Comments on: Ancient Rocks Show Oxygen Was Abundant Long Before Complex Life Arose

By: Jon Summers

Jon Summers — Sun, 14 Nov 2010 05:59:51 +0000

why did complex life wait so long to get going?
two words “neomuran revolution”….
In a nutshell, the simple single cell early life had rigid murein cell walls 2.8 Gyr ago.
It took 1.2 Gyr (the “boring billion” after the glycobacterial revolution ie 02 respiration
that triggered snowball earth) to evolve the neomuran cell wall, (indicating it was a non trivial evolution). This event allowed the phagotrophic origin of eukaryotes.
The new flexible cell walls could “swallow” food and lead to incorporation of mitachondria,
evolution of flagella, in short the whole explosion leading to multicellular life.

I highly recommend bending your brain around this:
Thomas Cavalier-Smith, Cell evolution and Earth history: stasis and revolution
Phil. Trans. R. Soc. B 2006 361, 969-1006
doi: 10.1098/rstb.2006.1842

By: Andrew Moseman

Andrew Moseman — Fri, 12 Nov 2010 16:00:13 +0000

@amphiox
It didn’t get into this short post, but in other news reports Parnell does raise that possibility.

@dewarrior
Excellent point. Since complex life obvious did arise, they’re looking for the triggers for it, but there’s certainly nothing inevitable about its evolution.

By: dcwarrior

dcwarrior — Fri, 12 Nov 2010 14:51:56 +0000

in addition to amphiox’s point (which is a great one), the excerpt also implies complexity was inevitable, once conditions were OK for it. Just because the conditions made complexity possible, doesn’t mean complexity was necessarily going to arise. Just as the advent of eucaryotes could have happened much later in earth’s history, much earlier… or never at all.

The dinos might never have risen if the mammal-like animals had not been decimated when they were, and for sure the mammals would not have risen if dinosaurs had survived the K-T event. And that is true even though in both cases, conditions were such taht their respective rises were possible. It’s just that there was an existing biota in the way.

By: VIP

VIP — Thu, 11 Nov 2010 22:51:51 +0000

It is very possible that we are making a great mistake assuming that earth’s elements and conditions were the only requirement for life. There can be life not requiring our conditions and there probably is. And those aliens probably wont believe that there can possibly be life on earth. Life is an amazing thing, it’s just there, probably everywhere, just accept it.

By: amphiox

amphiox — Thu, 11 Nov 2010 17:53:25 +0000

What we are now showing is that the conditions in the atmosphere were in place [1.2 billion years ago], so it probably needed some other factor to trigger the early evolution of complex life

Hmm. What about the alternate possibility that complex life did in fact evolve earlier than currently thought, but the fossils haven’t been found yet? Could indeed the Snowball Earth episode have contributed in destroying some of these hypothetical fossil sites (by scouring them away and/or dispersing the debris into the oceans, for example)?