The health and science-oriented magazine STAT has an article from Sharon Begley on recent research that looks at bird intelligence: “Brainiacs, not birdbrains: Crows possess higher intelligence long thought a primarily human attribute”.
The article covers two research papers. One looks at decision-making in crows, with an experimental method that distinguishes neurons that mark perception from those that respond to subjective experience. That’s interesting, but I wanted more to point to the second paper, which examines the structure of the pallium.
Humans and other mammals have an enlarged cerebral cortex. Birds have a structure that looks a bit similar to the mammal neocortex but is actually derived from the pallium in embryonic development, so a surface resemblance of mammal and bird brains actually is a convergence of different structures. Mammal cortical neurons have an organization into six layers but birds have not been thought to have this intricate organization. But…
A second study looked in unprecedented detail at the neuroanatomy of pigeons and barn owls, finding hints to the basis of their intelligence that likely applies to corvids’, too. Scientists have long known that crows and ravens have unusually large forebrains, but unlike mammals’ forebrains — the neocortex — corvids’ do not have the six connected layers thought to produce higher intelligence. But theirs do have “connectivity patterns … reminiscent of the neocortex,” scientists led by Martin Stacho of Ruhr-University in Germany reported.
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.
Again convergence of neural structure. Life finds a way.