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  • In a new study published this week in the journal PLOS Biology,

  • molecular biologists describe something unbelievable:

  • the sequence of the oldest RNA discovered to date.

  • This RNA is estimated to be a little over fourteen thousand years old.

  • Its very existence challenges

  • the long-held belief that ancient RNA just isn't a thing.

  • And it suggests there could be lots of RNA

  • waiting to be discovered in ancient remains.

  • Now, fourteen thousand years might not sound that impressive.

  • After all, a couple of years ago,

  • scientists were able to sequence the entire genome

  • of a seven hundred thousand year-old horse.

  • But that was DNAthe molecular blueprint inside cells.

  • And though DNA starts to break down when a cell dies,

  • under certain circumstances, it can be preserved for thousands of years.

  • RNA is thought to be much more temporaryand that's by design.

  • One of its main jobs is to carry the instructions written in DNA to the cell's protein-making

  • factories

  • a process which, ideally, is pretty quick.

  • Once those instructions have been delivered,

  • an army of enzymes goes after the RNA

  • to break it down and get it out of the way.

  • And because it's chopped up so quickly,

  • many researchers have long assumed there's no point to looking for RNA in samples that

  • are hundreds or thousands of years old.

  • Except, recent studies have suggested ancient RNA may exist after all.

  • So, the authors of the new study decided to look for it

  • in some exceptionally well-preserved canine remains.

  • Two of their samples were skins from wolves

  • shot in Greenland in the 1800s and 1900s.

  • The third was a sample of tissue from a “puppy

  • found in frozen Siberian soil which was carbon-dated to around 14,000 years old.

  • And amazingly,

  • the researchers were able to find and determine the sequences of RNAs from all three specimens.

  • They could even tell what type of tissue they sampled based on the RNA!

  • The Siberian sample now has the honor of being

  • the oldest RNA known to science by about nine thousand years, and the oldest sequenced by

  • over 13,000 years!

  • And that's especially exciting because

  • RNA can tell us things that DNA can't.

  • For example,

  • because it reflects what a cell is doing at a given moment in time,

  • it could reveal what conditions an organism was experiencing when it died,

  • and even hint at the cause of death in cases where there's no obvious physical trauma.

  • There are also some viruses that lack DNA, like HIV and influenza.

  • These are super significant for modern medicine,

  • so it'd be great to see how their sequences have changed over time or identify their presence

  • in an ancient body.

  • But that's basically impossible without ancient RNA,

  • because these viruses often don't leave any other trace in the archaeological record.

  • But it remains to be seen whether ancient RNA is actually all that common.

  • The authors pointed out that this Siberian sample

  • was particularly well-preserved, and such remains are quite rare.

  • Still, they're hopeful that there's more ancient RNA hidden in the frozen soils of

  • places

  • like Canada, Alaska, and Antarctica.

  • And it doesn't have to come from soft tissues.

  • Bones, keratin, even plant seeds

  • could potentially be untapped reservoirs for millennia-old RNA.

  • Speaking of big surprises from the past...

  • Paleontologists announced this week that they've unearthed a giant parrot in New Zealand

  • the first giant parrot known to science.

  • Today, the biggest parrot in the world is the kakapo,

  • a nocturnal flightless species native to New Zealand.

  • You may have seen this bird having sex with Stephen Fry's camera man's head.

  • That's why I know it mostly.

  • They can weigh up to 3 kilograms,

  • which is about twice the weight of the biggest macaw.

  • But that's downright wee compared to Heracles inexpectatus,

  • the fossil parrot researchers described this week in a paper in the journal Biology Letters.

  • The fossil was found in rocks dated to the Early Miocene Epoch,

  • between nineteen and sixteen million years ago.

  • Still, unique features of those bones made it clear

  • they came from a member of the parrot branch of the bird family tree.

  • And the team was able to calculate weight and height estimates based on the relationship

  • between leg proportions and body size in birds.

  • That math suggests this bird weighed a colossal seven kilograms

  • and stood about a meter tall.

  • Of course, with just leg bones to work with,

  • it's hard to say much about this Herculean parrot's daily life.

  • But at that size, it's a safe bet that it was flightless.

  • And it was probably doing the same thing that most enlarged birds on islands do:

  • taking over unoccupied environmental niches.

  • You see, evolution does weird things in isolation, and one of them is to make small animals big.

  • It's a phenomenon known as insular gigantism.

  • And the fossil record is full of examples of birds that got big on islands:

  • oversized ducks in Hawai'i, giant storks in Indonesia,

  • and the dodos of Mauritius, just to name a few

  • But New Zealand really takes the cake for big bird diversity.

  • It's been home to giant geese, humongous eagles,

  • and the famous moas in addition to the world's biggest parrots.

  • These birds were able to achieve such large sizes

  • because the islands were basically devoid of the sizable predators and plant-eaters

  • that lived on the mainland.

  • So, in the diverse subtropical forest of Miocene New Zealand,

  • there would have been lots of open opportunities for a big bird to take up browsing on vegetation,

  • or perhaps step into other roles normally filled by medium-sized mammals.

  • Some have even speculated this parrot-zilla may have eaten other parrots!

  • But, there's no actual evidence of that... yet.

  • Truth is, we won't know what they ate or how big they really got until we find more

  • fossils.

  • Such finds could also shed light on the birds' relatives

  • researchers aren't sure if Heracles is a close cousin of the kakapo

  • or a separate instance of gigantism in parrots.

  • Either way, these jumbo parrots shake up what we thought we knew about parrot evolution.

  • And hopefully,

  • more fossils will help us flesh out this unexpected titan.

  • Thanks for watching this episode of SciShow News!

  • And a special, giant thank you to you, SR Foxleytoday's President of Space.

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  • so thanks, all of you!

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Scientists Pull RNA from a 14,000 Year-Old Wolf | SciShow News

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    林宜悉 posted on 2020/04/06
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