Re: Earth without oxygen

On Apr 12, 7:30 pm, Gareth Wilson <wilso...@[EMAIL PROTECTED]
> wrote:

> I've just read a paper which discusses bottlenecks in the evolution of
> intelligent life. It points out that oxygen-producing photosynthesis
> evolved only once and might be one of the less likely steps towards
> the modern biosphere.

Perhaps. Or perhaps the first organism to make that jump got a head-
start on everything else, enough so that newly-evolved methods
couldn't compete. There's also only a few ways to fix CO2, with
RuBisCO dominating over everything else... and internal skeltons
haven't popped up repeatedly, nor calcification in the first place.

Do you have the paper reference? It sounds like an interesting one to
read.

--
Brian Davis