biotechnology company Colossal Biosciences has announced that dire wolves—the once-mighty, extinct predators of North America—have been “brought back” to life. Utilizing cutting-edge CRISPR gene-editing and cloning techniques, the company has generated three wolf pups that display the characteristics of the extinct dire wolf, sparking fascination and debate within the scientific and conservation communities alike.
What Are Dire Wolves?
Dire wolves, known by their scientific name Aenocyon dirus, once roamed North America during the Late Pleistocene and early Holocene epochs. These formidable canids were larger and more robust than modern gray wolves. They possessed expanded cheekbones, a broader skull, and powerful jaws that enabled them to hunt megafauna such as horses, ground sloths, and bison. Popular culture—especially the hit series “Game of Thrones”—has cemented the dire wolf’s image as a symbol of wild, untamed power. However, despite their legendary status, dire wolves went extinct approximately 10,000 to 13,000 years ago due to a decline in prey populations, climate change, and competition with other predators.
How Were Dire Wolves Brought Back?
Colossal Biosciences’ approach to de-extinction did not involve using ancient dire wolf DNA directly. Instead, scientists first extracted and sequenced DNA from two ancient fossils—a 13,000-year-old tooth found in Ohio and a 72,000-year-old skull fragment from Idaho. These samples allowed researchers to reconstruct key aspects of the dire wolf genome. By comparing this ancient data with the genome of the modern gray wolf—a close relative sharing approximately 99.5% of its DNA—the team identified around 20 genetic modifications across 14 genes that are responsible for traits such as a larger body size, broader head, and even a white coat.
Using these precise edits, scientists modified endothelial progenitor cells (EPCs) isolated from gray wolf blood through a non-invasive process. The edited cells, now containing the “dire wolf” gene variants, were then used to generate embryos via somatic cell nuclear transfer. These embryos were implanted into surrogate domestic dogs, which safely carried the pregnancies to term. The birth of these genetically engineered pups marks the first time in over 10,000 years that dire wolves—at least by phenotype—have walked the Earth.
How Big Are Dire Wolves?
One recurring question is, “how big are dire wolves?” Fossil evidence and morphological studies show that dire wolves were considerably larger than their gray wolf relatives. On average, dire wolves stood about 28 to 33 inches at the shoulder and measured approximately 5 to 6 feet in body length. Their weight typically ranged from 132 pounds to 150 pounds, with some specimens reaching up to 200 pounds in extreme cases. These impressive dimensions helped dire wolves to be formidable apex predators, perfectly adapted to hunting the megafauna of the Ice Age.
Remus, Romulus, and Khaleesi: The New Dire Wolves
The trio of de-extinct canids—Romulus, Remus, and the female pup Khaleesi—carry names that evoke both classical mythology and modern fantasy. Romulus and Remus, named after the legendary twin founders of Rome, along with Khaleesi (named after the iconic “Game of Thrones” character Daenerys Targaryen), serve as living embodiments of the dire wolf spirit. According to Colossal Biosciences, the two male pups, Romulus and Remus, were born on October 1, 2024, and have already reached a weight of about 80 pounds. They are projected to grow to nearly 150 pounds by maturity, reflecting the massive stature of the original dire wolves. Khaleesi, born on January 30, 2025, is expected to share similar physical and behavioral traits with her male counterparts.
Dire Wolves: Extinct, Then Reborn
The announcement that dire wolves have been revived has reignited debate about what it means to de-extinct a species. Critics argue that, since the pups were created by modifying gray wolf DNA rather than cloning a dire wolf directly, they may simply be genetically modified gray wolves that mimic dire wolf traits. However, proponents contend that if the animals look and behave like the extinct species—and fill its ecological niche—they fulfill the essence of what it means to bring a species back. Colossal Biosciences asserts that by restoring these unique traits, they are not simply recreating an animal, but reviving a symbol of lost biodiversity and wild heritage.
Future of Genetic Science
Colossal Biosciences’ pioneering work with dire wolves could have far-reaching implications for conservation. Similar techniques are being considered to help preserve the genetic diversity of critically endangered species—such as the red wolf—and perhaps even for reintroducing long-extinct species to restore natural ecosystems.
As debates continue over the scientific and ethical dimensions of de-extinction, the birth of Romulus, Remus, and Khaleesi stands as a landmark achievement. Whether these animals will one day be integrated into rewilded landscapes or serve primarily as a research tool, their existence challenges our understanding of extinction and conservation in the 21st century.
