National Geographic

Will we ever bring back the woolly mammoth?

This post was initially published on June 6, 2012, and is being resurrected as part of National Geographic’s special on de-extinction. When it comes to bringing back the mammoth, it turns out that the biggest hurdle is not getting mammoth DNA, but in navigating the complicated reproductive system of living elephants…

Tens of thousands of years ago, woolly mammoths roamed the northern hemisphere. These giant beasts may now be extinct, but some of their bodies still remain in the frozen Arctic wilderness. Several dozen such carcasses have now been found, and some are in extremely good condition. Scientists have used these remains to discover much about how the mammoth lived and died, and even to sequence most of its genome. But can they also bring the animal back from the dead? Will the woolly mammoth walk again?

Akira Iritani certainly seems to think so. The 84-year-old reproductive biologist has been trying to clone a mammoth for at least a decade, with a team of Japanese and Russian scientists. They have tried to use tissues from several frozen Siberian specimens including, most recently, a well-preserved thighbone. Last year, Iritani told reporters, “I think we have a reasonable chance of success and a healthy mammoth could be born in four or five years.”

A few months ago, a second team led by Korean scientist Hwang Woo Suk also expressed interest in cloning a mammoth. While Iritani comes with impressive credentials, Hwang’s resume is less reassuring. He is perhaps best known for faking experiments in which he claimed to have cloned the first human embryo and produced stem cells from it. The fact that he has confessed to buying mammoth samples from the Russian mafia does not help to instil confidence.

Regardless of their pedigree, both teams have their work cut out. Any attempt to resurrect the mammoth faces an elephantine gauntlet of challenges, including the DNA-shattering effects of frost and time, and the rather unhelpful reproductive tract of the eventual surrogate parent—the elephant.

Gene challenge

Siberian ice might preserve the bodies of mammoths, but it is not kind to them. Ice crystals puncture cells, spilling out their contents. Even if the DNA inside the cell is not exposed, it tends to break down over time. Stephan Schuster from Penn State University, who led the mammoth sequencing project, says, “Even the genomes from much younger organisms rapidly decay. It’s like smashing a mirror on the floor.” Schuster’s team compared the heavily fragmented DNA of a mammoth against the genome of an elephant. That approach allowed them to read the genome, but it cannot be used to reconstruct it.

Synthesising an animal genome from scratch is a massive challenge by today’s technological standards. It would require: a far more accurate draft than the one we have; knowledge of the number of chromosomes a mammoth had; the ability to stitch together such large stretches of DNA; ways of packaging that DNA into a nucleus; and hoping that all the DNA will still be in good working order.

There is another option. Rather than producing mammoth DNA from scratch, you could tweak DNA from an African elephant. The genomes of the two species differ by just 0.6 percent, half the difference between us and chimpanzees. By identifying and swapping the different sequences, you could potentially rewrite an elephant genome so that it reads like a mammoth one.

Palaeontologist Jack Horner is trying something similar by rolling back a chicken’s genes into a state more like its extinct dinosaur ancestors, and scientists like Harvard University’s George Church are developing techniques that can rewrite vast swathes of DNA at once. But even if the technology catches up with the ambition, Schuster says: “That’s not making a mammoth. It’s ‘mammothifying’ an elephant.” The resulting creature may be a more mammoth-like version of today’s pachyderms, but it won’t be the real deal.

These problems might be avoided if we could find intact nuclei from frozen mammoths, at least if experiments in other animals are anything to go by. In 2008, Sayaka Wakayama and colleagues from RIKEN, Japan cloned healthy mice from individuals that had been frozen for 16 years. They found intact nuclei in the chilled bodies, and fused them with empty eggs. By all accounts, Iritani is trying to do the same thing with frozen mammoth remains (he did not respond to a request for an interview). But Schuster does not mince words about the odds of finding intact mammoth nuclei. “It’s entirely impossible,” he says. Sixteen years in the freezer is one thing; 16,000 years is quite another.

Pregnant pause

Assuming that Iritani’s team gets an intact nucleus, they would still have to insert it inside an elephant egg. Collecting such an egg means navigating a reproductive tract that spans three metres from the uterus to the outside world. “It’s extremely challenging,” says Thomas Hildebrandt from the Leibniz Institute for Zoo and Wildlife Research, who knows the reproductive tract of elephants like the length of his arm.

A female elephant only ovulates once every five years, releasing one or two eggs at any time to ensure that she never becomes pregnant with several gargantuan foetuses. Each egg is a 2-centimetre-wide ball rattling around an enormous cavern. Once it is released, the female almost immediately has sex. “There are almost no wild elephants that are fertile without already being pregnant,” says Hildebrandt. So, collecting an oocyte from an elephant is like groping in a haystack for a needle that probably does not exist. If getting one egg sounds hard enough, would-be mammoth-makers need hundreds or thousands of eggs to ensure one successful clone.

There is a possible cheat. They could take ovarian tissue from a culled elephant, transplant it into a rat or a mouse, and tweak the rodent’s hormonal cycles to ensure that the eggs mature properly. This has been tried, but no one knows if the resulting eggs were actually viable. It’s a long shot, and “you still have the problem of transplanting the embryo,” says Hildebrandt.

Notwithstanding the distance into the uterus, the path is blocked by the hymen. This is essential to the elephant; it grows back after every birth and it cannot be broken without compromising the pregnancy. It has an opening just 2 to 4 millimetres wide that allows passage to sperm – that’s what an embryo-carrying tube would have to navigate through. “It’s not impossible but it would need quite a lot of technological development,” says Hildebrandt. “Most people don’t expect that. They think they biggest challenge is creating the embryo.”

Even if a baby mammoth comes to term, it may not last for long. In 2009, European scientists used preserved skin cells to clone the Pyrenean ibex, a type of goat that had been extinct since 2000. The glorious resurrection lasted all of seven minutes, before the newborn kid died of lung failure. Many (but far from all) cloned animals have suffered from similar health problems. If the woolly mammoth does the same, its resurrectors could end up with the world’s most expensive carcass.

Conservation boost

Despite these many hurdles, Schuster does not dismiss the possibility of cloning a mammoth, especially with improvements in genetic techniques. “Every time a journalist asks me about this, one of those hurdles has been taken out,” he says. “I think it’s a little irresponsible to stand there and say it’ll never happen, but that doesn’t mean we should spend money on it. Maybe it would be better spent on preserving endangered species today.”

Can we really justify trying to bring the mammoth back from extinction when all three species of living elephant are in danger of joining it? “If you’d interviewed me two or three years, ago, I would have been much more aggressive against it,” says Hildebrandt. He has changed his mind after struggling with efforts to conserve other large animals like the Sumatran rhino. Only a few hundred remain, and many are so old that no amount of assisted reproduction will help them to breed. “Our only option is to clone them,” he says.

Mammoth-cloning projects might act as an attractive funding magnet in a way that conservation projects of little-known rhinos cannot. “The mammoth may be able indirectly help future conservation projects, by developing cloning technologies that could help modern species,” says Hildebrandt. It’s a sobering thought: as impossible as cloning an extinct animal might sound, the one good reason to try is that it might prevent a number of species from suffering the same fate.

There are 19 Comments. Add Yours.

  1. Jim
    March 19, 2013

    Are we going to resurrect a mammoth in order to keep it in a zoo? What’s the point in that? If we bring back the mammoth, it should be to re-occupy its former niche in an existing ecosystem. But their ecosystem no longer exists. Our zoos already have a hard time preserving animals that are in danger of extinction in the wild because humans have manipulated their natural homes to the point they no longer support them. Wouldn’t it be more productive, useful, etc. to restore recently extinct animals to their still existing habitats? As a birder, I would be able to get behind restoring the Great Auk, Ivory-billed Woodpecker and other birds that would have a chance to re-establish wild populations. I am sure there are recently extinct mammal species that could also be brought back to live in the wild. I think that would be infinitely more worthwhile than bringing back a couple of mammoths – not even enough to establish a reasonable breeding group – to live in a zoo with no hope of ever living in the wild and possibly dying out after a few generations from inbreeding.

  2. Kate Jones
    March 21, 2013

    Species perish constantly, whether through human ageny or naturally. And hundreds of new species arise or are discovered annually. No one has mentioned whether our intercession to bring back extinct beings is potentially opening a Pandora’s box of potential harm to ourselves and the planet, perhaps by reviving deadly microbes as well. The insatiable human thirst for new knowledge and conquering new frontiers is, however, our birthright for having evolved such brains. Would the knowledge and technology gained thereby at some point help our own survival and adaptation to live in an altered world, or on other planets? We are genetically engineering new plants and foods. Is not that already a grave danger to our present wellbeing?

  3. Gaddy Bergmann
    March 23, 2013

    I think “de-extinction,” if at all possible someday, would be a great tool. In the debate on this issue, the most reasonable argument against “resurrection” is that it might create a false sense of security regarding extinction. However, I don’t anticipate this. As Ben Franklin put it, an ounce of prevention is worth a pound of cure. As long as we make it clear that conservation is clearly preferable to resurrection, then animals like woolly mammoths, thylacines, passenger pigeons, and others might be brought back after we banished them, to live alongside more abundant members of those ecosystems. This project is very technically difficult, but I think it is morally justified to pursue it.

  4. jeg
    March 26, 2013

    Why a mammoth? Wouldn’t it be easier to do an animal that hasn’t been extinct for as long? What about a passenger pigeon? I just think mammoth is a little over-ambitious. Also, it’s been gone so long there really isn’t a niche for it anymore. I understand you get more funding for something more interesting, I just think they should have picked something interesting and perhaps a little more doable.

  5. Dwayne
    March 27, 2013

    Cloning a mammoth is a GREAT idea! Why start with something small ( They’ve already experimented with a mouse). A large – pun intended- project like this, captures the imagination in the way that reviving the Indonesian Flores Cave Rat would never do. If these folks wish to revive a Mammoth, I say Gods Speed to them!

  6. Federico
    April 3, 2013

    Whilst the Mammoth(s) themselves would be more of a visual flare than an actual species inhabiting the earths’ ecosystem, their cloning would bring GREAT public attention (money) to conservation efforts, further it would boost the funding of cloning projects for extinct species that shouldn’t be extinct, like the thylacine and the passenger pidgeon which other commenters noted. We would have a very lucky single or few mammoths and a whole renewed interest for conservation.

  7. Greg
    April 23, 2013

    Even if the newborn mammoth died minutes after birth, something great has been done. Science now has a mammoth carcuss that is newly dead instead of dead for 1000’s of years. A lot can be learned from this.

  8. Alysss
    April 27, 2013

    I LOVE this. Mammoths r my favorite animals,but this kinda reminds me Jurassic Park. But i would love to see a mammoth in a zoo or something

  9. Natalee
    May 19, 2013

    I think the woolly mammoth has been extinct for many years now. It would be cool to see a long-extinct woolly mammoth now. We miss a lot of things 65 million and a half years ago when the woolly mammoth where living. I wonder where the woolly mammoth’s new habitat will be at when the come. It would also be cool to ride a woolly mammoth or keep it as a pet. I know that scientist can bring woolly mammoth’s back to life. In 2003 a team of Spanish and French scientist re-created the extinct Pyrenean ibex. Although the animal didn’t survive long. But the woolly mammoth might live long. It depends. Although I bet we can bring a new set of species that are known to be extinct back. Some people say it’s impossible but it’s not always impossible if you don’t give up. The woolly mammoth is a big specie and it is kind of like a elephant with hair. But it is a little different with the size and the shape a little. Woolly mammoth are related to elephant’s. I would love to see a woolly mammoth. Also I would love to learn more about it. Like where it’s going to live and how big it is. I hope other people learn more about it to. It is a fascinating animal. And a long-extinct elephant a little. But how will the woolly mammoth act when it comes? will it get along with the other animals? No one but the scientist maybe know for sure. I do hope the woolly mammoth may cause no harm. But I do hope we get to see one in person.

  10. Cord
    May 30, 2013

    The scientific rationale behind this is strong, but as others have noted, save in the case of animals who may presently be headed toward extinction without genetic intervention, why bring back a species that has already died out once? I have to give a Mary Shelley inspired shudder at the comment of one person above who suggests that, even should a baby mammoth be born and die, it is worth it to study the carcass. The old saw that “might is right at Rome” rings hollow in human issues, and with humans behind the science, I’m not so certain we wouldn’t be better off trying to figure out how to restore the environment rather than reintroducing something the environment killed off thousands of years ago.

  11. Bigtexun
    June 5, 2013

    If we try to clone a mammoth, and fail, the effort to try will have taught us a lot. I’m confident that the project will have gains in science worth having, and will have lessons that will bring advances in many areas.

  12. Peter
    August 19, 2013

    It’s remarkable that humanity even contemplates the possibility of bringing back an extinct species. We are becoming more and more powerful. But it is unlikely a mammoth would live long before getting this or that disease for which its DNA does not include immunity, it might need certain bacteria in it’s guts that no longer exist today. The chances of success seem minimal to me, but the whole idea, the possibility of doing this is intriguing. All the moral objections listed in these comments notwhithstanding.

  13. Jd archealogist
    September 7, 2013

    Im a young archeaolgist and just the and just the tiny thought of the mammoths birth brings me great confidence many commenters say “bring smaller creatures” or extinct turning creatures back to life by cloning heres something i have to say to that. Do you think people will be excited from something tiny like a meer pigeon or a ibex, or possibly something more childish? Those thoughts sicken me to the bone just by reading them. Ugh rethink about the possibilites,have HOPE! It may or may not be a success but……….. a fresh mammoth body would make it easier to make MORE! That’s a thought worth thinking about, nobody wants to see mice,or passenger pigeons anything like that you can and should,just forget about being cloned it wont be something that people want to see.

  14. Jd archealogist
    September 7, 2013

    One last thing, if the mammoths birth and if so,death is a success we can at the best have fresh mammoth to clone. Possibly one day,if lucky……You could see a T-Rex walk by your window.

  15. bigtexun
    September 9, 2013

    The Mammoth was alive recently enough that semi-intact DNA in mostly-intact cells exist in frozen animals frozen a few thousand years ago.

    No such T-Tex is likely to be found, at least on on the surface of the Earth. They lived in a warmer time when there was little if any solid ice deposits, and even fewer that are likely to have survived to today. A intact and frozen T-Rex DNA sample may have been blasted off the earth in an impact event, and could have landed on the moon, perhaps. It would likely be freeze-dried, and be far from the intact cell we might find of a mamoth. Sure. there could be blood in a mosquito trapped in amber, but that blood would have likely been consumed and re-consumed by several generation of bacteria before biologic processes stopped altering it’s structure.

    It is more likely we would re-create a similar creature by attempting to alter, isolate and/or activate old gene segments in a modern creature, and breed a modern version of a T-Rex like animal… that would then take over the earth, eating all of us.

  16. JCIBME
    November 9, 2013

    I think the scientist are looking more at the short term goals rather than the long term effect. Yes it would be fascinating to bring back a Mammoth just to say we have the knowledge and power to do so. But what about the long term effect? Can we guarantee that calf could even survive drinking the antibodies of its mothers milk? We know nothing about the internal workings of a Mammoth, we only can guess at what they may have needed. Would a calf even survive in today’s atmosphir? If a calf dies, that does not mean the DNA can be used, it means there was a defect and the carcass would be useless. And is anyone thinking about the moral and ethical issues? The thoughts of the woman who posted “I would like to ride it.” That comment, I am afraid shows all the reasons we do not have the right to bring anything back from the dead. We do not even know how to take care of the life we already have on this planet. What if something that is gone can not be brought back? What message will that tell us? I think we can modify and have a similar version that would be able to adapt to the environments atmosphir of todays world, but I do not see any creature from millions of years ago being able to live very long in todays world. It has changed to drastically. It would be the responsibility of Science to make sure if they are to bring one back, that it is not just because they can, it will be up to them to ensure the animal has all the resources it will need to survive. I think if science brings back an extinct species and does not provide it with the resources it needs to survive, then I think science should be held responsible in a court of law. Just because we can do something, does not mean we should because we become responsible for that life. And science should be held responsible when they fail to think ahead and find they cannot provide for that life they have just brought into this world.

  17. Blern
    February 8, 2014

    All of you, (who don’t think the it should be brought back), are wrong. The wooly mammoth would give scientists a chance to learn more about how are world has evolved and it would give large deposits of information and research to help us bring back animals such as the passenger pigeon.

  18. awesome
    February 27, 2014

    I AM AWESOME. I think this project is incredibly complex, I mean, could you find the amount of chromosomes in even a human, much less a far more extinct animal that we have only few fossils of?

  19. Ellen
    March 2, 2014

    I completely agree with JCIBME. It would be completely out of place. And it would be all alone, with no one to teach it to be a mammoth. It would be cruel to have it live in our world of today.

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