We went through a population bottleneck about 1mln years ago. There were only about 1000 humans. My theory is that the resulting genetic homogeneity allowed us to develop a society. Social animals like ants, bees, naked mole rats, are essentially clone colonies. Gene selfishness promotes collaboration among clones.

This could also explain the Fermi paradox. Life may have originated on many planets, but the conditions for intelligence to develop may be extremely rare. Most life just fizzles out or chokes on its own pollution (this almost happened during the oxydation event on Earth.)

@BartoszMilewski Ultimately, there are happy and sad explanations for the Great Filter. Any explanation that lies in our past is a happy one: our civilization made it through, e.g. such an exceedingly rare spark-of-culture event.

The sad ones posit a Great Filter event in our future—such as a runaway climate change, resource exhaustion, a tendency for civilizational collapse, or just the fact that communication between civilizations is next to impossible.