Woolly mammoths, the iconic giants of the last ice age, went extinct around 4,000 years ago.
But one company is trying to revive the species—or at least something resembling it—and the scientist at the head of the project envisions thousands of these animals roaming the Arctic.
Colossal Biosciences is a start-up launched by tech entrepreneur Ben Lamm and renowned geneticist George Church that is aiming to resurrect the woolly mammoth, or more accurately to create a genetically engineered Asian elephant that will be cold-resistant and have all the core biological traits of its extinct relative.
The company also announced this week that it is working on the de-extinction of the thylacine, or Tasmanian tiger.
While not an exact replica, the hybrid animal will look like a woolly mammoth and be capable of inhabiting the same ecosystem that the extinct animal once roamed.
The science side of the ambitious (and somewhat controversial venture) is being guided by Church, whose pioneering work has contributed to the development of DNA sequencing and genome engineering technologies.
Church leads synthetic biology research efforts at Harvard University’s Wyss Institute for Biologically Inspired Engineering. He is also a professor of genetics at Harvard Medical School, while also holding positions at the Massachusetts Institute of Technology (MIT), among other institutions.
Church has co-authored hundreds of scientific papers, has dozens of patents to his name, and has set up more than 20 companies. He has long dreamed of bringing back the woolly mammoth, and after teaming up with Lamm, this dream could become a reality, although significant scientific and logistical obstacles will need to be overcome first.
Genome Editing Examples
Colossal’s aim to create a hybrid elephant with woolly mammoth traits—such as thick fur and layers of insulating fat, among other cold climate adaptions—will involve the use of advanced gene editing technology.
Church told Newsweek that the approach is very similar to research one of his companies has demonstrated with pigs, where scientists made roughly 40 edits to the genome of these animals in order to make their organs suitable for transplantation into humans.
He said Colossal was planning to make a similar number of edits in cells taken from Asian elephants, an endangered species that is the woolly mammoth’s closest living relative, sharing around 99.6 percent of its DNA.
“Indeed, the Asian elephant and the woolly mammoth are closer to each other than either of them is to the African,” Church told Newsweek.
In order to determine which edits to make, Colossal’s researchers have to compare elephant genomes to that of the woolly mammoth to identify where the key differences are. Fortunately, some mammoth remains have been preserved remarkably well, with some tissue samples containing intact DNA, from which researchers can build at least partial genomes.
Once the differences are identified, scientists can begin making genetic edits to cells taken from Asian elephants with the aim of creating a more mammoth-like animal. The number of edits will be similar to the 40 or so made to the pig genome in previous research.
“We’d typically use CRISPR [Clustered Regularly Interspaced Short Palindromic Repeats], or a variety of other editing tools, to edit the cell by going in and adding DNA. And then we take the nucleus out of that cell and put it into an egg.
“Then we implant that into a surrogate mother and wait, in the case of elephants, 22 months. Then you’ve got a calf. That’s classical cloning, as was done with Dolly the Sheep,” Church said. “The point is not to resurrect a species, but to resurrect individual genes in a constellation that would help specifically with cold tolerance.”
Artificial Womb or Surrogate Mother
Another method that the Colossal team is working on in parallel is to develop the elephant-mammoth hybrid embryo in an artificial womb instead of using a surrogate mother.
The surrogate would likely be an African elephant rather than an Asian one because it is a larger species that will have less difficulty delivering an elephant hybrid and is slightly less of a conservation concern.
“We will let it develop outside the body as kind of happens for a little while in in vitro fertilization. But then, we want to carry it further, all the way to term,” Church said.
This has never been done before for any mammal, but researchers have previously made headway in some animals. For example, a team at the Children’s Hospital of Philadelphia managed to support a fetal lamb for four weeks, although the size of a mammoth calf, which usually weighs more than 200 pounds at birth, will present a far greater challenge.
While using a surrogate mother is more feasible because the technology has already been demonstrated (to some extent at least) in other mammals, Church said most of the team favors the artificial womb approach—despite the technological challenges—because it can scale better and doesn’t interfere with the reproduction of living elephants.
Colossal’s goal, which Church said was “not necessarily a promise,” is to produce a viable elephant-mammoth hybrid in six years.
If Colossal does manage to achieve this, the company hopes that introducing enough of them into the wild could restore the health of the Arctic environment and decelerate melting of the Arctic permafrost, a process which releases vast quantities of greenhouse gases, threatening efforts to curb climate change.
Mammoths were keystone species that were vital to maintaining the health and biodiversity of the ecosystems in which they inhabited. The loss of mammoths over the last few thousands years has contributed to a reduction of grasslands, which once efficiently absorbed carbon, in the Arctic regions. Now this ecosystem is dominated by mossy forests and wetlands.
Restoring these grasslands could help to prevent the thaw and release of greenhouse gases within the arctic permafrost, according to Colossal.
“Elephants tend to knock down trees, and hence restore grasslands,” Church said. “So, there’ll be a mixture of trees and grass, rather than right now, there’s almost no grass.”
“The main side effect that we’re interested in is the maintenance of cold arctic soil by [elephants] trampling the snow to let the cold air in in the winter.”
In addition, grasslands do a better job of reflecting sunlight than trees currently found across the Arctic because they are lighter in color. Thus, more grassland, would help to cool the ecosystem.
Church said Colossal is focusing on the regions of the Arctic that have the highest carbon content because more methane—a potent greenhouse gas—would be released if we let the permafrost thaw from these areas.
“The carbon content of these carbon-rich areas add up to more than the rest of the forests of the world put together,” Church said.
Thousands Roaming the Arctic
If Colossal is able to produce viable elephant-mammoth hybrids, according to Church, the plan, ideally, would be to have tens of thousands of these animals roaming the Arctic.
“There was on the order of one mammoth per square kilometer. And so we think that tens of thousands would be very impactful, possibly preventing more methane release than all the human activity put together each year,” he said.
The idea is to have hubs, Church said, which will have an incubator in the middle. “Then the elephant herds will spread out radially from that,” he said.
The timeline to reach these kinds of numbers would be extraordinarily long-term if breeding using elephant surrogates was required.
“But if we can produce an arbitrary number of eggs in the lab, and then grow those in parallel, then there’s no reason why we couldn’t produce the entire set that we need right after this six-year milestone,” Church said.
“So as soon as the six-year milestone is over, then we scale it up to tens of thousands dispersed in these hubs. And then it would take probably about 10 years before they’re really seriously migrating. Elephants are really good walkers—in their lifetime, they would cover roughly more than two trips around the world if they were going in a straight line.”
Colossal’s plans have faced criticism, with some experts questioning the feasibility of developing the elephant-mammoth hybrids in the first place, or arguing that the animals might not have the desired effect on Arctic ecosystems if they are introduced in significant numbers.
Others, meanwhile, have raised ethical concerns, noting that elephants are highly intelligent, social creatures that form strong bonds with their mothers.
“You don’t have a mother for a species that—if they are anything like elephants—has extraordinarily strong mother-infant bonds that last for a very long time,” Heather Browning, a philosopher at the London School of Economics, previously told The New York Times.
“Once there is a little mammoth or two on the ground, who is making sure that they’re being looked after?”
In response to critiques like these, Church said Colossal was working with groups that have significant experience dealing with elephant orphans.
“This is an unfortunate consequence of poaching and natural death and so forth,” he said. “There’s a great deal of knowledge about how to make artificial milk and how to nurture them with minimal herd involvement.”
He also pointed to other rewilding efforts that have been characterized as being successful, such as the reintroduction of captive-bred California condors to the wild.
“Some of those involve various training methods where they train the next generation if there’s unavailability of adults. So, for example, the California condor, they use little adult Condor puppets, hand puppets to do some of the feeding and behavior training and so forth.”