"Crows possess higher intelligence long thought a primarily human attribute"

The study shows that neurons in the most complex part of the crows’ brain, the pallium, “do have activity that represents not what was shown to them, but what they later report,” said Herculano-Houzel. Neurons “represent what the animals next report to have seen — whether or not that is what they were shown,” she said. The neurons figure this out, so to speak, during the time lapse between when Nieder tells the birds the rule and when they peck the target to indicate their answer.

“That’s exactly what one would expect from neurons that participated in building the thoughts that we later report,” she said, suggesting that corvids “are as cognitively capable as monkeys and even great apes.”

…Specifically, the pigeons’ and owls’ neurons meet at right angles, forming computational circuits organized in columns. “The avian version of this connectivity blueprint could conceivably generate computational properties reminiscent of the [mammalian] neocortex,” they write. “[S]imilar microcircuits … achieve largely identical cognitive outcomes from seemingly vastly different forebrains.” That is, evolution invented connected, circuit-laden brain structure at least twice.

“In theory, any brain that has a large number of neurons connected into associative circuitry … could be expected to add flexibility and complexity to behavior,” said Herculano-Houzel. “That is my favorite operational definition of intelligence: behavioral flexibility.”