By Sam Rory
In a scientific achievement that reads more like fiction than fact, Colossal Biosciences has successfully resurrected the dire wolf (Aenocyon dirus), an apex predator that vanished from Earth approximately 12,000 years ago. The Dallas-based biotech company announced on April 7, 2025, that it has produced three living dire wolf pups, marking what many are calling the first true de-extinction event in human history.
The Announcement That Shocked the World
When Colossal revealed the existence of three healthy dire wolf pups named Romulus, Remus, and Khaleesi, the scientific community and general public were equally stunned. The two males, Romulus and Remus, were born in October 2024, while the female, Khaleesi, arrived in January 2025. At roughly six months and three months old respectively, these animals aren’t just laboratory curiosities but thriving specimens displaying the characteristic traits of their Ice Age ancestors.
“These are not dogs, or even modern-day wolves. They’re dire wolf pups, back from extinction after some 12,000 years,” notes Colossal’s announcement. The white-furred pups already display classic dire wolf characteristics, including broad heads and hefty builds, with the older pups weighing approximately 80 pounds at just six months of age.
What’s particularly fascinating is that these animals exhibit true wild behavior. Unlike domestic puppies, Romulus and Remus maintain their distance from humans, demonstrating the wild lupine instincts encoded in their reconstructed genome.
The Science Behind the Resurrection
How exactly did Colossal accomplish this feat? The process combined cutting-edge genetic technology with reproductive science in ways never before attempted.
First, researchers obtained genetic material from dire wolf fossils, including a 13,000-year-old tooth and a 72,000-year-old skull. From these ancient remains, scientists sequenced and reconstructed the dire wolf genome, creating a genetic blueprint of the extinct species.
Next, the team identified 14 important genes containing 20 distinct genetic variants that give dire wolves their characteristic features. These included genes influencing the animal’s size, muscular build, skull width, tooth size, coat color, and even vocalization patterns.
Using CRISPR gene-editing technology, scientists modified living cells from modern gray wolves to carry these dire wolf genetic variants. Instead of invasively harvesting tissue, they drew blood from living gray wolves and isolated endothelial progenitor cells, which were then precisely edited to install the 20 dire wolf genetic variants.
The edited cells were used to create embryos through somatic cell nuclear transfer—removing the nucleus from dog egg cells and replacing it with the edited cell nucleus. These reconstructed embryos were implanted into surrogate mothers (domestic hound mixes) for gestation.
After approximately 65 days, the pups were delivered via planned cesarean sections. Remarkably, Colossal reported no miscarriages or stillbirths during these trials, suggesting an astonishingly successful process for such pioneering work.
Breaking Scientific Barriers
The dire wolf project set a new record in genetic engineering: 20 precise genomic edits in a vertebrate animal, the highest number achieved to date. This surpasses Colossal’s previous achievement of 8 edits in a “woolly mouse” demonstration.
Dr. George Church, Harvard geneticist and Colossal co-founder, described the achievement as proof that their “end-to-end de-extinction technology stack works.” He noted that delivering 20 precise edits in a healthy animal is unprecedented, calling it “the largest number of precise genomic edits in a vertebrate so far—a capability that is growing exponentially.”
Similarly, Dr. Beth Shapiro, Colossal’s chief science officer and leading ancient DNA expert, celebrated the project as “a new standard for paleogenome reconstruction.” The computational tools and DNA recovery techniques developed allowed the team to successfully link extinct DNA variants to key dire wolf traits.
Conservation Applications
Beyond the headline-grabbing resurrection of an Ice Age predator, Colossal emphasizes that de-extinction science directly benefits endangered species conservation. Alongside the dire wolf births, the company announced it had successfully cloned two litters of critically endangered red wolves (Canis rufus), producing four healthy pups using the same “non-invasive blood cloning” approach developed for the dire wolf project.
With red wolves being one of the most endangered canids on Earth, this cloning breakthrough could significantly contribute to species recovery efforts. Dr. Christopher Mason, a Colossal scientific advisor, highlighted this connection: “The same technologies that created the dire wolf can directly help save a variety of other endangered animals as well. This is an extraordinary technological leap for both science and conservation.”
The gene-editing toolkit refined through the dire wolf project is also being applied to other conservation challenges. Colossal scientists are working with the pink pigeon, a species suffering from severe genetic bottlenecks. By introducing greater genetic diversity into pink pigeon embryos, they aim to improve the species’ health and viability.
Living in the Modern World
The dire wolf pups currently reside on a 2,000+ acre secure expansive ecological preservesecure expansive ecological preserve under continuous care and monitoring. Certified by the American Humane Society, the facility includes naturalistic habitats and on-site veterinary support to ensure the animals’ well-being.
Robin Ganzert, Ph.D., CEO of the American Humane Society, praised Colossal’s high standards of animal welfare, calling the company “a shining example of excellence in humane care.” She further stated that “the technology they are pursuing may be the key to reversing the sixth mass extinction and making extinction events a thing of the past.”
What’s Next?
The successful resurrection of the dire wolf validates Colossal’s de-extinction platform and suggests that more ambitious targets may be within reach. The company is applying similar methods to its other headline projects, aiming to reintroduce the woolly mammoth by 2028, followed by the thylacine (Tasmanian tiger) and dodo.
In early 2025, Colossal demonstrated progress on the mammoth project by creating 38 “woolly mice”—laboratory mice edited with mammoth genes to grow shaggy coats. The company plans to attempt an elephant pregnancy with a mammoth-variant embryo by 2026.
A New Chapter for Conservation
The dire wolf’s return represents a revolutionary milestone in scientific progress. For the first time, humans have brought an Ice Age apex predator back from extinction—not as a one-off curiosity but as a living, thriving species that could potentially help restore ecosystems.
The project showcases how advances in ancient DNA analysis, CRISPR gene editing, and cloning technology can converge to undo extinction on a meaningful scale. It also demonstrates a model for leveraging these innovations to save today’s endangered species, blending bold vision with practical conservation.
As Mark Fox, Tribal Chairman of the MHA Nation, reflected, the dire wolf’s birth “symbolizes a reawakening—a return of an ancient spirit to the world,” suggesting that with ingenuity and care, extinction may no longer have to be forever.
