This is well said. No known natural mechanisms could account for this event. First the term carries a lot of metaphysicsl baggage. That the universe is just a giant mechanism, a machine. Organisms are also just machines.
Biologists are just glorified engineers since organisms are just machines.
I think this statement comes as quite a shock for most of us who have become accustomed to science giving us a mechanical view of nature. Needless to say, the contributers to this symposia do not feel that the phenomena they are studying are supernatural or beyond scientific study. The above slogan is typical of the self-organizing view of nature. I believe it boils down essentially to this point. In this sense then, self-organizing systems are certainly natural phenomena but are not mechanistic.