Re: The Great Filter

Robin Hanson (
Fri, 30 Aug 96 15:32:51 PDT writes:

Eric Watt Forste suggests that the great filter is in the
step to advanced tool use. What about the objection that
this step was completed relatively _shortly_ after the
humanoid monkeys came into existance?

This is a strong objection, I think. I've been researching it.

Mammal brains have been growing somewhat steadily since all the dinos
were killed off 65 mya, and dolphins brains as big as ours 15-20 mya.
One might suggest that the hard step was a combination of getting
whatever allows mammals to have big brains, plus some event to get the
dinos out of the way.

The problem with this theory is that birds also have brains as big as
mammals, and seem to have evolved from dinos, with the latest common
ancestor between mammals and birds being soon after land-eggs were
invented 310mya (before which animal land colonization was stymied).

So maybe the last hard step was the land-egg, or maybe the hard step
was some special organization of mammal brains relative to bird brains.
Is there an important different of organization here?

Robin Hanson