A genetic engineering company stunned the world by bringing the ancient dire wolf back from extinction — but it won't stop there.
The Texas-based Colossal Biosciences also plans to de-extinct the woolly mammoth, the dodo bird and the Tasmanian tiger.
The project aims to restore species that have been eradicated at least in part due to human activities such as overhunting, habitat destruction and pollution.
To de-extinct a species, Colossal scientists extract the extinct species' DNA from fossils or museum specimens, reassemble its full genetic code (or genome), then compare it to the genome of their closest living relative to pick out the differences.
Once they identify gene variants that are specific to the extinct species, they modify the living relative's genome to match the extinct species as closely as possible. In the case of the dire wolves, they made 20 changes to gray wolf DNA.
Then, they use this modified genome to make an egg cell that can be implanted into a surrogate — a female from the living relative species — who later gives birth to the previously extinct animal.
Colossal has already sequenced the woolly mammoth's genome, and in March, its scientists managed to create 'woolly mice' in a major step toward bringing this ancient giant back.
Ultimately, the company hopes to use Asian elephants as surrogates for their woolly mammoths, which they aim to birth by 2028.
After de-extincting the dire wolf, Colossal Biosciences plans to bring back the woolly mammoth, the dodo bird and the Tasmanian tiger too
Colossal’s Dire Wolves; Romulus and Remus at age three months
Scientists are also making strides toward resurrecting the dodo and the Tasmanian tiger by using museum specimens to reconstruct their genomes.
But some wildlife conservation experts warn that reintroducing long-extinct species to today's ecosystems could have significant consequences.
On Monday, Colossal Biosciences announced it had successfully birthed three dire wolves, naming them Romulus, Remus and Khaleesi. Made famous by the popular HBO series Game of Thrones, these ancient wolves went extinct 12,500 years ago.
The reason for their disappearance is unclear, but scientists think it may have been triggered by the loss of their megafaunal prey — perhaps due to overhunting.
'I could not be more proud of the team. This massive milestone is the first of many coming examples demonstrating that our end-to-end de-extinction technology stack works,' said CEO of Colossal Ben Lamm.
His company claims it is humanity's responsibility to bring these species back. 'We're committed to rectifying the past and rehabilitating nature on a global scale,' the website states.
Its experts say reintroducing these animals to nature will be beneficial to the environment in many ways, even when it comes to climate change.
De-extincting the woolly mammoth, for example, could combat global warming by restoring Arctic grassland ecosystems, they say.
But some other experts aren't so sure. 'I'd argue that the broader effort to de-extinct the mammoth is — as far as conservation efforts go — incredibly misguided,' conservation scientists Nitik Sekar wrote in an recent article for Ars Technica.
'Ultimately, Colossal's efforts won't end up being about helping wild elephants or saving the climate. They'll be about creating creatures for human spectacle, with insufficient attention to the costs and opportunity costs to human and animal life.'
Woolly mammoth
Ben Lamm, CEO and founder of Colossal Biosciences, has said he is 'positive' that the first woolly mammoth calves will be born in late 2028
These ancient giants haven't roamed the Earth for roughly 4,000 years, but Lamm has said he is 'positive' the first woolly mammoth calves will be born in the next few years.
His company sequenced a mammoth genome and found a way to produce elephant stem cells capable of giving rise to several different cell types — two important steps toward resurrecting the mammoth.
In March, Colossal scientists managed to create 'woolly mice' by modifying mouse DNA to express two mammoth traits: long, bushy hair and fat that helped them survive in the cold.
'We ended up with some absolutely adorable mice that have longer, woolly, golden-colored coats,' Beth Shapiro, chief science officer at Colossal, told NPR.
'This is exciting to us because it confirms that the genes and gene families that we identified using our comparative genomics approach really do cause an animal to have a woolly coat and a golden coat and longer hairs,' she said.
'And this is the way that we're going to create mammoths for the future.'
When that time comes, Colossal plans to use Asian elephants as surrogates.
Surprisingly, this species is more closely related to woolly mammoths than African elephants — they share 95 percent of their genetic code with the extinct giants.
Dodo bird
Most experts believe that the dodo was a fat, gawky bird. But because it has been extinct since the late 1600s, nobody really knows exactly what the dodo looked like
This ancient, 50-pound flightless bird once thrived on the island of Mauritius. The species was first documented by Dutch sailors around the year 1600.
But by 1681, they were wiped off the map.
The dodo bird was pushed to extinction by deforestation, overhunting and the destruction of their nests by animals that the Dutch brought to the island.
Now, Colossal wants to bring them back using dodo DNA preserved in museum specimens. Though the company has not set a target date for the bird's return, it has made progress toward this goal in recent years.
In 2022, Shapiro and her former colleagues at the University of California, Santa Cruz (where she worked prior to joining Colossal) managed to reassemble the extinct bird's genome.
This was an important first step toward de-extincting the dodo, but Colossal scientists still need to engineer genetic diversity into the genome so that they don't produce a population of clones, Lamm told LiveScience.
This hurdle, among others, will need to be cleared before the company can begin birthing dodos.
But gestating the birds will be much quicker and easier than it is for large mammals such as the dire wolf or woolly mammoth, because the dodo DNA is self-contained in an egg, Lamm said.
The extinct bird's closest living relative, the Nicobar pigeon, will gestate and lay these eggs, according to Colossal.
Tasmanian tiger
The last-known thylacine, or 'Tasmanian tiger,' died in captivity in a Hobart zoo in 1936 (pictured)
The thylacine, commonly known as the 'Tasmanian tiger,' was a large carnivorous marsupial that officially went extinct 89 years ago.
This coyote-like animal once roamed the mainland of Australia as well as the islands of Tasmania and New Guinea, with roughly 5,000 thriving in Tasmania alone.
But ultimately, the species disappeared due to overhunting, habitat destruction and the introduction of invasive, competing species to their lands. The last one died in captivity in 1936.
Because the Tasmanian tiger was featured in many museums around the world, Colossal scientists have lots of DNA specimens to work with.
'Every major museum wanted one in their collection, so there are hundreds of samples around the globe, and some are exceptionally preserved,' Andrew Pask, a professor of genetics and developmental biology at the University of Melbourne in Australia who is working with Colossal, told BBC Future in 2023.
He and his colleagues sequenced the full Tasmanian tiger genome in 2017.
Since then, they have compared its genome to that of its closest living relative — a mouse-sized marsupial called the dunnart — to identify the gene variants that make the Tasmanian tiger unique.
But there is still more work to be done before this species can be de-extinct. Next, Pask will edit the dunnart genome so that it matches the Tasmanian tiger's.
Once Colossal create an egg cell using this reconstructed genome, the company plans to implant it into a dunnart surrogate.
