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Illustration of woolly mammoths.

Illustration of woolly mammoths.

Into the Wild: Playing God With Resurrection Biology

A woolly mammoth tale.

Since its blockbuster debut in 1993, “Jurassic Park” and its five sequels have earned over $6 billion worldwide. That’s a fact. But the films’ narrative of humans recreating dinosaurs that died off 65 million years ago is pure fiction.

“We’re not getting the dinosaurs back because DNA is not preserved in species that old,” says Santa Clara environmental studies and sciences Professor Virginia Matzek of the premise behind the Michael Crichton novel, in which scientists “extracted” dinosaur blood from an ancient mosquito trapped in amber. The incomplete dinosaur DNA, added to the DNA from a frog, was implanted into an ostrich egg, from which a baby dinosaur later hatched. 

Yet today, millions of dollars actually are being invested in re-creating other extinct animals, most notably the woolly mammoth. DNA from the behemoths that once roamed Europe, Asia and North America until 10,000 years ago “is not so terribly degraded that you can’t piece it back together,” says Matzek.

With enough DNA samples from their preserved tissue, scientists are hoping to sequence the genome, then use cutting-edge gene editing techniques to modify the Asian elephant genome to produce mammoth traits like the long, hairy coat. The edited genome would be placed in a donor Asian elephant egg, and hopefully develop into an embryo that could be implanted into a surrogate elephant and result in a live birth. 

But … why? We asked Matzek to give us a crash-course on the pros and cons of resurrecting extinct species.

There are thousands of species scientists could try to revive. What’s so appealing about the woolly mammoth?

It's big, hairy, and everyone knows it's extinct. So it has some of that Jurassic Park dinosaur cachet. And their DNA tends to be quite good because many of them have been preserved in permafrost. For example, in the gold fields of the Yukon, the permafrost is being melted with hydraulic mining techniques to get the gold. As they do this, they’re exposing long-buried mammoth and other Pleistocene fauna bones. Sometimes you get an amazingly well-preserved sample—last year they pulled out a complete baby mammoth that was 30,000 years old and you could still make out its eyes and ears and its stubby little tail. But mostly they find bones, lots of them, and the DNA is extracted from the bones. And, then the other reason is that it fits into the narrative of re-wilding.

What does re-wilding mean?

It's when you return big animals back to ecosystems where they've been exterminated. You bring them back into a habitat because you think those animals have a role that’s missing in the ecosystem. It could be large predators like the wolf in the Western U.S. Or it could be something extinct, like the Pleistocene megafauna. There used to be these giant herbivores all over in North America. They ate large fruits and knocked over trees and dispersed seeds. But we no longer have these giant grazers, or giant dispersers. 

The idea with the mammoth is that herds of woolly mammoths could help return the tundra ecosystem to grasslands. The theory is that if the mammoths were reintroduced, they’ll trample the snow more, keeping the frozen soil underneath colder, so it would release less carbon dioxide. It ends up being an argument about mitigating climate change.

Is there another popular candidate for de-extinction?

The thylacine, also known as the Tasmanian tiger or Tasmanian wolf, which went extinct in 1936. They were pretty much the only large predator on Tasmania, but they were wiped out by sheep farmers who perceived they were a threat to sheep. There are stuffed ones in museums. There are pups pickled in alcohol, so you can get pretty good DNA out of those kinds of samples. Some researchers in Australia believe that bringing them back could restore a natural predator to help with overpopulation of other animals. 

As a restoration ecologist, what worries you about reintroducing extinct species?

Too much attention is paid to the kind of “gee whiz, can we do it?” and not about what the implications would be. It’s like the Jeff Goldblum character in “Jurassic Park” who told the scientists, “You only asked if you could do it; you never asked if you should.” I can see potential benefits coming from this technology. I can even see the possibility of the de-extinction happening. But I think we need to ask some bigger questions about ecosystems, and about habitats, and about animal welfare, and about a lot of other things that kind of get laid by the wayside because everybody is just so hot, hot, hot to see the mammoth come back. 

What specifically concerns you about bringing back the woolly mammoth? 

Oh my goodness, lots of things. What would a woolly mammoth eat today, now that our climate is completely different? We know nothing about how these extinct species would behave. What are their social lives like? Ask any zookeeper, or even a gardener, about how difficult it is to know exactly what a species requires to survive and thrive. This is well beyond the technical challenges of how do you get the genome reconstructed, and how do you get the DNA into a cell, and how do you find a surrogate mother that can bear it. I mean, those are big hurdles, but that's just to get one live animal born. My question is, how do you scale this? Because if you are going to resurrect an extinct species, the whole point of it should be that it should go out into the wild. But you can’t do that if you only have one. If we only manage to make one mammoth, it’s going to a zoo, and we already know that elephants are very difficult to keep in captivity. Until we have made 1,000 mammoths, a herd, something that could potentially migrate—then you have some claim to saying you've de-extincted a species. Another problem is that Asian elephants themselves are not in great shape, population wise; and they ovulate infrequently, their gestation period is two years long. Are we going to commit a lot of Asian elephant moms to producing woolly mammoth babies instead of Asian elephant babies? 

How far away are we from making any of this happen?

We’re a couple of technical limitations away, though I think they will eventually be conquered. But first of all, how confident are you that you have enough genetic information from the woolly mammoth to cover all the traits you think will make it complete? The hardiness for the cold, the woolly coat, etc. And will the Asian elephant successfully gestate the embryo and the fetus, give birth to it, and then will it be alive? Those are much bigger questions. In 1996, when Dolly the sheep was cloned, for example, she was maybe one of hundreds of attempts. But most of them didn’t result in embryos, and many of the embryos miscarried.

Has any extinct species ever been brought back to life?

There was a wild goat called a Pyrenean ibex, or bucardo. A Spanish and French team had cryo-preserved cells from the last living Pyrenean ibex that died in 2000, and put genetic material from the ibex cells into goat egg cells and incubated them, and implanted the embryo into a goat. And in 2003, a baby bucardo was born. But it only lived for seven minutes, and died of congenital lung deformities—and it probably died in a state of suffering. It’s the first species to be de-extincted; it’s also the first species to go extinct twice! Even if it had lived, the only living tissue they had was for a female. So that means all the clones would have to be females. They hadn't necessarily thought ahead to the part where you need to make males to have a self-sustaining population. That's why I say the technical challenges are running way ahead of the practical thinking. They need to talk to some ecologists.

So why continue funding this research?

Well, there’s “let’s bring back endangered or extinct species because we can, and wouldn’t it be cool?” Then there’s the argument that they’re actually needed to occupy their ecosystem roles, and that’s why we should do it—honestly I'm skeptical of this argument, but you hear it bandied about. The third thing that could come out of this is that developing the technologies might actually have other benefits. It might be a little bit like the space program—it’s something that attracts innovation and inspiration and money. And you may get these side benefits of other kinds of technologies, and applications that can be useful in human medicine. And these technologies can almost certainly help endangered species, as opposed to extinct ones. This has already happened—they've used preserved cells to bring back clones of animals that died decades ago, to add more genetic diversity into a species that is too inbred. 

The hurdles are many, but that was true of the space program, too. We didn’t say, “Oh, it’s pretty difficult, so let’s not try it.” There are gobs of money being spent here. I can wish that we would spend those gobs on living species and habitat conservation, but they're not. So I'll wish instead that when they try to bring back the extinct species, the technology also helps keep some of our existing species around.



CAS, Energy, Ethics, Faculty, Science, Sustainability, Technology

Re-sized drawing of woolly mammoths in a late Pleistocene landscape in northern Spain, by Mauricio Antón. © 2008 Public Library of Science.


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