In early April 2025, Dallas-based biotechnology firm Colossal Biosciences announced the birth of three genetically engineered wolf pups—Romulus, Remus, and Khaleesi—designed to exhibit traits of the extinct dire wolf (Aenocyon dirus). This development has ignited discussions within the scientific community regarding the feasibility and ethics of de-extinction efforts.

The dire wolf, a formidable predator that roamed North America during the last Ice Age, went extinct approximately 13,000 years ago. To recreate its characteristics, Colossal scientists extracted ancient DNA from dire wolf fossils, including a 13,000-year-old tooth from Ohio and a 72,000-year-old skull fragment from Idaho. They identified 20 genes associated with dire wolf traits and used CRISPR technology to edit these genes in gray wolf cells. The modified embryos were implanted into surrogate domestic dogs, resulting in the birth of the three pups.

Colossal Biosciences, founded in 2021 by Harvard geneticist George Church and entrepreneur Ben Lamm, focuses on de-extinction projects, including efforts to revive species like the woolly mammoth, the Tasmanian tiger, and the dodo bird. The company employs over 170 scientists and has raised significant funding, including a $60 million Series A round in March 2022.

While Colossal describes this as a de-extinction milestone, some experts caution that the animals are genetically modified gray wolves rather than true dire wolves. The pups are currently housed in a secure ecological preserve.

The announcement has sparked debate within the scientific community and the public. Supporters argue that such efforts could support biodiversity and cultural heritage. Critics, however, caution about the limitations and challenges of reintroducing species in modern ecosystems.

Colossal emphasizes the goal of restoring lost ecological functions rather than recreating exact genetic copies. Their work also revealed that dire wolves emerged through ancient canid hybridization and share 99.5% of their DNA with gray wolves.

The company envisions that such efforts could also support biodiversity and cultural heritage.

As the scientific community continues to evaluate the implications of this development, the birth of Romulus, Remus, and Khaleesi represents a significant step in the field of genetic engineering and de-extinction.