The Octopus, the Dolphin and Us: a Great Filter tale

Is in­tel­li­gence hard to evolve? Well, we’re in­tel­li­gent, so it must be easy… ex­cept that only an in­tel­li­gent species would be able to ask that ques­tion, so we run straight into the prob­lem of an­throp­ics. Any be­ing that asked that ques­tion would have to be in­tel­li­gent, so this can’t tell us any­thing about its difficulty (a similar mis­take would be to ask “is most of the uni­verse hos­pitable to life?“, and then look­ing around and not­ing that ev­ery­thing seems pretty hos­pitable at first glance...).

In­stead, one could point at the great apes, note their high in­tel­li­gence, see that in­tel­li­gence arises sep­a­rately, and hence that it can’t be too hard to evolve.

One could do that… but one would be wrong. The key test is not whether in­tel­li­gence can arise sep­a­rately, but whether it can arise in­de­pen­dently. Chim­panzees, Bono­bos and Go­rillas and such are all “on our line”: they are close to com­mon an­ces­tors of ours, which we would ex­pect to be in­tel­li­gent be­cause we are in­tel­li­gent. In­tel­li­gent species tend to have in­tel­li­gent rel­a­tives. So they don’t provide any ex­tra in­for­ma­tion about the ease or difficulty of evolv­ing in­tel­li­gence.

To get in­de­pen­dent in­tel­li­gence, we need to go far from our line. En­ter the smart and cute icon on many stu­dent posters: the dolphin.

Dolphins are cer­tainly in­tel­li­gent. And they are cer­tainly far from our line. It seems hard to find a definite an­swer, but it seems that the last com­mon an­ces­tor of hu­mans and dolphins was a small mam­mal ex­ist­ing dur­ing the reign of the dinosaurs. Hu­mans and dolphins have been in­di­cated by red rec­t­an­gles, and their last com­mon an­ces­tor with a red cir­cle.

This red cir­cle is well be­fore the K-T bound­ary (in­di­cated by the dot­ted line), hence rep­re­sents a mam­mal liv­ing in the literal shadow of the dinosaurs.

We can ap­ply a con­ver­gent evolu­tion ar­gu­ment to this com­mon an­ces­tor. Thus, as­sum­ing that sub­se­quent evolu­tion was some­what in­de­pen­dent, get­ting from that com­mon an­ces­tor to dolphin level of in­tel­li­gence is some­thing that can hap­pen rel­a­tively eas­ily.

Can we go fur­ther? Well, what if we ap­plied the ar­gu­ment twice? Let’s bring in the most alien look­ing of the high-in­tel­li­gence an­i­mals: the oc­to­pus.

Let’s make the fur­ther as­sump­tion that our com­mon an­ces­tor with dolphins was dumber than the mod­ern oc­to­pus. This doesn’t seem a stretch see­ing how in­tel­li­gent the mod­ern oc­to­pus can be, how minor in terms of ecolog­i­cal role the com­mon dolphin-hu­man an­ces­tor must have been, and see­ing the stu­pidity of many of the de­scen­dants of that com­mon an­ces­tor.

If we ac­cept that as­sump­tion, we can then start look­ing for the com­mon an­ces­tor of hu­mans and oc­to­puses. Our two species are re­ally far apart:

We there­fore have to go back to around the last com­mon an­ces­tor of the Bila­te­ria (crea­tures with bilat­eral sym­me­try, i.e. they have a front and a back end, as well as an up­side and down­side, and there­fore a left and a right). This is the (spec­u­la­tive) ur­bila­te­rian. There are no known ex­am­ples or fos­sils of it, which means that it was likely less than 1 cm in length. To quote Wikipe­dia: “The ur­bila­te­rian is of­ten con­sid­ered to have pos­sessed a gut and in­ter­nal or­gans, a seg­mented body and a cen­tral­ised ner­vous sys­tem, as well as a bipha­sic life cy­cle (i.e. con­sist­ing of lar­vae and adults) and some fea­tures of em­bry­onic de­vel­op­ment. How­ever, this need not nec­es­sar­ily be the case.” Very con­fus­ing, and with no in­for­ma­tion about in­tel­li­gence level. How­ever, since the or­ganism was so small and since it was the an­ces­tor of al­most ev­ery an­i­mal al­ive to­day (in­clud­ing worms and Bry­ozoa), our best es­ti­mate would be that it’s pretty stupid, with the sim­plest pos­si­ble “brain”.

Put­ting this all to­gether, it seems evolu­tion­ar­ily easy to get from ur­bila­trian in­tel­li­gence to Oc­to­pus in­tel­li­gence, and from Oc­to­pus in­tel­li­gence to dolphin in­tel­li­gence—thus from ur­bila­trian to dolphin.

Note that this ar­gu­ment as­sumes that in­tel­li­gence can be put on some­thing like a lin­ear scale. One could ar­gue that Oc­to­puses have low so­cial in­tel­li­gence, for in­stance. But then one could re­peat the ar­gu­ment with dis­tant an­i­mals with high so­cial in­tel­li­gence such as cer­tain in­sects. Espe­cially if one be­lieve in a more gen­eral form of in­tel­li­gence, it seems that this fam­ily of ar­gu­ments could be used effec­tively to demon­strate dolphin-level in­tel­li­gence emerg­ing eas­ily from very low lev­els of in­tel­li­gence.

Ap­pli­ca­tion to the Great Filter

The Great Filter (re­lated to the Fermi Para­dox) is the ar­gu­ment that since we don’t see any ev­i­dence of com­plex tech­nolog­i­cal life in the uni­verse, some­thing must be pre­vent­ing its emer­gence. At some point on the tra­jec­tory, some­thing is cul­ling al­most all species.

An “early” great filter wouldn’t af­fect us: that means that we got through the filter already, it’s in our past, so the empti­ness among the stars doesn’t say any­thing nega­tive for us. A “late” great filter is bad news: that im­plies that few civ­i­liza­tions make it from tech­nolog­i­cal civ­i­liza­tion to star-span­ning civ­i­liza­tion, with bad re­sults for us. Note that AI is cer­tainly not a great filter: an AI would likely ex­pand through the uni­verse itself

The real filter could be a com­bi­na­tion of an early one and a late one, of course. But, un­less the fac­tors are exquisitely well-bal­anced, its likely that there is one lo­ca­tion in civ­i­liza­tional de­vel­op­ment where most of the filter lies (ie where the prob­a­bil­ity of get­ting to the next stage is the low­est). Some pos­si­ble lo­ca­tions for this could be:

  • Life it­self is un­likely (very early great filter).

  • Life with a cen­tral ner­vous sys­tem is un­likely.

  • A lot of differ­ent pos­si­ble lo­ca­tions for the great filter in be­tween ur­bilatiran and dolphin in­tel­li­gence.

  • Get­ting from dolphin to hu­man in­tel­li­gence is un­likely.

  • Get­ting from hu­man in­tel­li­gence to tech­nolog­i­cal civ­i­liza­tion is un­likely (lat­est early filter).

  • Get­ting from tech­nolog­i­cal civ­i­liza­tion to star-span­ning civ­i­liza­tion is un­likely.

Th­ese cat­e­gories aren’t of same size, of course—the first three are very di­verse and large, for in­stance. Then what the evolu­tion­ary ar­gu­ment above says, is that the Great Filter in un­likely to be in the third, bolded cat­e­gory (which is in fact a multi-cat­e­gory).

For what it’s worth, my per­sonal judge­ment is that the filter lies be­fore the cre­ation of a cen­tral ner­vous sys­tem.