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Thinking is for suckers, but if you’re an octopus, suckers are for thinking

Octopuses “think” with neurons so distributed throughout their bodies that sometimes the left hand literally doesn’t know what the…left hand is doing.

ByAJ FilloNOVA NextNOVA Next

Octopuses have problem-solving abilities similar to some vertebrates. But the way these eight-armed enigmas process information is completely different. Image Credit: AJ Fillo, WGBH

Like humans, octopuses are incredibly intelligent. But an octopus’ mind is about as alien to the human mind as the human mind is…well, to an alien’s.

“I like to [ask], ‘How are they intelligent?’ rather than ‘How intelligent are they?’” says Dominic Sivitilli, a behavioral neuroscientist and astrobiologist at the University of Washington who presented a new octopus cognition model at the AbSciCon 2019 conference this week.

The model is designed to illustrate how octopuses process information, and Sivitilli believes it could eventually provide insight into how non-human intelligence evolved here—and possibly elsewhere in the universe.

Octopuses have problem-solving abilities similar to those observed in corvids (the group of birds that includes crows, ravens, and jays), parrots, and primates. But the way these eight-armed enigmas process information is completely different. Unlike humans and other vertebrates, which centralize mental processing in the brain, octopuses and other cephalopods use neurons throughout their suckers, arms, and brain to understand their world.

“What we’re looking at, more than what’s been looked at in the past, is how sensory information is being integrated in this network while the animal is making complicated decisions,” said David Gire, lead researcher on the project and neuroscientist at the University of Washington, in a statement.

The unique nature of octopus intelligence has sparked a rather peculiar debate recently: A group of researchers (not associated with Gire and Sivitilli’s study) has suggested that an octopus’ mind might seem so foreign because it may be alien. The hypothesis, published in 2018, states that octopus evolution may have arisen, in part, because of a retrovirus (a type of RNA virus) delivered to Earth by an asteroid during the Cambrian explosion about 541 million years ago.

But as alien as an octopus’ intelligence may seem, Sivitilli is careful to point out that they’re “definitely, based on the evidence in front of us, related to us at some point in our history.”

“I do not think that octopuses are aliens,” he says.


A Giant Pacific octopus at the New England Aquarium in Boston, Mass. Image credit: AJ Fillo, WGBH

Because of octopuses’ distributed mental structure, scientists have long said that each octopus arm has a mind of its own. But it may be even more accurate to say that each sucker has its own brain, Sivitilli says. “There are tens of thousands of both chemical and mechanical receptors in each sucker,” he says. “To put that into perspective, each of your fingertips has a few hundred mechanical receptors.”

To track how their arms think, Gire and his team filmed captive octopuses as they explored new objects in their enclosures. With the footage in hand, the researchers used a computer algorithm to determine if the arms were working together, which would suggest central direction from the brain, or independently, which would suggest the arms were making decisions on their own.

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The results, which are preliminary, show octopuses’ arms working both with the brain and on their own. But they also suggest that individual suckers can process information independently—something scientists had previously only hypothesized.

The team found that if one of an octopus’ suckers finds something interesting, like food, it triggers a sucker next to it to double check. If that sucker is also interested in the potential treat, it triggers the next one. This creates a cascade of neurons down the arm’s ganglia (nerve cell clusters), encouraging the octopus’ arm to then wrap around the item of interest.

This entire process bypasses the animal’s brain—but the system isn’t perfect. Because the suckers can act independently of the brain there’s not always consensus, Sivitilli explains. “Sometimes, the arm plays tug of war with itself,” he says.

“This is really exciting work,” said Jennifer Mather, a behavioral psychologist specializing in cephalopods at the University of Lethbridge who was not involved in the study, in an email.

But, she says, “they haven’t shown that the arms ‘make decisions.’”

Scientists have known that octopuses can pass information from arm to arm, bypassing the brain, for years. What they don’t yet understand is how the arms are able to process that coordination.

Because this study is based only on video observations, Mather says, it doesn’t track the neural information being passed between and within the arms.

Still, “thinking” with an arm is an impressive feat, Sivitilli says. And, better understanding the way octopuses process information—whether with an arm or their actual brain—may help us better understand other forms of intelligence radically different from our own, including any that may exist elsewhere in the universe, he says.

Octopuses are clearly from Earth, but that doesn’t mean they can’t teach us something about the stars, Sivitilli believes. “Studying models of cognition on Earth, especial those along different evolutionary paths, can really contextualize the search for extraterrestrial intelligence."

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