
First animals may have lived with almost no oxygen - prateekj
http://www.newscientist.com/article/dn25067-first-animals-may-have-lived-with-almost-no-oxygen.html#.UwOod0JdWoU
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rflrob
This is not at all what I study, but it seems possible to me that sponges have
evolved a tolerance for low oxygen conditions in the billion or so years since
they first arose. It's a common mistake to think that because something is
morphologically very similar to an ancient form (a so called "living fossil"),
that it hasn't undergone any evolution. As long as it has been reproducing and
mutating, better adapted versions have always had differential success, hence
they've evolved, even if the shape hasn't changed.

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chc
I thought the point of the study was that these sponges live in an oxygen-rich
environment, so there is no pressure for them to develop this trait in the
modern world. It doesn't prove it's a primitive trait, but it at least makes
it unlikely that it's a recent adaptation.

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thotpoizn
Is the "oxygen-rich environment" universally true, though? It's not as though
oxygen saturation in the ocean is perfectly homogeneous. There are plenty of
naturally occurring areas of hypoxia, and one could easily imagine an
adaptation which allowed better survival in or near these "dead zones" could
be quite useful, at least to localized populations. Is there some obvious
reason that dramatically reduces the likelihood that one or more pockets of
sponges might have capitalized on such a mutation more recently?

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nathannecro
For reference, the source paper:
[http://www.pnas.org/content/early/2014/02/13/1400547111.abst...](http://www.pnas.org/content/early/2014/02/13/1400547111.abstract)

It's not a completely novel idea, but it it an interesting find which may lead
to more interesting conclusions.

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xherberta
I tuned out when they started dating the emergence of a group of animals by
working backwards based on a guess of how long they would have needed to
achieve a certain level of genetic diversity. That's interesting as
conjecture, and I'll take it as such.

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leeoniya
recently read about early life conditions on wiki [1], says pretty much the
same thing. also relevant [2]

[1]
[http://en.wikipedia.org/wiki/Abiogenesis](http://en.wikipedia.org/wiki/Abiogenesis)

[2]
[http://en.wikipedia.org/wiki/Oxygen_catastrophe](http://en.wikipedia.org/wiki/Oxygen_catastrophe)

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marcosdumay
That's not about early life. It's about early animals, that only came to be
much, much later than the former, when oxygen was already plenty at the
atmosphere.

