The revival of the dire wolf (Aenocyon dirus) by Dallas-based Colossal Biosciences represents a watershed moment in conservation biotechnology. These iconic Ice Age predators, extinct for approximately 13,000 years, are now walking the earth once more through an innovative fusion of ancient DNA analysis, gene editing, and reproductive technology.
Colossal’s approach to bringing back the dire wolf required meticulous scientific work that began with obtaining genetic material from well-preserved fossils. Researchers extracted and sequenced DNA from two dire wolf specimens: a 13,000-year-old tooth from Sheridan Pit, Ohio, and a 72,000-year-old skull from American Falls, Idaho. This provided unprecedented genetic insight into these ancient predators.
“Our team took DNA from a 13,000 year old tooth and a 72,000 year old skull and made healthy dire wolf puppies,” explains Ben Lamm, CEO of Colossal. “It was once said, ‘any sufficiently advanced technology is indistinguishable from magic.’ Today, our team gets to unveil some of the magic they are working on and its broader impact on conservation.”
After sequencing the ancient DNA, Colossal’s scientists identified 14 crucial genes with 20 distinct genetic variants that give dire wolves their characteristic features. These included genes influencing their larger size, more muscular build, wider skull, bigger teeth, thick light-colored coat, and even their unique vocalizations.
The next step involved CRISPR genome editing—applying precise genetic modifications to living cells from modern gray wolves. Rather than invasively harvesting tissue, scientists drew blood from gray wolves and isolated endothelial progenitor cells (EPCs). Using CRISPR technology, they meticulously edited the nuclei of these cells, installing the 20 dire wolf genetic variants across the 14 target genes.
This careful engineering required extraordinary precision. For instance, when researchers discovered that some coat-color gene variants linked to dire wolves might cause deafness in gray wolves, they engineered alternative genetic changes to achieve the dire wolf’s white coat without harmful side effects.
Once the cells were genetically modified, Colossal used somatic cell nuclear transfer (cloning) to create embryos. Scientists removed the nucleus from dog/wolf egg cells and replaced it with the nucleus of an edited cell. These reconstructed ova developed into embryos in the lab before being implanted into surrogate mothers—domestic dogs (hound mixes)—chosen for their genetic compatibility.
Colossal transferred 45 edited embryos into two surrogate dogs, resulting in two successful pregnancies that produced Romulus and Remus after approximately 65 days of gestation. A few months later, a third surrogate carried another batch of edited embryos, resulting in Khaleesi. All three pups were delivered via scheduled cesarean section to ensure safety.
Dr. George Church, Harvard geneticist and Colossal co-founder, noted the significance of this achievement: “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 successful birth of these dire wolves also established a scientific record: 20 precise genetic edits were made to create the dire wolf—the highest number of deliberate genome edits in any animal to date. By comparison, Colossal’s previous feat, the “woolly mouse” with mammoth genes, had 8 edits.
Currently, the three dire wolf pups are thriving in a dedicated, secure wildlife facility. According to Colossal, the wolves reside on a 2,000+ acre protected reserve under round-the-clock care and monitoring. The site—certified by the American Humane Society—includes naturalistic habitats and on-site veterinary support to ensure the animals’ well-being.
“The wolves are thriving on a 2,000+ acre secure expansive ecological preserve that is certified by the American Humane Society and registered with USDA,” states a Colossal press release. “Colossal employs ten full time animal care staff to support the wolves’ physical and mental well-being.”
Dr. Robin Ganzert, CEO of American Humane Society, praised Colossal’s approach: “Colossal has achieved American Humane Certification, the prestigious designation ensuring excellence in animal welfare and care. Optimal welfare is evidenced by spacious habitats with ample space and opportunity for animals to socialize, exercise, and exhibit natural behaviors.”
Beyond the immediate scientific achievement, Colossal’s dire wolf revival has implications for broader conservation efforts. The same technologies developed for the dire wolf have already been translated into conservation outcomes for living wolves. Alongside the dire wolf births, Colossal announced it successfully cloned two litters of critically endangered red wolves (Canis rufus), producing four healthy red wolf pups using the same “non-invasive blood cloning” approach.
With less than 20 red wolves remaining in North America, making them the most endangered wolves on the planet, this breakthrough offers new hope for their preservation. The introduction of these new red wolf pups could increase the genetic diversity of the captive red wolf population by a substantial 25%.
As these technologies continue to develop, they may provide crucial tools for addressing the extinction crisis facing numerous species worldwide. The success with dire wolves suggests that Colossal’s other de-extinction targets—including the woolly mammoth by 2028 and eventually the thylacine (Tasmanian tiger) and dodo—may be increasingly feasible.
Through this unprecedented achievement, Colossal has demonstrated that the boundary between extinct and extant is no longer as absolute as once thought, opening new possibilities for conservation biology and ecosystem restoration in the decades to come.
