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“It’s probably the most significant thing so far in the project,” said George Church, a Harvard geneticist and co-founder of Colossal. “There are many steps ahead.”
For its defenders, recovering missing animals is an opportunity to correct humanity’s role in the current extinction crisis. They say advances in their field can bring benefits to animals still living among us, including endangered elephants.
However, the technical challenges involved in giving birth to a living, breathing mammoth into the world remain, well, colossal. And the project raises hairy ethical questions: Who decides what comes back? Where will the reborn species go? Could the money be better spent elsewhere? And how difficult will “de-extinction,” as revival efforts are known, be for the animals themselves?
“Lack of knowledge is what worries me about animal welfare,” said Heather Browning, a philosopher at the University of Southampton in England and a former zookeeper.
Can we really bring back the mammoth?
During the last ice age, the woolly mammoth owned the top of the world, lumbering across Eurasia and North America and as far south as today’s Midwest.
When the creatures became extinct 4,000 years ago, some corpses were frozen in a frozen tundra that preserved not only their bones but also their flesh and fur, giving paleontologists the opportunity to collect DNA fragments. Some of the mammoth meat was so well preserved that at least one adventurous researcher ate it.
In 2015, scientists sequenced their genetic model well enough to offer a potential manual for remaking a mammoth. But to test what exactly each of these genes does (which give the beast its curved tusks, its fatty build and, of course, its thick coat), Church wants elephant stem cells into which he can engineer mammoth DNA and culture tissue samples.
Scientists have produced these stem cells in the laboratory for other animals, including humans, mice, pigs and even rhinos. But for years, getting the right elephant stem cells to test all those cold-climate traits proved elusive, in part because elephant cells’ ability to stave off cancer made it difficult to reprogram them.
Colossal said they have produced the stem cells they need by suppressing anti-cancer genes and bathing the cells in the right chemical cocktail. Colossal published a preprint on Wednesday that has not yet been peer-reviewed. The company said it is working to publish the study in a peer-reviewed scientific journal.
“It hasn’t been easy,” said Eriona Hysolli, the company’s director of life sciences. “It hasn’t been immediately obvious. There were many innovations along the way.”
Jeanne Loring, a researcher at Scripps Research in California who helped develop powerful stem cells for the northern white rhino, said the work showed the perseverance of elephant researchers. “The hill ahead is incredibly steep,” she added. “The challenges become greater and greater with the size of the animal.”
In the end, the company wants to genetically edit a nucleus from a stem cell with mammoth genes and fuse it into an elephant egg. From there, if all goes as planned (still a big question mark), they will implant the embryo into a surrogate elephant and wait for her to give birth.
Even if we can, should we?
Matthew Cobb, a zoologist at the University of Manchester in England, said all those “ifs” may be insurmountable. There is no guarantee that modified chromosomes can be introduced into an elephant cell, or that an embryo will take root in an elephant’s uterus.
And perhaps more profoundly is the question of how a mammoth, if born, will learn to behave like one. “Most of the mammals and birds we talk about have complex social and cultural interactions that have been lost,” Cobb said. “It’s not just your genes.”
Modern elephants, for example, are highly social beings, passing knowledge about the location of watering holes and other survival skills from one generation to the next. Their ancient cousins may be similar. “They don’t have elders to raise them, to teach them,” Browning said. “They have no way of learning to be mammoths.”
And any live surrogate elephant destined to gestate and give birth to a new mammoth will go through some degree of hardship. “How many dead elephants are we willing to have to get a woolly one?” said Tori Herridge, a paleobiologist specializing in ancient elephants at the University of Sheffield in England.
Colossal said its long-term goal is to use artificial wombs to gestate the animals, which in itself is an arduous technological task. The company notes that its elephant cell research may help with current conversation efforts, such as possible treatments for a form of herpes that kills young elephants. In fact, the company hopes to make money by licensing or selling some of the technologies it creates along the way.
“It’s not so much about recovering the mammoth, it’s about saving an endangered species,” Church said. “It’s about developing technology that is useful for conservation and climate change.”
But Cobb said the biggest threats elephants face are hunting, habitat destruction and other conflicts with humans. “How will a greater understanding of cell biology help?”
What happens if they become extinct again?
One of Colossal’s general arguments for bringing back the mammoth is climate change. The company’s scientists say future Arctic herds can trample permafrost and prevent more of it from thawing and releasing atmospheric-warming carbon into the air.
“There are many reasons to restore that environment to what it was,” Church said. “This is the missing key species for that.”
Then this philosophical question arises: is a bioengineered mammoth really a mammoth? Or is it a hairier elephant that can tolerate the cold?
“A completely new organism is being created,” Herridge said. He added that there is still an open question about what killed the woolly mammoth: Was it humans overhunting them or the natural end of the last ice age? If the answer is the latter, then the Arctic may not be suitable for the resurrected creature, whatever you want to call it.
“I would love to see a live mammoth,” he said. “I would love to have a time machine where I could go back to the ice age and be able to see a herd of mammoths being mammoths in the landscape in which they evolved.”
“But all that is gone.”