Re: Possible solution to Fermi's Paradox?

Robin Hanson (
Wed, 03 Mar 1999 14:17:41 -0800

Scott Badger wrote:
>Besides, Jay Gould once stated that the contingency based character of
>natural selection was such that if evolution were replayed millions of times,
>intelligence would not appear on the planet. This was in stark contrast to
>my up-till-then cherished theory that attributes such as increased levels
>of awareness, neural comlexity, and consciousness would have good
>survival value. Point being, Dr. Annis seems to assume that if life appears
>on a planet, intelligent life is a highly probably outcome. Gould assumes
>the opposite. ...
>I would like to hear Robin Hanson's take on this new theory.

I had previously seen the data Annis cites, and it did convince me that we have seen a gradual rise in body size among all life, and in and in brain size corrected for body size for land animals. If one reasonably assumes that intelligence required a certain minimum brain size, then intelligence did arise remarkably quickly after brains were big enough. I conclude that the intelligence is probably not a hard step.

Gould himself, actually, points out the steady rise in body size. He takes pains to attribute this to the boundary condition of a minimum feasible size and a initially small size, rather than to fitness advantages. That issues, however, is irrelevant for the purposes above.

Brain size per body size does seem a fitness driven change.

Robin Hanson   
RWJF Health Policy Scholar             FAX: 510-643-8614 
140 Warren Hall, UC Berkeley, CA 94720-7360 510-643-1884 after 8/99: Assist. Prof. Economics, George Mason Univ.