# Tweet by [@keefmoon](http://twitter.com/keefmoon) on 2021-09-04 11:15:51 > [!INFO] Archived from [original tweet](http://twitter.com/keefmoon/status/1434112970087358464) In reply to: [@keefmoon](http://twitter.com/keefmoon/status/1434112968497766403) The combined unlikelihood of the Eurkareotic event, plus the Great Oxidation, would seem to suggest that the evolution of complex life is an incredibly unlikely event, that has probably only happened once in our galaxy... on Earth.