The Great Filter - Are We Almost Past It? http://hanson.gmu.edu/greatfilter.html
The Great Filter
Consider our best-guess evolutionary path to an explosion which leads to vis
ible colonization of most of the visible universe:
The right star system (including organics)
Reproductive something (e.g. RNA)
Simple (prokaryotic) single-cell life
Complex (archaeatic & eukaryotic) single-cell life
Sexual reproduction
Multi-cell life
Tool-using animals with big brains
Where we are now
Colonization explosion
