What makes crows so smart

These flows of information underlie cultural evolution that, rather than biological adaptations, may have helped swell urban corvid populations far beyond their historical numbers—a trend often explained purely in terms of garbage-eating.

But one of the most important cultural adaptations, McGowan says, involves how crows and ravens regard humans. Like our own societies, those of crows and ravens are fission-fusion. Groups form and split and come together in new configurations across time and space.

The lifestyle offers many potential benefits—safety in numbers, shared knowledge of food sources, cooperation to obtain it—and also disease, aggression, and competition. The need to manage social complexity has shaped many facets of crow and raven cognition, including extraordinary powers of recall. They seemed to remember their old friends. The results testified to the importance of social memory, and little wonder. Social bonds can be quite powerful: Melanie Piazza, director of animal care at the WildCare wildlife hospital in San Rafael, tells of how juvenile crows sometimes feed their cage-mates as if practicing to be parents.

In a variation on that experiment, ravens will also forgo the snack in exchange for a tool they can later use to open a box of food. The experiment suggests an ability to make plans, a profound faculty whose existence argues against the common trope that animals live—blessedly or cursedly, depending on your view—in the eternal present. Ravens, and quite likely crows, can live outside the moment. Cognitive intelligence—memory, reasoning, problem-solving—was easier to empiricize than were emotions, which are plenty slippery even in humans.

That has changed somewhat over time. Innovations in experimental methods have encouraged studies of animal emotions. Tests originally designed for very young children, whose willingness to gamble on uncertain outcomes reflects their emotional state, have been adapted to read the moods of pigs and sheep and even bees. And while crows and ravens have yet to take these tests, several lines of evidence point to the possible richness of their emotional lives.

Emotions are just mechanisms for shaping behavior. Evolutionary theory predicts they should be widespread, and complex social relations like those seen in corvids exert pressures that ought to select for their expression. And monogamy, the institution at the center of crow and raven life history, should be an especially fertile ground for emotions: how better to unite two individuals through a lifetime of nest-building and food-gathering and chick-raising than with feelings?

McGowan recounts the story of a male crow he named AP who chose between females vying for his attention; the one he spurned later became a very successful breeder, but the broods he and his partner raised failed, year after year. They were together pretty much every day they were paired. Whether their loves and griefs are the same as ours, he says, is impossible to say. Maybe it actually feels like something else to them. Still, those behaviors point toward emotional richness.

Not long after, he lost his territory and spent his final year at a local compost facility. Such outcomes are usually explained in utilitarian terms: a younger, stronger individual bests a rival weakened by age. They placed a floating treat in a deep tube. The crows in the test dropped dense objects into the water until the treat floated within reach. They didn't select objects that would float in the water, nor did they select ones that were too large for the container.

Human children gain this understanding of volume displacement around the ages of five to seven. Planning for the future isn't only a human trait. For example squirrels cache nuts to store food for lean times. Crows not only plan for future events but consider the thinking of other crows. When a crow caches food, it looks around to see if it's being observed. If it sees another animal is watching, the crow will pretend to hide its treasure, but will really stash it in its feathers.

The crow then flies away to find a new secret spot. If a crow sees another crow hiding its prize, it knows about this little game of bait-and-switch and won't be fooled.

Instead, it will follow the first crow to discover its new hoard. Crows have adapted to life in a human-dominated world. They watch what we do and learn from us. Crows have been seen to drop nuts in traffic lanes, so the cars will crack them open.

They will even watch traffic lights, only retrieving the nut when the crosswalk sign is lit. This in itself probably makes the crow smarter than most pedestrians.

Crows have been known to memorize restaurant schedules and garbage days, to take advantage of prime scavenging times. Do you remember the "analogy" section of the SAT test? While a crow is unlikely to outscore you on a standardized test, they do understand abstract concepts, including analogies.

Ed Wasserman and his Moscow-based team trained crows to match items that were the same as each other same color, same shape, or same number. Next, the birds were tested to see if they could match objects that had the same relationship to each other. For example, a circle and a square would be analogous to red and green rather than to two oranges.

The crows grasped the concept the first time, without any training in the concepts of "same and different. Cats and dogs can solve relatively complex problems, but they can't make and use tools. In reality, New Caledonians have evolved to make hooked tools from soft twigs as part of their usual foraging activity. New Caledonian crows belong to the corvid family of birds — as do jackdaws, rooks, jays, magpies and ravens.

In recent years, the brains of these birds have been studied ever more closely. There is no doubt that some of them display impressive cognitive abilities. But intelligence is a murky subject. What exactly is it, in the first place? And why has it evolved? The New Caledonian crow uses twigs and branches to extricate grubs and insects from inside trees Credit: Alamy. Intelligence is rooted in the brain. Clever primates — including humans — have a particular structure in their brains called the neocortex.

It is thought that this helps to make advanced cognition possible. Corvids, notably, do not have this structure. They have instead evolved densely packed clusters of neurons that afford them similar mental prowess.

This is an example of convergent evolution, where completely different evolutionary histories have led to the same feature or behaviour.

From identifying people who have previously posed a threat to them or others in their group to using gestures for communication — we too rely on abilities like these.

Rutz is unequivocal. Some birds, like the New Caledonian crows he studies — can do remarkable things. In a paper published earlier this year , he and his co-authors described how New Caledonians seek out a specific type of plant stem from which to make their hooked tools. Experiments showed that crows found the stems they desired even when they had been disguised with leaves from a different plant species.

While kids that were ages seven to 10 were able to learn the rules, it still took them a couple of tries to figure out how it worked. Children ages four to six, however, were unable to resolve the problem. Thus, in a water displacement test, the crows performed on a level that so far only seven- to year-old children have been able to complete successfully.

Crows have an uncanny memory for human faces. They can hold grudges against some of us—and tell other crows about it, too. In fact, they seem to have a good sense that every person is unique and that they need to approach each of us differently. These observers either wore a so-called neutral mask or one of the dangerous masks worn during the initial trapping events. Within the first two weeks after trapping, an average of 26 percent of the crows encountered scolded the person wearing the dangerous mask.

Around 15 months later, that figure was Three years later, with no action towards the crows since, the number of scolding crows had grown to 66 percent. Knowledge about threats is passed on between peers and from generation to generation. I suppose for some, it can be unsettling to realize that there are other beings besides ourselves who operate on a high level of what we term intelligence.