"Sanguine" Prospects for Wooly Mammoth De-Extinction?
What does the recent discovery of the "best preserved mammoth in the history of paleontology" mean for de-extinction?
The purportedly "best preserved mammoth in the history of paleontology" was discovered by a team of Russian scientists in Siberia last week. According to lead researcher Semyon Grigoriev, head of the Museum of Mammoths of the Institute of Applied Ecology of the North at the North Eastern Federal University, "when we broke the ice beneath her stomach, the blood flowed out." This is raising excited speculation about the imminent possibility of resurrecting the extinct species.
The mammoth de-extinction effort is somewhat monopolized by the South Korean bioengineering firm Sooam Biotech Research Foundation, led by stem cell scientist Hwang Woo-suk. Hwang achieved scientific stardom when he claimed to have created human embryonic stem cells and the world's first cloned dog, then fell from grace when it turned out he had fabricated some of his human stem cell data. (The dog is real.) Despite his tarnished reputation, Russian scientists with the North-Eastern Federal University of the Sakha Republic entered a research partnership with Sooam last year. According to the Siberian Times, the deal gives the South Korean scientists "exclusive rights" on cloning wooly mammoths from Siberian samples.
"If we dream about it, the ideal case would be finding a viable [wooly mammoth] cell, a cell that's alive," says Hwang in Carl Zimmer's National Geographic article, "Bringing Them Back to Life." Zimmer explains that such a cell could be used to create millions more cells. "These could be reprogrammed to grow into embryos, which could then be implanted in surrogate elephants, the mammoth's closest living relative."
According to Gigoriev, the discovery "gives us a really good chance of finding live cells which can help us implement this project to clone a mammoth." Does this mean we're about to see a wooly mammoth come back? Not so fast.
There are serious hurdles. Even if living cells are used to create embryos, implanting them into elephant ova is no simple task. "Nobody has ever even cloned a living elephant," Zimmer said in a recent interview. "Nobody knows how to get an egg out of an elephant or how to implant an egg back into an elephant. Nobody knows what combination of hormones you'd need to make sure the whole thing works right."
Furthermore, it's not at all clear that the recent mammoth discovery will yield up any living cells. Scientific American editor Kate Wong spoke with a colleague of Grigoriev, Daniel Fisher of the University of Michigan. Fisher had this to say:
"They have not found any 'living cell'—at most they could hope to find what the cloning enthusiasts might call a cell with 'viable' DNA, meaning that it would be intact enough to use in the context of a cloning effort. In fact, although there is much talk of 'viability' of this sort, I think it remains to be demonstrated that any DNA from a mammoth meets this criterion. In general, ancient DNA is highly fragmented and by no means 'ready to go' into the next mammoth embryo."
This doesn't mean there's no hope for cloning a mammoth. It's theoretically possible to reconstruct a wooly mammoth genome from DNA fragments. DNA does degrade over time, and it's not yet possible to construct whole molecules from digitized computer sequences. However, scientists can synthesize series of about a hundred thousand base pairs at a time. (Synthetic biology pioneer George Church is working on using this method to recreate Neanderthals.) It might be possible to identify genes that distinguish wooly mammoths from elephants—such as sequences that code for traits like wooly hair or special hemoglobin that helped mammoths to survive extreme cold—and transplant those sequences into elephant DNA. "In theory, this would produce a wooly mammoth baby, or at least something that looks a lot like a wooly mammoth baby," says Zimmer.
All this raises the question: Do we want to bring back wooly mammoths? Some conservationists argue that de-extinction distracts from efforts to maintain critically endangered populations of living animals. There's also the non-trivial question of where mammoths would go should scientists manage to bring them back. Covered in vast grasslands when mammoths roamed, the Siberian tundra is now blanketed in moss, which wouldn't be able to support mammoths.
Sergey A. Zimov, however, believes reintroducing Pleistocene era biodiversity to the tundra would restore the grasslands. The mega herbivores played a critical role in the steppe ecosystem by keeping the soil broken up and fertilized and by suppressing moss growth. "Moss communities, once they are in place, create and sustain their own environment," says Zimov. Furthermore, he continues, "Northern Siberia will influence the character of global climate change. If greenhouse gas-induced warming continues, the permafrost will melt. At present, the frozen soils lock up a vast store of organic carbon. With an average carbon content of 2.5%, the soil of the mammoth ecosystem harbors about 500 gigatons of carbon, 2.5 times that of all rainforests combined."
To study the feasibility of steppe renewal and its possible climate implications, Zimov has conceived and implemented Pleistocene Park. The Park is an area of about 160 square km of Siberia into which large, grazing herbivore species like bison, musk ox, moose, horses, and reindeer have been introduced. Zimoz told Zimmer he'd be happy to welcome de-extinct mammoths in his park, "but only my grandchildren will see them...Be prepared to wait."
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