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  • What could octopuses possibly have in common with us?

  • After all, they don't have lungs, spines, or even a plural noun we can all agree on.

  • But what they do have is the ability to solve puzzles,

  • learn through observation,

  • and even use tools,

  • just like some other animals we know.

  • And what makes octopus intelligence so amazing

  • is that it comes from a biological structure

  • completely different from ours.

  • The 200 or so species of octopuses

  • are mollusks belonging to the order cephalopoda,

  • Greek for head-feet.

  • Those heads contain impressively large brains,

  • with a brain to body ratio similar to that of other intelligent animals,

  • and a complex nervous system with about as many neurons as that of a dog.

  • But instead of being centralized in the brain,

  • these 500 million neurons are spread out in a network of interconnected ganglia

  • organized into three basic structures.

  • The central brain only contains about 10% of the neurons,

  • while the two huge optic lobes contain about 30%.

  • The other 60% are in the tentacles,

  • which for humans would be like our arms having minds of their own.

  • This is where things get even more interesting.

  • Vertebrates like us have a rigid skeleton to support our bodies,

  • with joints that allow us to move.

  • But not all types of movement are allowed.

  • You can't bend your knee backwards,

  • or bend your forearm in the middle, for example.

  • Cephalopods, on the other hand, have no bones at all,

  • allowing them to bend their limbs at any point and in any direction.

  • So shaping their tentacles

  • into any one of the virtually limitless number of possible arrangements

  • is unlike anything we are used to.

  • Consider a simple task, like grabbing and eating an apple.

  • The human brain contains a neurological map of our body.

  • When you see the apple,

  • your brain's motor center activates the appropriate muscles,

  • allowing you to reach out with your arm

  • grab it with your hand,

  • bend your elbow joint,

  • and bring it to your mouth.

  • For an octopus, the process is quite different.

  • Rather than a body map,

  • the cephalopod brain has a behavior library.

  • So when an octopus sees food,

  • its brain doesn't activate a specific body part,

  • but rather a behavioral response to grab.

  • As the signal travels through the network,

  • the arm neurons pick up the message

  • and jump into action to command the movement.

  • As soon as the arm touches the food,

  • a muscle activation wave travels all the way through the arm to its base,

  • while the arm sends back another wave from the base to the tip.

  • The signals meet halfway between the food and the base of the arm,

  • letting it know to bend at that spot.

  • What all this means is that each of an octopus's eight arms

  • can essentially think for itself.

  • This gives it amazing flexibility and creativity

  • when facing a new situation or problem,

  • whether its opening a bottle to reach food,

  • escaping through a maze,

  • moving around in a new environment,

  • changing the texture and the color of its skin to blend into the scenery,

  • or even mimicking other creatures to scare away enemies.

  • Cephalopods may have evolved complex brains

  • long before our vertebrate relatives.

  • And octopus intelligence isn't just useful for octopuses.

  • Their radically different nervous system and autonomously thinking appendages

  • have inspired new research

  • in developing flexible robots made of soft materials.

  • And studying how intelligence can arise along such a divergent evolutionary path

  • can help us understand more about intelligence and consciousness in general.

  • Who knows what other forms of intelligent life are possible,

  • or how they process the world around them.

What could octopuses possibly have in common with us?


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B1 中級

TED-ED】タコの脳はなぜこんなにすごいのか - Cláudio L. Guerra (【TED-Ed】Why the octopus brain is so extraordinary - Cláudio L. Guerra)

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    稲葉白兎 に公開 2021 年 01 月 14 日