
Tiny animal carcasses found in buried Antarctic lake - sohkamyung
https://www.nature.com/articles/d41586-019-00106-z
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avian
I wonder how carbon dating works in this case. My understanding is that the
dating method depends on the organism interacting with the carbon in the
atmosphere during its lifetime (where carbon-14 is produced by cosmic rays).
The interaction stops after organism dies, after which the level of carbon-14
in its body starts to decay.

But here the whole ecosystem was supposedly isolated from the atmosphere for
at least 10k years. Wouldn't all organisms, both alive and dead, just have the
same (decaying) level of carbon-14 after isolation happened?

EDIT: expanded for clarity.

~~~
JackFr
I think you have it backwards -- carbon works by some organic material not
interacting with the atmosphere. Atmospheric CO2 has a relatively constant
proportion of carbon-14. Once it stops interacting with the atmosphere it
begins to decay and have a different proportion than atmospheric carbon.

~~~
thaumasiotes
I don't understand this response. The model of the GP comment appears to be
that:

\- The atmosphere has a certain level of carbon-14, and living things stay at
the atmospheric level by virtue of the various processes by which they
interact with the atmosphere.

\- When they stop living, they also stop exchanging carbon with the
atmosphere, and their carbon-14 levels change due to radioactive decay over
time.

\- But here, an environment was sealed off from the atmosphere while some
organisms remained alive inside it. If we perform radiocarbon dating on such
an organism, will we get the date at which the organism died (and stopped
exchanging carbon with anything) or the date at which the environment was
sealed (and everything stopped exchanging carbon with the _atmosphere_ )?

Your comment isn't responsive to this question. To answer it, we'd need to
know why the atmosphere itself has constant levels of carbon-14 instead of
decaying like everything else, and whether the sealed environment would have
behaved more like the atmosphere or like something else.

~~~
yesenadam
>To answer it, we'd need to know why ...

This page is good:
[https://en.wikipedia.org/wiki/Radiocarbon_dating](https://en.wikipedia.org/wiki/Radiocarbon_dating)

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pasta
The embedded movie shows some more details (the bottom of the lake is at 1098
meters) but still not a single picture of the 'plankton' they found.

For the curious:
[https://en.wikipedia.org/wiki/Crustacean](https://en.wikipedia.org/wiki/Crustacean)

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pavel_lishin
Tardigrades are pretty well known for their toughness - I wonder what the odds
of one surviving a 10,000 year freeze is.

~~~
dekhn
i think it's unlikely in this case- all the tardigrade toughness comes from
entering the cryptobiotic state (extreme desiccation) while I believe all
these samples were in water or ice.

~~~
emptybits
At least one tardigrade has been frozen in "a block of ice for three decades",
then thawed, and gone on to reproduce. A tardigrade egg in the frozen sample
also thawed, hatched, and reproduced. So it's possible.

[http://blogs.discovermagazine.com/d-brief/2016/01/18/frozen-...](http://blogs.discovermagazine.com/d-brief/2016/01/18/frozen-
for-30-years-a-tardigrade-springs-back-to-life/#.XEH7wi0ZPOQ)

Apparently when they find themselves in an extreme environment (wet or dry?)
they replace their body's water with sugar (trehalose) which doesn't
crystallize and cause cellular damage when frozen.

~~~
dekhn
I read the original article, and they don't know what the conditions were when
they entered cryptobiotic state:

The moss sample used in the current study most probably contained, initially
at least, moisture from snowmelt in early summer, since at the time of
collection they were not covered by winter snow accumulation. However, the
possibility of freeze-drying during 30.5 years of frozen storage cannot be
discounted, and whether the animals obtained here were hydrated or dehydrated
(thus in an anhydrobiotic state) before or after storage is unknown.

My understanding (I'm a bioinformaticist, not a wet lab biologist, but I've
collected tardigrades and read up on them), the process occurs in very dry
conditions.

However, in good faith, I did some searching and found some pages which claim
that cyrobiosis (a form of cryptobiosis that occurs in wet, cold enviornments)
is exploited by tardigrades. So I guess you're right.

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foamclutching
I'm curious about those tartigrades. Will the scientists put them in the water
and bring them back to life? As far as I know about tartigrades, once immersed
in water, the body returns to a normal metabolic state over the course of a
few hours, even though they died hundreds of years ago.

~~~
luhn
The current record for tartigrade revival is 30 years. These recently found
ones are many thousands of years, I think revival is unlikely.

~~~
gnulinux
Why is revival after 30 years of freeze an easier problem than revival after
2000 years? Entropy?

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war1025
When I first read this I thought they meant small mammals that had been buried
by people at some point in the distant past.

~~~
aldoushuxley001
That's exactly what I thought when I read the headline; I was mildly
disappointed, though I do love tardigrades.

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metalliqaz
Did they find anything that was alive?

~~~
avian
As I understand the article, nothing more complex than bacteria was alive in
the retrieved samples.

It is unclear how recently the animals mentioned in the title died.

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neves
wow, is possible that they find a complete frozen animal? Maybe with perfect
DNA samples! That would be very cool.

~~~
goatlover
Like an ice dragon?

