Somewhere on an undisclosed 2,000-acre site in the United States reside Remus, Romulus, and Khaleesi. The three spend their days as any normal puppy does: eating, sleeping, playing, and socializing with each other. However, despite their simple routines, their existence marks a profound step in the science of de-extinction. Remus, Romulus, and Khaleesi are dire wolves, members of a species that has been extinct for over 10,000 years.
How to “De-Extinct” a Species
The twin boys, Romulus and Remus, were born on October 1, 2024, and their female counterpart, Khaleesi, was born on January 30, 2025. Though these pups are flourishing now, bringing back these prehistoric wolves was far from easy for scientists. Colossal Biosciences, the company responsible for these pups’ existence, used DNA taken from dire wolf fossils in order to assemble two high-quality dire wolf genomes. The Colossal team then compared the genomes to members of the Canidae family, and they were able to identify genetic variations that led to dire wolf-specific traits, like white coats and thick fur. Since dire wolves and gray wolves were found to share 99.5% of their DNA, the Colossal team used a gene editing technology called CRISPR to alter gray wolf cells and replace gray wolf gene variants with traits associated with dire wolves. The researchers would then clone the most promising cells and transfer them into donor eggs from domestic dogs. Once healthy embryos developed, they were transferred into large mixed-breed hounds that served as surrogate mothers. This process was attempted eight times, with an average of 45 embryos being transferred on each trial.
Colossal Bioscience and Its Plans for the Future
The dire wolf is not Colossal Bioscience’s only attempt at de-extinction. In March of this year, Colossal announced that they had copied woolly mammoth DNA and used similar genetic engineering techniques to create the woolly mouse, a mouse with the golden coat and metabolism of a woolly mammoth. Other animals that the company has on their de-extinction to-do list include the Tasmanian tiger and the dodo bird.
The Colossal team has acknowledged that Remus, Romulus, and Khaleesi are not completely dire wolves genetically. However, Beth Shapiro, the chief science officer of Colossal, has stated that creating carbon copies of extinct animals is not the purpose of the company’s experiments. As Shapiro puts it, “Our goal with de-extinction is always [to] create functional copies of these extinct species.” The three pups may not be 100% dire wolves, but they definitely have the looks and behaviors of one.
Colossal hopes that this technology could be beneficial to animal conservation efforts. Take the red wolf, for example. This species used to be common in the U.S. Southeast, but started dying out due to habitat loss and predator-control programs. Eventually, the U.S. Fish and Wildlife Service was forced to introduce a captive-breeding program in the 1960s. The red wolf population suffered from a lack of genetic variation, so the Colossal team created clones of these wolves. These cloned wolves now inhabit an enclosed area similar to where Remus, Romulus, and Khaleesi live.
While this technology presents many advantages, many critics argue that de-extinction could imperil the animal surrogates of these hybrid creatures, and that the money invested in these projects could be used more efficiently elsewhere. One can only wonder what the future may hold for genetic engineering. Until then, Remus, Romulus, and Khaleesi will continue living out their lives, fighting, tussling, and chasing each other around: blissfully unaware about how special they really are.