The Great Filter

John K Clark (
Sat, 31 Aug 1996 10:08:07 -0700 (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?

>Robin Hanson Writes:
>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

I don't think the key step was making the first tool, it was making the first
hand that could make the first tool, and I don't think brain growth was
steady, it took an enormous spurt as soon as that first hand came into
existence. Three and a half million years ago Australopithecus Afarensis
(Lucy) had a hand almost as good as ours but her brain was small, it ranged
from 380 to 450 cc. That's not much better than a modern chimpanzee which has
a range of 300 to 400 cc. In just 3 million years Lucy's children increased
their brain size to the level of modern humans with a range of 1000 to over
2000 cc.

A lot of the mystery about Human evolution could be cleared up if we could
answer 2 questions:

1) Why did bipedalism develop? It's very hard to do, makes us slow, and
causes us back problems.

2) Why did Lucy have a hand capable of moving things with precision when it
doesn't look like she had a brain good enough to take advantage of it?
The first very primitive tools appeared over a million years after Lucy's
kind first came on the sense and were made by a more advanced species,
Homo Erectus. If not making tools Lucy must have been doing something with
that hand that greatly enhanced her survival. She didn't have much else
going for her, she was small, weak, slow and had puny teeth and claws, yet
for some reason she thrived.

John K Clark

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