The Great Filter

Robin Hanson (
Tue, 20 Aug 96 10:47:39 PDT

John K Clark writes:
>I an sending this to both the Extropian and Transhuman list because I think
>everyone should read Robin's fine article.

Thanks for your praise John! To everyone else, I apologize that I
posted the URL a week ago to Extropians, and yet have continuously and
dramatically changed it since then. So if ten of you read it, you
each probably read a substantially different version. I guess I'll
learn to hold stuff back longer before I announce it.

>4. Multi-cell life
>5. Animals with big brains
>6. Where we are now
>7. Explosion
>in spite of this I have a hunch the bottleneck is in the first 6 stages, I
>sure hope so. I want to talk a little about stages 5 and 6. Arthur C Clarke
>wrote a short story about a race of noble horse like beings who had
>developed a complex and beautiful philosophy, possessed profound mathematical
>ideas, and were more intelligent than humans, but they had no technology
>because the had no hands. Dolphins and whales in our world have very large
>brains, but not only are they lacking hands they have other handicaps they
>must overcome. If you live underwater you can't know anything about fire, an
>essential ingredient in technology. Also, It's hard enough to deduce the
>basic laws of Physics living in an atmosphere, most of the laws are only
>really obvious in a vacuum, surely a bizarre concept for any life form
>living in a thick heavy medium like water.

As I mentioned in the paper, a big problem with this theory is the
cosmologically short time it took our ancestors to go through these
stages. If this step was so astronomically improbable, why did it
happen so quickly after the previous step? Can land-dwelling
creatures really be that improbable (given multi-cell life)?

Robin Hanson