0:02 Look at this. This is rare footage from
0:04 1933. You see this dog looking animal
0:06 pacing back and forth in a cage. That's
0:09 a Tasmanian tiger. One of the very last
0:12 of its kind. It died in 1936. And the
0:15 species was ultimately declared extinct.
0:17 But now scientists are trying to bring
0:19 them back. And it's not alone. You might
0:21 have seen headlines about direwolves or
0:23 woolly mammoths or dodo birds or
0:25 passenger pigeons or dinosaurs.
0:29 deextinction has become a new and urgent
0:31 scientific debate that we should all
0:32 know about. But when I took a deep dive
0:35 into what's really going on here, I
0:36 realized that we're getting this
0:39 conversation very, very wrong. Because
0:42 we're on the cusp of a huge genetic
0:44 breakthrough. But the most huge if true
0:46 thing happening here isn't actually
0:48 bringing back extinct animals. It's what
0:51 this means for all the animals alive
0:54 today. And very few people seem to know
0:55 about it. >> Deextinction.
0:56 >> Deextinction.
0:57 >> The extinction.
0:58 >> Trying to bring back creatures from the past.
0:59 past.
0:59 >> We can do this.
1:01 >> Resurrect the woolly mammoth. >> Direwolf.
1:01 >> Direwolf. >> Tasmanian.
1:02 >> Tasmanian.
1:03 >> It sounds like something out of a
1:04 science fiction movie.
1:06 >> It's no longer science fiction.
1:09 >> That's the future. [Music]
1:15 >> All right. Imagine you're a mad
1:17 scientist and you want to bring back an
1:19 extinct animal. Here's the recipe. Step
1:22 one, choose your animal. like a mammoth.
1:23 Now, from here, you need to choose one
1:25 of three paths, and for each, you'll
1:27 need different ingredients. You could
1:28 try to take a close- living relative of
1:30 the animal that you chose and breed a
1:32 bunch of them together until you get an
1:34 animal with traits that roughly match
1:35 the one that you wanted. This is the
1:38 same basic process that made my dog Thor
1:40 out of a wolf. But instead of trying to
1:41 make something new and adorable, you're
1:43 trying to make something old. It's
1:44 called back breeding, and it can work.
1:46 Like with this guy, it's called a quaga.
1:49 >> I actually have a little uh toy quaga
1:51 right here. It's a subspecies of zebra
1:52 native to South Africa.
1:54 >> They have stripes on the head and neck
1:56 and the stripes fade away along the body.
1:56 body.
1:59 >> It was hunted to extinction by 1883, but
2:01 we've already been able to bring a
2:03 version of it back using back breeding.
2:06 This is a really exciting approach and
2:08 it can work for both animals and plants,
2:12 but it is incredibly slow. It takes many
2:14 generations of zebra to get there and
2:15 it's a guessing game. You don't know
2:17 which genes will appear when and which
2:19 will go away. In reality,
2:22 >> it's a cool method that's been done, but
2:23 probably pretty limited.
2:24 >> Okay, but how about option two? I
2:26 remember in Jurassic Park, they pulled
2:29 dinosaur DNA from blood inside a
2:31 fossilized mosquito.
2:34 >> Bingo. Dino DNA.
2:36 >> And then they cloned the animal based on
2:37 that DNA.
2:39 >> It's all part of the miracle of cloning.
2:41 >> Cool. Let's do that. In real life,
2:42 though, the ingredients that you need
2:44 for this method aren't just the extinct
2:46 animals DNA. You need a whole living
2:48 cell. Because cloning is actually a very
2:49 specific scientific technique.
2:52 >> The long name is sematic cell nuclear
2:55 transfer. It means removing the nucleus
2:57 out of an egg cell and replacing it with
2:59 the nucleus of a body or sematic cell of
3:01 the animal you want to clone. And then
3:03 you put that egg with its new nucleus
3:06 into an animal where it can grow. And
3:09 this actually works almost.
3:09 almost.
3:12 >> People tried this in the early 2000s
3:14 with an extinct species called the
3:17 bukardo. These animals are so cool. But
3:20 by 2000, there was only one Bicardo
3:22 left. But luckily, this was 4 years
3:24 after Dolly the sheep was famously
3:26 successfully cloned. So, in an attempt
3:28 to save the species, some quick-thinking
3:30 biologists put tissue samples from the
3:31 remaining Bicardo in storage. And then
3:33 they were able to take the nucleus from
3:35 those cells and put them into the cells
3:38 of domestic goat hybrids. And in 2003, a
3:41 baby Bicardo was born. Unfortunately,
3:44 their first clone that was born had a
3:47 malformed lung and didn't survive. Um,
3:48 this hasn't been tried again.
3:51 >> So, we are able to clone animals when we
3:54 have living cells, which is wild. But
3:56 unlike the bicardo, nobody carefully
3:58 preserved the whole cells of a mammoth.
4:00 The biggest challenge is needing those
4:02 living cells in the first place. Because
4:04 it turns out that cells have a shelf
4:06 life. Once an animal dies, their cells
4:08 are typically pretty shortlived, dying
4:11 off within hours or days. But freezing
4:13 can dramatically slow this process,
4:14 which is why there's been hope that
4:16 animals found preserved in ice, like
4:20 this 40,000-year-old baby mammoth, might
4:22 have some usable cells. But so far, no
4:25 revivable cells have been found. So
4:27 cloning is hard. But we've got one more
4:30 option, and this one is by far the most popular.
4:30 popular.
4:33 >> For the 99.99%
4:35 of extinct species, we have to use the
4:38 third method, gene editing. If you
4:40 imagine DNA as a group of blocks, each
4:42 block here could represent a gene. Like
4:43 this one tells me the shape of the
4:45 skull, and this one tells me ear size,
4:47 and maybe this one tells me thick woolly
4:49 coat. And then stacked together, they
4:50 give me the instructions for how to
4:52 build this specific animal. The
4:54 challenge is like living cells have a
4:56 shelf life. So does DNA. Once an animal
4:59 dies, the DNA in its cells starts to
5:01 break down into tinier and tinier and
5:03 tinier fragments until eventually
5:04 there's nothing left. That's why right
5:06 now we can't bring back animals that
5:08 went extinct too long ago, like the
5:10 dinosaurs. Too much time has passed and
5:12 their DNA is way too fragmented. But if
5:14 we use an animal that died off fairly
5:16 recently or was frozen in just the right
5:18 way, scientists can figure out what some
5:20 of those key missing pieces are and
5:22 replicate this stack of blocks in
5:24 another animal. This is gene editing.
5:26 You compare the stack of DNA blocks of
5:28 the extinct animal with the blocks of a
5:30 close living relative to see where the
5:32 two are different and edit the DNA in
5:34 the living relative. So, it resembles
5:36 the DNA in the extinct one. This is what
5:38 they're trying to do with woolly
5:41 mammoths and direwolves,
5:44 but they won't be exactly like the
5:46 extinct animal. In fact, people online
5:47 were really quick to point out that
5:50 these actually aren't really direwolves
5:52 at all. It's better to think of them as
5:54 genetically modified greywolves. But the
5:56 thing is, that was intentional.
5:58 Scientists are choosing which exact
5:59 traits to manipulate to get the outcomes
6:01 that they want. and they want to do it
6:03 by making the least amount of edits
6:05 possible. I asked the scientist in
6:07 charge of the direwolf project why I'm
6:09 thinking about deextinction and I'm also
6:10 thinking about animal welfare. Every
6:12 time we change the sequence of DNA in a
6:15 genetic background, there's a risk that
6:16 something happens that we didn't
6:18 predict. I want healthy animals in the
6:21 end. Therefore, my goal is the fewest
6:22 number of changes necessary to
6:25 de-extinct those important
6:27 characteristics. So deextinction might
6:29 have a branding problem because people
6:31 on one side are looking at the literal
6:33 definition and saying that's not
6:35 de-extinction and they're right that's
6:37 not the exact animal. But then on the
6:38 other side of this you have scientists
6:40 who are saying bringing back exact
6:42 replicas isn't really the point. They're
6:45 not trying to deextinct the exact
6:48 animal. They're trying to deextinct what
6:51 the animal did. In the end the whole
6:53 direwolf or not direwolf debate doesn't
6:55 really matter. Branding them this way
6:58 makes for a good headline, but it's not
6:59 technically accurate. And while the
7:01 effort to bring back a version of a
7:03 direwolf or a woolly mammoth is totally
7:06 cool, I think it's a distraction from
7:10 what is the real huge, if true, use of
7:12 this technology. But first, let me show
7:14 you something. This new phone case is
7:15 special. It's not just that it's built
7:17 with insane impact resistance and
7:19 durability, or that it has a lifetime
7:21 warranty against yellowing. Those things
7:22 are important, but what's even more
7:24 important is their mission to tackle
7:28 plastic waste. Every year, 19 to 23
7:31 million tons of plastic waste leaks into
7:33 lakes and rivers and oceans. First, they
7:35 plan to become plastic neutral. So, they
7:37 built a closed loop model. The phone
7:40 cases are 100% recyclable. You can send
7:41 back your old phone case and they break
7:43 it down and repurpose it into a brand
7:45 new one, giving it a second or third or
7:48 more life. It's even got a QR code on
7:49 the inside so you can track the
7:51 product's life cycle. But what they
7:53 really wanted was to tackle all plastic
7:55 waste, not just modern plastic, but also
7:58 legacy and future plastic, too. What if
8:00 you could take plastic waste out of the
8:03 ocean, and then use or upcycle it?
8:05 That's exactly what they do. They've
8:07 built a solar powered floating platform
8:09 that uses water jets to create pressure
8:11 differences that guide floating garbage
8:13 into its collection area. It's like a
8:16 robot vacuum for ocean cleanup. This is
8:18 new. They're testing it right now, but
8:19 it's the kind of effort that I find
8:21 really optimistic. Protecting your phone
8:23 and protecting oceans, too. If you want
8:25 to check it out, use the code cleo for
8:28 10% off at the link in my description.
8:30 There have been five times in the
8:32 history of Earth where over 75% of all
8:34 life was lost. And many scientists say
8:36 we're going through a sixth right now.
8:37 And while prior mass extinctions were
8:40 caused by natural disasters, this one
8:42 seems to be caused by us. But hang on,
8:44 even if you don't care about animals and
8:47 biodiversity, this sucks for us. This
8:48 has huge impacts on our food and our
8:50 homes and everything we rely on to
8:52 survive. And here's the optimistic part.
8:54 The same tools that we've been talking
8:56 about to bring back extinct animals can
8:58 also be used to help animals not go
9:00 extinct in the first place. This is the
9:02 part that got me most excited, and this
9:03 is what I don't see enough people
9:05 talking about. It's called genetic
9:07 rescue. Meet the blackfooted ferret.
9:09 This adorable little guy is in need of
9:11 genetic rescue because
9:13 >> every living blackfooted ferret alive
9:15 today are first cousins. >> Yikes.
9:17 >> Yikes.
9:19 This little guy nearly went extinct in
9:21 1979. Because of humans, the population
9:23 crashed. But fortunately, they've
9:26 started to come back. The problem now is
9:27 that this new group of blackfooted ferrets,
9:28 ferrets,
9:30 >> it has really, really low diversity.
9:31 Very small gene pool.
9:33 >> Scientists call this the bottleneck
9:34 effect. If your group doesn't have
9:36 enough genetic variety, you're
9:38 vulnerable to things like disease and
9:40 weird genetic mutations. This is a
9:42 problem facing dozens of species whose
9:44 populations put them at risk for genetic
9:47 bottlenecking. But today, scientists are
9:50 exploring gene editing to create more
9:52 genetic diversity in some of those groups.
9:52 groups.
9:55 >> We can take DNA from a museum stuffed
9:57 animal from a 100 years ago, sequence
10:00 its DNA, and then edit it into living
10:02 blackfooted ferrets.
10:04 One way to get diversity back, which we
10:05 are working on.
10:06 >> Another great example of using minimal
10:10 gene editing to save a species, is this
10:12 little guy, the northern qu from
10:14 Australia. Look how cute he is. But
10:15 they're expected to be extinct in the
10:18 wild within the next 10 years because of
10:20 this guy, this toad. This is the cane
10:22 toad, and it's an invasive species. It's
10:25 got a deadly toxin on its skin. So what
10:25 happens is
10:28 >> so our carnivorous little qual will eat
10:30 the cane toad and they die instantly
10:31 from that toxin.
10:33 >> But scientists found that it's just one
10:35 single letter of genetic code that makes
10:37 them either die from eating a cane toad
10:40 or completely resistant. Just one
10:42 letter. So they're working on a way to
10:44 introduce that one change into the
10:46 population and make coals that are able
10:48 to eat cane toads without dying, saving
10:51 an entire species. In theory, you could
10:52 do a lot of this. Not just making key
10:54 animals poison resistant, but also
10:56 disease resistant or heat resistant.
10:58 There are projects to do this on coral
11:02 reefs. Huge if true. But then why are we
11:06 trying to deextinct animals at all? That
11:08 brings us back to the Tasmanian tiger.
11:10 Humans hunted these tigers until there
11:11 were none left in the wild. But they
11:13 didn't understand what would happen
11:15 next. Without the tiger, Tasmania lost
11:17 its only apex predator, a keystone
11:19 species, meaning it has a huge impact on
11:21 its ecosystem. And without them,
11:23 >> there's been an explosion of walabeees
11:25 and kangaroos there. They're eating all
11:26 the shrubs, they're eating all the
11:28 bushes, you know, that's impacting the
11:30 bird populations. It's changing the landscape,
11:30 landscape,
11:32 >> which means that now other species are
11:34 at risk, like the Tasmanian devil.
11:36 >> They developed this incredibly strange
11:38 disease, and it's actually like a cancer
11:40 tumor that grows on their face, and they
11:42 spread it from animal to animal. Apex
11:44 predators used to reduce diseases like
11:46 this. By eating sick members of the
11:49 population by killing all the Tasmanian
11:51 tigers, we created a butterfly effect
11:52 that's rippling through the food chain
11:55 to this day. So, some are proposing
11:56 >> the only way we'll ever be able to bring
11:58 that ecosystem back into balance is to
12:01 put the Tasmanian tiger back into it.
12:03 >> Tasmania is an island cut off from other
12:05 natural predators. And many scientists
12:06 agree that there's no other living
12:08 species that could replace what the
12:11 thyloine could do here. But could we
12:12 actually do this? Well, they're
12:14 following the recipe. They've identified
12:17 the animal. They've sequenced the DNA.
12:19 As for close relatives, this is the
12:20 closest living animal to the thyloine.
12:23 Their genetic makeup is 99.9% identical.
12:24 identical.
12:27 >> And then you just edit that.1% where
12:28 they're different. And that will turn
12:32 that then into a Tasmanian tiger or a
12:33 thyloine cell. >> Wait.1%.
12:34 >> Wait.1%.
12:36 That's actually a lot genetically. And
12:38 that's the bit that's going to take a
12:40 really, really long time um to get that
12:41 bit done.
12:42 >> At this point though, you might be
12:44 wondering, whoa, whoa, whoa, whoa, whoa.
12:45 Did we not learn our lesson from
12:47 Jurassic Park?
12:50 What are the consequences of actually
12:52 doing this? When is it okay to use this
12:54 technology? And when is it not? In other
12:57 words, how do we get this right? What
12:59 happens when you drop a predator back
13:00 into an environment that hasn't seen it
13:04 in decades? Well, in this case, it seems
13:07 like a lot of the animals remember them.
13:09 >> We made some replica thyloines and we
13:11 took them out into the bush in Tasmania.
13:14 We saw that they absolutely without
13:16 doubt, even though it's been over a
13:17 hundred years since they were really
13:19 there. All of those animals remember the
13:21 thyloine. If there's a fox or a goat,
13:23 they don't really care. But if they see
13:25 the thyloine, they are out of it.
13:27 >> But what about the thyloine's instincts?
13:29 How would it know to behave right like a
13:31 predator? How much of an animal is
13:33 nature versus nurture? There's real
13:34 debate here.
13:36 >> I frankly don't think that it will ever
13:38 happen that we will see thyloines into
13:38 the wild.
13:40 >> But advocates for the thyloine would argue
13:41 argue
13:44 >> those behaviors are really hardwired in
13:46 any animal's brain. The best example of
13:48 this would be domestic cats. These are a
13:50 pounce predator animal that have been
13:52 living in our houses now for hundreds of
13:55 generations, eating tinned cat food or
13:57 little crispy biscuits. But if you
13:58 wiggle a feather in front of them or a
14:00 mouse runs across the floor, they
14:02 immediately know that they are a pounce
14:05 predator and they will pounce and kill
14:06 and eat that that animal.
14:08 >> We don't really know until we try. And
14:10 they're trying. This is all hard, but
14:12 it's not like we're creating things that
14:14 are suddenly going to just be released
14:15 into the wild.
14:16 >> You would have them in a very large
14:19 enclosure. you would really study them
14:21 very very closely and make sure that
14:23 they have taken on all of the behaviors
14:25 so that by the time we get a population
14:27 that we could think about releasing into
14:28 the wild, we know that they're going to
14:30 be able to really thrive once again.
14:33 >> What this all means, best case, is we're
14:35 still decades away from a wild Tasmanian
14:38 tiger, but this technology is coming and
14:40 we need to be part of that conversation
14:42 right now. It's obviously fun to imagine
14:44 Jurassic Park or bringing back a
14:47 direwolf, but as we have this
14:48 conversation, we got to be careful.
14:50 We're talking about manipulating
14:52 billions of years of evolution. There
14:54 are huge stakes, ethical stakes about
14:56 using animals as lab experiments,
14:57 environmental stakes that could
14:59 accidentally devastate entire
15:02 ecosystems, and of course, the stakes of
15:05 not doing absolutely everything we can.
15:07 To me personally, the most huge, if
15:10 true, optimistic bit of all of this
15:12 isn't actually bringing back animals
15:14 from the past. It's using all of this
15:17 incredible science and technology to
15:19 help keep the animals and the world that
15:21 we live in now healthy.
15:22 >> I would love people to go away from this
15:25 and be like, deextinction science is
15:27 conservation science and we absolutely
15:28 have to use it.
15:30 >> We are living in a world that we changed
15:32 before we understood the consequences.
15:34 The real debate about de-extinction
15:36 isn't what's a direwolf. It's what
15:39 responsibility do we have to the world
