How did the squishy oc­to­pus evolve its unique in­tel­li­gence? Per­haps by play­ing fast and free with the ge­netic code. EL­IZ­A­BETH FINKEL in­ves­ti­gates.

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SURE ENOUGH THE per­pe­tra­tor was ap­pre­hended: Otto, a six-month-old oc­to­pus.

He had crawled out of his tank and us­ing his siphon like a fire hose, aimed it at the over­head light. Ap­par­ently it an­noyed him or maybe he was just bored. As di­rec­tor El­friede Kum­mer told The Tele­graph, “Otto is con­stantly crav­ing for at­ten­tion and al­ways comes up with new stunts... Once we saw him jug­gling her­mit crabs in his tank”.

Anec­dotes of the mis­chievous in­tel­li­gence of oc­to­puses abound. In­di­vid­u­als have been re­ported to solve mazes, screw open child-proof medicine bot­tles and recog­nise in­di­vid­ual peo­ple. Keep­ers are in­clined to give them names be­cause of their per­son­al­i­ties.

Prob­lem solv­ing, tool use, plan­ning, per­son­al­ity: th­ese are hall­marks of the com­plex, flex­i­ble in­tel­li­gence that we as­so­ciate with back-boned an­i­mals, mostly mam­mals. But a squishy oc­to­pus? Some re­searchers who study the oc­to­pus and its smart cousins, the cut­tle­fish and squid, talk about a ‘sec­ond gen­e­sis of in­tel­li­gence’ – a truly alien one that has lit­tle in com­mon with the mam­malian design.

While the oc­to­pus has a large cen­tral brain in its head, it also has a unique net­work of smaller ‘brains’ within each of its arms. It’s just what th­ese crea­tures need to co­or­di­nate the mind-bog­gling com­plex­ity of eight pre­hen­sile arms and hun­dreds of sen­si­tive suck­ers, which pro­vide the oc­to­pus with the equiv­a­lent of op­pos­able thumbs (roboti­cists have been tak­ing note). Not to men­tion their abil­ity to cam­ou­flage in­stantly on any of the di­verse back­grounds they en­counter on coral reefs or kelp forests. Us­ing pix­e­lated colours, tex­ture and arm con­tor­tions, th­ese body artists in­stantly melt into the seascape, only to reap­pear in a daz­zling dis­play to at­tract a mate or threaten a ri­val.

“They do things like clever an­i­mals even though they’re closely re­lated to oys­ters,” says neu­ro­sci­en­tist Clifton Rags­dale, at the Univer­sity of Chicago. “What I want to know is how large brains can be or­gan­ised not fol­low­ing the ver­te­brate plan.”

So how did evo­lu­tion come up with this sec­ond gen­e­sis of in­tel­li­gence or what film-maker Jac­ques Cousteau re­ferred to as ‘soft in­tel­li­gence’ back in the 1970s?

Cousteau in­spired many a re­searcher to try and

find an­swers. But it has been hard to ad­vance beyond Tech­ni­color screen­shots and jaw-drop­ping tales – what zo­ol­o­gist Michael Kuba at Ok­i­nawa In­sti­tute of Science and Tech­nol­ogy (OIST), refers to as “Youtube science”.

For decades the num­ber of oc­to­pus re­searchers could be counted on one hand. They were poorly funded, and their valiant ef­forts were held in check by no­to­ri­ously un­co­op­er­a­tive sub­jects and in­ad­e­quate tools. “You re­ally had to be a fa­natic,” says Kuba.

In the last few years, with more and more re­searchers lured to th­ese enig­matic crea­tures, the field ap­pears to have achieved crit­i­cal mass. And th­ese new­com­ers are the beneficiaries of some pow­er­ful new tools. In par­tic­u­lar, since 2015 they’ve had the an­i­mals’ DNA blueprint, the genome, to pore over. It has of­fered some com­pelling clues.

It turns out the oc­to­pus has a pro­fu­sion of brain­form­ing genes pre­vi­ously seen only in back-boned an­i­mals. But its se­cret weapon may not be genes as we know them.

A com­plex brain needs a way to store com­plex in­for­ma­tion. Star­tlingly, the oc­to­pus may have achieved this com­plex­ity by play­ing fast and free with its ge­netic code.

To build a liv­ing or­gan­ism, the de­cod­ing of the DNA blueprint nor­mally pro­ceeds with ex­treme fidelity. In­deed it’s known as ‘the cen­tral dogma’. A tiny sec­tion of the vast blueprint is copied, rather like pho­to­copy­ing a sin­gle page from a tome. That copy, called mes­sen­ger RNA (MRNA), then in­structs the pro­duc­tion of a par­tic­u­lar protein. The process is as pre­cise as a three­hat chef fol­low­ing her prized recipe for ap­ple pie down to the let­ter.

But in a spec­tac­u­lar ex­am­ple of dogma-break­ing, the oc­to­pus chef takes her red pen and mod­i­fies copies of the recipe on the fly. Some­times the re­sult is the tra­di­tional golden crusted va­ri­ety; other times it’s the de­con­structed ver­sion – ap­ple mush with crumbs on the side.

This recipe tweak­ing is known as ‘RNA edit­ing’. In hu­mans only a hand­ful of brain protein recipes are edited. In the oc­to­pus, the ma­jor­ity get this treat­ment.

“It in­tro­duces a level of so­phis­ti­ca­tion and com­plex­ity we never thought of. Per­haps it’s re­lated to their mem­ory,” says Eli Eisen­berg, a com­pu­ta­tional bi­ol­o­gist at the Univer­sity of Tel Aviv. Though he quickly adds, “I must stress this is com­plete spec­u­la­tion”.

Jen­nifer Mather, who stud­ies squid and oc­to­pus behaviour at the Univer­sity of Leth­bridge in Al­berta, Canada, sug­gests it might go some way to ex­plain­ing their dis­tinct per­son­al­i­ties.

There’s no doubt that link­ing oc­to­pus in­tel­li­gence to RNA edit­ing is the realm of fringe science. The good news is it’s a testable hy­poth­e­sis.

Re­searchers are now gear­ing up with state-of-theart tools such as gene edit­ing tech­nol­ogy CRISPR, new types of brain recorders and rig­or­ous be­havioural tests to see whether RNA edit­ing is in­deed the key to oc­to­pus in­tel­li­gence.


Some 400 mil­lion years ago, cephalopods – crea­tures named for the fact that their heads are joined to their feet – ruled the oceans. They feasted on shrimp and starfish, grew to enor­mous sizes like the six-me­tre long Nau­tiloid, Came­ro­ceras, and used their spi­ral-shaped shells for pro­tec­tion and flota­tion.

Then the age of fishes dawned, de­thron­ing cephalopods as the top preda­tors. Most of the spi­ral­shelled species be­came ex­tinct; modern nau­tilus was one of the few ex­cep­tions.

But one group shed or in­ter­nalised their shells. Thus un­en­cum­bered, they were free to ex­plore new ways to com­pete with the smarter, fleeter fish. They gave rise to the oc­to­pus, squid and cut­tle­fish – a group known as the coleoids.

Their in­no­va­tions were daz­zling. They split their mol­lus­can foot, cre­at­ing eight highly dex­ter­ous arms, each with hun­dreds of suck­ers as ag­ile as op­pos­able thumbs. To il­lus­trate this dex­ter­ity, Mather re­lates the story of a col­league who found his oc­to­pus pulling out its stitches af­ter surgery.

But those lim­ber bod­ies were a tasty treat to fish preda­tors, so the oc­to­pus evolved ‘think­ing skin’ that could melt into the back­ground in a fifth of a sec­ond. Th­ese quick-change artists not only use a palette of skin pig­ments to paint with, they also have a reper­toire of smooth to spiky skin tex­tures, as well as body and arm con­tor­tions to com­plete their per­for­mance – per­haps an im­i­ta­tion of a patch of al­gae, as they stealth­ily per­am­bu­late on two of their eight arms.

“It’s not or­ches­trated by sim­ple re­flexes,” says Roger Han­lon, who re­searches cam­ou­flage behaviour at the Ma­rine Bi­o­log­i­cal Lab­o­ra­tory in Woods Hole, Mas­sachusetts. “It’s a con­text-spe­cific, fast com­pu­ta­tion of de­ci­sions car­ried out in mul­ti­ple lev­els of the brain.” And it de­pends crit­i­cally on a pair of cam­era eyes with keen ca­pa­bil­i­ties.

It takes se­ri­ous com­put­ing power to con­trol eight arms, hun­dreds of suck­ers, ‘think­ing skin’ and cam­era eyes. Hence the over­sized brain of the oc­to­pus. With its 500 mil­lion neu­rons, that’s two and a half times that of a rat. But their brain anatomy is very dif­fer­ent.

A mam­malian brain is a cen­tralised pro­ces­sor that sends and re­ceives sig­nals via the spinal cord. But for the oc­to­pus, only 10% of its brain is cen­tralised in a highly folded, 30-lobed donut-shaped struc­ture ar­ranged around its oe­soph­a­gus (re­ally). Two op­tic lobes ac­count­ing for an­other 30% and 60% lies in the arms. “It’s a weird way to con­struct a com­plex brain,” says Han­lon. “Ev­ery­thing about this an­i­mal is goofy and weird.”

Take the arms: they’re con­sid­ered to have their own ‘mini-brain’ not just be­cause they are so packed with neu­rons but be­cause they also have in­de­pen­dent pro­cess­ing power. For in­stance, an oc­to­pus es­cap­ing a preda­tor can de­tach an arm that will hap­pily con­tinue crawl­ing around for up to 10 min­utes.

In­deed, un­til an ex­per­i­ment by Kuba and col­leagues in 2011, some sus­pected the arms’ move­ments were in­de­pen­dent of their cen­tral brain. They aren’t. Rather it ap­pears that the brain gives a high-level command that a staff of eight arms ex­e­cute au­tonomously.

“The arm has some fas­ci­nat­ing re­flexes, but it doesn’t learn,” says Kuba, who stud­ied th­ese re­flexes be­tween 2009-2013 as part of a Euro­pean Union project to design bio-in­spired robots.

And then there’s their ‘think­ing’ skin. Again the brain, pri­mar­ily the op­tic lobes, con­trols the pro­cess­ing power here. The ev­i­dence comes from a 1988 study by Han­lon and John Mes­sen­ger from the Univer­sity of Sh­effield. They showed that blinded newly hatched cut­tle­fish could no longer match their sur­round­ings.

03 | Oc­to­pus are fa­mous es­cape artists.

04 | Pig­ment filled sacks on oc­to­pus skin are called chro­matophores

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