Re: Cell Biology's "big bang"

Tim Ikeda (
Tue, 13 Apr 1999 20:44:05 -0400

Thanks for the note Art.

> "The emerging revisionist view of eukaryotic evolution is a
> scenario characterized by a massive and virtually simultaneous
> radiation (big bang) at the base of the eukaryotic tree,
> involving virtually all extant eukaryotic phyla (34)."
> (Gray M.W., et. al., 1999, p1480).
> It even calls this "simultaneous creation":
> "Alternative hypotheses describing the origin of eukaryotic cell
> Lavender arrows, simultaneous creation of the eukaryotic nucleus
> (gray) and mitochondrion (orange) by fusion of a hydrogen-
> requiring, methanogenic Archaebacterium (host) with a hydrogen-
> producing a-Proteobacterium (symbiont)." (Gray M.W., et. al.,
> 1999, p1480).

Cool. I'll have to look at that issue of Science. This would
go a long way toward explaining why it's been so difficult to
find eukaryotes that lack evidence of ever possessing mito-

> The problem with explaining this simultaneous fusion fully
> naturalistically is why would it happen *only once*?

A rare and exceptional event? A filling of a niche?
Why would one expect the formation of a nucleus and
final capture of the mitochondion to be a common, recurring
event? Wouldn't that require some estimate of probabilities
(which is currently beyond our technical capabilities)?
Even the chloroplasts were only captured a few times.

> It certainly seems most un-Darwinian

I'd say that the early eukaryotes must've kicked ass,
evolutionarily speaking. But it's impossible to determine
what the biotic evironment must've been like then.

> and is indistinguishable
> from what Geisler calls a "second class miracle":

Well, it's certainly not a de novo miracle. Both parts of the
first eukaryotic cell appear to have had precursors, under the
scheme described. Sounds like common descent; not special

Tim Ikeda (despam address before use)