These days, when people hear the term “dire wolf,” they’re most likely to think of the huge (fictional) wolves associated with House Stark in Game of Thrones. Yet the direwolves of Westeros were inspired by a real species, Aenocyon dirus, that went extinct in North America around 12,000 years ago.
Dire wolves have made headlines around the world recently, and it’s not because of Game of Thrones. The Dallas-based biotechnology firm Colossal Biosciences announced this week that it had brought back the dire wolf, making it the “world’s first successfully de-extincted animal.”
This incredible comeback was achieved by extracting DNA from dire wolf fossils and editing the genetic code of a gray wolf, the dire wolf’s closest living relative. The genetic engineering process resulted in the birth of three pups. The males, Romulus and Remus, were born on October 1, 2024, while the female, Khaleesi, was born on January 30, 2025.
However, not everyone is convinced. Many scientists have pointed out that these pups are not true dire wolves but rather hybrids that look similar to prehistoric dire wolves, thanks to their white fur and large skulls. Perhaps, based on how they came into existence, it would be more accurate to call them genetically modified gray wolves.
The ancient DNA extracted from fossilized dire wolf remains (a 13,000-year-old tooth and a 72,000-year-old ear bone) was too degraded to use for cloning purposes. Rather than splicing dire wolf DNA into the gray wolf genome, the Colossal team mapped the dire wolf genome and determined which segments of the gray wolf’s genetic code they needed to edit. They used CRISPR technology to edit 14 gray wolf genes (out of a total of 19,000), with the result of expressing 20 dire wolf traits.
The genetically modified embryos were implanted into surrogate mothers (large mixed-breed dogs) who carried them for about two months until they were delivered by planned C-section.
Making a comeback:
- Despite the skepticism about whether Romulus, Remus, and Khaleesi should even be called “dire wolves,” Colossal shows no signs of rethinking its plans to revive other extinct animals, including the Tasmanian tiger, dodo, and woolly mammoth. Colossal says that it’s planning to create the first woolly mammoth calves by 2028.
- Many scientists and conservationists have suggested that Colossal’s funding (the company is valued at $10.2 billion, and they’ve raised $435 million) and cutting-edge technology could be better used to help reintroduce genetic diversity among existing species and preserve endangered animals instead of recreating extinct ones.
- Colossal researchers have admitted that even if their efforts are successful, they wouldn’t be truly resurrecting these long-extinct species but rather reintroducing animals that look and behave in a way that is similar to their ancestors. Yet serious ethical and logistical issues remain, perhaps none greater than the question of what ecological role a revived, hybrid species would serve if the population ever became large enough to be released into the wild.
