This episode is brought to you by the song Like This
Patrick Olsen’s new release single.
You can check out the link in the description to start listening.
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Imagine taking a nap at a time
when woolly mammoths roamed the plains…
and then waking up in the twenty-first century.
That may sound like a science fiction story,
but it might be the real experience of tiny aquatic animals called rotifers.
According to a report in Current Biology,
these little creatures can survive being frozen in ice
for at least twenty-four thousand years.
Seems like too long.
Rotifers are microscopic invertebrate animals,
usually less than one millimeter long.
They live in wet environments all over the world, including moist soils.
And we already knew that they could survive being frozen.
Experiments have shown that rotifers can remain frozen
for up to ten years
before thawing out and just continuing to live their tiny lives.
But maybe ten years is nothing for a frozen rotifer.
Researchers found these Rip Van Rotifers in a sample of frozen soil,
or permafrost, from northeastern Siberia.
The soil sample came from three and a half meters underground,
and radiocarbon dating estimated it to be
around twenty-four thousand years old.
Like, imagine sleeping so long you have to be
radiocarbon dated when you wake up.
When the researchers thawed the soil, they found living rotifers inside.
Now, it’s possible for something as small as a rotifer to have like
maybe snuck into the soil after it originally froze,
or even during the sample collection,
but the scientists claim this is not the case here.
First, because the icy soil is solid enough
that even something as tiny as a rotifer
shouldn’t have been able to squeeze in.
And second, because they identified fragments of DNA
within the frozen soil that matched with the rotifers.
This evidence seems to suggest
that the tiny animals were frozen all that time.
Yet, these rotifers weren’t only able to keep on living,
they began reproducing.
Since rotifers reproduce asexually, that meant the researchers
had a convenient culture of rotifer clones to study.
They were able to compare these ancient rotifers’ DNA
to more modern specimens,
and it looks like they are probably distinct
from the rotifers wiggling around today.
And they were also able to run a series of experiments,
re-freezing the cloned rotifers and showing that they are fully capable
of surviving being slowly frozen into ice.
Like many other rotifers, they appear to have some sort of mechanism
that prevents their cells and tissues from being damaged
or destroyed by ice crystals,
though researchers don’t know how that works yet.
Amazing as all of this sounds, these aren’t the first multicellular
organisms reported to survive thousands of years of deep freeze.
A 2018 study reported a pair of nematode worms
that survived being frozen in permafrost for over thirty thousand years.
And a 2012 study reported plant seeds that were able to germinate
after being frozen for nearly thirty-two thousand years.
Now, it’s worth pointing out that these previous studies
have drawn skepticism from other scientists,
who worry that they haven’t fully ruled out the possibility
of contamination by modern organisms.
But it’s definitely true that rotifers and other organisms
can survive being frozen for long periods of time
… possibly very long periods.
Scientists are hopeful that studying these organisms might help us
develop better techniques for storing frozen tissues and organs.
So if you’re clinging to the sci-fi dream of freezing yourself
for thousands of years into the future,
the secret to success might be held within these tiny invertebrates.
And if those rotifers really were frozen for twenty-four thousand years,
they totally slept through a major historical event
the domestication of goats!
That’s right, that was our transition.
Humans started domesticating crops and livestock
around ten thousand years ago,
and it was a pretty big deal for us as a species.
Goats were one of the ones we started with.
But there’s a lot we don’t know about the early parts of that process.
And now that picture is a little bit clearer.
A new study in the journal PNAS reports ancient goat DNA
from a time when they were just beginning their path to domestication.
The DNA samples come from remains of goats
in two archaeological sites in the Zagros mountains of western Iran,
dating to about ten thousand years ago.
Researchers were able to sequence DNA
from thirty-two goats at these sites.
To date, these are the oldest livestock genomes ever sequenced.
The results show a group of animals that were not fully wild,
but weren’t fully domesticated yet either.
The physical remains of these goats look a lot like their wild cousins,
with large bodies and big, scimitar-shaped horns.
And their DNA is lacking some of the genetic signs
associated with domestication,
including changes in genes linked to coat color.
But they were clearly on the way
the analysis found that most of these ancient goats
represent an early branch of the domestic goat lineage.
Amazingly, these goats’ DNA held clues
to how humans were managing them
a mixture of modern and ancient practices.
See, some of the sampled goats
were genetically very similar to wild goats,
so it seems that humans of the time were still in the habit
of capturing wild goats to add to their herds.
But on the other hand, the Y chromosomes of these goats,
which are passed down by males,
were much less diverse than mitochondrial genomes,
which are passed down by females.
This suggests the ancient herders were in the habit of
culling most males and reserving only a select few for breeding,
a practice still used today by goat herders of that region,
and also by animal breeders all over the world.
Altogether, this reveals a picture of a transitional period
in goat domestication.
Ten thousand years ago,
humans were already managing goats as livestock,
using some of the same strategies as today.
But it would still be some time before they were
the domesticated animals we know today:
crucial sources of food, milk, and also hilarious internet videos.
But in addition to hilarious videos, the Internet also has music.
And today’s sponsor, Music for Scientists by Patrick Olsen,
has a bunch of songs you can choose from.
Such as the new single, Like This!
This is a fun catchy single that focuses on our place on Earth.
It’s a total banger that’s all about seeing
very familiar things in new ways.
If you want to check this new single out,
check out the link in the description to start streaming Like This by Patrick Olsen.
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