[zw123456]

Maybe there were multiple intelligent civilizations before humans, then the Great Filter Theory kicks in and they wipe themselves out with Global warming or whatever.

I have a pet theory (just a fantasy really) that Dolphins were once land mammals with an advanced civilization but then they too heated the planet up until all the ice melted and they had to adapt and evolve to be sea mammals.

[8note]

Afaik we don't see any geological evidence of such a thing

[ErikCorry]

I mean, it's true that dolphins evolved from land mammals.

[gjvnq]

Sounds like something Douglas Adams would write.

[parineum]

Or something Kurt Vonnegut did write (Galapagos).

[zw123456]

Thanks!