Scientists say we're on track to lose species at a mass-extinction pace, due to climate change and other rapid environmental shifts — so can we just clone them back into existence?
That's what some Russian and South Korean researchers are hoping to do: They're trying to recover genetic material from a frozen woolly mammoth carcass and repopulate a "Pleistocene Park" with cloned herds of the currently extinct species. Some folks are talking about doing something similar for the passenger pigeon, which once flocked across America by the billions but went extinct in 1914.
Evolutionary biologist Beth Shapiro of the University of California at Santa Cruz has even written a book about the subject, helpfully titled "How to Clone a Mammoth." But Shapiro admits that the title is a bait-and-switch.
"There's a lot of hyperbole that comes out about de-extinction," she told NBC News. "It's not possible to bring an extinct species back to life. The main reason for that is, once an animal is extinct, there are no living cells."
Even that frozen mammoth recovered from the Siberian permafrost has suffered massive tissue damage, thanks to tens of thousands of years' worth of degradation. For that reason, Shapiro said, the Russian-Korean team is "never going to find a living cell" for cloning.
So are such exercises in genetic engineering a waste of time? Some experts think so. Paul Ehrlich, president of the Center for Conservation Biology at Stanford University, called it a "fascinating but dumb idea" in an influential essay written for Yale Environment 360.
"It's an employment program for people who can't get jobs doing something sensible," Ehrlich told NBC News.
Shapiro, however, said that genetic modification could someday play a role in the preservation of endangered species. "There are species on the brink of extinction today, and many argue that the environment is changing so fast that evolution can't keep up — so why not use this as a 'genetic booster shot,' so to speak?" she said.
How it could work
What Shapiro is talking about isn't cloning per se, but a molecular-scale operation aimed at inserting snippets of specially designed DNA coding into a species' genome. The operation makes use of a gene-editing technology called CRISPR/Cas9, which is rapidly gaining ground in laboratories around the world. (Reports about CRISPR's use of non-viable human embryos stirred a controversy on Wednesday.)
Theoretically, it might be possible to add genetic traits from the extinct passenger pigeon's reconstructed genome to a closely related species, such as the band-tailed pigeon. Similarly, Montana paleontologist Jack Horner is trying to produce chickens with dinosaur traits, such as a long tail and dino-like forelimbs.
In the most famous such case, Harvard geneticist George Church is involved in a project to produce elephants with some of the characteristics of the woolly mammoth. Last October, Church told NBC News that his research group was using the CRISPR method on the elephant genome, to add cold-climate traits such as freeze-resistant hemoglobin, a furry coat and a thicker layer of subcutaneous fat.
The next step is to insert that revised genetic coding into elephant stem cells and produce hybrid organoids — cellular structures that perform the functions of organs in the lab. Last week, Church told NBC News that the stem cell step was turning out to be harder than the researchers may have thought.
Why do it?
Church's objective is to create a more mammoth-like, hardier breed of Asian elephants, which are significantly more endangered than their African cousins. Such elephants could have a wider variety of ecosystems to choose from, and wouldn't be trapped in a rapidly shrinking range of habitats.
What's more, Russian geophysicist Sergei Zimov contends that woolly mammoths played a key role in sustaining ancient grasslands in Siberia — and that cold-resistant elephants could play a similar role in the future. Bringing herds of mammo-elephants into a "Pleistocene Park" setting could help stabilize Siberia's melting permafrost.
"We've got two and a half times the carbon that's in all the forests at stake," Church said. "Cold-resistant elephants aren't 'the' solution, but it's in the right direction."
If the gene-editing technique works, Church said it could be applied to other threats facing a wide variety of species: Frogs and salamanders could be genetically modified to make them impervious to the pathogens that are killing them off. Mosquitoes have already been modified in the lab to keep them from transmitting malaria, to cut down on breeding, or to keep the female bugs from flying.
Church acknowledged that species engineering has been criticized as costing too much and posing too many risks, especially when other environmental remedies are available. "I don't think it's an either-or thing," he said. "It's like saying we should invest in iron lungs rather than a polio vaccine, or in kidney dialysis rather than kidney transplants."
What are the alternatives?
The technical questions that surround species engineering are a long way from being answered, but even if they are, there are ethical conundrums galore. Is it a good idea for humans to be tweaking the genomes of endangered species? What good would it do to restore extinct creatures to the ecosystem that was unable to support them the first time around? Could there be unintended consequences, a la "Jurassic Park"?
"For each species that people are considering for de-extinction, there are different technical and ethical challenges," said Shapiro, who delves into the challenges in her book.
She cited the example of the passenger pigeons. "Can you imagine how people would feel about a flock of a billion birds flying over their farm, or over their freshly waxed SUV?" Shapiro said.
Nevertheless, there are cases where species engineering is already making a change for the better. For example, a fungus apparently imported from Asia virtually wiped out American chestnut forests beginning in the early 1900s. Today, a scientific consortium is using genetic engineering to create a blight-resistant strain of the American chestnut, and thousands of the trees are taking root.
"There are definitely scenarios in which I see the benefit of developing the technology," Shapiro said.