Never underestimate the mind of a crow. Members of a family of birds that includes ravens, rooks, magpies, and jays, crows have been known to bend wire into hooks to retrieve food; drop nuts in a road so passing cars will crack them open; and recognize humans who have posed a threat, harassing them on-sight even months after their first encounter. But some of the smartest crows of all may be found in the animal physiology lab at the University of Tübingen in Germany. It’s there that the birds are mastering a skill you couldn’t manage until you were up to 4 years old: counting.
In a new study published in Science, researchers trained three crows to emit one to four caws in response to seeing the numbers 1, 2, 3, or 4 projected on a screen. The birds also learned to count out the proper number of vocalizations when cued by sounds, with a guitar chord eliciting a single caw, a cash register eliciting two, a drum roll signaling three, and a frequency sweep calling for four. In doing so, the birds matched or beat the numeracy skills of human children who often don’t master rudimentary counting until kindergarten.
Says animal physiologist and study co-author Andreas Nieder: “When faced with a set of three objects and asked, ‘How many?’ toddlers recite the speech sounds ‘one, two, three’ or even ‘one, one, one.’ We show that crows have the ability to count vocally [too].”
And crows aren’t the only creatures that understand simple math. Similar skills have been observed in studies of comparatively intelligent animals including gorillas, dolphins, elephants, the rhesus macaque, and the squirrel and capuchin monkeys. Even the less-clever rat can fathom basic arithmetic, with a recent study in Science Advances showing that the animals can be trained to hear two or three tones and then press a button corresponding to one number or the other. The learning didn’t come easy: It took two months for the rats to make that distinction, but it was the fact that they could do it at all—not that they were slow on the uptake—that was the true news.
The last few months alone have been something of a boom time for research into the intelligence and behavior of animals. German researchers discovered a sort of pre-verbal stage in finches—similar to the babbling stage in humans—that leads to their becoming fluent in song. Studies in Sweden and Vienna explored the role of play among barnyard chicks and a species of falcon. French researchers studied advanced use of sticks as tools in chimps, and other work in the U.S. made similar findings among otters. And perhaps most remarkably, researchers in Indonesia published a study about a wild orangutan, nicknamed Rakus by the scientists, that was observed chewing the leaves of a plant with known medicinal and analgesic properties and applying the resulting pulp to a wound on its face.
“It may be that Rakus learned this behavior from other animals in his birth area,” says lead author and animal behaviorist Isabelle Laumer of the Max Planck Institute in Germany. It is also possible that he came upon the discovery on his own, she says, accidentally applying the plant juice to himself by touching his wound while feeding on the leaves. “Rakus may have felt immediate pain release, causing him to repeat the behavior several times and subsequently apply solid plant matter,” adds Laumer.
All of these studies and more have implications not just for our understanding of animals, but for our understanding of ourselves, as creatures with often-similar brain structures. In one European study, researchers pinpointed twin regions in the human brain that allow us to recognize emotions in other people’s faces, and found corresponding regions in the brains of mice, raising the possibility that one of our most sophisticated traits—our ability to read the minds and moods of others—might be distributed throughout the animal kingdom.
“These evolutionarily conserved mechanisms should be common in most mammals,” says Francesco Papaleo, senior researcher at the Instituto Italiano de Tecnologia in Genoa, Italy, and a co-author of the study. “Properly recognizing and appropriately responding to altered emotions in others is essential for survival.”
The play is the thing
Of all of the recent research, it is the studies that explore play that illustrate the most engagingly ingenuous side of animals. Domestic chickens may be nobody’s idea of a personable species, but a May study in Frontiers of Ethology observed extensive play behavior in young hatchlings, especially males. Investigators raised the chicks in relatively spartan cages and then periodically transferred them to playpen areas with other chicks, aged from 6 to 53 days. In the presence of the rest of the flock, the males engaged in a wide range of play behaviors—all in sight of females—including frolicking, wing-flapping, jumping, and sparring. When the researchers introduced a rubber worm into the pens, the nearest male would pick it up and scurry around with it. Known in the wild as worm-running or tidbitting, the behavior, which can involve other forms of food as well, is an apparent display for the benefit of the females—a means of impressing them with the male’s resource-gathering skills.
“We still don’t know the adaptive function of play for any species,” said Per Jensen, professor of ethology at Linköping University in Sweden and a co-author of the study, in a statement. “However the present study indicates that a possible function is to prepare animals for specific challenges they may encounter later in life. In a species like the chicken, where only males compete for territories, it makes sense that they engage in more social play as young.”
Falcons display similar behavior for equally practical reasons. A February study in the Journal of Raptor Research documented the Falkland Islands species known as Striated Caracaras routinely engaging in play with sheets of plastic, sea cabbage, stones, and even sheep dung. To qualify as play, animal and human behavior has to meet several criteria, including being voluntary and repeatedly performed, appearing intrinsically rewarding, and lacking apparent purpose. But appearances notwithstanding, there may be decidedly practical functions to play.
In the case of the falcons, which live in a place in which food resources are more available in some seasons than in others, playing with objects might reveal an unexpected nutrient source. “The more caracaras interact with the world around them, the more opportunities they have to learn what is food and what isn’t,” said study co-author and behavioral ecologist Katie Harrington, of the University of Veterinary Medicine in Vienna, in a statement.
Animals, including homo sapiens, also play to practice combat, hunting, mating, and territorial claims, all of which are needed later in life. “That we see play in so many different species—including humans—tells us that it’s a really important component of our behavioral repertoire,” adds Harrington in an email to TIME. “We tend to see age differences, where younger individuals play more than older individuals. Studying the diversity of play can help us learn how and why it developed to be so important.”
The canine mind
Far and away the most studied animal mind in the world may belong to the domestic dog, if only because, with 471 million pet dogs worldwide, every home becomes something of a real-time, real-world behavioral lab. Still, it is the formal, peer-reviewed research that produces the most rigorous findings, and there is no shortage of that work. In one May study published in Animal Behaviour, investigators from the University of Helsinki subjected 987 dogs to various tests of behavior and problem-solving skills, looking for the traits such as impulsiveness, persistence, independence, and willingness to turn to humans for assistance, which help dogs function better either as working animals, domestic animals, or both.
In one test, the dogs were shown a short, clear cylinder containing a treat that was accessible only by an opening at either end of the container rather than through its transparent but impenetrable middle. The fewer times a subject dog mouthed the closed part of the cylinder before turning to the open end, the higher it scored. Another, similar test placed a treat behind a clear, V-shaped wall that required the dog to detour around the barrier, rather than simply bumping up against it in an attempt to get at the reward. A third test placed a treat inside a clear, locked box that was impossible for the dog to open—measuring how persistent the animal would be before giving up and turning to a human for help. A little persistence is considered good. Too much suggests a lack of learning curve.
On the whole, says Saara Junttila, doctoral researcher with the university’s faculty of veterinary medicine and lead author of the paper, dogs with lower inhibitory control were good problem solvers and excelled in working roles and in canine sports, but were less tractable and trainable in the home.
“As an example, the Belgian shepherd Malinois was one of the fastest breeds at solving the V-detour task, and this breed spent a lot of time trying to solve a problem independently rather than looking at a human. [But it] is considered to be a more challenging breed [to train],” Juntilla says. “Other breeds such as the golden retriever may be more suitable for the role of pet dog, as they turn to humans during a problem-solving situation and have higher inhibitory control.”
The findings have implications not just for canine behavior but for humans, too. Some researchers have found parallels between attention deficit hyperactivity disorder (ADHD) in people and similar distractibility and impulsiveness in dogs.
“Our results do seem to indicate that ADHD-type traits occur together,” says Junttila. “We found that dogs with low inhibitory control were more impulsive, less trainable, and had higher activity levels. People with ADHD [also] often have lower inhibitory control, impaired academic success, and higher impulsivity and hyperactivity.”
Dogs and people overlap in other ways, too. In one recent study published in Biologia Futura, investigators found that dogs that had been trained to imitate human behavior—such as turning or sitting or nodding their heads—do not need the cues to be delivered only in person, but could also obey them when simply seeing an image of a person on a computer screen. The dogs were better at imitating behavior when they saw the human from a perspective with which they were familiar—from the front or the side, for example, as opposed to from above. But either way, the investigators saw significance in the ability of the animals to make the leap that a two-dimensional image was effectively equivalent to a three-dimensional person.
Says lead author Claudia Fugazza, professor of ethology at Eötvös Loránd University in Budapest: “In general, dogs seem to be able…to extract the relevant information from 2D projections and use it to act appropriately in the 3D, real life context.” The findings have meaning that go beyond canine parlor tricks, opening up the possibility of virtual human-dog communications, serving to entertain the animals and provide emotional support to human companions.
Tooling about
The ability to use even simple tools was once seen as a talent limited to humans. Research has long since upended that belief, with studies showing a range of tool use among animals, including orangutans, which create whistles out of leaves to chase away predators; dolphins, which use marine sponges to scour the seafloor and stir up prey; and even the degus, a chinchilla-like rodent, which can be taught to use small rakes to look for food. New research is now turning up insights into the talents of one of nature’s most prodigious tool-users—the otter—with findings suggesting that the female of the species outperforms the male in this sophisticated skill.
The otters’ most common tool is a rock, which the animals use to crack open abalone shells to get to the tender meat inside. In a new study in Science, researchers from the University of Texas, Austin, and elsewhere observed 196 radio-tagged sea otters off the coast of California and discovered that the animals were using other tools as well—including shells and hard trash—to break open their prey. Females generally employed a wider array of tools than males did, an innovation they arrived at by necessity, as their smaller size and somewhat weaker jaws make cracking or biting open prey harder. Not only does more sophisticated tool use spare them tooth damage that they might otherwise sustain by trying to bite prey, it also provides them greater energy needed to raise and feed pups.
Chimps too are even better at tool use than commonly understood. The animals are most famously known for their ability to use twigs stripped of leaves to fish into small openings in logs and extract termites as food. New research in PLOS Biology found that this is not a static talent, but rather one that the animals improve throughout their lives, learning to fish for the insects by age 2 or so, and steadily improving their grip and eye-hand coordination over the years.
“The most efficient grips and actions to hold and manipulate stick tools continue to develop at least until [age] 15 [and] well into adulthood,” says lead author Mathieu Malherbe, primatologist with the Max Planck Institute in Germany.
This means war
Not every new trait animals exhibit is a noble one—a fact that is borne out by a recent study of bonobos. Colloquially known as the hippie chimp, for their generally peaceable ways and their matriarchal social structure, the great ape species turns out to be a lot more aggressive than thought, at least when it comes to male-on-male violence. Writing in the journal Current Biology, researchers from Harvard University found that male bonobos actually engage in three times the amount of mano-a-mano combat than their more warlike cousin, the chimpanzee. But the reason for the difference is paradoxical.
On the whole, chimps are significantly more violent as a group than bonobos, with bands of males engaging in sometimes mortal combat with other bands over access to food, territory, and females. This makes it essential that bonds within each tribe remain close—ensuring that the group presents the most united front when facing other tribes. Bonobos, which do not engage in organized warfare, can afford more squabbling and friction within the group without making themselves vulnerable to outsiders.
“The most likely causes of male aggression [among bonobos] are over who gets to stay in a feeding tree or at a good feeding spot,” says Martin Surbeck, assistant professor of human evolutionary biology at Harvard and a co-author of the study. “Chimpanzees depend on each other and thus have a lot of incentive not to make a fuss out of each potential conflict, while the individualistic nature of bonobo society makes aggression just way less costly and more frequent.”
The lovable scavenger
If the Striated Caracaras falcon is known for play, its cousin, the Chimango Caracaras, is developing a reputation for domestic bliss. In another study in the Journal of Raptor Research, investigators found elaborate co-parenting behavior between male and female pair-bonded birds. Among most species of raptors, the larger female incubates the eggs and defends the nest while the smaller male hunts for prey. Male and female Chimango Caracaras, however, which are scavengers, show little difference in size, and thus share responsibilities for gathering food as well as caring for the young.
A team led by PhD candidate Diego Gallego-Garcia of the Center for the Study and Conservation of Birds of Prey in Argentina studied 70 of the species’ nests and observed incubation, brooding, and food delivery responsibilities being evenly shared by both parents. The male and female alike also showed an understanding of the chicks’ needs throughout the day—brooding them more in the morning when temperatures were lower, for example. It is the species least lovely trait—its carrion diet—that contributes most to such an egalitarian household.
In raptors that kill live animals, says Gallego-Garcia, smaller males bring prey to the nest, but do not feed the chicks, relying on the larger female to “chunk the food” into bite-sized pieces. This, he says, “ties the female to the nest and prevents it from leaving to hunt. However in scavenger species, since carrion is usually brought as pieces of raw meat, it is more manageable for nestlings. This way the female is free to leave the nest and hunt, allowing for the biparental care that we observe.”
The balanced home is an animal grace note—one of a great many across both the human and the non-human world. “The case of the Chimango Caracara is rare among raptors, but is a general rule in most other birds, and not uncommon in mammals,” says Gallego-Garcia. “This reinforces the idea that, in these cases, both members of the couple are necessary for the successful rearing of the offspring.” As it goes in animals, so it goes in us.
