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By Caroline Delbert, Popular Mechanics
In a 2020 study, crows performed a complex task that involved hundreds of firing sensory analytical neurons.
Crows can do jobs, share knowledge, and even ritualistically mourn their dead.
Recent research suggests crow brains tightly pack neurons to help make them smart.
Crows are extremely intelligent. They can use tools to get what they want, like New Caledonian crows in a single South Pacific island of the same name, which shape twigs into hooks to catch grubs from rotting logs. And according to new research, crows are even smarter than we thought.
Crows and other corvids (a family of birds that includes ravens and magpies) “know what they know and can ponder the content of their own minds,” according to a 2020 study in Science. This is considered a cornerstone of self-awareness and shared by just a handful of animal species beside humans, such as monkeys and great apes. Crows can also use their complex brains to find creative solutions, such as dropping nuts on the road so passing cars can crack them open, for example.
But do they have true consciousness?
Crows Have Brains Packed With Neurons
The ability to think through a problem and work out an answer may be due to crows possessing a high number of brain cells that process information. This trait appears not only in humans, but in non-human primates, too. A study published in the Journal of Comparative Neurology in January 2022 comparing corvid brains with those of chickens, pigeons, and ostriches found that corvid brains have more tightly packed neurons—between 200 and 300 million neurons per hemisphere—enabling efficient communication between the brain cells. Crow intelligence is at least on par with some monkeys, and in fact, may be closer to that of great apes (like gorillas), according to a 2017 study published in Current Opinion in Behavioral Sciences.Evolution Gave Crows Great Ability to Reason
In the 2020 study, scientists put crows through a series of puzzling tasks. The researchers measured neural activity in different kinds of neurons with the goal of tracking how crows were sensing and reasoning through their work. They sought to study a specific kind of thinking, called sensory consciousness, and they chose birds in particular as representative of a branching point in the evolutionary tree of life. The task is simple, but involves some high-level brain stuff, as described in the study:After the crow initiated a trial... a brief visual stimulus of variable intensity appeared... After a delay period, a rule cue informed the crow how to respond if it had seen or had not seen the stimulus. [A] red cue required a response for stimulus detection ( “yes”), whereas a blue cue prohibited a response for stimulus detection..
The researchers write that sensory consciousness is the ability to have subjective experiences that can be “explicitly accessed and thus reported,” and that it comes from brains that have evolved over time. Consciousness is associated primarily with the primate cerebral cortex. Bird brains are different, “since they diverged from the mammalian lineage 320 million years ago,” the researchers write.
However, the crows performed in a way that affirms their sensory consciousness, which scientists in the 2020 study say could mean the “neural correlates of consciousness” date back to at least the last time birds and mammals shared that brain section:
To reconcile sensory consciousness in birds and mammals, one scenario would postulate that birds and mammals inherited the trait of consciousness from their last-common ancestor. If true, this would date the evolution of consciousness back to at least 320 million years when reptiles and birds on the one hand, and mammals on the other hand, evolved from the last common stem-amniotic ancestor.
In an analysis in the same issue of Science, another researcher, Suzana Herculano-Houzel of Vanderbilt University, makes a critique of the study’s hypothesis. The structure being studied, she says, could resemble another structure because of physical properties more than a shared evolution or an indication of extremely early consciousness. The size of the structures matter a great deal, too.
“[T]he level of that complexity, and the extent to which new meanings and possibilities arise, should still scale with the number of units in the system,” Herculano-Houzel explains. “This would be analogous to the combined achievements of the human species when it consisted of just a few thousand individuals, versus the considerable achievements of 7 billion today.”
Either way, crows have bird brains they can be proud of.
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