Parker on Fermi

Randall Parker's answer to the Fermi Paradox:

I have a proposal for the "Why Aren't The Aliens Here Already?" question: Every time biological intelligence evolves it eventually creates artificial intelligence before spreading out into the stars. The AIs always wipe out their creators. Then the AIs are smart enough to realize that this is a universal pattern and that they are now threats to each other. So each AI civilization hides.

(Via Instapundit.)