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 implications of de-extinction efforts.

The dire wolf, a formidable predator from the last Ice Age, went extinct approximately 13,000 years ago. To achieve this genetic engineering feat, Colossal Biosciences extracted ancient DNA from 13,000 and 72,000-year-old fossils and edited 20 genes in gray wolves—the dire wolf's closest living relatives—to instill dire wolf characteristics. The modified embryos were implanted into surrogate dogs, resulting in the birth of the three pups. While Colossal describes this as the first successful de-extinction, some experts caution that the animals are genetically modified gray wolves rather than true dire wolves. The pups, larger than typical gray wolves, are currently housed in a secure ecological preserve. Colossal emphasizes that their goal is to restore lost ecological functions rather than recreate exact genetic copies of extinct species.

Founded in 2021 by Harvard geneticist George Church and entrepreneur Ben Lamm, Colossal Biosciences focuses on de-extinction projects, including efforts to revive species like the woolly mammoth, Tasmanian tiger, northern white rhinoceros, and dodo bird. The company employs genetic engineering and reproductive technologies for conservation biology. As of 2025, Colossal has raised $435 million in funding, achieving a valuation of $10.2 billion, and employs 170 staff members.

Colossal's approach involved extracting ancient DNA from dire wolf fossils dated at 13,000 and 72,000 years old. Using CRISPR gene-editing technology, scientists identified and modified 20 specific genes in gray wolf embryos to express traits associated with dire wolves, such as larger size, white fur, and more robust jaws. These edited embryos were implanted into surrogate dogs, leading to the birth of Romulus, Remus, and Khaleesi. The pups, now aged between three to six months, weigh approximately 80 pounds and are expected to reach around 140 pounds, surpassing typical gray wolf sizes.

While Colossal hails this achievement as the first successful de-extinction, the scientific community remains cautious. Experts argue that the resulting animals are genetically modified gray wolves rather than true dire wolves, as they lack the learned behaviors and ecological roles of their extinct counterparts. Geneticist Gemma Marfany described the project as producing "tuned-up" animals rather than authentic de-extinct species. Critics also highlight ethical concerns, suggesting that resources might be better allocated toward conserving existing endangered species rather than attempting to resurrect extinct ones.

The birth of these genetically engineered pups raises significant questions about the role of de-extinction in modern conservation efforts. Colossal emphasizes that their goal is to restore lost ecological functions rather than recreate exact genetic copies of extinct species. However, the introduction of such animals into current ecosystems could have unforeseen consequences, including potential disruptions to existing wildlife populations and habitats. The broader societal debate centers on the balance between scientific innovation and ethical responsibility in conservation biology.

This development is part of a broader trend in de-extinction efforts. Colossal has previously pursued projects to recreate traits of extinct species like woolly mammoths and dodos. The company also announced the successful cloning of four red wolves to enhance the genetic diversity of the critically endangered U.S. red wolf population. While some scientists acknowledge the potential conservation uses of this technology, they caution about its limitations and the challenges of reintroducing species in modern ecosystems.

Colossal Biosciences' announcement marks a significant milestone in genetic engineering and de-extinction efforts. While the birth of Romulus, Remus, and Khaleesi showcases scientific advancements, it also prompts critical discussions about the ethical, ecological, and societal implications of such endeavors. As the field progresses, ongoing dialogue among scientists, ethicists, conservationists, and the public will be essential in navigating the complex landscape of de-extinction and its role in modern conservation strategies.