Gene-Edited Dire Wolves Brought Back from Extinction Get Their Year 2 Check-Up. Here’s What Their Exams Revealed

**Colossal Biosciences’ Dire Wolf Experiment Celebrates Two-Year Milestone**

Colossal Biosciences has announced that its pioneering project involving cloned dire wolves, Romulus and Remus, is showing promising results as they celebrate their second birthday. The identical twins, who turned two on 1st October, and their younger sister Khaleesi, have reached the anticipated sizes predicted by scientific research on the extinct species.

According to a health report acquired by PEOPLE, the two brothers are in excellent health, now weighing 134 pounds (61 kg) and 132 pounds (60.25 kg) respectively. The report also confirms that both wolves have achieved ideal body conditions, with growth plates completely closed, aligning with estimates drawn from the researched fossil records of dire wolves dating back over 10,000 years. Colossal’s chief animal officer, Matt James, shared that the wolves’ physical conditions have been closely monitored through a series of tests and examinations over the past two years.

Colossal Biosciences embarked on this ambitious project by editing the DNA of grey wolves to recreate traits believed to belong to the dire wolf species. These traits were derived from the fossilised remains found at the Rancho La Brea site in Los Angeles. As a result of these genetic modifications, the wolves exhibit enhanced size and muscle density, alongside a characteristic white coat reminiscent of their ancient ancestors.

Beth Shapiro, the chief science officer at Colossal, explained that these genetic innovations have proved successful, as the wolves have indeed reached full size. She added that the alterations were intentionally designed to cultivate the physical characteristics that would make the dire wolves larger and more robust than their grey wolf counterparts.

The report also includes observations regarding Khaleesi, now 20 months old, who weighs approximately 102 pounds (46.35 kg). While she is still growing, it is expected that she will remain around 20% smaller than her brothers, a common occurrence among female wolves. Her physical measurements are equally impressive, standing at 94 centimetres (about 37 inches) at the shoulder and stretching to a total of 201 centimetres (approximately 6 feet 6 inches) from nose to tail.

An interesting aspect of this trio is that all three wolves share genetic material from the same male grey wolf donor. However, Khaleesi possesses a unique gene configuration that results in her having XY chromosomes typically associated with male animals, despite developing as a female. This phenomenon, as detailed in the health report, has been witnessed previously in both cloned and naturally bred canines, confirming her robust health.

In light of her health and genetic profile, Khaleesi has recently undergone a spay procedure where she was administered anaesthesia in a manner that ensured her comfort. The procedure was successful, and she resumed her normal activities within hours after surgery. Given the similarity in their genetic backgrounds, breeding among the trio is not planned. Colossal aims to expand their pack by introducing genetically diverse wolves, leading to natural breeding in future generations.

The health report also highlighted the positively robust health of all three wolves, revealing that they exhibit no significant medical concerns. Imaging further indicated normal hip, spine, and dental health, with their only prior health issue being a temporary case of intestinal coccidiosis during their juvenile phase.

In terms of behaviour, the pack demonstrates distinct roles, with Remus often taking the lead while Romulus, being slightly larger, tends to follow. James humorously described Remus as having a “little Napoleon” quality to him, while Khaleesi is the one most at ease around humans, actively seeking attention from keepers.

Currently, the dire wolves are thriving in their preserve, where they are able to hunt rabbits and engage in more natural predatory behaviours. While there have been discussions regarding their reintroduction into the wild, the current focus remains on further understanding and refining the care for gene-edited animals for the benefit of future conservation efforts.

Colossal’s groundbreaking approach to gene editing doesn’t only focus on wolves. The team is applying similar techniques to other species in danger of extinction, further exemplified through their work with quolls in Australia, a species threatened by invasive cane toads. By introducing genetic resistance to the toxin produced by these toads, the team aims to enhance survival rates among quoll populations.

As Colossal Biosciences continues its innovative journey, its research on dire wolves and other species may pave the way for advancements in conservation efforts, illustrating how gene editing can facilitate the acceleration of evolutionary advantages in a rapidly changing environment.