In May 2013, Russian researchers found a perfectly preserved Woolly Mammoth carcass
frozen in the ice on an island off
Siberia. As if it were pulled straight out of a meat locker, the animal's body still had fresh red muscle tissue, and the real prize,
liquid blood. The female mammoth had been laying there like Snow White in her glass coffin for four thousand to ten thousand years
before the Russians came excavating, bringing with them the hope that she might live again to feel the sun on her shaggy brow.
Scientists have cracked much of the mammoth's genetic code from preserved hair,
but the potential to clone the animals isn't possible without living cells and this mammoth is
currently being examined for just that. But even if the scientists don't find any viable cells in their specimen,
there's more than one way to skin a mammoth and one way or another, humans now have the technology
to bring animals back from extinction.
sort of.
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The concept of bringing extinct species back from the void has titillated scientists long before those crafty velociraptors jiggled doorknobs in Jurassic Park.
It's called de-extinction or, if you're feeling more poetic,
resurrection biology and it's a real hot topic nowadays. So let's cut to the chase: will you ever get to feed a baby Stegosaurus?
No. Sorry. While Jurassic Park got some things right, there are some major biological limitations to resurrecting extinct species. DNA
naturally degrades over time, and you need some intact genetic material to reconstruct a genome.
Scientists recently determined that DNA can remain intact for no more than about 6.8 million years. Not bad,
but dinosaurs haven't been around for about 65 million years so, for better or for worse, you will never have to
escape a
velociraptor. Instead, the only vanished species that we can attempt to revive are the ones that died relatively
recently, within the past few tens of thousands of years. Which is really kind of fitting considering
that's the very same timeframe in which humans got serious about hunting and expanding and general domination. Many proponents of
de-extinction think that, if these species were driven to extinction at the hands of humans, then it's our moral
obligation to restore them if we can. So, how
exactly, would you resurrect a vanished species? Well, there are currently three possible methods: cloning, genetic
reconstruction, and back breeding. In 2003, French and Spanish
scientists did bring back a dead species to life for, like, ten minutes.
The Pyrenean Ibex, a type of wild large goat with majestic horns, also known as the
Bucardo, once climbed among the mountains between Spain and France until it was hunted to extinction by the late 1990's.
Scientists used frozen cells collected from the last known
Bucardo, a female named Celia, to create a new embryo through the nuclear
transfer method of cloning, which was perfected by the people who gave us Dolly the sheep,
the first mammal cloned from an adult cell back in
1996. Researchers injected nuclei from the Bucardo cells into goat eggs that had been stripped of their own DNA and then
implanted the eggs into living mama goats. In nearly 60 attempts, only 7 lady
goats got knocked up, and only one carried her clone
baby to term.
Sadly, the newborn came out with deformed lungs and didn't survive. Still, in terms of bringing an extinct animal back to life, those scientists had
way better genetic material to work with than the average de-extinction lab.
But, say you want to clone something that isn't newly extinct, like the Baccardo. Say, a Woolly Mammoth.
Researchers have already found a decent payload of mammoth parts: bone marrow, hair, skin, muscle tissue, fat, and that blood I
mentioned. The ideal cloning scenario starts with finding an intact
frozen cell. The last Mammoth went extinct nearly 4000 years ago and permafrost does a decent job of
preserving genetic material compared to, say, the tropical island where dodos last nested.
So, it'll be a lot easier to scrounge up material to make a mammoth than a dodo.
But most scientists doubt that an animal cell could survive several
millennia under the Siberian Tundra Still, for the sake of
exercising the
imagination, say they did find a genetically viable mammoth cell, you can remove the nucleus of this cell and transfer it into a hollowed-out
elephant egg, since elephants are the mammoths closest living relatives.
But then there's another problem. Elephants only ovulate every five years, and to get the eggs you have to navigate a reproductive tract
that's three
meters long! This makes egg extraction from elephants, uh, hard, to say the least. And it could require
hundreds of eggs to create one viable offspring.
So, again, we have to assume that we overcome that hurdle. So, if the mammoth DNA is healthy enough it could take command of an
elephant egg. With the help of a little chemical or electrical boost, the cell would start dividing. From there,
you just got to put on a little Barry White and implant the egg into a surrogate elephant's womb and, after nearly two years of
gestation, you've got a baby mammoth.
Maybe. But, in the absence of the viable cells or nuclei required for cloning, scientists have another path to bring back host species:
genetically reconstructing a genome. This new DNA technology is cutting-edge, and requires only
fragments of broken genetic material from hair, horn, fur, or feather - things that you can often just find from museum specimens. You basically just
sequence and line up the DNA of extinct species, say, a passenger pigeon and compare it to the DNA of closely-related
existing species, like a common pigeon, a rock dove. After comparing the two, you essentially start cutting and pasting,
substituting chunks of passenger pigeon DNA into the cells of the common pigeon's. The resulting hybrid stem cells could be coaxed into egg and sperm
cells, and then used in cloning.
Eventually, you'd end up with a living bird with enough passenger pigeon DNA to
pretty much be a passenger pigeon. Another lower-tech and very slow method to restore extinct species is to back breed
it. Back breeding is kind of like reverse engineering evolution, much in the way that dog breeders work out
particular traits, like body shape or coat color, back breeders look to the past to bring out old
ancestral genes in an animal. Take something like the Aurochs, an ancient, wild, cow-like beast formerly found in Europe and Asia.
Researchers know some of the Aurochs genes are still swimming around in certain cattle strains, kind of like how humans have 1 - 4 percent
Neanderthal DNA in their blood. The European
TaurOs project has identified some of these Aurochs genes in existing cattle breeds and is selectively breeding them to bring out those
ancient traits. Over the course of multiple generations, they hope to produce a breed that would be a close match to the Aurochs and, ultimately,
Introduce it into the wild. In theory, like, crazy insane theory, you could even bring back Neanderthals
this same way, although, since it takes between one and two decades for a single human generation to reach sexual maturity,
this much breeding would take a long, long time. And also, as previously mentioned,
it would be totally, like, immoral and wrong and crazy, which brings us to the potential problems with
resurrection biology. Like, for one, would these test tube clone babies be a bunch of inbred hybrid weirdos?
Critics of de-extinction worry that resurrected species would suffer from poor genetic variation. Like, if scientists created 20
identical Great Auks from a single egg, there wouldn't be enough genetic diversity to usher in a viable new
population. After all, bringing to life one
individual does not constitute the restoration of a species. And, even if you do manage to create a gaggle of Great Auks,
where would you put them if there's no habitat left for them? It comes down to the question of where and how
they will live. Most species we're even capable of resurrecting were initially driven to extinction at the hands of humans.
But, if current policy won't allow for a living species - bison, for example - to freely roam
it's original Great Plains habitat, or if African farmers worry about rampaging elephants, who's
realistically going to welcome Woolly Mammoths into their backyard? And who's going to teach those first mammoths how to be mammoths?
What will they eat?
How will they act? How will they learn? Do you think that they're going to be elephants putting on shaggy coats and moving to Siberia?
The whole concept is a big Pandora's Box. And critics also
worry that domino effects may spring from
reintroducing extinct species to landscapes that they've been away from for too long. Would passenger pigeons really be more like an invasive species that might
outcompete existing birds?
And if their numbers approach the sky blackening
proportions that they used to, would New Yorkers be cool with their fancy shoes getting soiled by
slogging through so much bird poop? These are all things we need to think about before we throw a lot of time and money into
this kind of research.
But, on the pro side, fans of de-extinction point out that resurrection biology has multiple awesome applications.
This kind of technology could help preserve and bring back from the brink of extinction
vulnerable living species, for instance, which, in itself, could make it worth developing. And it offers a lot of learning opportunities
to be found in dead species.
You know, we've already revived at least one life form for educational purposes, the notorious
1918 Spanish influenza virus that slaughtered perhaps 50 million people back in the day. In 2005, researchers from the Centers for Disease Control and Prevention
cloned the killer in order to study it and we've since learned a lot about how that flu
evolves, spreads, and so efficiently kills. This is potentially vital information that could help us prevent future epidemics.
Another argument for de-extinction has to do with filling
ecological niches, when a species is eliminated from its natural environment,
It leaves a void that could have far-reaching effects. Some de-extinction proponents fantasize about
correcting ecosystems like the Arctic by reintroducing
mammoths, who once helped maintain the permafrost layer by knocking down trees and allowing grasses to flourish.
We're just starting to realize how important it is to preserve permafrost since its melting releases an incredible amount of methane into the atmosphere
The thought is mammoths on the landscape might help with that kind of natural regulation. And, finally,
It's just cool!
Just admit it, the thought of watching a giant ground sloth grazing in the real world, in real life, with your eyes.
That's exciting!
So, once again, our technological capabilities have shot beyond our capacity to fully understand their
implications. However you personally feel about
bringing extinct species back to life and all that comes with it, know that it is no longer a question of can we, but rather
a matter of should we. Thanks for watching this episode of SciShow. If you have any questions or comments
or ideas for us you can leave them on Facebook or Twitter or down in the comments below and if, you want to keep getting
smarter with us here at SciShow, you can go to
youtube.com/scishow and subscribe.
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