The woolly mammoths, emblematic giants of the last ice age, disappeared around 4,000 years ago.
But a company is trying to revive the species – or at least something like it – and the scientist leading 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 aims to resurrect the woolly mammoth, or more precisely, to create a genetically modified Asian elephant that will resist the cold and possess all the basic biological traits. of his missing 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 resemble a woolly mammoth and be able to inhabit the same ecosystem the extinct animal once roamed.
The scientific side of this ambitious (and somewhat controversial) endeavor is guided by Church, whose pioneering work helped develop 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 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 founded more than 20 companies. He has long dreamed of bringing back the woolly mammoth, and after teaming up with Lamm, that dream could come true, although significant scientific and logistical hurdles will have to be overcome first.
Examples of genome editing
Colossal’s goal of creating a hybrid elephant with woolly mammoth traits, such as thick fur and layers of insulating fat, among other cold-climate adaptations, will involve the use of advanced game-editing technology. Genoa.
The church said Newsweek that the approach is very similar to research that one of his companies demonstrated with pigs, where scientists made about 40 changes to the genome of these animals in order to make their organs suitable for transplantation into humans.
He said Colossal plans to make a similar number of modifications in cells taken from Asian elephants, an endangered species that is the woolly mammoth’s closest living relative, sharing around 99.6% of its DNA.
“Indeed, the Asian elephant and the woolly mammoth are closer to each other than either of them is to the East African,” Church said. Newsweek.
To determine what changes to make, Colossal researchers need to compare the genomes of elephants to those of the woolly mammoth to identify key differences. Fortunately, some mammoth remains have been remarkably well preserved, with some tissue samples containing intact DNA from which researchers can construct at least partial genomes.
Once the differences are identified, scientists can begin making genetic changes to cells taken from Asian elephants in an effort to create an animal that looks more like a mammoth. The number of changes will be similar to the quarantine made to the pig genome in previous research.
“We typically use CRISPR [Clustered Regularly Interspaced Short Palindromic Repeats], or a variety of other editing tools, to edit the cell by entering and adding DNA. And then we take the nucleus out of that cell and put it in an egg.
“Then we implant that into a surrogate and wait, in the case of elephants, 22 months. Then you have a calf. It’s classic cloning, like it was done with Dolly the Sheep,” Church said. . “The goal is not to resurrect a species, but to resurrect individual genes in a constellation that would specifically help with cold tolerance.”
Artificial uterus or surrogate mother
Another method the Colossal team is working on in parallel involves developing 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 elephant, as it is a larger species that will have less difficulty producing an elephant hybrid and is of slightly less conservation concern.
“We’re going to let it grow outside the body like it happens for a little while in in vitro fertilization. But then we want to take it further, to term,” Church said.
This has never been done before for any mammal, but researchers have already made progress in some animals. For example, a team from Children’s Hospital in Philadelphia successfully supported a fetal lamb for four weeks, although the size of a mammoth calf, which typically weighs over 200 pounds at birth, will present a challenge though. bigger.
Although using a surrogate is more feasible because the technology has already been demonstrated (at least to some extent) in other mammals, Church said most team members are in favor of the artificial womb approach, despite technological challenges, because it can scale better and does not interfere with the reproduction of live elephants.
Colossal’s goal, which Church said was “not necessarily a promise”, is to produce a viable elephant-mammoth hybrid within six years.
If Colossal manages to pull this off, the company hopes that introducing enough of it into the wild could restore the health of the Arctic environment and slow the melting of Arctic permafrost, a process that releases large amounts of greenhouse gases, threatening efforts to curb the climate. change.
Mammoths were keystone species that were essential to maintaining the health and biodiversity of the ecosystems in which they lived. The loss of mammoths over the past few thousand years has contributed to a reduction in grasslands, which once efficiently absorbed carbon, in arctic regions. Now this ecosystem is dominated by mossy forests and wetlands.
According to Colossal, restoring these grasslands could help prevent thawing and the release of greenhouse gases into Arctic permafrost.
“Elephants tend to cut down trees and therefore restore grasslands,” Church said. “So there will be a mix of trees and grass, rather than right now there’s almost no grass.”
“The main side effect we are interested in is the maintenance of cold arctic ground by [elephants] trampling the snow to let in the cold winter air.”
Additionally, grasslands reflect sunlight better than the trees currently found in the Arctic, as they are lighter in color. Thus, more grasslands would help cool the ecosystem.
Church said Colossal focuses on 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 those areas.
“The carbon content of these carbon-rich areas is more than the rest of the world’s forests combined,” Church said.
Thousands of wanderers in 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 tens of thousands would have a very large impact, preventing perhaps more methane release than all human activity put together each year” , did he declare.
The idea is to have hubs, Church said, that will have an incubator in the middle. “Then the elephant herds will expand radially from that,” he said.
The time frame to reach these types of numbers would be extremely long if breeding using elephant surrogates were necessary.
“But if we can produce an arbitrary number of eggs in the lab and then grow them in parallel, there’s no reason why we can’t produce the full set we need right after that six-year milestone. “Church said.
“So as soon as the six-year milestone is passed, we extend it to tens of thousands of people scattered across these centers. And then it would probably take about 10 years before they really seriously migrated. The elephants are of very good walkers—in their lifetime they would make about more than two trips around the world if they went in a straight line.”
Colossal’s plans have come under criticism, with some experts questioning the feasibility of developing elephant-mammoth hybrids in the first place, or arguing that the animals might not have the desired effect on Arctic ecosystems if they happen. 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, while it looks like elephants, has extraordinarily strong mother-child bonds that last a very long time,” said Heather Browning, a philosopher at the London School of Economics. The New York Times.
“Once there’s a small mammoth or two on the ground, who makes sure they’re taken care of?”
In response to such criticism, Church said Colossal works with groups that have significant experience treating elephant orphans.
“It’s an unfortunate consequence of poaching and natural death etc,” he said. “There is a lot of knowledge about how to make artificial milk and how to feed them with minimal herd involvement.”
He also pointed to other rewilding efforts that have been called successful, such as the reintroduction of captive-bred Californian condors back into the wild.
“Some of them involve various training methods where they train the next generation if there are no adults available. So, for example, the California condor, they use small adult Condor puppets, puppets hand to do some of the feeding and behavior training etc.”