“This is probably the most important project we've ever done,” said George Church, a Harvard University geneticist and co-founder of Colossal. “There are many steps in the future.”
For advocates, bringing back lost animals is a chance to right humanity's role in the ongoing extinction crisis. They say breakthroughs in their field could benefit the animals still with us, including endangered elephants.
However, the technical challenges of bringing a living, breathing mammoth into the world remain enormous. And the project raises ethical questions about who decides what comes back. Where will the reborn race go? Would that money be better spent elsewhere? And how difficult is “de-extinction'', also known as recovery efforts, for the animals themselves?
“What worries me about animal welfare is the lack of knowledge,” says Heather Browning, a philosopher and former zookeeper at the University of Southampton in the UK.
Can we really bring back the mammoth?
During the last ice age, woolly mammoths dominated the world, living across Eurasia and North America, as far south as the modern-day Midwest.
The creature went extinct 4,000 years ago, but some of its carcasses were frozen in the icy tundra, preserving not only bones but also meat and fur, giving paleontologists the opportunity to collect DNA fragments. Some mammoth meat was so well preserved that at least one adventurous researcher ate it.
By 2015, scientists had sequenced enough of the mammoth's genetic blueprint to provide a possible manual for recreating it. But to test what exactly each of these genes does, giving elephants curved tusks, fatty physiques, and, of course, thick fur, Church manipulated mammoth DNA and tissue samples. They want elephant stem cells that can be propagated.
Scientists have created such stem cells in the lab for other animals, including humans, mice, pigs, and even rhinos. However, obtaining suitable elephant stem cells to test for all their cold-climate properties has proven difficult over the years. Part of the reason is that the elephant cells' ability to evade cancer made it difficult to reprogram them.
Colossal said he generated the necessary stem cells 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 Colossal published a preprint on Wednesday that has not yet been peer-reviewed.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 research in a peer-reviewed scientific journal.
“This was no easy feat,” said Eliona Hisori, the company's head of biological sciences. “It's not immediately obvious. There was a lot of innovation along the way.”
Gene Loring, a researcher at California's Scripps Research Institute who helped develop the powerful northern white rhino stem cells, praised the elephant researchers' tenacity. “This is an incredibly steep hill that they are waiting for,” she added. “As the size of the animals increases, the challenges become greater and greater.”
Ultimately, the company wants to gene-edit the nucleus. Stem cells containing mammoth genes are collected and fused into an elephant egg. From there, if all goes as planned (though it's still a big deal), the embryo will be implanted in an elephant surrogate and await birth.
Even if you can, should you?
Matthew Cobb, a zoologist at the University of Manchester in the UK, says all of these “what-ifs” may be insurmountable. There is no guarantee that the modified chromosomes will be able to be introduced into the elephant's cells or that the embryo will settle in the elephant's uterus.
And perhaps more seriously, if a mammoth were born, how would it learn mammoth-like behavior? “Most of the mammals and birds we talk about have complex social and cultural interactions that have been lost,” Cobb said. “They're not just genes.”
For example, modern elephants are highly social creatures, passing on knowledge about the location of watering holes and other survival skills from generation to generation. Their ancient cousins may be similar. “They don't have elders to raise them and teach them,” Browning said. “They have no way of learning how to become mammoths.”
And the live surrogate elephants that become pregnant and plan to give birth to new mammoths will experience some difficulty. “How many elephants would have to die to get one hairy elephant?” says Tori Herridge, a paleontologist at the University of Sheffield in the UK who specializes in ancient elephants.
Colossal said its long-term goal is to use artificial wombs to impregnate animals, which is a technically difficult challenge in itself. The company notes that research on elephant cells could inform current dialogue efforts, including potential treatments for a type of herpes that kills young elephants. In fact, the company hopes to make money by licensing and selling some of the technology it develops along the way.
“This is less about bringing back mammoths and more about saving endangered species,” Church said. “We are developing technology that helps conservation and climate change.”
But Cobb said the biggest threats elephants face are hunting, habitat destruction and other conflicts with humans. “How can a deeper understanding of cell biology help?”
What will happen if we become extinct again?
One of Colossal's most important arguments for bringing back mammoths is climate change. The company's scientists say future Arctic swarms could trample permafrost, preventing it from melting further and releasing atmospheric warming carbon into the air.
“Those are a lot of reasons to restore the environment to its original state,” Church said. “This is the keystone species that is missing for that.”
Then there's the philosophical question: Is a bioengineered mammoth really a mammoth? Or is it a cold-hardy, furry elephant?
“This is a completely new organism being created,” Herridge said. She added that there are still unanswered questions about what caused the woolly mammoth to become extinct. Did humans overhunt the mammoths, or was it the natural end of the last ice age? If the answer is the latter, then the North Pole, whatever you want to call it, may not be suitable for a resurrected creature.
“I want to see mammoths alive,” she said. “I would love to have a time machine that would allow me to go back to the Ice Age and see mammoths in the landscape where they evolved.”
“But that's all gone.”
