Introducing the brain: comparing bird and human brains (Introduction)

by David Turell , Monday, April 07, 2025, 19:07 (6 days ago) @ David Turell

Intelligence in both:

https://www.quantamagazine.org/intelligence-evolved-at-least-twice-in-vertebrate-animal...

"Humans tend to put our own intelligence on a pedestal. Our brains can do math, employ logic, explore abstractions and think critically. But we can’t claim a monopoly on thought. Among a variety of nonhuman species known to display intelligent behavior, birds have been shown time and again to have advanced cognitive abilities. Ravens plan(opens a new tab) for the future, crows count and use tools(opens a new tab), cockatoos open and pillage(opens a new tab) booby-trapped garbage cans, and chickadees keep track(opens a new tab) of tens of thousands of seeds cached across a landscape. Notably, birds achieve such feats with brains that look completely different from ours: They’re smaller and lack the highly organized structures that scientists associate with mammalian intelligence.

“'A bird with a 10-gram brain is doing pretty much the same as a chimp with a 400-gram brain,” said Onur Güntürkün(opens a new tab), who studies brain structures at Ruhr University Bochum in Germany. “How is it possible?”

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"A series of studies published in Science(opens a new tab) in February 2025 provides the best evidence yet that birds and mammals did not inherit the neural pathways that generate intelligence from a common ancestor, but rather evolved them independently. This suggests that vertebrate intelligence arose not once, but multiple times. Still, their neural complexity didn’t evolve in wildly different directions: Avian and mammalian brains display surprisingly similar circuits, the studies found.

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"Rather than neat layers, birds have “unspecified balls of neurons without landmarks or distinctions,” said Fernando García-Moreno(opens a new tab), a neurobiologist at the Achucarro Basque Center for Neuroscience in Spain. These structures compelled neuroanatomists a century ago to suggest that much of bird behavior is reflexive, and not driven by learning and decision-making.

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"What he found was a surprise: The brain regions thought to be involved only in reflexive movements were built from neural circuits — networks of interconnected neurons — that resembled those found in the mammalian neocortex. This region in the bird brain, the dorsal ventricular ridge (DVR), seemed to be comparable to a neocortex; it just didn’t look like it

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"They found that the mature circuits looked remarkably alike across animals(opens a new tab), just as Karten and others had noted, but they were built differently, as Puelles had found. The circuits that composed the mammalian neocortex and the avian DVR developed at different times, in different orders and in different regions of the brain.

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"By comparing the bird pallium to lizard and mouse palliums, they also found that the neocortex and DVR were built with similar circuitry(opens a new tab) — however, the neurons that composed those neural circuits were distinct.

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Taken together, the studies provide the clearest evidence yet that birds and mammals independently evolved brain regions for complex cognition. They also echo previous research from Tosches’ lab, which found that the mammalian neocortex evolved independently from the reptile DVR.

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"Similarly, “there’s limited degrees of freedom into which you can generate an intelligent brain, at least within vertebrates,” Tosches said. Drift outside the realm of vertebrates, however, and you can generate an intelligent brain in much weirder ways — from our perspective, anyway. “It’s a wild west,” she said. Octopuses, for example, “evolved intelligence in a way that’s completely independent.” Their cognitive structures look nothing like ours, except that they’re built from the same broad type of cell: the neuron. Yet octopuses have been caught performing incredible feats such as escaping aquarium tanks, solving puzzles, unscrewing jar lids and carrying shells as shields."

Comment: same sort of intelligent action based on totally different brain organizations. Amazing.