New Efforts to Bring Extinct Species Back to Life

MS. DIANE REHM

11:06:53
Thanks for joining us. I'm Diane Rehm. Through recent advances in DNA technology, scientists are attempting to bring extinct species back to life. But conservationists say resurrecting animals like the passenger pigeon and woolly mammoth are no panacea to the current extinction crisis. Here with me in the studio to talk about the pros and cons of de-extinction, Elizabeth Kolbert -- she's a staff writer at The New Yorker -- and Will Turner, chief scientist at Conservation International.

MS. DIANE REHM

11:07:32
Joining us from KQED in San Francisco, Ryan Phelan. He (sic) is executive director of Revive and Restore. Throughout the hour, I hope you'll join us as we talk about what I'm sure will become a controversial subject. Call us on 800-433-8850. Send us your email to drshow@wamu.org. Follow us on Facebook or send us a tweet. And welcome to all of you.

MS. ELIZABETH KOLBERT

11:08:05
Thanks for having us.

MR. WILL TURNER

11:08:07
Thanks for having me.

MS. RYAN PHELAN

11:08:08
Good morning, Diane.

REHM

11:08:09
And, Ryan, forgive me for introducing you as a he. Now that I can see you on Skype, I realize you are a she. And if you would, tell us what you mean by the term de-extinction.

PHELAN

11:08:29
De-extinction is really about bringing back species that we've lost from potentially the possibilities of human intervention. And I would say, in 99 percent of the cases, it's human -- humans actually hunting species to death, habitat loss, a variety of reasons that have caused these species to go extinct over now many years, including thousands of years, such as the mammoth. The idea of de-extinction is to actually use ancient DNA to help bring these species back to life.

REHM

11:09:06
And how much of this kind of investigation into possibility is going on now, Ryan?

PHELAN

11:09:19
Well, I would say that there's a number of scientists working worldwide using different techniques for de-extinction. But I'd also like to say that many of these genomic technologies are being used to aid in what we're calling genetic rescue of endangered species.

REHM

11:09:37
Such as?

PHELAN

11:09:39
Well, such as one that many species, as, I think, Elizabeth is going to be able to talk a lot about here today, are on the brink of extinction. And I think your introduction that de-extinction is no panacea is a really important point. There's no -- there is no one, you know, quick cure for this huge extinction crisis that we're facing. But we do know that technologies in genomics can add genetic variation to these species that are losing genetic diversity because of these bottlenecks.

REHM

11:10:16
Ryan Phelan is co-founder and executive director of Revive and Restore. That's a research organization in California trying to bring back endangered species. Elizabeth Kolbert, I gather you have serious reservations about de-extinction.

KOLBERT

11:10:44
Well, I think there are a lot of issues here that sort of tend to be conflated. And I guess I'd want to start by saying, you know, just like everyone else, I -- you know, if a Tasmanian tiger, let's say, which is an animal that was hunted to extinction in the 1930s, or a passenger pigeon were to be -- I'll use the verb -- de-extincted, (sic) you know, I would think that that was spectacularly, you know, cool, just like, I assume, just about everyone would. So there's a real cool, wow, that's cool, factor here that I think wows people.

KOLBERT

11:11:21
And I understand that. And I relate to it, and I'm there. But I think there are, you know, several layers of questions here that need to be asked. The first is obviously technical. When you're trying to bring back a species for which there are no living cells, that's a tremendous technical burden. Ryan knows this better, you know, than anybody probably right now. You know, it's never been done.

KOLBERT

11:11:47
The question of whether it even can be done with current technologies is wide, wide open. So you could say, well, OK, maybe, you know, technology's moving very rapidly. Genomics is moving very rapidly. That's absolutely true. Maybe one day we'll solve these technical hurdles. But then I think you get to a more essential question which is an animal is more than its genome. We all know that.

KOLBERT

11:12:09
If you were -- for example, if humans had become extinct and you decided you were going to revive them by recreating the human genome, creating this single human being, and you were going to raise it in a tank, let's say, you know that you don't really have a human being because humans learn a lot from their parents, from their societies. And most animals also learn a lot. You know, we are just beginning to appreciate, in fact, how much they learn.

KOLBERT

11:12:35
So certainly a bird, we all know that birds learn from their parents, from their social group, so you don't really have, for example, a passenger pigeon, a single passenger pigeon -- what you have, even if you have that single bird. And then, even if we were to ever get over all those hurdles, I think we have a pretty big ethical question that we have to ask because we are dealing with living things.

KOLBERT

11:12:59
They have, you know, a -- there's a very, very high hurdle when you do that. And there's really been one effort, one semi-successful -- you can't call it successful ever to bring back a subspecies. And this is a subspecies of ibex -- this was in Spain -- that went extinct. We did have living cells from the last surviving member of the subspecies. A very complicated effort was undertaken to clone this species.

KOLBERT

11:13:26
Many of these goats, these hybrid goats that had been sort of created for this purpose, were implanted with these clones. Only a few of them took. Most of the goats miscarried. One was carried to term. It was severely impaired, deformed. It had an extra lobe to one of its lungs, I believe, and it died immediately. And so there is pain and suffering involved here, quite possibly, almost inevitably, that I think we need to be very conscious of.

REHM

11:13:54
Elizabeth Kolbert, she's the author of a new book. It's titled "The Sixth Extinction: An Unnatural History." And we'll get back to talking with her about that sixth extinction. But, first, to you, Will Turner. As a scientist and conservationist, what's your thinking about de-extinction?

TURNER

11:14:25
Well, look, this is big. The idea of bringing back extinct species, it's extraordinary. It's going to continue attracting people's attention. The technology is fascinating. And it could happen soon.

REHM

11:14:39
How far along do you believe we are with the technology?

TURNER

11:14:45
Well, it varies. I think there are examples, as in the case of the (word?) that Elizabeth just mentioned where it seems like we're very close. Of course, that didn't actually succeed. But it's -- we're close. There's also a frog in Australia that they -- Australian scientists succeeded in getting to the early embryo stage. So with different tacts of different species, they're talking about the barriers not as barriers but more speed bumps. When you talk to these people...

REHM

11:15:19
Hmm.

TURNER

11:15:20
...even the people that are talking about cloning mammoths, they're talking about real progress on the matter of less than a decade. There can always -- it's not 100 percent certain. There can always be biological challenges that may yet prevent this from happening. But I wouldn't -- certainly wouldn't bet against it.

REHM

11:15:41
So what is your thinking about some of the issues that Elizabeth raised, primarily the ethics?

TURNER

11:15:50
Yeah. So there are two sort of schools of thought. One is that some conservationists argue that there's a danger in de-extinction in that it's going to be the end of conservation effort. So as we gain the ability to bring back extinct species, we're no longer going to be able to save the species that are still with us. I don't...

REHM

11:16:13
Or we're not going to pay enough attention?

TURNER

11:16:15
We're not going to -- because we're not focusing on them, allocating our resources to them, looking at the issues of one you've got a few individuals in captivity, how do you get from that to actually restoring populations in the wild, bringing them back to their more full role in ecosystems? But I don't think this is going to happen, this idea that it's going to be the end of conservation efforts because it's not going to take funding from those efforts.

TURNER

11:16:47
Look, the global conservation budget is about one-thousandth of the global economy. If we're worried about fighting over that with de-extinction and biotechnological approaches to conservation versus parks and restoring broader landscapes, then we've got much bigger problems.

TURNER

11:17:07
What we are, I think, are going to see, if the technology proves successful, is that it's growing the pie, the public, the range of actors that are interested in -- aware of extinction, interested in bringing species and their roles in the ecosystems back, and it's a different set of people, biotechnology, people who are interested in different factors from those that have traditionally been directly engaged in resourcing conservation.

REHM

11:17:40
So -- but what about the ethical issues, Will?

TURNER

11:17:44
Yeah. There's clearly some very complicated ethics associated with this. I think the -- but the trick is not to look at one or the other extreme. Either this is a dangerous technology, therefore we shouldn't do it at all. Or this is just really exciting, and we should do it without thinking about it. The challenge is going to be having the conversation where we're actually looking across the range of species.

TURNER

11:18:12
For example, across species, there's variation in how technically difficult they might be to bring back. There's variation in what their potential benefits could be to people or to ecosystems. There's variation in their potential to harm us. So I noticed on Revive and Restore's website, they actually had the saber-toothed cat as an example, which raises some obvious questions.

REHM

11:18:41
Will Turner, he's chief scientist at Conservation International. Short break. Right back.

REHM

11:20:00
And welcome back. As we talk about recent advances in DNA technology, scientists are attempting to bring extinct species back to life. In this hour, we're talking about those possibilities as well as the ethical and even moral implications. Here with me in the studio are two people. Will Turner is chief scientist at Conservation International. Elizabeth Kolbert is author of a new book. It's titled, "The Sixth Extinction: An Unnatural History."

REHM

11:20:50
She is a staff writer at the New Yorker. And joining us from KQED in San Francisco, Ryan Phelan. She is co-founder, executive director of Revive & Restore and that is a research organization in California trying to bring back endangered species. I'd like to ask you, Elizabeth Kolbert, about the title of your book, "The Sixth Extinction," and what you mean.

KOLBERT

11:21:25
Well, the implication of "The Sixth Extinction" is obviously that there have been five of these extinction events, mass extinctions, major mass extinctions in the past and that's absolutely. The one people are most familiar with, the most popular, if you will, is the extinction event that did in the dinosaurs, not to mention 75 percent of all species on the planet roughly. And there's a pretty broad consensus among scientists that that extinction event 66 million years ago was caused by an asteroid impact.

KOLBERT

11:22:01
And you will now hear scientists say -- I have heard scientists say that we, human beings, are the asteroid or impacts or on a such a scale that's so rapid we are changing the planet so profoundly that we are in danger of having an impact, you know, not unlike an asteroid impact.

REHM

11:22:23
In other words, doing such damage to the planet itself that we are ourselves could be a part of that sixth extinction.

KOLBERT

11:22:37
Well, some scientists definitely warn of that. I mean, if you are choosing a moment in history to be around, you would not choose the moment of a mass extinction because, as one of the paleontologists that I quote in my book puts it, the rules of the survival game seem to change at moments of mass extinction. So you don't really know what's going to come out at the end of that. You know, on the other hand, if you were betting -- if you're a betting person, I mean, as Ryan alluded to, we already have driven many, many, many species extinct in the time we've been here.

KOLBERT

11:23:10
And our number keep growing and growing and growing. So it's unclear, you know, exactly what the relationship between our flourishing and the rest of the many, many other species disappearing is at this point.

REHM

11:23:23
On the other hand, Ryan, wouldn't this be a perfect time to then develop the de-extinction process that much more rapidly?

PHELAN

11:23:37
Exactly. And I think timing is to our advantage right now. Many of these species that are on the brink of extinction, we still have an opportunity to use some of these pioneering technologies to help prevent their extinction. So one of the things that I know is in Elizabeth's book is a mention of the frozen zoo, which is in the San Diego Zoo in California, where they have over a thousand specimens, frozen specimens, many of them endangered species, that could be potentially used to help right now do the genomic comparison to try to figure out what genetically is helping these species become more and more vulnerable potentially to disease.

PHELAN

11:24:23
That kind of susceptibility can build up with inbreeding and what are the ways that we could genetically help these species that are on the brink. So I think timing is right at numerous levels. One from the science, but even more importantly for the discussion that we're now helping to foster about preserving habitat, for avoiding the fragmentation of the landscape. There are so many things that conservationists are working on very productively.

PHELAN

11:24:50
But I think even more awareness by the public, like with your show here today, is extremely valuable. And I think the extinction is really just something that is helping highlight all of these multitude of challenges that we can create a concerted effort around.

REHM

11:25:08
Elizabeth, how do you react to that, Beth, this is the perfect time considering the concerns that you've raised and other scientists have raised?

KOLBERT

11:25:22
Well, I think that it's important to, you know, once again, sort of discuss what we're talking about in the context of an extinction crisis, which I think most conservation biologists, perhaps universally, all conservation biologist would agree we are in the midst of right now. You know, we're losing species at a very rapid rate. We're losing species we do not know exists. So it's...

REHM

11:25:48
Such as? Such as?

KOLBERT

11:25:50
Well, since we didn't know they existed, I can't name them. But, you know, we definitely -- there was just a piece recently about this, a whole new kind of snail that was discovered in Southeast Asia on these limestone cliffs that are being quarried for limestone, you know, and their habitat is going to be lost. And so, as soon as they were identified, they were identified as highly endangered because their whole habitat is about to be destroyed.

KOLBERT

11:26:17
So that sort of story is something you could open up a publication and read pretty much and, well, can credit me. But pretty much I'd say every day, certainly every week we find something and we realize it's on the brink of extinction and we have to assume there are a lot of things we didn't find before they went over the edge. So we're talking about an absolutely, you know, worldwide, global, very serious problem.

KOLBERT

11:26:40
And on the de-extinction front, we're talking about working, you know, at best, on the margins and, you know, at worst you could I say, I have to say, a bit of a side show to what the essential problem is. And the essential problem is the ways in which we are changing the planet on different, you know, different levels but globally on planetary, geological scale that is pushing species that can's adapt fast enough over the edge.

KOLBERT

11:27:06
And, you know, until and unless we deal with those problems, everything else is just unfortunately, as they say, it's an entertainment a little bit and it maybe gives people something to talk about. And I think that's very useful, as Ryan says, but it's not a addressing the issue.

REHM

11:27:20
Ryan?

PHELAN

11:27:21
But, Elizabeth, that's really dismissive of a number of scientists worldwide that are not doing this for entertainment purposes at all. They're doing this in part to raise and highlight something that I think we can really agree on, which is the extinction crisis. And I don't believe that it's a side show at all. I believe that these are technologies and a lot of thought that's going into habitat, challenges and a number of things that are going to really help prevent extinction.

PHELAN

11:27:54
So, yes, the number of species that we could, quote, "de-extinct" is a fraction, just a sliver of life. But it's not about just those species. It's about putting those species back where there's a gap in nature. And I think that's the really important part.

REHM

11:28:10
Will?

TURNER

11:28:13
Yeah. I think these are some really important questions here. And in particular I think those idea of what is causing extinction and what can the role of de-extinction be in alleviating the problem. It's important to think about, as we talk about this potential mass extinction that we're in, there's no question that the rates of extinction are much, much higher than they are in anytime except for past mass extinctions.

REHM

11:28:38
Are we talking across the board or certain species that are becoming extinct?

TURNER

11:28:47
Well, there are certainly variation among taxon. In Conservation International, one of the things that we've done is we have worked with the IUCN to drive the Red List.

REHM

11:28:54
The IUCN.

TURNER

11:28:56
IUCN, International Union for Conservation of Nature. It's an international organization. Most country governments in the world are members of, many non-government organizations. So it's a really good place for the kind of systematic global thinking of, like, the Red List of Threatened Species, which (unintelligible) is celebrating its 50th anniversary this year. It's been around for 50 years and it's cataloging the species of the planet and assessing their conservation status.

REHM

11:29:23
What's at the top of the list?

TURNER

11:29:24
So, amphibians as a group, their entire vertebrate class, there are more than 5,000 species and perhaps a third of them are threatened with extinction.

REHM

11:29:36
Alligators, crocodiles.

TURNER

11:29:38
These are frogs, amphibians, toads.

KOLBERT

11:29:43
Salamanders.

TURNER

11:29:44
Salamanders, yes.

REHM

11:29:44
All right, okay.

TURNER

11:29:46
And so their -- if you look at mammals, it's perhaps a quarter of all mammals. Again, it's more than 5,000 species. And that's fairly consistent across the range of mammals. Birds perhaps a bit less, but it's still, you know, an eighth of all bird species. And we see them going extinct, you know. I just had the pleasure of seeing some being in Hawaii and seeing some of the endangered honeycreepers there.

TURNER

11:30:10
In Hawaii, 10 bird species have gone extinct in the last hundred years. So these are -- it's happening across the board. And including other taxa, beetles done to microorganisms that we -- and these are things that we can't, as Elizabeth alluded to, we're losing them before we really know they exist. But the drivers of those -- as we look across them and understand what's their threat status is and what's driving those extinctions in particular.

TURNER

11:30:42
It's really important information. So the dominant ones continue to be habitat loss. This year, loss of the places, the ecosystems where these -- forests -- the ecosystems where these species formerly lived, invasive species and diseases. So with amphibians, there's a fungus called chytrid fungus, which is perhaps in terms of a taxonomic or tree of life level is really unprecedented in history.

TURNER

11:31:12
It's a single fungus that is in danger of wiping out a quarter or more of all amphibian species. So in understanding these threats, it points us to solutions. And if the threat is hunting, it may be that you can -- if you can control that threat, bringing back a species with de-extinction so that you have individuals, you then have the possibility of releasing them into the wild. They may have habitats they can go into.

TURNER

11:31:41
You might have some success. For the vast majority of species, it's habitat loss. And climate change is really coming on as something that's jeopardizing a lot of species in the future. We might be -- we run the risk of bringing species back only to have them sort of stuck in this limbo where they're in captivity but we aren't able to release them in the wild. And we already have some species there where their habitat simply aren't left. The problem isn't having the individuals, it's restoring them. So we need to define what success looks like.

REHM

11:32:10
Ryan?

PHELAN

11:32:11
I'd like to echo what Will has said in addition to habitat loss and invasive species, this challenge of diseases and disease susceptibility with these vulnerable endangered animals. It's critical. This is, I think, a role for genetic rescue. And it's a big part of our focus is using genomic technology to look at areas of potential disease susceptibility at a genetic level and potentially figure out solution.

PHELAN

11:32:38
So I think that with chytrid fungus, there's another one that's affecting all the bats with white-nose syndrome. We've seen with chestnut trees with chestnut blithe that, you know, another pathogen that, you know, has now been genetically engineered to create trees, chestnut trees that are resistant to blithe. I think we're going to be increasingly seeing this going on if we are proponents of science and we're open to science.

REHM

11:33:05
And you're listening to "The Diane Rehm Show." I think there is perhaps lying beneath this discussion perhaps the Frankenstein fear that is that in talking about de-extinction of endangered species, we could indeed be referring without referring to it, talking about de-extinction of human beings. Is that something, Elizabeth Kolbert, that is part of your concern?

KOLBERT

11:33:47
Well, I don't know that I would put that in my quiver of concerns. I think that the question of, you know, we're definitely in -- once again, I don't want to necessarily raise the Frankenstein spectrum, but we were, you know, you're engineering life or re-engineering life if you're saying we're just replicating life that existed. But the fact is that if we have no living cells from that organism, we really don't know exactly what those cells were like.

KOLBERT

11:34:16
We're just basically taking our best guess. It's a very, very sophisticated guess. I really, you know, as Ryan says, there are lot of very, very serious scientists looking into this and, you know, I absolutely don't want to, in any way, to denigrate their efforts. But we will be getting an approximation of what these animals are and then you definitely do get into the idea of, well, if you can create an approximation of something, maybe you can create something entirely new.

KOLBERT

11:34:43
You know, and that -- that goes way beyond the extinction. That is a question of generic -- genetically engineering life, which is something we may be getting very close to being able to do.

PHELAN

11:34:54
Well, I think, technologically, we may be able to go down that path of synthetic biology. But I think what we're really talking about here is the fact that we are already using species today that are approximations of what was there in the past. So we've done this with the peregrine falcon. Already that peregrine falcon was never in the actual region that it was in today all over the U.S. It's a subspecies of the subspecies.

PHELAN

11:35:20
But when look up in the sky, we're very happy there's a peregrine that we almost lost. We're happy there's a condor. So I think an approximation is not necessarily a bad thing. We don't even notice it.

REHM

11:35:32
Tell me about the work on the passenger pigeon thus far. How far are you in sequencing each genome?

PHELAN

11:35:43
Right now, we're in the process of doing that sequencing at the University of California both Santa Cruz and San Francisco. And I'm so glad you brought this up, Diane, because what we're doing is we're comparing that genome of the passenger pigeon with its most closely related relative, which is called the band-tailed pigeon. And this is a really important point. These de-extinction efforts are not being done in a vacuum.

PHELAN

11:36:07
This is not a one-off. What we're doing is we're comparing something that is very close. And so, this is not like making up a new animal. This is using something that, as a surrogate species, that we all teach the parents -- as parents, we'll teach the offspring so that a lot of these behavior is learned from the potential surrogate, but most of these behavior is hardwired in birds.

REHM

11:36:32
And for you, Elizabeth, that raises questions such as?

KOLBERT

11:36:38
Well, you know, I -- it's not just for me. These are questions obviously that, you know, Ryan has spent a lot more time actually thinking about. But, for example, in this particular, take the case of the passenger pigeon and its closest relative the band-tailed pigeon. They are behaviorally very, very different so far as we know. Once again, in innocence, we don't have passenger pigeon behavior exactly. All we have, we have a lot of written records but no one really did...

REHM

11:37:03
So you can duplicate the object, but you cannot duplicate the sensibility, if you will.

KOLBERT

11:37:10
Exactly. And we see this even -- I mean, and, you know, and Ryan makes a good point. We are -- we do have a lot of approximations out there. But in the case of a condor, their behavior is very odd actually.

REHM

11:37:23
Elizabeth Kolbert and her new book is titled, "The Sixth Extinction: An Unnatural History." Short break here. When we come back, time to open the phones. Stay with us.

REHM

11:39:59
And welcome back as we talk about efforts at de-extinction. That is bringing back creatures that have gone extinct. We're talking with some real experts in this field. Ryan Phelan is co-founder and executive director of Revive and Restore. That's a research organization in California trying to bring back endangered species. Will Turner is chief scientist at Conservation International.

REHM

11:40:41
Elizabeth Kolbert is author of a new book titled "The Sixth Extinction: An Unnatural History." She is a staff writer at The New Yorker. Ryan, before we open the phones, I want to mention you're also aiming to bring back the woolly mammoth from extinction. Tell me why.

PHELAN

11:41:11
Well, it is what we call a big, hairy, audacious goal, Diane. It is going to be probably the most, by and far, charismatic of all the species that we talk about bringing back and probably the most controversial. And it is a decades-long project. I mean, you know, we've really thought a lot about how to have de-extinction be viewed as a long-term project. This is not something that's going to happen tomorrow in anybody's backyard. And the woolly mammoth is a perfect example of that.

PHELAN

11:41:42
What is going on is there's a team of scientists at Harvard University, headed by Dr. George Church, who are making significant progress right now actually using Asian -- using elephant cells and trying to actually adapt them at a cellular level in a lab to see if they can transfer over some of the gene traits of a woolly mammoth, which includes everything from the way that those cells develop subcutaneous fat, the kind of hair that would allow them to live in a cold environment. So a lot of science is happening.

REHM

11:42:20
But one might say, just because you can, why do it? What would be the value of doing it?

PHELAN

11:42:28
Well, the -- sure. So, again, the biggest value of all of this -- and I think Will and others have talked about it today -- is the science that is going to be developed along the way. That's, I think, critical. And these pioneering scientists right now are working on this for, I think, their major goal is to actually move the science forward, to use these new genome-editing techniques.

PHELAN

11:42:53
But there are people in Pleistocene Park, in Siberia, Russian scientist named Sergey Zimov, who believes woolly mammoths could actually affect climate change. And I'm sure your other speakers here will have some thoughts on that as well. But it -- bringing back the mammoth steps, using these big megavores, would make a big difference.

REHM

11:43:16
All right. I'm going to open the phones first to Benjamin in Washington, N.C. You're on the air.

BENJAMIN

11:43:27
Yes. Speaking of the woolly mammoth, and also of all other ancient species that might de-extincted, as your guests said that they're using elephant cells. If we create a hairy elephant today, can we really call that woolly mammoth? Have we de-extincted anything? Or have we just created a whole new modern species that resembles an extinct species?

REHM

11:43:59
Elizabeth.

KOLBERT

11:44:00
Well, you know, I'm not in George Church's lab. But certainly, as someone who is quoted (unintelligible) eminent paleogeneticist was quoted recently in The Times saying she was worried that George was going to create, you know, a slightly harrier elephant and call it a mammoth. I mean, who -- you know, there are many, many -- elephants and mammoths are quite closely related.

KOLBERT

11:44:22
Existing elements are quite closely related. And you could do lots of things to a -- you know, you'd just sort of have a genetically-engineered elephant. At what point would you say it's a mammoth? You know, on some level, never. You know, but it -- there's -- I suppose there are many, you know, grades between here and there.

KOLBERT

11:44:37
But, you know, there are a lot of profound questions here, whether such an embryo could be brought to term by an existing elephant is a question we simply don't know. And that also gets us back to sort of ethical questions of creating animals that may actually, you know, unfortunately, suffer in the process.

REHM

11:44:55
And here is an email from Tom in Miami, Fla. who says, "I lost my dear mother to cancer last year. Why stop with bringing back animals? Can I extract my mother's DNA and insert it into a willing female embryo?" Will?

TURNER

11:45:21
Well, first of all, I'm sorry for your loss. But I think that's a great question, and it raises some interesting issues. So issues about what, if anything, is different between resurrecting a living -- a single human being versus what we're talking about with potentially de-extincting a species. So with a human being, I think what would be of most of interest is preserving what -- or resurrecting what we could consider the soul of a person in a single individual.

TURNER

11:45:48
You know, and among other things, that new clone, if it existed -- it may be possible. We know that cloning living animals is possible, Dolly the sheep, for example. It may be possible. If it existed, it would still take, you know, years to grow up into something. It might now look a whole lot like your mother or might not -- certainly wouldn't behave (unintelligible) like your mother.

REHM

11:46:10
And wouldn't have the soul.

TURNER

11:46:11
Yeah. Yes. On the other hand -- so what, if anything is different about extinct species, well, I think it's important to ask about what extinction means to us in terms of what have we lost as species go? There are certainly ethical and intrinsic value in species, but, in addition, there's the value that species have in ecosystems. And the fact that Earth's biodiversity provides us -- is the foundation of much of what makes life on Earth possible, our atmosphere absorbing carbon dioxide.

TURNER

11:46:48
An interesting connection of parents, my father survived an infection last December because of the drug Vancomycin. It's an antibiotic of last resort that came from a soil microbe in the forests of Borneo. So the fact that species exist, provide us thousands upon thousands of benefits that we cannot live without -- we are in de-extinction or conservation, more broadly, maintaining Earth's species -- is having the species exist itself has value, which is a bit different from the question of the human soul.

REHM

11:47:28
All right. Here's an email from Mark in St. Louis who says, "De-extinction does not restore a destabilized ecosystem. And in a system that's evolved by dealing with consequences of a loss of a species, a restored species may well turn out to cause problems similar to the introduction of an alien species. Let's face it. This is about power and fascination, not saving the endangered life already critically threatened." Ryan.

PHELAN

11:48:13
Well, I guess I would answer that by saying I just completely disagree. I think this is much more than power and fascination. I think this is an extension of the fact that we're really in a biological sanctuary and that we are now in a position where we can use these tools for conservation, to enrich whole ecosystems, and I think that -- people have given reference to the fact of cancer here today several times.

PHELAN

11:48:39
And my background is in human medicine, and what we've seen in the last year -- last decade is that cancer isn't treated by one targeted -- now it's treated with many targeted drugs, not treated as one disease. The same thing, I believe, is going to happen in conservation. We're entering an area of precision conservation with these new genomic tools.

REHM

11:49:02
All right. And to you, Elizabeth, let's take a call from Sally in Plainwell, Mich. Hi. You're on the air.

SALLY

11:49:16
Hello. Thank you so much for your program. And I love the way you think, Diane.

REHM

11:49:22
Thank you.

SALLY

11:49:22
Elizabeth, I have read your book "Sixth Extinction." I've bought 10 more copies to share with friends.

KOLBERT

11:49:29
Thank you.

SALLY

11:49:29
I would like to introduce the term Anthropocene. I do think that -- I haven't heard that during this program. I would rather just fix it -- just shortly say, rather than try to recreate what we've lost, let's save what we already have. It's so important to address the rapid rate of extinction of our precious planet animals. I went down to the zoos in Cincinnati to see the Sumatran rhinos written in your book. And one has died in the last two weeks.

KOLBERT

11:50:02
Yeah. I think that's a very, very -- you know, that's a really good, good point that you make. And it sort of brings the conversation back down to Earth. To be honest, this is a -- the caller's alluding to there are actually a pair of Sumatran rhinos at the Cincinnati Zoo. Sumatran rhinos are critically endangered. We're talking about a hundred individuals left in the world. And there were two. They were actually brother and sister at the Cincinnati Zoo. And they were trying to breed them. They were so desperate that they were trying to breed a brother and sister.

KOLBERT

11:50:33
That's what's actually happening in the world of conservation. And unfortunately the sister died from a -- probably from a disease that causes you to sort of accumulate iron. So the real problems in the world of trying to save species, you know, are really critical and urgent. And I certainly agree with Ryan that, you know, genetic tools, to the extent that they can be brought to bear, are certainly worth bringing to bear. But we are now in a situation where we have only a hundred of these rhinos left.

KOLBERT

11:51:05
And you can watch what's really happening, which is that these are very, very difficult in captivity to get them to breed. And even then, you have to also ask the question, which some callers have alluded to -- let's say you could breed them. What are you going to do with them? Their whole problem is that they have nowhere to go. They're being poached. And they're habitat's being destroyed. So what exactly would you do with them, even, if by some really -- and at this point, you'd have to say miracle, we managed to get through this bottleneck?

REHM

11:51:32
Elizabeth, talk about the frozen zoo in San Diego and the stores of endangered species. What are your concerns there?

KOLBERT

11:51:45
Well, I think the frozen zoo is a -- you know, it's a tool, and that's how it would be described by the people who started it, a Dr. Oliver Ryder, who runs it. It's basically just a collection of vats of cell lines that are preserved in liquid nitrogen. I've been there. I've seen these little vials of cell lines. And that's just really all it is.

KOLBERT

11:52:06
It's just it's this germ tissue, germ lines. And, you know, the question then becomes, well, what are you going to do with those? And that's where the de-extinction question comes up. I don't think the question comes up when you're just storing these things in liquid nitrogen. They are a research tool, absolutely. They're quite possibly a very valuable research tool.

REHM

11:52:26
Ryan.

PHELAN

11:52:27
Yes. Hear, hear. They're a hugely valuable research tool. They're much more than just a collection. The frozen zoo specimens, I believe, really hold the key to understanding genetic variation and could very well help bring back from extinction threatened species like the black-footed ferret. We're working with the San Diego Zoo right now trying to ensure that we can compare those genomes to see if we can, you know, help create tools for better managing that population.

REHM

11:52:58
But now, Will, talk about the environment if one were successful, say, in bringing back the woolly mammoth. What about the environment in which that creature lived at that time? How could you recreate that?

TURNER

11:53:18
Right. That's a really important question. I think -- and it's going to vary across species. The farther back in time you go that a species left the environment, the more changes happened since then in a number of ways, the environment, potentially the species that it would have interacted with, maybe its own microbiome, the other organisms that live inside our -- the bodies of animals, or plants. I think it's really important to think about what success means.

REHM

11:53:46
And you're listening to "The Diane Rehm Show." And defining success is really what everybody has to do in thinking about all this.

TURNER

11:54:00
Yeah. I would say there's no species for which having a few individuals in a zoo or in a vault somewhere is an acceptable definition of success. So we need to have an informed debate on that as a basis for our plans for conservation and other considerations, but as...

REHM

11:54:14
Ryan, how would do you define success?

PHELAN

11:54:17
I define success as a viable population in their native habitat, thriving. So it's never about, you know, just creating a zoo creature.

REHM

11:54:28
So if a woolly mammoth were brought back, what kind of an environment could that creature survive in?

PHELAN

11:54:38
Well, it's a wonderful question because there's somebody there working in Russia, Sergey Zimov, building what he's calling Pleistocene Park, thousands and thousands of acres of arctic tundra. And he says he welcomes not one woolly mammoth, but thousands of woolly mammoths, to break up that arctic tundra, to create grassland, and to create a home for thousands of other species that could be maintained there from all the little creatures that are running the world -- and that's what's going extinct the fastest -- to other herbivores. So it's a beautiful vision that he's got. He's thinking African savannah, the equivalent.

REHM

11:55:15
Elizabeth, what are you thinking?

KOLBERT

11:55:18
I'm thinking I'm not going to be around to see that. How's that?

REHM

11:55:22
You're not going to be around to see that?

KOLBERT

11:55:23
I don't think so. I don't think Sergey's going to be around either, sadly, but...

PHELAN

11:55:26
No. But we can -- if we can dream it, we can build it for others.

KOLBERT

11:55:31
Okay.

REHM

11:55:32
Is that what you're all thinking, that this could be the beginning of something, but there are a great many questions that have to be resolved?

TURNER

11:55:46
Look, as a conservationist, I would be happy to have this in our toolbox. But we need to think about what -- defining success carefully, and I think I give both Elizabeth and Ryan a lot of credit in Ryan's organization for thinking through some of this. We also need to look at the -- across the range of species and actually take a critical look at which ones actually make sense and define some clear criteria because there are ethical, technical, ecological issues that are going to be raised.

TURNER

11:56:24
And I think -- I personally -- although I find the idea of mammoths really fascinating in bringing them back, I think there are some that -- organisms that might have a more clear role of fitting back into an ecosystem that needs their role and might be technically more feasible. And so we need more discussion about that.

REHM

11:56:48
Much, much more discussion. I can tell. Will Turner, chief scientist at Conservation International. Elizabeth Kolbert, she is the author of "The Sixth Extinction: An Unnatural History." She's a staff writer at The New Yorker. And joining us from San Francisco, KQED, has been Ryan Phelan, co-founder, executive director of Revive and Restore. Fascinating discussion. Thank you all so much.

PHELAN

11:57:27
Thank you.

TURNER

11:57:28
Thank you for having me.

KOLBERT

11:57:29
Thank you.

REHM

11:57:29
And thanks for listening. I'm Diane Rehm.
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