Topic: Complex, Multicellular Life from Over Two Billion Years Ago Discovered

[Nemesis]

Link to first full article

The discovery in Gabon of more than 250 fossils in an excellent state of conservation has provided proof, for the first time, of the existence of multicellular organisms 2.1 billion years ago. This finding represents a major breakthrough: until now, the first complex life forms (made up of several cells) dated from around 600 million years ago.

The next part has the assumption that there could not be complex life without oxygen.  I don't see why not.

In order to be able to develop 2.1 billion years ago and become differentiated to a degree never attained previously, the authors suggest that these life forms probably benefited from the significant but temporary increase in oxygen concentration in the atmosphere, which occurred between 2.45 and 2 billion years ago. Then, 1.9 billion years ago, the level of oxygen in the atmosphere fell suddenly.

Backing up my comment:

Link to second full article

Deep under the Mediterranean Sea, small animals have been discovered that live their entire lives without oxygen and surrounded by 'poisonous' sulphides. Researchers writing in the open access journal BMC Biology  report the existence of multicellular organisms (new members of the group Loricifera), showing that they are alive, metabolically active, and apparently reproducing in spite of a complete absence of oxygen.

If complex life without oxygen can exist now why couldn't it exist then?  Evolved to match the environment. 

[Dash Jones]

I'm not certain why they insist that there had to be a rise in oxygen either.  Perhaps they found indicators that there was oxygen content in the cell fossils indicating higher levels of oxygen?

[Nemesis]

It is probably an unconscious bias.  If signs of life were found on another planet scientists would look for large and small lifeforms without concern for oxygen.  Since it is the Earth they just assume that since large lifeforms NOW require oxygen then it must always have been so. 

Hopefully scientists will take note of these newly discovered forms and realize that there could have been such forms before the atmosphere was oxygenated and that they might either have evolved to adjust or died out.  Alternately they could be the ancestors of these forms and wholly new forms evolved into modern oxygen using life.  Genetic analysis might reveal these to be either truly ancient in the split from other life or relatively newly evolved to handle the environment they are in.

[Centurus]

This discussion reminds me of an article in Scientific American, I believe it was, in where they talked about the possibility that life could have evolved on this planet at several places at the same time, each form of life being anywhere from slightly to considerably different, because they each would have formed from different types of amino acids, in different ways.  I can't remember too much about that article, it was a while ago since I read it, but for some reason, this new discovery that was made in the article that Nem posted, and the implications that these organisms have on the current theory of when complex forms of life first evolved, makes me wonder.

Just thought I'd share that.

[Nemesis]

Are you thinking of the concept of a "Shadow ecology"?

That idea is that there could be a separate microbial ecology on Earth totally missed due to its different chemical basis.  In the hypothesis such an ecology could be wide spread or only exist in small patches that are suitable to it (like in the 2nd article above).   Such an ecology could have evolved in parallel with the one we know or originated elsewhere and arrived from space by various mechanisms.

[Lono]

In the hypothesis such an ecology could be wide spread or only exist in small patches that are suitable to it (like in the 2nd article above).   Such an ecology could have evolved in parallel with the one we know or originated elsewhere and arrived from space by various mechanisms.

I'm pretty sure they already covered that on Fantasy Island:

http://www.crackle.com/c/Fantasy_Island

 

(loved that episode as a kid)


Seriously though - this is some pretty significant findings - I am surprised this is the first I am hearing about this!

The article doesn't really seem to give a clue about the Oxygen bias - except maybe for as a possible explanation for why there seem to be so few fossils of multicellular organisms between 1.9 Billion and 600 Million years.

And since we don't really have the tech well developed to do deep sea forensics/archeology yet - probably there will be such a bias towards oxygen utilizing fossils for the next 100 years or so.

(although Oxygen - probably more than anything else - allows for a much greater explosion of multicellular form diversity - at least here on Earth)