How to Clone a Mammoth

mammoth_cover_crop_3269793aBeth Shapiro
2015

Should we try to bring back the woolly mammoth?

News reports today trumpet the sequencing of the complete genome of the woolly mammoth. This accomplishment brings science one step closer to the potential “revival” of this extinct species.

I’m particularly interested in this topic, as I’ve recently finished reading Beth Shapiro’s newly-published How to Clone a Mammoth: The Science of De-extinction.

Shapiro’s book is timely not just for her insights into the science, as an active “revival” researcher, but also for the many cautions and moral issues that she identifies. Sometimes, the thrill of the scientific chase makes “can do!” threaten to overwhelm “should do?”

The new study, from Sweden, says nothing about reviving the mammoth. Its focus is on comparisons of genetic deterioration in a dwindling population, using the genome data to compare an older Siberian specimen (about 44,000 years old) to a Wrangel Island specimen that lived at the very end of the mammoth line (about 4,000 years ago).

But the complete genome sequences from these two specimens bring species revival tantalizingly closer. As Shapiro points out in her book, until now only shorter fragments of mammoth DNA had been sequenced.

So, now that we have the mammoth genome, the rest is easy, right?

Shapiro outlines all of the other challenges of species revival in interesting detail, arriving at the short answer, “No, not easy.” But possible? And, if possible, why not?

Here is where Shapiro’s book rises above the “merely” scientific and becomes a much more important consideration of the issues that should caution enthusiastic groups like the eager potential revivers of the Long Now group.

How to Clone a Mammoth starts with a clear statement that, in Shapiro’s view, there is no point in bringing back an extinct species to create scientific curiosities, zoo animals, or mammoth theme parks: “What is the point, after all, of bringing a species back from the dead if it is not to reestablish a wild population?”

When I imagine a successful de-extinction, I don’t imagine an Asian elephant giving birth in captivity to a slightly hairier elephant under the close scrutiny of veterinarians and excited (and quite possibly mad) scientists. I don’t imagine the spectacle of this exotic creature in a zoo enclosure, on display for the gawking eyes of children who’d doubtless prefer to see a T. rex or Archaeopteryx anyway. What I do imagine is the perfect arctic scene, where mammoth families graze the steppe tundra, sharing the frozen landscape with herds of bison, horses, and reindeer—a landscape in which mammoths are free to roam, rut, and reproduce without the need of human intervention and without fear of re-extinction. This—building on the successful creation of one individual to produce and eventually release entire populations into the wild— constitutes the second phase of de-extinction. In my mind, deextinction cannot be successful without this second phase.

Once you’ve decided that you will, indeed, bring a species back from extinction, how do you decide which one to revive? Should we choose the species that will be the easiest to bring back? The most awe-inspiring? The most likely to draw attention, perhaps motivating further investment into the technology? Or should we focus on those species whose de-extinction is clearly scientifically justifiable? And, if the latter, what does that mean exactly? Finally, and just as importantly, who is the “we” that gets to decide?

Shapiro argues that there must be a “compelling reason” to bring a species back. We’ll need someplace for them to live if we’re going to establish a wild population, and that means careful consideration of the “new” animal’s impact on the existing ecosystem into which it is to be introduced.

What about the mechanics? After all, we can’t just zap a gene sequence and, one puff of smoke later, say hello to Woolly Bully, the first Mammoth II. How much you think a living elephant would relish carrying and giving birth to a baby from a different, much larger species? Or do we not care about that, being willing to sacrifice a few elephant females for the good of the cause?

Shapiro discusses the ongoing project to “deextinct” the auroch. The “back-breeding” team is not trying to bring back an actual auroch; rather, they hope to introduce enough auroch DNA into existing cattle populations to “ resurrect a phenotype that can do in that environment what the auroch used to do…. something similar in function but not necessarily identical in form.”

In my mind, it is this ecological resurrection, and not species resurrection, that is the real value of de-extinction. We should think of de-extinction not in terms of which life form we will bring back, but what ecological interactions we would like to see restored.

Another unknown that Shapiro considers is the effect of epigenetic changes. We simply can’t predict “how much of looking and acting like a mammoth is due to having a mammoth genome, and how much of it is due to living life in the steppe tundra.”

And it’s life in the Siberian tundra that Shapiro insists should be the goal of any attempt to revive the woolly mammoth.

Some advocates for mammoth de-extinction probably don’t care what ecological role unextinct mammoths might play on the Siberian tundra. Some probably don’t even care if they ever make it to the Siberian tundra, as long as they make it to a zoo or a park where they can be observed and possibly ridden. I, however, and others including George Church and Sergey Zimov, care very much about how unextinct mammoths—or, more correctly, genetically engineered Asian elephants—might change the Siberian tundra. In fact, their potential to invigorate the Siberian tundra is precisely why we are motivated to work on this project.

Shapiro devotes a chapter titled “Should We?” to many of the more serious objections that have been raised against the entire idea of reintroducing extinct species.

First, and easiest to refute, is the idea that de-extinction might revive dangerous pathogens. The short answer: “No.” Pathogens don’t set up house in DNA, and even if some ancient virus were found in incidental blood or tissue samples, the genetic material inside it will be too degraded to “revive.”

Another objection is that we should prioritize conservation of species that are still alive. Shapiro argues that there is little, if any, overlap in funding that goes to conservation and the much smaller amount that supports revival efforts. Money that could save Siberian tigers simply is not being spent on speculative reanimation of Siberian mammoths.

“Unextinct speices have nowhere to go.” Yes, Shapiro admits,“finding sufficient amounts of suitable habitat will certainly present a challenge for some de-extinction projects.” Mammoths need a  lot of room. Shapiro counters that public interest in the problems of finding habitats for “returning” animals may spur activism in species conservation and ecosystem enhancements in general. That would be a good thing.

Almost the same objection is concern about the impact of releasing de-extinct species on existing ecosystems. Shapiro spends a lot of time on this objection, acknowledging that we can’t know every consequence in advance. However, while “reintroducing the extinct species may upset the existing dynamics within that ecosystem,” Shapiro rejects the idea that that ecosystem will be “destroyed.” Changed, maybe changed back, but not “destroyed.” One unappetizing but possible way to restore the existing ecosystem if the changes introduced by de-extinction are unacceptable would be to “re-extinct” the revived species. (This is also a good reason to restore only large, slower-breeding animals!)

Shapiro writes that “conservation strategies can be thought of as a continuum between entirely managed ecosystems (think “gardening”) and allowing nature to fend for itself (think “preserving”).”

Purely preservationist strategies are, however, also risky. What if sufficient habitat can’t be preserved? What if species do not reestablish populations in the habitat that is preserved? Few habitats have avoided completely the effects of human population growth, suggesting that, at some level, intervention has already occurred. Further intervention may be required simply to reduce the damage that has already been done.

Shapiro deals just as fairly with other objections before sounding her final, positive note:

De-extinction is a process that allows us to actively create a future that is really better than today, not just one that is less bad than what we anticipate.

Thanks to both her caution and her enthusiasm, Shapiro has produced a highly-readable and quite sensible look at new technical and ethical territory.

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