“You’re hearing the first howl of a dire wolf in over 10,000 years. Meet Romulus and Remus—the world’s first de-extinct animals, born on October 1, 2024.” [Colossal Biosciences]
Earlier this week, Colossal Biosciences, which bills itself as “the world’s only de-extinction company,” reported the rebirth of the once-extinct dire wolf, “the world’s first successfully de-extincted animal,” which last roamed our planet 12,500 years ago. The successful birth of three dire wolves is “a revolutionary milestone of scientific progress that illustrates another leap forward in Colossal’s de-extinction technologies and is a critical step on the pathway to the de-extinction of other target species,” according to the Dallas-based company.
To say that the announcement—initially only via a press release and major coverage in the New Yorker and TIME—set off a firestorm of controversy would be a gross understatement.
![The Colossal team screen edited cell lines via whole genome sequencing and karyotyping and cloned cell lines using somatic cell nuclear transfer into donor gray wolf egg cells. Domestic dogs served as surrogate mothers for the embryos. Three litters of Colossal’s dire wolves were born, including two adolescent males and one female puppy were born. [Colossal Biosciences]](https://www.genengnews.com/wp-content/uploads/2025/04/home-science-img-4duplicate-1024x424.jpg "The Colossal team screen edited cell lines via whole genome sequencing and karyotyping and cloned cell lines using somatic cell nuclear transfer into donor gray wolf egg cells. Domestic dogs served as surrogate mothers for the embryos. Three litters of Colossal’s dire wolves were born, including two adolescent males and one female puppy were born. [Colossal Biosciences]")
The Colossal team screen-edited cell lines via whole genome sequencing and karyotyping and cloned cell lines using somatic cell nuclear transfer into donor gray wolf egg cells. Domestic dogs served as surrogate mothers for the embryos. Three litters of Colossal’s dire wolves, including two adolescent males and one female puppy were born. [Colossal Biosciences]
The process involved the Colossal team extracting and sequencing ancient DNA from two dire wolf fossils—a 13,000-year-old tooth and a 72,000-year-old inner ear bone. The team assembled the genomes from both fossils and compared them to genomes from living wolves, jackals, foxes, and dholes (a canid native to South, East, and Southeast Asia). A manuscript reporting this work will shortly be posted on bioRxiv preprint server.
The scientists then identified gene variants specific to dire wolves and discovered that these wolves had a white coat color and long thick fur. The investigators subsequently carried out multiplex base editing on a donor genome from the dire wolves’ closest living relative, the gray wolf, resulting in 20 discrete edits in or adjacent to 14 identified genes that provided them with the same DNA sequences as the fossil wolves.
The team screen-edited cell lines via whole genome sequencing and karyotyping and cloned cell lines using somatic cell nuclear transfer into donor gray wolf egg cells. Domestic dogs served as surrogate mothers for the embryos.
Three litters of Colossal’s dire wolves, including two adolescent males (Romulus and Remus) and one female puppy (named Khaleesi after the Game of Thrones character) were born.
“Preserving, expanding, and testing genetic diversity should be done well before important endangered animal species like the red wolf are lost,” said George Church, MD, PhD, from Harvard Medical School and a co-founder of Colossal. “Another source of ecosystem variety stems from our new technologies to de-extinct lost genes, including deep ancient DNA sequencing, polyphyletic trait analyses, multiplex germline editing, and cloning.”
“The dire wolf is an early example of this, including the largest number of precise genomic edits in a healthy vertebrate so far. A capability that is growing exponentially.”
The immediate reaction to the Colossal Biosciences’ claims from a broad section of the scientific community was highly skeptical.
“[Colossal Biosciences] are claiming this as the world’s first de-extinction, but while no doubt it has required some amazing technological breakthroughs, the cute pups Romulus, Remus, and Khaleesi are not dire wolfs—they are genetically modified gray wolves,” noted Philip Seddon, PhD, professor, department of zoology, University of Otago, in a comment to the Science Media Center in New Zealand.
“Wolves and dire wolves, despite the wolf part of their names, are not closely related, having parted ways from a common ancestor some 6 million years ago, and the African jackal might be more closely related to dire wolves,” Seddon continued.
“Dire wolves are in their own genus, so a quite different species. What Colossal has done is introduce a small number of changes to the genetic material of a gray wolf to produce gray wolf pups with dire wolf features such as pale coats and potentially slightly larger size. So, hybrid gray wolves, or a GMO wolf. The pups will spend their days in a large enclosure being hand-fed and closely monitored.
“Certainly, this involves advances in genetic technology, and these might have applications for the conservation of existing species—but the return of dire wolves? No. In the same way that Colossal’s plans for woolly mammoths and dodos will involve the genetic modification of related species. We have GMO wolves and might one day have GMO Asian elephants, but for now extinction really is forever.”
Even an eminent paleoanthropologist such as Ian Tattersall, PhD, curator emeritus at the American Museum of Natural History and an expert taxonomist on human evolution, weighed in.
“I don’t know much about dire wolves, but my understanding is that the genomic differences between gray and dire wolves go far beyond the genes that Colossal edited,” Tattersall told GEN. “Sharing a few genes, however acquired, doesn’t mean we are the same thing.”
In an ABC News interview, “I don’t think they are actually dire wolves. I don’t think what we have is dire wolves,” said Julie Meachen, PhD, professor, anatomy, at Des Moines University. “What we had is something new—we have a mostly gray wolf that looks like a dire wolf.”
Meachen, who specializes in the study of wolves, was a co-author on a 2021 paper on dire wolves in Nature, a section of which read as follows:
“Our results indicate that although they were similar morphologically to the extant gray wolf, dire wolves were a highly divergent lineage that split from living canids around 5.7 million years ago. In contrast to numerous examples of hybridization across Canidae, there is no evidence for gene flow between dire wolves and either North American gray wolves or coyotes. This suggests that dire wolves evolved in isolation from the Pleistocene ancestors of these species.”
Beth Shapiro, PhD, Colossal CSO
It turns out that the other co-author of that 2021 paper is Beth Shapiro, PhD, Colossal Biosciences’ CSO, who sees things differently.
“I think that the best definition of a species is if it looks like that species, if it is acting like that species, if it’s filling the role of that species, then you’ve done it,” she said in the ABC News story. “So when I saw them born and they were white, I was like, we’ve done it. Those are dire wolves.”
Shapiro addressed the criticisms leveled at the company announcement in a video that was posted on X and Reddit.
John Sterling is Editor-in-Chief of GEN.
Using advanced multiplex gene editing, our team successfully introduced precise genetic edits at 20 loci across 14 genes, strategically modifying the genome to bring this iconic species back to life. This unprecedented level of extinct DNA restoration in a living canid not only sets a new benchmark in de-extinction science but also redefines what is possible in species restoration.
To me, that means they are modern wolves with some genes that have been determined to be associated with certain traits that are supposedly characteristic of the species from 10,000 years ago. I think “sets a new benchmark in de-extinction science” is valid.
The next sentence is this: By using cutting-edge CRISPR-based editing, Colossal has resurrected a species lost to time, demonstrating the power of synthetic biology to reverse extinction and reshape the future of conservation.
To me, that’s a jump. I don’t believe they’ve “resurrected a species lost in time.” Perhaps this is a greater question—what makes a species a species? Is it the classical reproductive capacity? Or is it phenotypic and genotypic?
One thought experiment:
If I swap out every single human coding gene into a chimp’s DNA, will I get a human? Let’s say this organism lives and looks exactly like a human, is that a human or a different species? Given what we’ve learned about noncoding DNA, the interactions between the inserted gene and the surrogate would have differences. If we share 99% of the genome with chimps, then there are somewhere around 30,000,000 nucleotide differences between the human and chimp genomes (3 billion nucleotides multiplied by 0.01).
Don’t get me wrong, there’s some really amazing innovation happening here. I’m just being a stickler for some of the terminology being used.
The post Dire Wolves? Gray Wolves? What Kind of Wolf Am I? appeared first on GEN - Genetic Engineering and Biotechnology News.
Earlier this week, Colossal Biosciences, which bills itself as “the world’s only de-extinction company,” reported the rebirth of the once-extinct dire wolf, “the world’s first successfully de-extincted animal,” which last roamed our planet 12,500 years ago. The successful birth of three dire wolves is “a revolutionary milestone of scientific progress that illustrates another leap forward in Colossal’s de-extinction technologies and is a critical step on the pathway to the de-extinction of other target species,” according to the Dallas-based company.
To say that the announcement—initially only via a press release and major coverage in the New Yorker and TIME—set off a firestorm of controversy would be a gross understatement.
The Colossal team screen-edited cell lines via whole genome sequencing and karyotyping and cloned cell lines using somatic cell nuclear transfer into donor gray wolf egg cells. Domestic dogs served as surrogate mothers for the embryos. Three litters of Colossal’s dire wolves, including two adolescent males and one female puppy were born. [Colossal Biosciences]
The process involved the Colossal team extracting and sequencing ancient DNA from two dire wolf fossils—a 13,000-year-old tooth and a 72,000-year-old inner ear bone. The team assembled the genomes from both fossils and compared them to genomes from living wolves, jackals, foxes, and dholes (a canid native to South, East, and Southeast Asia). A manuscript reporting this work will shortly be posted on bioRxiv preprint server.
The scientists then identified gene variants specific to dire wolves and discovered that these wolves had a white coat color and long thick fur. The investigators subsequently carried out multiplex base editing on a donor genome from the dire wolves’ closest living relative, the gray wolf, resulting in 20 discrete edits in or adjacent to 14 identified genes that provided them with the same DNA sequences as the fossil wolves.
The team screen-edited cell lines via whole genome sequencing and karyotyping and cloned cell lines using somatic cell nuclear transfer into donor gray wolf egg cells. Domestic dogs served as surrogate mothers for the embryos.
Three litters of Colossal’s dire wolves, including two adolescent males (Romulus and Remus) and one female puppy (named Khaleesi after the Game of Thrones character) were born.
“Preserving, expanding, and testing genetic diversity should be done well before important endangered animal species like the red wolf are lost,” said George Church, MD, PhD, from Harvard Medical School and a co-founder of Colossal. “Another source of ecosystem variety stems from our new technologies to de-extinct lost genes, including deep ancient DNA sequencing, polyphyletic trait analyses, multiplex germline editing, and cloning.”
“The dire wolf is an early example of this, including the largest number of precise genomic edits in a healthy vertebrate so far. A capability that is growing exponentially.”
Nyet say the naysayers
The immediate reaction to the Colossal Biosciences’ claims from a broad section of the scientific community was highly skeptical.
“[Colossal Biosciences] are claiming this as the world’s first de-extinction, but while no doubt it has required some amazing technological breakthroughs, the cute pups Romulus, Remus, and Khaleesi are not dire wolfs—they are genetically modified gray wolves,” noted Philip Seddon, PhD, professor, department of zoology, University of Otago, in a comment to the Science Media Center in New Zealand.
“Wolves and dire wolves, despite the wolf part of their names, are not closely related, having parted ways from a common ancestor some 6 million years ago, and the African jackal might be more closely related to dire wolves,” Seddon continued.
“Dire wolves are in their own genus, so a quite different species. What Colossal has done is introduce a small number of changes to the genetic material of a gray wolf to produce gray wolf pups with dire wolf features such as pale coats and potentially slightly larger size. So, hybrid gray wolves, or a GMO wolf. The pups will spend their days in a large enclosure being hand-fed and closely monitored.
“Certainly, this involves advances in genetic technology, and these might have applications for the conservation of existing species—but the return of dire wolves? No. In the same way that Colossal’s plans for woolly mammoths and dodos will involve the genetic modification of related species. We have GMO wolves and might one day have GMO Asian elephants, but for now extinction really is forever.”
Even an eminent paleoanthropologist such as Ian Tattersall, PhD, curator emeritus at the American Museum of Natural History and an expert taxonomist on human evolution, weighed in.
“I don’t know much about dire wolves, but my understanding is that the genomic differences between gray and dire wolves go far beyond the genes that Colossal edited,” Tattersall told GEN. “Sharing a few genes, however acquired, doesn’t mean we are the same thing.”
In an ABC News interview, “I don’t think they are actually dire wolves. I don’t think what we have is dire wolves,” said Julie Meachen, PhD, professor, anatomy, at Des Moines University. “What we had is something new—we have a mostly gray wolf that looks like a dire wolf.”
Meachen, who specializes in the study of wolves, was a co-author on a 2021 paper on dire wolves in Nature, a section of which read as follows:
“Our results indicate that although they were similar morphologically to the extant gray wolf, dire wolves were a highly divergent lineage that split from living canids around 5.7 million years ago. In contrast to numerous examples of hybridization across Canidae, there is no evidence for gene flow between dire wolves and either North American gray wolves or coyotes. This suggests that dire wolves evolved in isolation from the Pleistocene ancestors of these species.”
Beth Shapiro, PhD, Colossal CSO
It turns out that the other co-author of that 2021 paper is Beth Shapiro, PhD, Colossal Biosciences’ CSO, who sees things differently.
“I think that the best definition of a species is if it looks like that species, if it is acting like that species, if it’s filling the role of that species, then you’ve done it,” she said in the ABC News story. “So when I saw them born and they were white, I was like, we’ve done it. Those are dire wolves.”
Shapiro addressed the criticisms leveled at the company announcement in a video that was posted on X and Reddit.
John Sterling is Editor-in-Chief of GEN.
Perspective from Jonathan D. Grinstein, PhD
North American Editor of GEN’s sister publication Inside Precision Medicine
I have a different semantic view on the Colossal announcement. From their website:
Using advanced multiplex gene editing, our team successfully introduced precise genetic edits at 20 loci across 14 genes, strategically modifying the genome to bring this iconic species back to life. This unprecedented level of extinct DNA restoration in a living canid not only sets a new benchmark in de-extinction science but also redefines what is possible in species restoration.
To me, that means they are modern wolves with some genes that have been determined to be associated with certain traits that are supposedly characteristic of the species from 10,000 years ago. I think “sets a new benchmark in de-extinction science” is valid.
The next sentence is this: By using cutting-edge CRISPR-based editing, Colossal has resurrected a species lost to time, demonstrating the power of synthetic biology to reverse extinction and reshape the future of conservation.
To me, that’s a jump. I don’t believe they’ve “resurrected a species lost in time.” Perhaps this is a greater question—what makes a species a species? Is it the classical reproductive capacity? Or is it phenotypic and genotypic?
One thought experiment:
If I swap out every single human coding gene into a chimp’s DNA, will I get a human? Let’s say this organism lives and looks exactly like a human, is that a human or a different species? Given what we’ve learned about noncoding DNA, the interactions between the inserted gene and the surrogate would have differences. If we share 99% of the genome with chimps, then there are somewhere around 30,000,000 nucleotide differences between the human and chimp genomes (3 billion nucleotides multiplied by 0.01).
Don’t get me wrong, there’s some really amazing innovation happening here. I’m just being a stickler for some of the terminology being used.
The post Dire Wolves? Gray Wolves? What Kind of Wolf Am I? appeared first on GEN - Genetic Engineering and Biotechnology News.