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Octopus Intelligence Is Unlike Anything We Know

Could such a different neurology really evolve purely by natural selection acting on random mutations?

The octopus, considered to be separated from us by about 700 million years of evolution, is believed to be the most intelligent invertebrate. It challenges many common assumptions about animal intelligence because it is also a short-lived loner. And we are discovering that its nervous system apparatus for intelligence is also completely different from typical mammal or bird models.

Rather than having a centralized nervous system, the octopus’ nervous system is spread throughout its body. Two-thirds of its neurons are not inside its brain. Researchers aren’t even sure how this system can work, but it does …

But it gets even more interesting. Many of these neurons can communicate with each other without going through the brain. Essentially, the nervous system inside the octopus’ arms can bypass the brain and communicate with each other …

In other words, the octopus brain is not even aware of what the arm is doing, which is hard to even fathom.

– Mihai Andrei, “Octopus arms can make decisions on their own without a brain,” ZME Science, September 27, 2023 The conference paper is open access.

One recent study found that the octopus’s memory system is also different from what we might have expected:

Unlike typical models, the vertical lobe’s network operates in a feed-forward configuration, like a one-way street, with information only from the input neurons to output neurons that control octopus behavior.

Central to this simplicity is the organizational structure of approximately 25 million interneurons, divided into two distinct groups: simple amacrine cells (SAMs) and complex amacrine cells (CAMs). The SAMs, numbering around 23 million, specialize in learning visual characteristics through synaptic reinforcement. In contrast, the CAMs, totaling approximately 400,000, play a pivotal role in consolidating activity levels.

The two types of cells send their axonal branches to connect with bigger cells in the output layer. Simple cells, that transmit “learned” information, make the big cells active, while complex cells make them less active, controlling how the brain works efficiently.

– Hebrew University of Jerusalem, Unlocking mysteries of octopus cognition: Paving the way for memory research, Phys.org, August 16, 2023. The paper is open access.

The octopus’s system is consistent with considerable intelligence.

An octopus’s remarkable intelligence makes it a unique subject for marine biologists and neuroscientists as well. Research has revealed the brain power of the octopus allows it to unscrew a jar or navigate a maze. But, like many children, the octopus also develops an impish tendency to push the boundaries of behavior. Several aquariums have found octopuses memorizing guard schedules to sneak into nearby tanks to steal fish; meanwhile, marine biologists have discovered that wild octopuses will punch fish… for no apparent reason.

– Kenna Hughes-Castleberry, “We’re one step closer to reading an octopus’s mind,” Ars Technica, April 8, 2023

Dominic Sivitilli, a University of Washington behavioural scientist and co-author of the first paper mentioned above, is interested in octopus research because it may help us test the limits of how life could survive elsewhere in the universe. But extraterrestrial life is hardly the only question the octopus raises. But, if the universe is supposed to be without intelligence or design how do — not just one — but at least two quite different systems for enabling it come to exist? What are the odds?

As it turns out, jellyfish can learn without a brain too. And currently, a dispute rages about the intelligence of plants.

If it is “natural” for vastly different life forms to develop altogether different systems of intelligence, there is probably something underlying our universe that drives some life forms toward intelligence. It cannot just be Darwinian natural selection for survival because vast numbers of other life forms can survive quite well with very limited intelligence.

It’s the same problem as we encounter with arguments for the evolution of human consciousness. We are informed that human consciousness evolved simply to enable humanoids to hunt more efficiently. But packs of wolves, prides of lions, and pods of orcas have never needed anything like a human type of consciousness to hunt efficiently. A theory whose aim is to show that there is really no intelligence or consciousness underlying the universe is not very good at accounting for how either comes to exist.

We have only begun to study the topic of different systems for enabling intelligence seriously. And there are apt to be more surprises along the way.

You may also wish to read: Octopus intelligence shakes up Darwin’s tree. There does not seem to be a Tree of Intelligence, which deepens the mystery of intelligence.

Denyse O'Leary

Denyse O'Leary is a freelance journalist based in Victoria, Canada. Specializing in faith and science issues, she is co-author, with neuroscientist Mario Beauregard, of The Spiritual Brain: A Neuroscientist's Case for the Existence of the Soul; and with neurosurgeon Michael Egnor of the forthcoming The Human Soul: What Neuroscience Shows Us about the Brain, the Mind, and the Difference Between the Two (Worthy, 2025). She received her degree in honors English language and literature.

Octopus Intelligence Is Unlike Anything We Know