The vast majority of those pregnancies failed, and the few animals that were born were often beset with health problems. Over the past decade scientists have improved their success with cloning animals, shifting the technology from high-risk science to workaday business. Researchers have also developed the ability to induce adult animal cells to return to an embryo-like state.
These can be coaxed to develop into any type of cell—including eggs or sperm. The eggs can then be further manipulated to develop into full-fledged embryos. Such technical sleights of hand make it far easier to conjure a vanished species back to life. Scientists and explorers have been talking for decades about bringing back the mammoth. Their first—and so far only—achievement was to find well-preserved mammoths in the Siberian tundra. Now, armed with the new cloning technologies, researchers at the Sooam Biotech Research Foundation in Seoul have teamed up with mammoth experts from North-Eastern Federal University in the Siberian city of Yakutsk.
Last summer they traveled up the Yana River, drilling tunnels into the frozen cliffs along the river with giant hoses. In one of those tunnels they found chunks of mammoth tissue, including bone marrow, hair, skin, and fat. The tissue is now in Seoul, where the Sooam scientists are examining it.
If the Sooam researchers do find such a cell, they could coax it to produce millions of cells. Most scientists doubt that any living cell could have survived freezing on the open tundra. But Hwang and his colleagues have a Plan B: capture an intact nucleus of a mammoth cell, which is far more likely to have been preserved than the cell itself. Cloning a mammoth from nothing but an intact nucleus, however, will be a lot trickier.
The Sooam researchers will need to transfer the nucleus into an elephant egg that has had its own nucleus removed. This will require harvesting eggs from an elephant—a feat no one has yet accomplished. If the DNA inside the nucleus is well preserved enough to take control of the egg, it just might start dividing into a mammoth embryo. Then, as Zimov cautions, they will need patience. If all goes well, it will still be almost two years before they can see if the elephant will give birth to a healthy mammoth.
In , while traveling along the Ohio River from Hardensburgh to Louisville, John James Audubon witnessed one of the most miraculous natural phenomena of his time: a flock of passenger pigeons Ectopistes migratorius blanketing the sky. When Audubon reached Louisville before sunset, the pigeons were still passing overhead—and continued to do so for the next three days. Multitudes were thus destroyed. In it would have been hard to imagine a species less likely to become extinct. Yet by the end of the century the red-breasted passenger pigeon was in catastrophic decline, the forests it depended upon shrinking, and its numbers dwindling from relentless hunting.
In the last confirmed wild bird was shot by a boy with a BB gun. Fourteen years later, just a century and a year after Audubon marveled at their abundance, the one remaining captive passenger pigeon, a female named Martha, died at the Cincinnati Zoo.
Two years ago Brand and his wife, Ryan Phelan, founder of the genetic-testing company DNA Direct, began to wonder if it might be possible to bring the species back to life.
One night over dinner with Harvard biologist George Church, a master at manipulating DNA, they discovered that he was thinking along the same lines. But he could envision a different way of re-creating the bird. Preserved specimens contain fragments of DNA. By piecing together the fragments, scientists can now read the roughly one billion letters in the passenger pigeon genome.
He could theoretically manufacture genes for passenger pigeon traits—a gene for its long tail, for example—and splice them into the genome of a stem cell from a common rock pigeon.
Rock pigeon stem cells containing this doctored genome could be transformed into germ cells, the precursors to eggs and sperm. Squabs hatched from these eggs would look like normal rock pigeons—but they would be carrying eggs and sperm loaded with doctored DNA. When the squabs reached maturity and mated, their eggs would hatch squabs carrying unique passenger pigeon traits.
These birds could then be further interbred, the scientists selecting for birds that were more and more like the vanished species. So even if the Sooam team fails to find an intact mammoth nucleus, someone might still bring the species back.
Scientists already have the technology for reconstructing most of the genes it takes to make a mammoth, which could be inserted into an elephant stem cell. And there is no shortage of raw material for further experiments emerging from the Siberian permafrost.
Though the revival of a mammoth or a passenger pigeon is no longer mere fantasy, the reality is still years away. For another extinct species, the time frame may be much shorter.
The animal in question is the obsession of a group of Australian scientists led by Michael Archer, who call their endeavor the Lazarus Project. Archer previously directed a highly publicized attempt to clone the thylacine, an iconic marsupial carnivore that went extinct in the s.
Wary of the feverish expectations that such high-profile experiments attract, Archer and his Lazarus Project collaborators kept quiet about their efforts until they had some preliminary results to offer. That time has come. Early in January, Archer and his colleagues revealed that they were trying to revive two closely related species of Australian frog. Until their disappearance in the mids, the species shared a unique—and utterly astonishing—method of reproduction.
The female frogs released a cloud of eggs, which the males fertilized, whereupon the females swallowed the eggs whole. A hormone in the eggs triggered the female to stop making stomach acid; her stomach, in effect, became a womb.
A few weeks later the female opened her mouth and regurgitated her fully formed babies. This miraculous reproductive feat gave the frogs their common names: the northern Rheobatrachus vitellinus and southern Rheobatrachus silus gastric brooding frogs. Unfortunately, not long after researchers began to study the species, they vanished. To bring the frogs back, the project scientists are using state-of-the-art cloning methods to introduce gastric brooding frog nuclei into eggs of living Australian marsh frogs and barred frogs that have had their own genetic material removed.
There are some species that are extinct that before the last individual died, living tissue was taken and put into deep freeze. This is, for example, the bucardo, which a lot of people have heard of.
There was an individual the last living individual was a female, and part of her tissue, skin tissue was taken while she was still alive and put into deep freeze.
Later on, that was revived and used in cloning, the same way that people cloned Dolly the sheep. In fact, a bucardo was born, but it had a problem with one of its lungs and it died shortly after it was born. Of course, mammoths actually lived until relatively recently. This surprises some people when they find out that mammoths were alive only maybe thirty five hundred years ago… Still, there is no living mammoth material.
There are no living mammoth cells. So we can not clone a mammoth. Now no one is going to buy my book. Marshall Poe: Well, the way you presented in the book is hilarious. So you need a living cell, a viable cell. So one avenue to cloning an extinct animal would be to create a viable cell. Is that possible at all? This is a little bit disingenuous. We has skin cells from Asian elephants, which are the closest living relative of mammoths.
Asian elephants and mammoths diverged evolutionarily about five or six million years ago. George and his team have so far made about fifty different edits. Then we have a cell living in a dish in a lab.
Let me take a step back. How many projects aimed at de-extinction are going on today. Are there people working on this in this way? Are these kinds of things going on? Instead, what we like to think of this is a separate umbrella term, which we call genetic rescue. There are many genetic rescue projects that are going on. They have some incredible details of supercool projects that are going on right now involving things including the mammoth.
This was great. They make a lot of black-footed ferrets in captivity, but when they are released back into the wild, they eat a prairie dog and they get plague and they die. That is not good news for black-footed ferrets. So the population is almost too small to survive.
So Florida panthers got to be very small population, highly inbred, and only a few individuals, and they started to show signs of of this inbreeding. So they had kinked tails, a crooked thing in their tail. They were making very few mobile sperm. They had heart defects. They were really susceptible to disease. And what people did was they took panthers from Texas, just the nearest population to Florida panthers, and introduced a few healthy individuals into Florida.
So instead of going geographically, we go to a place called the Frozen Zoo in San Diego where before black-footed ferrets nearly went extinct, they captured some few individuals. They took some cells, and they put them in the deep freeze.
So now we have these living deep frozen cells from individuals who have different DNA sequences because they were alive before this near extinction event. Can we use those individuals and clone those individuals and introduce them to that population, providing an increase in diversity and giving them and giving them a chance at surviving?
Marshall Poe: Right. Because with these very small populations, cloning is not exactly what you need because that produces a copy. What you need is increased genetic diversity. They took frog DNA and they stuck it into other things.
So why so far away in the evolutionary tree is a little weird, but whatever. But they were smashing things together, you know, filling in holes with different species, which is kind of crazy. But, you know, what do we mean by de-extinction? Is it really to have a mammoth that we can look at and hug and maybe put in a zoo and maybe have kid rides on and stuff like that? Is there some ecological rationale for wanting to bring them back? I think for some recently extinct species whose extinction might have thrown their community that they lived in out of balance, then maybe there is a reason to try to bring them back and to reestablish ecological connections that that existed prior to their disappearance.
But then you have to ask yourself, do you really need that exact species, or could you use something in its iplace? They want mammoths to be back in Pleistocene Park because they think mammoths play a really critical role in establishing this ecosystem just by wandering around and knocking down shrubs, just like elephants do.
But do they actually need a mammoth, or could they use an elephant that maybe has been modified using gene editing technologies to be able to survive and even thrive in the cold habitat up in Siberia? But if we could identify mutations in their DNA that would make them better able to survive in that environment, then maybe we could just create a cold adapted elephant.
So if they were to succeed, maybe they would create a cold adapted elephant. So you have an elephant cell, mostly elephant, that has a bit of mammoth DNA in it. Does that count as a de-extinction? To me, no, I guess. What do you think, Marshall? Is that a de-extinction? Marshall Poe: I would call it speciation or something like that. It reminds me of the process of speciation, where a new species emerges in a kind of natural way.
I have to stop and ask you this question. What do you think of the metaphor of DNA as the blueprint for life? In fact, a lot of what we look like is really based on that. If you want to know how important the DNA letters are in determining what somebody looks like, then just see identical twins. They look identical. They have the same DNA, but extend that a little bit and no identical twins as they get older, as they live different lives, and experience different things and have different illnesses and different stressors and different joys, they diverge in the way that they look and the way that they act.
This is because we are a combination of what is coded by our DNA and the environment in which we live. The same would be true for any clone. A clone is just an identical twin that happens not to be born at the same time.
Technological hurdle, number whatever. De-extinction is a process that begins with creating a single animal in the lab and then ends, many years later, with the release and survival of sustainable populations in the wild. Ecosystems are fluid, dynamic entities — they change quickly. But if a species has gone extinct recently, there is a chance it could be returned to its original ecosystem.
A de-extinct Christmas Island rat, however, would not be so lucky. Since its extinction over years ago, Christmas Island has become riddled with invasive species that would likely pose a problem. In this case, a suitable alternative habitat would have to be found. It may seem an odd thing to say, but one of the ideal de-extinction candidates could be an animal that is actually still alive… just. There are only two northern white rhinos left alive on the planet, both of them female, who spend their days at the Ol Pejeta Conservancy in Kenya.
But they are too old, too ill and too related to breed naturally. Saving it counts as an act of de-extinction. The northern white rhino is currently the focus of a de-extinction project.
Some people are against de-extinction because they say it feels unnatural. They are wary of genetic modification and accuse scientists of playing God. But proponents argue that the techniques being developed to make de-extinction happen all have natural counterparts in the wild.
For example, there are species of lizard that reproduce via cloning, while the gene-editing process being used to bring back the mammoth hails from a primitive bacterial immune system. Just as IVF has become an accepted medical technique, so de-extinction researchers hope that concerns about their experiments will fade once the science has proved its worth.
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Critics also claim that de-extinction is stealing funds and attention from traditional conservation efforts. But although the doppelganger will look like your faithful friend, it will never be the same. If we can resurrect animals, could we bring back long-dead humans? Take Elvis Presley as an example. Reproductive human cloning is illegal and unethical, and the process carries many risks.
But this cheeky thought experiment does show how far the science underpinning de-extinction can take us. Maybe not. Cloning — This is one of the principle methods used to bring back certain animals. Ecosystem — This is a biological community of interacting life forms and the space they live in.
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