Robert J. Bradbury, <firstname.lastname@example.org>, writes:
> On Sat, 11 Sep 1999 email@example.com wrote:
> > But actually assembling some kind of self-replicating
> > system or cycle is still not well understood.
> Given that we get a stable crust ~4 billion years ago and life seems
> to appear at 3.86 billion years ago, that says that (a) it either
> came from space (panspermia); or (b) it is easy.
Or (c) there are multiple hard steps. See Robin Hanson's paper at http://hanson.gmu.edu/greatfilter.html. If there are ~5 hard steps then it is not surprising that a couple of them took only a few hundred million years, if we conditionalize our expectations on the fact that we are alive today.
> You may want to look up: "The orgin of life--a review of
> facts and speculations", by L. E. Orgel, Trends Biochem Sci.
> Dec 1998 23(12):491-5.
Thank you, I will look at this today. The reference I had been using on this topic was published in the 80s so it may be out of date.