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ScienceThe Loom

De-Extinctions and Straw Men

In my feature on de-extinction in the April issue of National Geographic, I tried to capture the debate in the scientific community about whether we should try to bring vanished species back to Earth. It’s been gratifying to see a spirited, sustained conversation going on ever since. The prospect of de-extinction raises important issues that have to be grappled with. Is it better to spend money trying to revive a mammoth or to secure a vast swath of rain forest? Are objections to de-extinction driven by a flawed notion of what’s natural? Would it make more sense to use the emerging tools of biotechnology to prevent endangered species from disappearing, rather than attempting to bring back the extinct ones?

But I’m frustrated by a column by George Monbiot that just appeared in the Guardian, entitled, “Resurrecting woolly mammoths is exciting but it’s a fantasy.” Monbiot singles out National Geographic for scoffing, declaring,

the double-page painting published by National Geographic in April, depicting tourists in safari vehicles photographing a herd of Siberian woolly mammoths roaming the Siberian steppes, is pure fantasy: the animals it shows are mumbo-jumbos.

(We Yanks use mumbo-jumbo to refer to gibberish, but after reading Monbiot’s piece, I did some dictionary-ing and discovered that the Brits use it to refer to a meaningless idol.)

It’s not Monbiot’s position that bothers me. In my article, I wrote about harsh critics of de-extinction as well as advocates. It’s the way he frames his argument at the outset:

There is an obvious, fatal but widely overlooked problem with de-extinction. 

Wow! Both obvious and fatal. Not just obvious and fatal, but also widely overlooked! What could this problem be, a problem that conservation biologists and molecular biologists who are exploring de-extinction have somehow failed to notice, a problem that Monbiot is here–at last–to unveil?


The scarcely credible task of resurrection has to be conducted not once but hundreds of times, in each case using material from a different, implausibly well-preserved specimen of the extinct beast. Otherwise the resulting population will not be genetically viable.

Really? That’s it?

I felt a distinct lack of surprise at Monbiot’s big reveal.  That’s because I had addressed this very issue in my own article four months ago, noting that reviving a single animal is not the same as bringing back an entire species.

But I didn’t go so far as saying that this was a “fatal” problem, because I discussed the issue with the scientists I interviewed. You’d think from reading Monbiot’s column that these scientists hadn’t the faintest clue of this problem. I picture them sitting in front of their screens, reading Monbiot’s revelations, and smacking their foreheads all at once, roaring, “Of course! How stupid of us!”

You’d have to be a truly stupid scientist to not be aware that the long-term viability of a species depends on a genetically viable population. If a small population is only made up of nearly genetically identical individuals, they run the risk of inbreeding, which can make them unhealthy, vulnerable to diseases, and even infertile.

The scientists exploring de-extinction are aware of this challenge, and they have actually given this matter some thought. They have ideas about how to deal with it. There’s a good debate to be had over whether those ideas could really work in practice, but Monbiot shows no signs of being familiar with them.

Monbiot is arguing that de-extinction cannot work, period, because it would require discovering an intact cell for every individual animal or plant scientists wanted to produce. There are several reasons why this is wrong. For one thing, scientists already have the technology required to engineer diversity into a species.

Museums have hundreds of preserved passenger pigeons, for example, and those birds are not clones of one another. By sequencing the DNA from a number of passenger pigeons, scientists could learn about the genetic diversity of the species. Based on the experiments scientists are already doing on animal cells, it’s conceivable that researchers could synthesize gene variants and plug them into the genome of an extinct animal. By engineering the genomes of the pigeons, scientists would create a flock containing some of the genetic viability that existed before the species became extinct.

If scientists can produce a few dozen genetically diverse passenger pigeons–or gastric brooding frogs, or thylacines, for that matter–it’s an open question whether those creatures could seed a sustainable population. Monbiot seems to be down on the whole idea of restoring small populations. He points to European bison, which have gone from 54 animals to 3,000, but which still have trouble with inbreeding.

But there are more heartening stories, too. Northern elephant seals were hunted down to the same population level, and today their numbers are up to 160,000.

Now we’ve drifted off the original course, though. We are no longer talking about de-extinction, but about the broader question of captive breeding. There’s another good debate to be had about whether to save the black-footed ferret and the California condor. But I guess it’s not as fun as shouting mumbo-jumbo!