A Blog by Carl Zimmer

De-Extinctions and Straw Men

In my feature on de-extinction in the April issue of National Geographic, I tried to capture the debate in the scientific community about whether we should try to bring vanished species back to Earth. It’s been gratifying to see a spirited, sustained conversation going on ever since. The prospect of de-extinction raises important issues that have to be grappled with. Is it better to spend money trying to revive a mammoth or to secure a vast swath of rain forest? Are objections to de-extinction driven by a flawed notion of what’s natural? Would it make more sense to use the emerging tools of biotechnology to prevent endangered species from disappearing, rather than attempting to bring back the extinct ones?

But I’m frustrated by a column by George Monbiot that just appeared in the Guardian, entitled, “Resurrecting woolly mammoths is exciting but it’s a fantasy.” Monbiot singles out National Geographic for scoffing, declaring,

the double-page painting published by National Geographic in April, depicting tourists in safari vehicles photographing a herd of Siberian woolly mammoths roaming the Siberian steppes, is pure fantasy: the animals it shows are mumbo-jumbos.

(We Yanks use mumbo-jumbo to refer to gibberish, but after reading Monbiot’s piece, I did some dictionary-ing and discovered that the Brits use it to refer to a meaningless idol.)

It’s not Monbiot’s position that bothers me. In my article, I wrote about harsh critics of de-extinction as well as advocates. It’s the way he frames his argument at the outset:

There is an obvious, fatal but widely overlooked problem with de-extinction. 

Wow! Both obvious and fatal. Not just obvious and fatal, but also widely overlooked! What could this problem be, a problem that conservation biologists and molecular biologists who are exploring de-extinction have somehow failed to notice, a problem that Monbiot is here–at last–to unveil?


The scarcely credible task of resurrection has to be conducted not once but hundreds of times, in each case using material from a different, implausibly well-preserved specimen of the extinct beast. Otherwise the resulting population will not be genetically viable.

Really? That’s it?

I felt a distinct lack of surprise at Monbiot’s big reveal.  That’s because I had addressed this very issue in my own article four months ago, noting that reviving a single animal is not the same as bringing back an entire species.

But I didn’t go so far as saying that this was a “fatal” problem, because I discussed the issue with the scientists I interviewed. You’d think from reading Monbiot’s column that these scientists hadn’t the faintest clue of this problem. I picture them sitting in front of their screens, reading Monbiot’s revelations, and smacking their foreheads all at once, roaring, “Of course! How stupid of us!”

You’d have to be a truly stupid scientist to not be aware that the long-term viability of a species depends on a genetically viable population. If a small population is only made up of nearly genetically identical individuals, they run the risk of inbreeding, which can make them unhealthy, vulnerable to diseases, and even infertile.

The scientists exploring de-extinction are aware of this challenge, and they have actually given this matter some thought. They have ideas about how to deal with it. There’s a good debate to be had over whether those ideas could really work in practice, but Monbiot shows no signs of being familiar with them.

Monbiot is arguing that de-extinction cannot work, period, because it would require discovering an intact cell for every individual animal or plant scientists wanted to produce. There are several reasons why this is wrong. For one thing, scientists already have the technology required to engineer diversity into a species.

Museums have hundreds of preserved passenger pigeons, for example, and those birds are not clones of one another. By sequencing the DNA from a number of passenger pigeons, scientists could learn about the genetic diversity of the species. Based on the experiments scientists are already doing on animal cells, it’s conceivable that researchers could synthesize gene variants and plug them into the genome of an extinct animal. By engineering the genomes of the pigeons, scientists would create a flock containing some of the genetic viability that existed before the species became extinct.

If scientists can produce a few dozen genetically diverse passenger pigeons–or gastric brooding frogs, or thylacines, for that matter–it’s an open question whether those creatures could seed a sustainable population. Monbiot seems to be down on the whole idea of restoring small populations. He points to European bison, which have gone from 54 animals to 3,000, but which still have trouble with inbreeding.

But there are more heartening stories, too. Northern elephant seals were hunted down to the same population level, and today their numbers are up to 160,000.

Now we’ve drifted off the original course, though. We are no longer talking about de-extinction, but about the broader question of captive breeding. There’s another good debate to be had about whether to save the black-footed ferret and the California condor. But I guess it’s not as fun as shouting mumbo-jumbo! 

24 thoughts on “De-Extinctions and Straw Men

  1. I, a computer scientist, roomed with a houseful of biologists when I was a graduate student. With the usual curiosity of youth, we quizzed each other about our disciplines. One thing I quickly learned: If a question occurs to a nonspecialist, it’s long since occurred to, and been deeply thought about by, the specialists. Mr. Monbiot must have forgotten the technique of interviewing when he wrote that piece.

  2. What about Mitochondrial Eve? Doesn’t the fact that all humans come from a single mother disprove Monbiot’s assertion?

  3. Doesn’t every newly evolved trait begin with a few individuals? Wouldn’t some inbreeding be expected for the trait to become established?

  4. George introduces the topic of revival in a very negative and frankly myopic way. The fact is, brilliant people are developing new technology which in all likelihood will have spin-off applications we haven’t even thought of yet. The financial possibilities are potentially vast.

    A not entirely unreasonable application will be come about when we begin colonize far off worlds. We undoubtedly will want to bring elements of our biosphere with us. Possessing nothing more than data and materials gathered at the site, we will be able to create entire ecosystems analogous to those on earth.

    I was astonished that he appears to be unaware of the most critically important process that creates genetic diversity: Meiosis. Every time a germ cell is generated, it will inherently differ in some degree from others because it will possess transcription errors. This is the raw engine of diversity.

    Furthermore, the assumption, while on the surface “truthy” that genetic diversity reduces the risk of an entire population succumbing to disease, the mammalian immune system is incredibly powerful and entirely capable of adapting to changing pathogens as they are encountered.


  5. Great post. In my experience, most Brits use ‘mumbo-jumbo’ to mean gibberish. The other usage is vanishingly rare.

  6. But presumably, even if we can fix the problem of low diversity, de-extinction National Geographic style would require an initial pair of opposite sex.

  7. It is technically possible to re engineer the de-extinction process. But the survivability of the this re-engineered specie based on environmental factorials that have long altered post extinction is another kettle of fish. The Chromosome/Gene is a very complex protein and with it inherent ability for mutation and replication in ways that retunes with current environmental variables of nature means that is not completely foolhardy to experiment such. The pertinent question here is the outcome of the interaction between the de-extinct specie(s) and other living species…including man.

  8. @Paul Braterman; that is easy; if you have a preserved male specimen simply copying an x chromosome in place of the y will give you an opposite sex pair, albeit nearly identical. The same swapping trick could be used however with two preserved males or any other sample of preserved species.

  9. Don’t believe everything you read in Wikipedia. We Brits also use ‘mumbo-jumbo’ to refer to gibberish.

  10. Clearly Monbiot is NOT a scientist and has not taken the time to research the complex details and reality of theory and practical application of the science of conservation biology, which harnesses a range of techniques to grapple with the challenges of conserving biodiversity in an age when humans have and will continue to have profound impacts, largely detrimental, but with science-driven conservation biologists collaborating with experts in other fields, potentially beneficial, to the diversity of life forms that we might share this planet with. His article reeks of using catch-words just to inspire contraversy because as a journalist that makes him seem edgy. As usual Zimmer, from someone such as myself who is a scientist, it is refreshing to read your science stories written by someone who understands the complexities of science and doesn’t see ‘science’ as a gimmick, thank you.

  11. This idea remains out of touch with the reality of wild animals on our planet, and there are serious practical and ethical concerns about undertaking it. For starters:

    We don’t have enough land/public concern to maintain the species we have. Wild animals proliferate and then look for new territory in areas where people live and are routinely run over/shot. Many corporations and individuals simply don’t care about wildlife (no judgment, it’s just a fact): see everything from the constant corporate challenges to EPA protections to the complaints from East Coast beach-goers who have to give up some of their driving-on-the-beach rights for a month so piping plovers can nest.
    We drove most of these animals to extinction in the first place, and our mentality as a species hasn’t changed, i.e., “we don’t know what we’ve got til it’s gone” syndrome. We didn’t think nature would be so remiss as to ever run out of passenger pigeons, or buffalo (pls read Rinella’s “American Buffalo” for the scale of this last one), just as others don’t care that we’ll run out of rhinos so long as they can make money killing the last dozen of them and selling their horns as quack medicine. “Whaling for the purposes of scientific research,” and on and on.

    Beyond the human problem is the exploitation of the actual animals used in or produced by this experimentation: Who’s going to guarantee that those animals won’t suffer? People who stand to gain from their existence? We can see how well this works out at SeaWorld (where even human lives have been lost as a result). We’re all guilty of animal exploitation of some kind, but I don’t see any help for the problem of extinctions in plunging deeper into this ethical cess.

    1. Re: DB

      I agree wholeheartedly with you on your comments in respect to the indifference and disrespect (to say the least) shown for wildlife and the natural world, however, it appears you throw the baby out with the bathwater. Just because a certain segment of the population may currently exhibit a negative attitude does not mean that projects of this nature should not occur. We would be living under the thumb of Great Britain, for example.

      Also, it is a logical fallacy to insist that one event necessarily precludes the occurrence of another event. There are more than sufficient resources available and more than enough people with expertise to perform these projects. Funding also need not come from purely governmental areas.

      Have you considered that by using this technology to revive species that the public may view the dangers of extinction in the light of realization that each species possesses distinct characters and that it is far easier to maintain that which is currently alive, than to revive that which as passed before, at our own hands?

  12. The Przewalski’s horse is another example of re-introduction of a viable species from a small sample: from 31 captive horses in 1945 to ~300 wild horses now (plus +1500 captive horse).

  13. I would vote for saving the species we have then reviving the last ones. Even if we could just replant the forests we have logged you will give ample habitat to lots of species to survive and help the climate as well.

  14. I was surprised that neither of the authors mentioned a simple solution to the problem of sustaining the population of any said animal we bring back. If we can bring the animal back from extinction genetic diversity and they ability to procreate are moot. We simply produce more in the test tube. Actually I personally think this would be a ethical way to address that problem. This would prevent any of the animals that escape captivity from destroying any ecosystem they may enter.

    As to the question of it being natural or not, well both are correct. If an animal went extinct do to its lack of adaptation to changes in its environment then bringing that animal goes against everything natural. However bringing back an animal that went extinct do to human causes, without witch the animal would survive and thrive today, well this would be less unnatural. If nature made made an animal extinct it is natural this animal stays such. At least in my opinion and what little I know about natural selection and animal adaptations. I have heard that the mammoth was hunted to extinction and I have heard the climate did it, and I have heard a mix of each.

    Though regardless of adaptations to ecosystems we do today maintain species outside of their normal habitats they would not be able to survive in without human intervention in zoos and other such wildlife sanctuaries today. So maybe my earlier statement natural selection is moot also. I think these questions will be better answered when we can actually bring back and extinct species, and by minds much greater than my own.

  15. I think that not all people are seeing the issue in the proper perspective.
    The de-extinction is not something we’ll see in 3 to 5 years. I think that it’s something that we can see as an opportunity comprehensive. If conservation biologists and molecular biologists can work together, this project can go far beyond bringing back animals that have already disappeared. It can serve as a platform for restoring ecosystems under threat, which is where they are supposed to return these animals, can help create a conservation awareness in the population, there are many things that can happen between the publication of the article of NG and the return of the first pigeon.

  16. A colleague knowledgable about statistics once told me five individualls selected at random out of a normally distributed population would represent 95% of the variation in that population. If this is true, how many individuals would you need to clone to get most of the variation in the extinct population? Would five be plenty?

    1. @Jim Thomerson:

      It depends how much you mean by ‘most’; for variants that are widespread in the population you acquire 50% of the remaining diversity with each individual you clone. (1 captures 50% of the diversity, 2 75%, 3 87.5% and 5 96.875%.) For these traits a handful of individuals suffices. (10 individuals nets you 99.90% of the variation.)

      But rarer alleles are harder to get, to acquire 2/3 of something present in only 10% of individuals you need 10 individuals. It also assumes you have the choice of any individual from a completely mixed population. If your samples are only from one small area or are highly related this knocks your diversity down.

  17. I really, really want to see a living thylacine.
    As for mammoths, couldn’t they cross-breed them with elephants to ensure a healthy population?

  18. I think George should tell the invasive lionfish populations in the Atlantic that low genetic diversity is a ‘fatal’ flaw. They seem to have forgotten that detail when a few handfuls turned into millions.

  19. Oh my god, I would give anything to be able to see a huge herd of mammoths walking the steppes and feel as the earth trembles beneath them!

  20. Monbiot is usually pretty sharp in his pieces. Wonder what went wrong this time.

    I’d love to see species come back. But where do we put them? Mammoths on the prairies? Farmers might object.

    Or Passenger Pigeons required large flocks in order to be stimulated to breed. Can we put enough out to have them breed in the wild, and with most bird populations plummeting what makes us think the Passenger Pigeon will be an exception?

    I’m not so sure I want to see an extinct animal that only exists in a zoo. Okay, I probably do want to see that (sabre-tooth of some kind, for e.g., giant beavers and sloths and bears). Yeah, I’d be torn between wanting to see and my own personal opinions/ethics on the matter. Damn.

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