Your De-Extinction Questions Answered

On Friday, I was down in Washington to speak at (and mostly watch) TEDxExtinction, a day-long meeting dedicated to exploring the possibility (and advisability) of bringing extinct species back into existence. The meeting coincided with the publication my story in the new issue of National Geographic on the subject. I invited readers to ask questions raised by either the story or the meeting, and then on Monday, National Geographic hosted a tweet chat on Twitter, which became an hour-long rapid-fire volley. So I’m only now getting a chance to write this long-promised post. Here are some answers to a few of the questions posted on the Loom and on Twitter–first on the logistics of de-extinction, and then the ethics.

This is an interesting question, because dodos were dinosaurs. Not to mention robins and hawks and other living birds. If your idea of Jurassic Park is being surrounded by dinosaurs, you are living the dream. If, on the other hand, you desire (or fear) the lineages of dinosaurs that became extinct 65 million years ago, such as tyrannosaurs, then you are out of luck. No viable cells or nuclei can survive 65 million years. And while scientists have recovered lots of DNA from species that became extinct tens of thousands of years ago, they can’t reach back tens of millions of years.

Peteykins said, “Too bad the dodo died out too long ago for viable DNA to survive. Now THAT I’d love to see.”

Dodos only became extinct less than 400 years ago. While there are no intact dodo cells left today, scientists have retrieved bits of dodo DNA from a specimen stored at the University of Oxford. If scientists could find a lot more dodo DNA, they might be able to identify the genetic variations that turned the ancestors of dodos–small, flying pigeons–into big flightless birds. Then they might be able to reverse engineer the genome of a stem cell from a closely related pigeon species and then turn that cell into eggs and sperm, which could produce dodos.

Size would present a problem, if a small pigeon had to lay a massive dodo egg. But you could imagine gradually developing dodos over several generations, getting bigger and bigger. Mind you, all this is just speculation from a few facts–the fact that we now have a little dodo DNA and that scientists are doing amazing research on cloning based on stem cell engineering. Lots of practical obstacles stand in the way, some of which might simply be insurmountable. For example, the home of the dodo, Mauritius, is a tropical island where conditions are terrible for preserving DNA. Ironically, scientists have reconstructed much more of the mammoth genome, despite the fact that the last mammoths became extinct 3700 years ago. That’s because cold permafrost is pretty good at storing DNA fragments.

When a population gets tiny, its genetic variation gets tiny, too. Thanks to the random shuffle of heredity’s dice, gene variants can disappear, leaving the organisms more and more similar to each other. That can be dangerous, because it can leave populations unable to reproduce as quickly and may leave them less capable of adapting to new challenges. If scientists created a dozen genetically identical dodos from a single egg, they’d face some serious problems with genetic diversity. This is just one of many practical challenges scientists would face in trying to truly revive a species, rather than getting one animal alive again just long enough to be photographed. But we should not assume these challenges are insurmountable. It might be possible to find variants of genes in ancient DNA from fossils or museum specimens, for example.

I agree that it is important to think about Deep Time when we think about extinction. Perhaps 99.99% of all species that ever existed are gone from this planet. But what’s happening now is unusual for two reasons.

One is the rate at which species are going extinct. In the past few centuries, the rate of extinction for some groups of species has jumped by roughly a factor of a thousand. That jump is due to us–to our hunting, logging, and other actions that leave species struggling to hold on to existence. If those actions continue into the future, and if we continue pumping carbon dioxide into the atmosphere at a rising rate, we could jack that extinction rate to levels that life has achieved only five times in the past half billion years. So we’re not in a “things come, things go” situation. It’s more like, “Things go, and a lot more things go after them.”

The other reason that what’s happening now is unusual is us. In no previous pulse of mass extinction did a single species consciously drive a number of other species extinct. I’m not saying that a bird hunter shooting into a flock of passenger pigeons 200 years ago realized he was part of an exercise that would drive the entire species of passenger pigeons extinct within 100 years. But as a people, we know it now. And we know that other species are on the ropes, because of what we are doing. Hence we can decide if we want to let this extinction crisis continue to balloon.

The whole conservation movement is organized around the proposition that biodiversity is something worth saving. When a species goes extinct, it can leave a hole. Its ecosystem may suffer because the species can no longer carry out some important task, such as pollinating plants or filtering water. We lose the opportunity to investigate its biology and discover some fascinating piece of natural history or even find a valuable molecule for curing infections or sequencing DNA. And we end up living in a world without Great Auks and gastric brooding frogs. Is de-extinction a tool for slowing or reversing this trend? That’s a good question. But one thing’s for sure. We’re not playing God. We’re coming to terms with our own powers, as well as the unexpected results of our actions.

Aaron asks, “Should we bring any animal back from extinction which could threaten human life?”

What constitutes a threat? We have a habit of perceiving threats where the risks are tiny or non-existent. In fact, some species, such as the thylacine, were eradicated because they were considered a threat to human life–specifically, that they were killing off herds of sheep. That was untrue, but it didn’t stop people from driving the species extinct. Bringing them back would not pose a threat either.

I’m not saying that no revived species would pose a risk. But we do have to make sure we aren’t letting emotions ride roughshod over our decisions. Scientists have already revived a very dangerous life form: the flu virus that killed 50 million people in 1918. But no one has died from it, because precautions have been taken. And scientists have learned a great deal about how influenza evolves and kills–information that could help us in the future. This was a de-extinction of sorts that presented both risks and benefits.

This is a point raised by many conservation biologists, both in my interviews for my article and at TEDx. “At this moment, brave conservationists are risking their lives to protect forest elephants from armed poachers,” David Ehrenfeld of Rutgers University said at the meeting. “And we’re talking in this safe auditorium about bringing back the woolly mammoth?”

If de-extinction really did make it harder to, say, pay guards to stop poaching, then I could definitely see a problem here. But where is the evidence of a zero-sum game at play? I don’t see it. No one at TEDx proposed cutting guard salaries to bring back a mammoth.

This concern could apply just as well to experimental research on animal reproduction–efforts to freeze cells of endangered species for research, assisted reproduction, and so on. They all cost money, they are not guaranteed success, and they all require people to do something other than guard against poaching. Yet some species have been introduced back to the wild, saved for now from extinction, thanks in large part to this kind of research.

These issues don’t just apply to extinct animals, but to the near extinct. There are four Red River giant softshell turtles left on Earth. They are not breeding with each other. We might be able to use stem cells to produce lots of new sperm and eggs and fertilize them to grow their population. Is this just a waste of resources, or will this end up saving the species? If we engineer frogs to resist chytrid fungus infections, is this just a simplistic technological fix, or the only way to keep them from going extinct?

My fellow Phenom blogger Brian Switek considers de-extinction little more than a slick marketing term. I disagree, if only because the issues that have emerged with its unveiling are going to stick around for a long time, even if no one tries to bring an extinct species back to life.

If you want to go deep into everything that would be required in bringing back Neanderthals, check out this piece by fellow Phenom Virginia Hughes. Do not worry about meeting a Neanderthal on the street tomorrow, or next year.

If we could bring them back, should we? I think not, for many reasons. Neanderthals were humans, and research on humans requires informed consent, which is hard to get from someone who belongs to an extinct lineage. It would be unethical to bring people back without a place where they could live with dignity, and we have no idea what such a place would be for a Neanderthal in the twenty-first century.

I am quite taken with the idea of bringing back Steller’s sea cow. The first scientist to describe it was Georg Wilhelm Steller, who was on a voyage across the Bering Sea in 1741. He and his crewmates were shipwrecked on an island there, where they discovered herds of these amazing animals. They were relatives of manatees, reaching 25 feet long or more and weighing six tons. Here’s a wonderful image of them by the great illustrator Carl Buell, which is now on display at the Smithsonian.

Steller survived to write about the sea cows because his crew slaughtered some of the animals to eat on the voyage home. A single sea cow could feed a crew of 33 sailors for a month. Sailors on North Pacific ships killed so many sea cows that they vanished in 1768, just 27 years after Steller first described them.

Steller’s sea cow was part of the Pacific ecosystem for millions of years, and we are personally responsible for wiping it out. It would be quite something to figure out how put it back where it was just a couple centuries ago. But given the size of their potential surrogate mothers–not to mention many other obstacles–I’ll content myself with a daydream for now.

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Stelle’s sea cow.