Some people will tell you that the dire wolves are back, while others will tell you they are not. Colossal Biosciences kicked off an avalanche of media coverage, including both hype and harsh criticism, when the company said it brought back dire wolves, an extinct species given renewed popularity by its role in the Game of Thrones franchise, using gene-editing and cloning technology.

We will discuss the details of what Colossal has accomplished, but this technology also raises a bigger question with wider-reaching implications: What does de-extinction mean for the living world and endangered species fighting for survival?

Proxy dire wolves

Three animals — two males named Romulus and Remus and a female named Khaleesi — are at the center of the controversy. 

Colossal created the wolf pups by taking DNA from an existing species, the gray wolf, and making 20 edits to 14 genes designed to produce traits associated with the dire wolf: size, the color of their coats and more. The embryos were implanted into large dogs and reportedly delivered by a planned cesarean section.

Much of the debate around this issue has centered on whether gene-edited gray wolves can be accurately called «dire wolves» and if their creation can truly be considered «de-extinction.»

«It’s never gonna be possible to bring something back that’s genetically identical to a species that used to be around, and also a species is more than just its DNA,» said Beth Shapiro, Colossal’s chief science officer. «It’s the DNA interacting with the ecosystem, which also isn’t present.»

The International Union for the Conservation of Nature defines de-extinction as «the process of creating an organism that resembles an extinct species,» with the critical caveat that the term itself is misleading. Thinking of de-extinct versions of animals as a proxy for the original animals, rather than a faithful reproduction, adds some clarity to the conversation.

How Colossal’s de-extinction works

To understand how it works, look at the first gene-edited species Colossal announced: woolly mice. This demonstrates the company’s ability to make several gene edits at once.

«It’s the same genes that evolved in elephants and evolved in mice, but it was variants in those genes we know are compatible with a healthy mouse,» Shapiro said.

Colossal has produced about 38 woolly mice, and more are on the way. The mice are also reproducing.

Colossal seeks to answer some of the questions with its wooly mice include whether the edits will affect the mice’s ability to thrive in colder climates and the long-term effects of CRISPR gene editing at multiple sites in the animal’s genome.

Animal welfare

Colossal says it prioritizes the creation of healthy animals over things like editing the maximum number of genes or adding in genes exactly as they existed in extinct species. «Every edit carries some risk,» Shapiro said. «We did AI modeling of 3D protein folding, turning genes up and down slightly rather than changing them in some dramatic way.»

Even with precautions, Shapiro acknowledged things don’t always go according to plan. Khaleesi, Colossal’s female proxy dire wolf, had a sister who died at about day 10 due to an infection. «It was confirmed not to be a result of our editing,» Shapiro said.

Endangered species

Along with the proxy dire wolves, Colossal says it has cloned four endangered red wolves. The US Fish & Wildlife Service has estimated that fewer than 20 red wolves are left in the wild and about 270 are in captivity.

Colossal’s red wolf clones were made using genes from what the company is calling «ghost wolves,» a population of what were believed to be coyotes living in western Louisiana and eastern Texas that were revealed to have a significant portion of red wolf DNA.

Colossal CEO Ben Lamm says the clones «increased genetic diversity of the captive breeding pool by up to 25%.»

Lamm also highlighted the company’s pledge to make much of its de-extinction technologies available for free, including genetic rescue (adding genetic diversity to small at-risk populations), biobanking (preservation of biological samples) and cryo-freezing (cold storage of biological samples). 

What’s next?

Questions and concerns still loom, many of which have been laid out by the IUCN, the same organization that provided Colossal’s working definition of de-extinction and acknowledged it as misleading.

Among the potential disadvantages to de-extinction raised by the IUCN is a possible decrease in support for preventing extinctions. If the public misbelieves that extinction is reversible due to the popularity of de-extinction in the news, could that promote apathy about ongoing conservation efforts?

Risk to animals, including those created by gene-editing and cloning, surrogate animals and any potential future offspring or hybrid species (even re-extinction), is also a concern.

Then there are the challenges of potential rewilding, its effects on the ecosystem, the potential for invasiveness of proxy species in their new environment and the risk of disease.

This brings us back to where we began, with the trio of proxy dire wolves who will live out their lives on a 2,000-acre preserve in an undisclosed location.

Check out the video in this article to see Colossal’s proxy dire wolves in action and hear our interviews with the company’s CEO and chief science officer.