Russell Standish, <R.Standish.domain.name.hidden>, writes:
> From our "frog" perspective, we must with great probability be sitting
> at the end of a long chain of contingent events that ends up producing
> a complex SAS. If we look at the history of evolution as we know it
> today, most (maybe 60-70%) complexity growth occurred during Cambrian
> Explosion (aka Life's Big bang) about 550 million years ago. There
> were a couple of other minor complexity growth periods at other stages
> during evolution, but for the bulk of evolutionary history, the
> various sorts of complexity indicators used remain flat or actually
> decrease in time. Tom Ray showed a hand drawn graph illustrating this
> at Alife6 at UCLA this year.
>
> My thought is that this indicates that evolution of complex SAS is
> exteremely unlikely, a rather pessimistic view compared with the
> optimism of Sagan, or for that matter most Alife theorists.
You might want to take a look at Robin Hanson's paper at
http://hanson.berkeley.edu/greatfilter.html, specifically the section
http://hanson.berkeley.edu/greatfilter.html#biology, which identifies as
many as four separate "hard steps" in the evolution of intelligence, of
which the last is the Cambrian explosion. Robin also proves that hard
steps should be roughly equally spaced regardless of their intrinsic
difficulty.
Hal Finney
Received on Mon Nov 16 1998 - 22:04:30 PST