Are Octopuses Intelligent? It Depends on How You Define Intelligence

If you're going to evaluate the intelligence of an animal, it's not enough to measure the size of its brain. Researchers are convinced that octopuses have an intelligence so sophisticated that they can display emotions and individual personalities. But it's a different sort of intelligence that has to be assessed in a different way:

Octopuses have the largest brains of any invertebrate. Athena's is the size of a walnut -- as big as the brain of the famous African gray parrot, Alex, who learned to use more than one hundred spoken words meaningfully. That's proportionally bigger than the brains of most of the largest dinosaurs.

Another measure of intelligence: you can count neurons. The common octopus has about 130 million of them in its brain. A human has 100 billion. But this is where things get weird. Three-fifths of an octopus's neurons are not in the brain; they're in its arms.

"It is as if each arm has a mind of its own," says Peter Godfrey-Smith, a diver, professor of philosophy at the Graduate Center of the City University of New York, and an admirer of octopuses. For example, researchers who cut off an octopus's arm (which the octopus can regrow) discovered that not only does the arm crawl away on its own, but if the arm meets a food item, it seizes it -- and tries to pass it to where the mouth would be if the arm were still connected to its body.

"Meeting an octopus," writes Godfrey-Smith, "is like meeting an intelligent alien."


Link -via Kottke | Photo: maureen lunn

Comments (6)

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Intelligence is generally related to brain-body mass ratio. Bigger bodies require more neural mass to articulate them. An octopus has virtually no skeleton and it's limbs are muscular hydrostats - like the human tongue. The neural real estate needed to articulate a hydrostatic limb is quite a bit greater than that needed for a limb supported by bone. For example; the cortical homunculus depicts this fact in humans. The neural mass needed to support the tongue is close to the same amount needed to articulate the entire leg and foot.

Octopuses consist almost entirely of hydrostatic limbs and probably there are more sensory nerve fibres innervating the limbs as well. This means the octopus can have a disproportionate brain-body mass ratio compared to typical animals without being super intelligent in the sense of being able to write any Broadway musicals.
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I would add that some human neurons are not in the brain either. In particular the lower motor neurons. The upper motor neurons originate in the sensory motor cortex of the brain. They course down the corticospinal tract - decussating at the medulla - and terminate in various parts of the spinal cord. If I remember correctly the arm UMNs terminate in the lower cervical spine (vertebrae C5-T1) of the spinal cord where they innervate Lower Motor Neurons (LMNs). It is these LMNs that actually articulate the limbs. So as in the octopus, our limb articulating neurons are not in our brains either. However the signal to articulate the limbs originates in the brain.
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Natalia, octopus can be pluralised as: octopuses, octopi or even octopodes. Arguably, the latter is correct as octopus is a greek word and adding the latin -i seems incongruous.
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This is the ultimate Dungeon an Dragons outdoor die, oil rig edition...

You only need one throw to simultaneous get three results...

The holes and the rods are for loading the die... if it takes to long to fight dragons...

My Neighbor's Breakfast size m suggested colour
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A Christmas cracker for the puzzle-lover. If you solve the combination, you can open the cracker and get your crown and prize. If you fail, it explodes.

Bad Joke, white, XL

Thanks!
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It's a primitive bowling ball. Scores were marked on the side, meaning that not only was it hard to control, but only good for one game. It was quickly decided that round would be better.

Storm Neon Candy Trooper, M
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It could be a storage box for e.g. cleaning rods or locking wire,

The numbers may indicate the number of rods or wires necessarry for maintenance of a machine / device.

My Neighbor's Breakfast size m suggested colour

I think numbers actually form two interleaved rows:

666 555 444 333 222 111 and
344 334 112 122 556 566
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Bottom poured, fluted ingot. These ingots are commonly used to manufacture forged products for diverse markets from gear makers to machine shops, to end-use markets such as oil, gas and mining.

Battle Damage, 2x, Black
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It's a post to tie your boat on, they pulled the beam from a very busy dock, there any numbered slots so the harbormaster knows where each boats rented spot is at.

Timey Wimey Sweater xl
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