The Great Filter

Eric Watt Forste (
Fri, 30 Aug 1996 22:28:30 -0700

At 9:40 PM 8/30/96, 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?

>The step could have happened long ago though, if it was something
>basic about mammal brains, that just needed time to flower into us.
>We don't need fossil evidence for this - looking at today's mammals
>and birds is good enough. Is there anything lacking in bird brains so
>they couldn't have become like us, had they had hands and large social

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. Furthermore, having wings puts up a big barrier against the
development of hands even among those birds that do not fly, and having
hands seems to have something to do with being able to take advantage of
language use in a takeoff of memetic technological evolution. 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.

But I have a basic problem with trying to pin the Filter on some internal
development of the brain, which is that this will not even come close to
closing the question until we have a significantly better understanding of
the mind/brain than we do now, an understanding that is really nowhere in
sight (though we've been making much faster progress in its vague direction
over the last ten years or so than previously).

Then again, the original objection, if I recall correctly, was that the
various specialists in the study of each step were proposing plausible
stories, making it seem likely that the Filter lies in our future. Since
neuroscientists don't yet fully understand the workings of the mind/brain
or of language use, they're the only ones whose stories we're not yet
really able to judge the plausibility of. And that itself constitutes an
argument for seeking the Filter in some yet unknown steps in
neuropsychological evolution, if we hope to find it in our past.

Eric Watt Forste <>