[ThirdMate]

There is another argument to suggest that intelligent life is rare or unique. That is the simple observation that we are the only intelligent species on Earth.

If conditions are ideal on earth for the development of one intelligent species, why haven't two species developed? A strong conclusion would be that we are unique.

rgds,
3/M

[Joe Hadenuf]

If conditions are ideal on earth for the development of one intelligent species, why haven't two species developed? A strong conclusion would be that we are unique.

There can only be one human species, and there are plenty of other types of species on this planet, literally thousands.

[Steve Eisenberg]

If conditions are ideal on earth for the development of one intelligent species, why haven't two species developed?

It may have. Primitive warfare is ubiquitous and, relative to population, far more deadly than modern war. A slightly less intelligent species would have been wiped out.

[Joe Hadenuf]

If conditions are ideal on earth for the development of one intelligent species, why haven't two species developed? A strong conclusion would be that we are unique.

Make that,

There can only be one human species, and there are plenty of other types of species on this planet, literally thousands, some that do have a limited degree of intelligence.

[zeugma]

Actually, I believe two did. Cro-magnon(sp?) didn't survive the experience though.

[zeugma]

Crapweasles. I just knew I shouldn't post before I'd had two cups of coffee this morning. The neanderthals where the folks I was thinking about in my previous post.