Re: The Great Filter

Eric Watt Forste (
Tue, 3 Sep 1996 18:56:49 -0700

At 2:08 PM 9/2/96, Robin Hanson wrote:
>>>As Nicholas said, its implausible that a very hard step, such as
>>>language, happened so soon after its enabling large brains prior step,
>>>unless some special very usual environment was involved (and its hard
>>>to see what that could be).
>>In that case, I suppose that evidence for language use among pongids and
>>cetaceans would strengthen the argument for identifying the bulk of the
>>Filter with the development of linguistic ability, would it not?
[Robin again]
>Do you mean that a potential for language ability developed long ago,
>and just flowered "recently" as brains got big?

That's the possibility that occurred to me after reading your citation of
Nicholas. Certainly Churchland's theory of neurocomputational prototypes
and his related theory of semantics would indicate that most of the
semantic machinery of concepts-in-general (not necessarily our
memetically-evolved modern human concepts) is already in place in the
brains of most higher mammals, and that the special trick that human beings
developed was using these fuzzy cognitive maps (if that's what they turn
out to be like) to generate sequences of sounds that would stimulate and
change the fuzzy cognitive maps in the brains of other human beings. In
other words, language. But the underlying semantic/conceptual machinery of
thought is probably there already in most biggish-brained mammals (and
birds? who knows?). I'm out past the edge of my expertise here, but what
the heck.

>>One thing about birds is that they have wings, and so most of them have
>>strong selective pressure favoring flight, which selects against large
>>brains. ... These two
>>factors might be enough to keep the birds "Filtered" out for at least a few
>>million more years even if their brains have the same neurostructural basis
>>necessary for the ultimate development of language use.
>The question is: had there not been mammals around when the dinos were
>wiped out, could the birds have radiated to fill the gap, and followed
>a similar trajectory to our position within a hundred million years?
>If yes, this is not a hard step.

If yes, then the hard step (following the usual assumption that there's
only one really hard step in the Great Filter) happened in the development
of some common ancestor of birds and mammals. And now that I think about
how far back that common ancestor is, I'm inclined to think that birds
could not have done the trick, wings, hands, or otherwise. If I thought the
step were that far back, I'd probably prefer my earlier suggestion that the
hard step was the evolution of eukaryotic endosymbiosis... and protist
phylogeny (because it all happened in the past and the fossils are so tiny
and the genes are so full of junk) is about as poorly understood as
mammalian and avian brains are.

I'm starting to feel like the opposite of the drunk who was looking for his
lost wallet under the streetlamp on the corner because "That's where the
light is best." We're looking for the Great Filter in our past, because we
don't like the idea that it might lie in our future, and it seems that I
keep wanting to locate it in the places where the light is poorest, to
account for the fact that I can't find it. Ominous.

Damn this Fermi Paradox anyhow, he said peevishly.

Eric Watt Forste <>