The Promise and Pitfalls of Resurrection Ecology

Every species becomes extinct eventually. Some leave descendants that continue the evolutionary proliferation of life that kicked off on this planet over 3.5 billion years ago, but no parent species is immortal. Life on Earth is in continual flux, with new lineages emerging as others die back.

But what if we could resurrect lost species? And even if we developed the technology to do so, are such efforts wise during a time when the same attention and energy could be applied to preventing extant species from slipping away? This Friday, researchers are going to converge at the TEDX DeExtinction symposium, partnered with National Geographic, to discuss the possibilities and pitfalls of reviving species that have been lost over the past 12,000 years.

The woolly mammoth – the shaggy Ice Age icon that persisted until a scant 3,700 years ago – is probably the most charismatic “deextinction” candidate. For decades now, scientists have been considering how the lost proboscidean might be brought back through cloning, and we’re continually told that the necessary advances to accomplish the task are just around the corner. (Although, much like a Windows software release, the debut of woolly mammoth 2.0 has long been delayed. I’m not optimistic about estimates that we’re only four or five years away from squeeing over the photos of the first cloned baby mammoth.) But the woolly mammoth may be more of a symbolic conversation-starter that has obscured other Lazarus-wannabes, including the Tasmanian tiger, passenger pigeon, Steller’s sea cow, and the Xerces blue butterfly.

These candidate species, the “Revive & Restore” project says, were selected according to three sets of criteria. These requirements run the gamut from the squishy and snuggly – “Is the species missed?” – to matters of technological knowhow and whether the species is “rewildable.” What seems missing, or at least glossed over, are the ecological and ethical implications of reviving these lost species, and the focus on charismatic species has skewed attention towards animals that may not actually be good selections for resurrection.

Just as the woolly mammoth symbolizes the great hope of species revival, the proboscidean also highlights the lack of attention ecology receives in such proposals. The challenge of deextinction is almost always framed in technological terms – can we bring back species? – but what will happen to the animals after they have been recreated has received comparatively little attention.

Let’s say that scientists are able to clone a woolly mammoth within their ambitious five year time frame. Where would such an animal live? The woolly mammoth’s natural habitat – the cold, dry mammoth steppe of the last Ice Age – does not exist anymore. Perhaps there are modern ecological proxies in scattered refugia, but should we really strive to bring back an animal that might only exist in zoos, or may face shrinking habitats in the wake of future climate change?

To bring back a species that no longer has a place in the world would be irresponsible and undercuts the moral imperative that deextinction advocates so often rely on to make their case. Indeed, one of the primary arguments for deextinction is that we must pay penance by restoring animals that previous generations of humans have wiped out, yet we’d only repeat our mistakes if we brought back a species without consideration of the creature’s future survival on a changing planet. Trying to replicate the Ice Age doesn’t make much sense when our species is hurtling the planet towards a greenhouse world.

The long-fanged gape of Smilodon, on display at the Page Museum. Photo by Brian Switek.
The long-fanged gape of Smilodon, on display at the Page Museum. Photo by Brian Switek.

Smilodon, a sabercat also listed as a top candidate, is an even worse choice. Wildlife specialists in and around Yellowstone National Park have enough trouble trying to get the public to accept the presence of wolves – carnivores that were extirpated from the area within recent history before being reintroduced two decades ago – and conservationists continue to struggle with the persistent conflict between jaguars and ranchers in South America. Can you imagine the uproar over sabertoothed cats being returned to the western United States or South American grasslands? There may not be a country for revived sabercats.

A simplistic argument could be made that Smilodon de nouveau would be necessary to keep cloned mammoths and mastodons in check at some future date, but such a position relies on the assumption that the cat actually hunted the large herbivores. Thanks to geochemical and anatomical evidence, paleontologists have found that Smilodon preferentially targeted camels and bison, not the giant proboscideans of its time. This isn’t just technical nitpicking. If we’re not only going to restore species, but try to recreate communities and interactions from deep time, we must heed the evidence of the fossil and historical record and not just restore species because we think it would be cool to see them.

The Shasta ground sloth might be a better deextinction candidate. Chris Clarke recently made a case for bringing back the trundling herbivore. Thankfully, Clarke totally avoided the guilt trip that deextinction advocates often use to insist that we have a duty to bring an extinct species back, and instead considered how the sloth might resume its role as a seed disperser within imperiled Joshua tree habitats. I’m not entirely convinced that reviving the Shasta ground sloth would be a worthwhile endeavor, especially since we don’t know exactly why the species died out nor whether the sloth would be able to cope to environmental changes that are already underway due to climate change, but I believe Clarke made a far better case for his favorite sloth than woolly mammoth or sabercat advocates have made for their candidates of choice. (And, I must admit, seeing baby sloths cling to the backs of their plodding mothers would be absolutely adorable.)

The passenger pigeon is one of the top deextinction candidates, but would the revived birds be able to thrive in the wild? Image from Wikipedia.
The passenger pigeon is one of the top deextinction candidates, but would the revived birds be able to thrive in the wild? Image from Wikipedia.

Of course, the Ice Age megamammals are extreme examples. Most of the candidate animals were wiped out much closer in time. But the same questions still apply. The best candidates for deextinction may not be the biggest, most beautiful, or famous, but species that will be resilient and adaptable to the altered nature of their old haunts and to future ecological fluctuations. More than that, some of the candidate animals might face the same threats to their existence that exterminated them in the first place. Human conflict might be just as bad, if not worse, for revived species, particularly carnivores such as the Tasmanian tiger and sport animals that require populations of staggering size to survive, such as the passenger pigeon.

Conjuring extinct species back into life will require a great deal of care, planning, and management. Is all the effort worth it, especially when conservation efforts worldwide are suffering from a lack of funding?

One way that deextinction advocates could make a stronger case for their projects would be to identify applications to threatened and endangered species that are still living. Perhaps genomic engineering could add variation to populations of animals suffering from the effects of population decline and inbreeding, such as cheetahs. And maybe cloning could help keep a truly critically-endangered species afloat long enough to have a chance to keep adapting and evolving. Some of these techniques are already being used, or at least considered.

Hybridization and careful back-breeding, Carl Zimmer points out, has given the American Chestnut tree a chance at long-term survival. Other techniques might not be so useful. As Ferris Jabr reported in Scientific American yesterday, conservation biologists aren’t optimistic about the prospect of restoring or saving species through cloning. Beyond the technological difficulties, cloning doesn’t address habitat loss, poaching, climate change, and other pressures that have pushed species to the edge of existence. Creating more of a species will not save that organism if it no longer has a place to live. Furthermore, as Stuart Pimm argues in an online National Geographic piece, sexy deextinction projects might distract from more pressing conservation problems that living species face.

I’m not totally against deextinction efforts. Some, such as Clarke’s Shasta ground sloth proposal, may actually have significant benefits for ecosystems that are at risk of deteriorating. But the conversation needs to move beyond charismatic characters and details about technology to the ecological consequences of reviving lost creatures – not only for the species in question, but for the ecosystem it might be reintroduced into and still-living animals that are nearing extinction.

And despite the question posed in National Geographic’s own promotional video for the event, deextinction is not a matter of scientists “playing god.” That’s trite fluff that the film adaptation of Jurassic Park tried to sell audiences through Ian Malcolm’s rambling soliloquies. Our species has driven others to extinction, and is having such a substantial impact on global ecology that the imprint of what we’re doing today will be visible for thousands of years to come. We’re already intervening and rearranging nature, intentionally or not. Once we own that fact, we can start to make decisions about conservation triage and what the future of wildlife might look like. Should resurrected species be part of the future? That’s the question driving this week’s DeExtinction symposium, and I’ll be tweeting and blogging my reaction to the day-long discussion of that critical and controversial place where past and future ecology meet.

[TEDxDeExtinction will be held at the National Geographic Society in Washington, DC this Friday. If you’re in town, you can look into tickets, and anyone can watch a free livestream of the talks on the web. And for a little more background on the methods of deextinction, see this brief news piece I wrote for the National Geographic news site, as well as the National Geographic deextinction hub.]

31 thoughts on “The Promise and Pitfalls of Resurrection Ecology

  1. I think bringing back any extinct creature into today’s world would be a crime. We are killing off extant species every day, and that is not going to stop until we humans get back to a significantly smaller population. I wish I could think of even one good reason to attempt such a thing. Getting to play with yet another rare zoo animal or exotic pet does not qualify.

  2. I’m not sure I understand the guilt argument for bringing back the wooly mammoth or the sabercat. Unless I am mistaken, humans were not responsible for their extinction.

    As for more recently extinct species, I could see the point if an ecosystem was collapsing due to the lack of a key species. Of course, if that species became extinct due to human activity (as opposed to exposure to a particular disease), it’s possible we’d only repeat our previous mistake.

    In terms of resurrecting the species via cloning, as I said on facebook, the lack of genetic diversity would likely doom the species in any case. They would have to successfully clone several animals, each with the DNA from different individuals, in order to address that issue. Bioengineering won’t cut it because we are not capable of artificially recombining genes on the scale of what happens during natural reproduction. Looking at the American chestnut story, you can see that it took them years to be able to introduce just one gene into the species.

  3. It’s not just the external ecology that is a factor, but the internal ecology. Each animal is home to dozens of different species of bacteria, some of which are necessary to survival (such as those who break down food in the gut). This was one of my questions coming out of Jurassic Park – how will those creatures survive if the microbiota they depend upon are also extinct, and they can’t find anything analogous that can do the same job?

    On the other hand, life so often finds a way. I suspect that sabercats 2.0 would find something to eat – they might even evolve a primitive social behaviour to allow them to more effectively hunt wooly mammoths or some such. And bacteria would, I suspect, manage to evolve to give these animals what they need. It might just need several releases of cloned animals into the wild – watching them all die, and having their carcasses scavenged, and releasing a new batch…until some bacteria evolve to do the job these animals need.

  4. Where would such an animal live?

    In a zoo? Even conceding the possibility of doing something like this, it wouldn’t be a cheap process, and the likelihood of finding the funding to produce a viable “wild” population from the get go must be disappearingly small.

  5. Another problem with releasing such animals into the wild is, how exactly could they survive? There seems to be an assumption that once an animal is plopped into an appropriate habitat, instinct will take over and tell them what to do. In fact, most animal species learn survival skills to some degree or another from their parents (as documented in Susan McCarthy’s excellent book Becoming a Tiger). Animals brought back from extinction would be, for all intents and purposes, orphans. Where would a woolly mammoth learn how a woolly mammoth lives?

  6. I am so happy that 1 day we will try to bring back all of creatures and i love saber cats i will love to see them we give them a another chance and help them and extinction will be gone forever and prehistoric creatures be alright and saber cats we will try to put them somewhere else

  7. @Elisabeth. You are mistaken. Mammoths almost certainly went extinct due to human activity. Climate change may have weakened them, but they had survived previous cycles of glaciation-deglaciation. Human hunters with advanced lithic technology gave the coup-de-grace. See Nogues-Bravo PLoS Biology 2008 or Prescott PNAS 2012

  8. LIFE on our planet consist of flora and fauna. Why should we focus first to fauna when it can not be supported by the environment (which was the reason for their extinction in the first place). I suggest that DEEXTINCTION activists should plna first to de-extinct their habitat prior to actually re-creating these candidate species. We would be cruel to these species if we bring them back in an inhospitable ecosystem for them, amounting to ‘cruelty to animals’!

  9. @Ross: Interesting! It was my understanding that there wasn’t much evidence suggesting humans actually hunted wooly mammoths.

  10. There isn’t much archaeology. On the order of a dozen or two “kill-sites” but given the v. short overlap between humans arriving and mammoths & mastodons going extinct this suggests quite intense persecution.

  11. I think this project would be worthwhile to reestablish amphibian species decimated by the chytrid fungus, habitat loss, etc.

    And why is no one talking about bringing back Neanderthals?

  12. @Ross: If there isn’t archeological evidence for hunting can we really say that it was hunting that did them in? That is to say, are there other ways humans could have led to the extinction of mammoths and mastodons? For instance (and I’m totally making this up, perhaps I should read those papers you pointed me to) perhaps mammoths, etc. shied away from areas patrolled by humans, or maybe humans over-hunted another creature that led to some sort of ecosystem collapse that affected the mammoths.

  13. I think species killed off by man should get first priority. Also preserving a species already in trouble due to deforestation and loss of habitat. The Great Auk was fully hunted to extinction and the California Condor is still in trouble due to poisons used by man. Is the ecosystem so different from then to now? I mean for species extinct in the not so distant past. Tasmanian Tigers also killed off by man. A mammoth would be a great start, would love to see it happen. The real test, after of course recreating the species, is of course human nature. Would it be another case of ” kill ’em just cause we can”, or can the fox guard this chicken coop?

  14. @Elisabeth Well, when a lack of sites is a prediction of the model then it argues for the model being correct. There is also evidence from isolated populations e.g. St Paul Island and Wrangel Island which suggest that climate alone was not enough for mammoths to go extinct. In fact, genetically, and population-wise the Wrangel mammoths were in robust health until their extinction 4000BP. Which, just happens to coincide with the first appearance of humans on the island. As for the nature of human-mammoth interaction it is likely that, at first, continental mammoths were naive to human presence (think Galapagos/other islands). This would have allowed for efficient slaughter. The co-evolution of African and Asian elephants with hominids probably allowed those species to evolve efficient avoidance techniques that their sister species did not. And of course, other knock on effects of human presence (burning of forest, exploitation of other animals, forest-clearing) would probably have had a negative effect on mammoths/ mastodons as well.

  15. I worry that extinct species cannot *really* be resurrected in the manner proposed. It’s not technological feasibility I’m concerned with. No, it’s – it’s metaphysics. (Wait, wait – just here me out!) Biologists and philosophers aren’t altogether clear on what it is for an organism to belong to a species – or, alternately, what species are. Given this uncertainty, it’s not clear that ‘de-extinction’ is really any such thing. ‘De-extinction’ may involve not the resurrection of extinct species, but the creation of convincing copies.

    Suppose we are able to create something that looks and behaves like a passenger pigeon, has a genome that is qualitatively extremely similar to that of passenger pigeons, and so forth, but is not the offspring of a passenger pigeon, but rather, was produced through the manipulation of the genome of some existing pigeon species. Is this organism *really* a passenger pigeon? First off, I don’t think there’s an intuitively clear answer. Secondly, according to the dominant view of species, the answer is ‘No’. “The organisms of a species must be parts of a single evolving lineage. If belonging to a species turns on an organism’s insertion in a lineage, then qualitative similarity can be misleading. Two organisms may be very similar morphologically, genetically, and behaviorally, but unless they belong to the same spatiotemporally continuous lineage they cannot belong to the same species.” (Ereshefsky:

    You might think this is totally pedantic. You might be right. Who cares, right? I kind of expect that people do care, though. Compare the emotional appeal of the following messages: “We can bring extinct species back to life”; “We can create very convincing copies of extinct species”. The latter doesn’t quite inspire. Obviously, many arguments for ‘de-extinction’ would remain in place, but something of the immediate emotional shimmer will have gone off the idea.

  16. Until we have learned to be better stewards of the resources of our planet, I feel it would be irresponsible to resurrect any extinct species.
    A successful attempt at de-extinction of a single species, given the shortsightedness and greed continually demonstrated by our own species, might in fact lead to a dangerous complacency about preventing extinction and preserving precious biodiversity. The temptation then becomes thinking that any misuse or overharvesting of resources can be corrected later. This I fear is a mindset that could be too easily adopted by those who would place profit over preservation, currency over conservation. Unfortuntately de-extinction has the potential to be the excuse used to allow more extinctions to occur.

  17. A couple things. One, the woolly mammoth may not have been a tundra-only animal. Two, there is VAST amounts of Ice-Age-like habitat in the TIbetan plateau and areas of Siberia, where no-one lives. 3, we killed them off, so it’s just that we bring them back.

  18. Some of the comments have hinted at this, as did the article, but a major concern I have about De-extinction is species relations. Currently, the human world has documented perhaps 5% of all living species on Earth–meaning that we don’t know of or understand the impact of 95% of the world’s species. How can we argue for bringing back an organism when we don’t understand 95% of the consequences? Perhaps you think it cruel, but I would rather humans understand the 5% species we do know, experiment with methods of mitigating extinction of current species, and counteract climate change.

  19. The woolly mammoth survived interglacial periods that were probably warmer than it is now and may be for thousands of years. They were killed off by humans. We also almost killed off the bison and the musk ox. We brought those species back and they flourish, when we get out of their way. There is no reason to believe that mammoths cannot create their own habitat, just as macrograzers do wherever they are allowed to by humans. We need to put our population and rapaciousness in check very soon or we will follow all of these species into extinction sooner rather than later. The good news is that our extinction will allow all these other species to survive.

  20. I believe that bringing back certain species from extinction would be a good thing, it would have to be carefully planned and the bugs worked out but if it benefits the overall ecosystem I believe we should do it. As for the Wooly Mammoth and other “sexy” species that are more popular in the public’s eye, it may be a way to generate the public’s interest to gain funding for the not so “sexy” ones that are more critical to the web system. I for one would love to see a Wooly Mammoth one day.:)

  21. Xerces blue butterfly was loved to death by over collecting and use as decoration. Native pollinators need all the help they can get and though the invertebrates are critical they are overlooked. This could be the poster child for restoration ecology in all forms including habitat.

  22. I think there are interesting arguments pro and con. I do believe that resurrecting a species that would occupy an important niche that is now vacant in an extensive ecosystem ought to have sufficient merit to overcome most if not all the con arguments. The Stellars Sea Cow would be such a candidate. I believe that Native Americans, followed by Russians, were responsible for wiping out a species that, through kelp grazing, kept sea otter populations in check. Transplanted sea otters, once extirpated from Southeast Alaska, are now over-running the place. Many populations of species commercially harvested for food, such as crab, abalone, sea cucumbers and others are threatened in many areas where sea otters have over populated. Direct control of sea otters would be an easier alternative except for the marine mammal protection act and wide-spread sentiment to provide complete protection for all individuals of charismatic macrofaunal species. Sea cow grazing could increase sea otter pup mortality by reducing thick kelp mats that provide safety for pups as their mothers forage. Native Americans harvested sea otters, filling in for the role sea cows once provided before their populations were decimated by human harvesting for food. Bringing back sea cows could provide an improved ecological “balance”.

  23. i think that resently extinct animals like the taz tiger,passnger pigen,stellers sea cow,and moa shuoud be brought back and relesle into the wild and mammoth and saber thooths shoud be eather put in zoos or left alone

  24. One point of view: the interest of reviving extinguished species is economical and mediatic. The ecological interest is an illusion. They want to revive some mammoths in order to put them in a zoo and making people pay for it. That is immoral.
    I think we are in the same siutation that before putting a feet on the moon. Every country wanted to be the first and in the media, people were talking about raising home and living there… But the reality has been very different, 50 years latter, there is no more trip to the moon, and none of the now-fantasist expectatives occur. What I want to mean, is that creating a population of disappeared species is not viable if it disappeared more than one thousand year ago. And nobody wants to put so huge aount of money for creating a population.
    Finally, the problem of de-extinction is a little bit the same that reintroduction. It is attractive mediatically but it is not as efficient for nature conservation as if the money would have been put for the conservation of habitats, for instance…

  25. Of all the arguements against De-Extinction, this arguement of their ecological value and where they would go are among the most compelling to sertainly approach the issue with caution. A number of animals, such as the Woolly Mammoth or the Saber-Tooth Cat don’t have many convincing arguements for actual resurrection, although some argue that Arctic Tundras deteriorated after they went extinct.

  26. I am intrigued in this topic although I am only 13. One thing I do not get is what is the purpose of bringing back wooly mammoths and sabertooth tigers if they were suppose to be extinct. If we were to bring them back it would be hard to find a perminant habitat that isn’t just a small inclosue. The climate has also dramticlly changed. So has the landscape. For smaller animalls that we killed off i would be some what ok whith bringing those back. Those animals were supose to live untill we abruptly killed them off. I also think we should bring recently extinct animals that we killed offf because the climate and habitat hasn’t chaned that much over the years. The only question I have is will history repeat itself? mabye it will mabye not, we will only know if we try. if we do bring them back we are not playing god because we are simply fixing our horrible mistakes. Since population has increased I think the only way these animals can live is if the population decreases in size.
    The animals that are cloned don’t have a mother to take care of them but the closest reletive might be able to take care of it and show the animal the ways of life. For an exaple the passenger pigeon may be taught to fly by its serrogate mother. If the surrogate excepts it as its own. Overall I think we should do d’extinction only if we bring those that WE killed off. This may cost a lot of money but it may restore parts of our ecosystem that is still there.

  27. The argument that the determination of species de-extinction be based on the role humans played in their demise is somewhat ludicrous. There is first, the assumption that humans are not part of the natural world. Following that is the assumption that the species was not already on the road to extinction . Next, there is the assumption that the species would have flourished without human intervention. There is also the assumption that the return of a species would not threaten the survival of existing populations.
    Yes, we should take better care of the global environment; if not for the sake of other species, for that of our own.
    But, why bring back extinct species for entertainment value. There is no real value to the environment (local or global ecosystem) in the return of Dinosaurs, Mammoths, Smilodon, Moas, or such. It seems to me to be purely for curiosity sake. There is little beneficial learning that this experiment would produce. We would be creating
    To quote the character Ian Malcolm in “Jurassic Park”, “…scientists are so preoccupied with whether or not they could, but did not stop to think if they should.”
    There is a continuing list of human blunders when we decide to tamper with genetics and ecology as nature dictates. We think we have enough information to make the “right” decision, yet retrospect shows we did not. (i.e. hybridized corn and the corn blight, roundup ready soybeans and the indestructible weeds, cane beetles and cane frogs, etc.) Genetics and genetic engineering are awesome powers. But, to quote another movie line, “with great power, comes great responsibility!” How can we expect to be responsible with something we do not even fully understand?

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