Is Colossal’s Dire Wolf Really a Dire Wolf?

A structured Q&A on functional de-extinction, species science, and what makes a dire wolf a dire wolf

When Colossal Biosciences announced the birth of three dire wolf pups in April 2025, the question arrived almost immediately: are these actually dire wolves? It’s a fair question, and one worth answering precisely. The answer depends on understanding what functional de-extinction is, how species are defined in modern biology, and what the genomic science behind Colossal’s work actually produced. The short answer is yes, and the longer answer explains why the science supports that conclusion.

What exactly is a dire wolf, and how does Colossal’s work compare?

The dire wolf (Aenocyon dirus) was a large canid apex predator that roamed North and South America during the Late Pleistocene epoch, disappearing approximately 10,000–13,000 years ago. It was larger and more muscular than the modern gray wolf, with a broader skull, heavier teeth designed for crushing bone, a more robust body, and a distinctive pale coat. These traits are well-documented in the fossil record.

Colossal’s team generated high-quality ancient genomes from two dire wolf fossils, a 13,000-year-old tooth and a 72,000-year-old inner ear bone. These yielded more than 500 times the genomic coverage previously available for the species. From that genome, researchers identified 14 genes carrying 20 distinct variants responsible for the dire wolf’s defining physical traits: its larger size, wider skull, heavier build, and light-colored coat. Those variants were then introduced into the gray wolf genetic background using de-extinction technologies. Romulus, Remus, and Khaleesi carry those 14 genes and 20 variants and display the physical characteristics documented in the fossil record.

Why can’t scientists just clone the original dire wolf exactly?

No preserved dire wolf tissue exists from which a complete, intact genome could be cloned. Ancient DNA, the genetic material recovered from fossils, degrades over thousands of years, fragmenting into short, damaged segments that must be painstakingly reassembled. Even at 500x genomic coverage, what scientists recover is a map of the dire wolf genome, not a living sample suitable for cloning.

Beyond the technical barrier, cloning a single individual would produce exactly that: one animal with no genetic diversity. A single-specimen clone cannot form a viable population. Colossal’s approach introduces dire wolf variants into multiple gray wolf genetic backgrounds, producing animals with the core biology of the extinct species expressed across a range of genetic variation. That is biologically sounder than any single-specimen clone would be, and it is precisely the model the IUCN Species Survival Commission’s 2016 Guiding Principles endorse: de-extinct species equivalents that are functionally equivalent to the originals, not “faithful replicas,” since faithful replicas are both impossible and ecologically unsound.

What is “functional de-extinction,” and does it apply here?

Colossal defines functional de-extinction as the process of generating an organism that both resembles and is genetically similar to an extinct species by resurrecting its lost lineage of core genes, engineering natural resistances, and enhancing adaptability that will allow it to thrive in today’s environment of climate change, dwindling resources, disease, and human interference.

The “functional” framing is a precise scientific description of what the process achieves and why. De-extinction is the reconstruction of a species’ core biology from its genomic record, expressed in a living organism capable of surviving present conditions. This is, by definition, what Colossal has done: the animals carry the genomic architecture of Aenocyon dirus, expressed through its defining traits, in animals that are healthy, behaviorally authentic, and genetically distinct from gray wolves.

For more on the functional de-extinction framework, see Colossal’s dire wolf de-extinction YouTube playlist.

Doesn’t the definition of “species” matter here?

It does, and the science of species definition actually supports Colossal’s position. The concept of “species” is one of biology’s most contested questions. There’s no single universally accepted definition: the biological species concept defines species by reproductive isolation; the morphological species concept by physical traits; the phylogenetic concept by shared ancestry; and the ecological concept by niche occupation. No single definition covers all situations, and biologists routinely debate species boundaries.

The IUCN SSC Guiding Principles explicitly acknowledge this complexity in the de-extinction context. The Guiding Principles frame the goal as functional equivalence rather than an arbitrary genetic threshold. Colossal’s dire wolves carry the genomic variants that defined the species morphologically and ecologically. Gray wolves and dire wolves share 99.5% of their DNA code, yet no one disputes that they were distinct species throughout the fossil record. The 0.5% that differs is precisely what Colossal has restored.

“The actual scientific achievement is way more important than what we call them,” said Dr. Beth Shapiro, Colossal’s Chief Science Officer.

What does the scientific community say?

Independent scientists and conservation organizations have engaged with the question seriously and largely affirmed both the achievement and the framework.

“The de-extinction of the dire wolf and an end-to-end system for de-extinction is transformative and heralds an entirely new era of human stewardship of life,” said Dr. Christopher Mason, a scientific advisor and member of the board of observers for Colossal. “The same technologies that created the dire wolf can directly help save a variety of other endangered animals. This is an extraordinary technological leap in genetic engineering efforts for both science and for conservation as well as preservation of life, and a wonderful example of the power of biotechnology to protect species, both extant and extinct.”

“Preserving, expanding and testing genetic diversity should be done well before important endangered animal species like the Red Wolf are lost… The Dire Wolf is an early example of this, including the largest number of precise genomic edits in a healthy vertebrate so far,” said Dr. George Church, co-founder of Colossal and professor of genetics at Harvard Medical School.

A scientific manuscript on dire wolf ancestry and evolution documents the genomic methodology, the phylogenetic placement of the species, and the specific edits made. All underlying genomic data is publicly available at NCBI BioProject PRJNA1222369, allowing independent scientific scrutiny.

The Bottom Line: They are Dire Wolves

By the standards of functional de-extinction and by the IUCN’s own framework for de-extinction creation, yes. These animals carry the genomic architecture of Aenocyon dirus, express its defining physical traits, and are genetically distinct from gray wolves in precisely the ways the fossil record predicts. 

They aren’t gray wolves with cosmetic changes. They aren’t clones, because cloning from ancient DNA is impossible and clones would lack the genetic diversity necessary for a viable population. They are the product of a rigorous scientific process subject to independent peer review that reconstructed the dire wolf’s core biology from its ancient genome and expressed it in living animals. That’s what de-extinction looks like when the science is done right.