We knew crows were smart, but now they’re doing as well as kiddies and better than macaques at an advanced mental ability

We have a lot of pretensions, we humans. We’re the smartest, the acme of evolution, the only species that can (fill in the blank).

Goldfish, it turns out, can drive. Cats, bats and possibly all vertebrates can speak – so much for you, Shakespeare. Chimps can premeditate murder, which had also been thought to be a uniquely human faculty.

And now we learn that carrion crows are capable of generating recursive sequences, an ability until now assumed to be uniquely human. Or at least, uniquely primate.

“Recursion, the process of embedding structures within similar structures, is often considered a foundation of symbolic competence and a uniquely human capability,” Diana Liao of Germany’s University of Tübingen and colleagues begin their paper in Science Advances, published Wednesday.

Okay. We can think of recursion as nested structures creating a whole, complex structure. It enables us to see patterns in complex information. In humans, recursion is best known in language. An example might be: “The cat ate a fish. The cat, who you own, ate a fish. The cat, who you own, ate a fish that had been mine.” (It has been separately demonstrated that any use of hierarchical strategy requires memory ability.)

Humans were knocked off their recursive pedestal a few years ago with a report that other primates have the same ability too, and can generate sequences.

Now here we are: Crows can apparently also grasp recursive thinking and if anything seem to outperform the macaque monkey, Liao and the team reported.

A Rhesus macaque hanging from a fence in New Delhi, India.Credit: Manish Swarup / AP

It’s hard to prove what a corvid is thinking – they’re a cagey lot – but the team made a game stab at it. As has been done with humans, young children and monkeys, the researchers created a test environment involving a bracket system with an embedded element.

The crows were trained to peck at bracket pair components in an order that demonstrated relationships between the embedded structure to other pieces. Then, and this is the kicker, the crows were tested to see how well they transferred this center-embedded idea to new bracket pairings. They did well.

When challenged with longer, more deeply embedded sequences, crows did as well as kindergarten children aged 3 to 4, and better than macaques, the researchers say.

We may feel diminished to be in the company of the carrion crow, a member of the corvid family, but perhaps we shouldn’t be. It has been proven time and again that in terms of vertebrates, not just birds, crows are smart.

The New Caledonian Crow has been shown to not only to make tools (in the wild) but store them for future use, again begging equivalency with human kiddies, who can do that too. Crows recognize faces, not only their own but ours. They have been filmed dropping stones into a narrow-necked vessel to raise the water level so they can drink, and fashioning hooks out of metal wire to snag snacks.

Video can be accessed at source link below

One drawback to this story is that recursive ability was proven in exactly two crows (n=2).

But if one Neanderthal is shown to have cooked with fire, then one can argue that Neanderthals could light fire. Could they all? Probably not (can you, without a match?), but the ability was there. Can all crows boast of recursive abilities? Who knows, but the indication is there.

“While a sample size of two is not enough to infer that any crow in the population may generate center-embedded recursive sequences, we present a ‘proof of existence’ showing that this cognitive capacity is, in principle, within the reach of carrion crows,” the team states.

Cognitive capacity, and so much more. Crows may be much smarter than we ever thought. They don’t just make tools: they cleverly select twigs from the most apposite species of plant to achieve their aims. James Bond, Q – hang your heads. Here is the story of a real 007:

Video can be accessed at source lin below

Not impressed yet? Crows have been observed dropping nuts on paved roads so cars will run over them (the nuts) and crack them open – and only hop or fly over to retrieve the nut-meat when the crosswalk sign shows it’s safe. And before you sniff at their recursive ability, they too have language or at least, a complex system of communication of their own and may even, possibly – again much like us – use their communication abilities to lie.

One implication of the crows-recursion study is that the ability may have arisen much deeper in evolution than we thought. Or, it’s a case of convergent evolution, developing separately in the primate and avian lineages, and probably in others as well.