
Scientists find 3.7B-year-old fossil, oldest yet - Cozumel
http://phys.org/news/2016-08-scientists-billion-year-old-fossil-oldest.html
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dredmorbius
In a related bit of paleogeology, a large share of iron ore, particularly
banded iron formations (BIF) date from about this time -- they're typically
about 1.2 - 3.7 billion years old, and date to the periods of early life, a
large amount of free molecular (unoxidised) iron, a methane atmosphere, and
early cyanobacteria whose metabolic waste product was oxygen. This combined
with free dissolved iron in early oceans, precipitated out as iron oxides, and
left the deposits now mined for ores. Exhaustion of the dissolved iron
resource lead to a rise in atmospheric oxygen (poisonous to the
cyanobacteria), a depletion of the methane which served to warm the Earth
under the light of a much cooler sun, and resulted in a half-billion year
"Snowball Earth" period -- an earlier form of overzealous biological organisms
triggering catastrophic environmental pollution and climate change.

I find it fascinating to think about how and where minerals came from (iron
originates in stellar fusion, it's the low point of the atomic potential
curve, and hence you cannot fuse nor fission iron nuclei to release energy),
and how they came to be organised in deposits. Many minerals are concentrated
through prior biological activity -- iron, limestone, and of course, coal and
petroleum.

[https://en.m.wikipedia.org/wiki/Banded_iron_formation](https://en.m.wikipedia.org/wiki/Banded_iron_formation)

(Edit: Corrected erronious initial explanation of iron deposition --
precipitation, not biological binding.)

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tempestn
The discoverer of the previous oldest fossil (3.48B years) suggests that this
find may not be organic in origin. Would be nice if other experts had been
interviewed on that possibility, since there could potentially be some bias
there.

Edit: perhaps "organic" was a poor choice of words. My meaning was that she
disputed the claim that the artifact is in fact a fossil created by life, and
suggested that it might be a geological formation of some sort instead.

~~~
Practicality
I am not sure what the relevance would be. Are you using the term "organic" as
in biological, or as in carbon-based?

In either case, what would it mean if it wasn't organic?

~~~
scott_s
I believe tempestn is referring to the end of the article, where the scientist
who found the previously oldest fossil says it may not actually be a fossil:

 _The dating seems about right, said Abigail Allwood, a NASA astrobiologist
who found the previous oldest fossil, from 3.48 billion years ago, in
Australia. But Allwood said she is not completely convinced that what
VanKranendonk 's team found once was alive. She said the evidence wasn't
conclusive enough that it was life and not a geologic quirk.

"It would be nice to have more evidence, but in these rocks that's a lot to
ask," Allwood said in an email._

~~~
tempestn
Right, yes. I don't know anything about this person, but certainly there are
people out there who would be biased against having their little place in
history overshadowed by a new discovery, perhaps even unconsciously. Not
saying she is biased, just that it would be nice to see the opinions of some
other experts, not involved in the discovery.

In fact, even if it were a completely unbiased third-party opinion it would
still be nice to have more than one, since as a lay-person I'm currently left
with no idea how likely it is that this is in fact evidence of early life.

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nxzero
As a little context, the oldest known minerals on Earth are a 4.4 billion-
year-old and Earth itself is 4.543 billion years-old.

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usaphp
Can someone explain me how do they determine the age?

~~~
CodeSheikh
Carbon dating

[https://en.wikipedia.org/wiki/Radiocarbon_dating](https://en.wikipedia.org/wiki/Radiocarbon_dating)

[https://www.boundless.com/biology/textbooks/boundless-
biolog...](https://www.boundless.com/biology/textbooks/boundless-biology-
textbook/evolution-and-the-origin-of-species-18/evidence-of-
evolution-129/carbon-dating-and-estimating-fossil-age-520-13098/)

~~~
dkurth
According to that boundless.com link, "The half-life of carbon-14 is 5,730
years, so carbon dating is only relevant for dating fossils less than 60,000
years old."

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hownottowrite
Side note: Interesting paper on mathematical model often used in analyzing the
patterns in stromatolites and other growing interfaces: the
Kardar–Parisi–Zhang equation.

"Pattern formation in stromatolites: insights from mathematical modeling"
[http://rsif.royalsocietypublishing.org/content/9/70/1051](http://rsif.royalsocietypublishing.org/content/9/70/1051)

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okket
FWIW, Ed Yong:

    
    
      The newly discovered rocks suggest that life arose very
      quickly after the Earth was formed.
    

[http://www.theatlantic.com/science/archive/2016/08/the-
world...](http://www.theatlantic.com/science/archive/2016/08/the-worlds-
oldest-fossils-are-37-billion-years-old/498056/)

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swayvil
3.5 billion years ago the skies were orange, the oceans were green and the
land was black.

~~~
dredmorbius
It was a true iron age.

Do you have any refs on the Earth's appearance at the time?

~~~
andrewflnr
It's at the bottom of TFA. First I've seen it, too.

~~~
dredmorbius
Ah, missed that, thanks.

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mpnagle
hail helix

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sattoshi
They measured a foot and the head of a mammoth to magnitudes of difference
already.

You can't measure stuff that old. They almost decide how old they want it to
be.

