had graduated. It wasn’t quite Mr. Ed, but scientists said the horses understood both how their choices affected their own comfort level and how to communicate through symbols.

CHICKENS ARE NO DUMB CLUCKS

It turns out that the lowly chicken may have a bad rap. Chickens possess basic arithmetic skills. They can demonstrate self-control, perceive time, and they may even have the ability to anticipate events, according to a researcher at a Utah center for animal advocacy, who recently surveyed a number of scientific reports on chickens. One study found that roosters will sometimes use deception to attract females, making a “come-and-get-it” squawk, even when there’s no food around. For their part, the hens quickly learn to ignore the birds who cried wolf about the food.

BATS ARGUE

Egyptian fruit bats spend a lot of time griping at one another, according to a December study from Tel Aviv University. In fact, they quibble with their cave mates about many of the same things cohabiting humans do, such as who gets the biggest piece of fruit or the best spot on the cave wall. Researchers also found that bats squabble about sex. No means no, even when you’re a bat.

YOUR CAT HAS A NAME FOR YOU, BUB

Fluffy the feline may not come when called, but she expects you to. Cats invent specific meows meant for their owners and no one else, a University of Georgia researcher found. Also, cats use body language differently than we’d think. A sick or hurt cat will purr even though it’s unhappy: It’s telling its owner, “Don’t go anywhere, please.” And that cat cue of rubbing against you and wrapping its tail around you doesn’t mean “Feed me.” Feral cats use the same behavior when they return from hunting; it’s a sort of cat hug and greeting.

CROWS CAN MacGYVER

Gulls and tuskfish use rocks to break open clams, but New Caledonian crows gin up tools out of found materials such as twigs, fashioning them into levers and hooks, and not just for food. In July, a research team from Sweden’s Lund University reported on a crow that figured out how to carry off a wooden ball too big for its beak. Researchers had never seen an animal use a tool to carry something, but this bird grabbed a stick and tried to put the stick in a hole in the ball. The stick was too big, so he found a thinner stick, stuck it in the hole, and flew off with the ball.

Deborah Halber is a science journalist and author based in Lexington. Send comments to magazine@globe.com. Follow us on Twitter at @BostonGlobeMag.