“Evolution built minds twice over. The octopus is probably the closest we will come to meeting an intelligent alien.” — Peter Godfrey-Smith, philosopher 🐙🧠
These two octopus books came out a few months apart from each other, and I have been meaning to read them back-to-back. They cover similar material — even their subtitles highlight the lessons learned about consciousness. I wonder if the publishers knew of the coincidence because Sy’s book, the first out of the gate, has a bizarre bifurcation: the first third of the book is fascinating (I’ll summarize below), but then the subsequent 160 pages are nearly devoid of information about the octopus. Instead, it pivots to a collection of aimless anecdotes and awkward personal-life details about aquarium staffers. It reads like a repurposed diary, some filler to get a book out the door… which then became a NYT bestseller.
Some fascinating book details about the octopus:
• Three hearts, pumping blue-green blood because their oxygen carrying metal is copper (versus iron in the heme of our blood). They can spend 30 minutes out of the water, to scoot between tidepools.
• Alien intelligence: from a distant branch in the tree of life, the octopus/cuttlefish are the only invertebrates to have developed a complex, clever brain:
– Our common evolutionary ancestor is a tubule so ancient, neither brains nor eyes yet existed. They evolved independently, on land and by sea.
– From the Cambrian explosion of sensing, body plans, and predation, minds evolved in response to other minds. It was an information revolution. It’s where experience begins.
– The brain rings around its throat. 500M neurons, similar to dog (vs.human: 86B, fly: 100K).
– The octopus has over 50 different functional brain lobes (versus 4 in human)
– And furthermore, 60% of its neurons are out in the arms, with a high degree of autonomy. A severed arm can carry on as if nothing has changed for several hours.
– It is a distributed mesh of ganglia (knots of nerves) in a ladder-like nervous system. Recurrent neural loops serve as a local short-term memory latch.
– “The octopus is suffused with nervousness; the body is not a separate thing that is controlled by the brain or nervous system.” Unconstrained by bone or shell, “the body itself is protean, all possibility. The octopus lives outside the usual body/brain divide.” (PGS)
– Structurally, our eyes ended up strikingly similar to the octopus (camera-like with a focusing lens, through a transparent cornea and iris aperture to a retina backing the optic nerves). But octopus eyes have a wide-angle panoramic view, and they move independently like a chameleon.
– Their horizontal slit pupil stays horizontal as the body moves, like a steady cam. This is made possible by special balance receptors called statocysts (a sac with internal sensory hairs and loose mineralized balls that roll around with movement and gravity).
– They can see polarized light, but not color (making their color-matching camouflage skills all the more intriguing; they also see with their skin).
– Their playful interactions with humans exhibit mischief and craft, a sign of mental surplus
– Humans internalized language as a tool for complex thought (we can hear what we say and use language to arrange and manipulate ideas). Octopuses are on a different path.
• Their entire skin is a layered screen, with about a megapixel directly controlled by the brain.
– Skin color, pattern and fleshy texture can change in 0.7 seconds.
– Three layers of skin cells control elastic sacks of pigments, internal iridescent reflections, even polarization (which the octopus can see), over a white underbody. They are regulated by acetylcholine, one of the earliest neurotransmitters in evolution.
– The octopus can create a voluntary light show on its skin, e.g., a dark cloud passing over the local landscape, or a dramatic display to confuse a predator while fleeing.
– Over thirty ritualized displays for mating and other signaling.
– Some octopuses have regions of constant kaleidoscopic restlessness, like animated eye shadow.
• Their ink squirts contain oxytocin (perhaps to soothe prey) and dopamine, the “reward hormone” (perhaps to trick predators that they had caught the octopus in the billowy cloud).
• 1,600 suckers. 35 lbs. of lift capacity per 2.5” sucker. 10,000 tasting chemoreceptors per sucker. Each is controlled individually.
• Octopus muscles have radial + longitudinal fibers (agile like our tongues, not our biceps).
– Opposing waves of activation can create temporary elbows at the region of constructive overlap, or pass food sucker-to-sucker like a conveyor belt.
– The octopus’ arm muscles can pull 100x its own weight.
• It can squeeze through a hole about the size of its eyeball.
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