Romulus, Remus, and Khaleesi

Romulus, Remus, and Khaleesi

Species	Canis lupus
Sex	Romulus and Remus: Male Khaleesi: Female
Born	Romulus and Remus: (2024-10-01)October 1, 2024 Khaleesi: (2025-01-30)January 30, 2025
Known for	Purportedly being the first revived dire wolves (Aenocyon dirus)
Named after	Romulus and Remus Daenerys Targaryen (Khaleesi)

Romulus, Remus and Khaleesi are genetically modified gray wolves (Canis lupus) created by Colossal Biosciences Inc. with the goal of replicating the phenotype of the extinct dire wolf (Aenocyon dirus). Romulus and Remus were born on October 1, 2024; Colossal claims that the two males represent the first living examples of the species since its extinction approximately 10,000 years ago. Khaalesi, a female, was born later, on January 30, 2025. As dire wolves belonged to a completely different genus, Aenocyon, Romulus, Remus, and Khaleesi are in fact genetically engineered gray wolves.

Scientists rewrote 14 key genes in gray wolf EPC cells to express 20 dire wolf traits meaning that "no ancient dire wolf DNA was actually spliced into the gray wolf's genome." The public announcement of their birth in April 2025 was subject to significant public attention.

Genesis

The creation of these modified gray wolves involved analyzing ancient DNA samples from two sources: a 13,000-year-old tooth discovered at Sheriden Cave, an Ice Age archaeological site in Wyandot County, northwestern Ohio, and a 72,000-year-old ear bone found in American Falls, Idaho. Colossal Biosciences's scientists stated that rather than directly inserting ancient DNA into modern animals, that they had identified approximately twenty genetic modifications across fourteen genes that differentiate dire wolves from modern gray wolves.

The scientific team isolated endothelial progenitor cells (EPCs) from gray wolf blood samples, then used CRISPR gene editing to modify 14 genes to express 20 traits which the company claims are found in dire wolves, including a larger body size, wider head, and pale coat color. Only 15 of the 20 trait changes are directly based on dire wolf genome and the remaining 5 changes are known to produce light coat color. These modified nuclei were transferred into denucleated ova, which developed into embryos in laboratory conditions. From 45 engineered ova, three viable embryos were successfully implanted in surrogate mother dogs.

The surrogate mothers were selected domestic dog mixes chosen for their general health and size sufficient to accommodate the larger dire wolf pups. One particular surrogate mother, a domestic dog named Skyla, played a crucial role in the project. The pregnancies were continuously monitored with weekly ultrasounds, and all three births occurred via planned caesarean section to minimize complications.

Characteristics and growth

Born on October 1, 2024, Romulus and Remus are housed in a secured 2,000-acre (810 ha) ecological preserve within the United States surrounded by 10-foot (3.0 m) fencing, at an undisclosed location to protect them from disturbance. The facility includes a smaller 6-acre (2.4 ha) area containing a veterinary clinic, extreme weather shelter, and natural dens. They receive around-the-clock veterinary supervision. Romulus and Remus were named after the legendary twin brothers who founded Rome, and in Roman mythology had been suckled by a she-wolf as infants. As pups, a picture was taken of them resting on the original Iron Throne prop from Game of Thrones, an allusion to their alleged species' presence in the franchise.

Their diet consists of deer, beef, and horse meat, supplemented with organ meats and specialized nutritional supplements. Initially fed pureed meat after weaning, they now receive whole portions that allow them to engage in natural tearing behaviors. The wolves have not been provided with live prey, though staff note they have not observed any interactions with small wildlife that may enter their enclosure.

Their genetic modifications resulted in several key physical differences from gray wolves, including a white coat coloration and distinctive vocalizations, particularly bearing unique howling patterns. Morphologically, the wolves have a larger overall body size with a more "powerful" shoulder structure, wider head shape, larger teeth and jaws, and more muscular legs. Behaviorally, the wolves exhibited natural wolf tendencies from birth, including early howling (beginning at approximately two weeks of age), stalking and hunting behaviors, and a natural wariness around humans. Unlike domesticated canines, they maintain distance from people, including their handlers, and display characteristic wolf retreat behaviors when approached.

Based on unreviewed genetic research, Colossal claims that dire wolves would have had a pale coat coloration. The pups' white coat results from a coat coloration gene expressed in dogs, chosen as a replacement for the purported original gene, which carries "a risk of blindness and deafness".

By six months of age, the male wolves measured nearly four feet (~122 cm) in length and weighed approximately 36.3 kg (80 lb) each. They are projected to reach six feet (~183 cm) in length and 68 kg (150 lb) at full maturity.

Their sister Khaleesi was born on January 30, 2025. She was named in homage to the Game of Thrones character Daenerys Targaryen. The three wolves are maintained as a small pack.

Reception

Independent experts disagreed with the Colossal Biosciences' claim that these animals are revived dire wolves. The zoologist Philip Seddon and the paleontologist Dr. Nic Rawlence from Otago University explained that the animals are genetically modified hybrid grey wolves. Rawlence noted that ancient dire wolf DNA is an extremely fragmentary source for constructing a biological clone and that dire wolves diverged from grey wolves anywhere between 2.5 and 6 million years ago. His criticism was likewise directed at the small number of genetic changes (20 in only 14 genes) Colossal administered to the gray wolf genome - suggesting a closer relation to the gray wolf genetically than the company's marketing often acknowledged - and was concerned about this project giving a wrong message in biodiversity conservation.

The geneticist Adam Boyko at Cornell University stated that the wolves are only functional versions of "dire wolves", instead of a resurrection of the legitimate species Jeremy Austin, Director of the Australian Centre for Ancient DNA, stated that the result was "not a dire wolf under any definition of a species ever", disputing the phenotypic species definition used by Dr. Beth Shapiro of Colossal Biosciences, arguing that hundreds of thousands of genetic differences exist between dire and grey wolves. He also questioned whether the purported dire wolves have any ecological place left in the modern world or will merely become zoo animals.

According to Time Magazine, the Mandan, Hidatsa, and Arikara Nation has expressed interest in Colossal Biosciences potentially releasing their modified wolves into a controlled area of the Fort Berthold Reservation in northwestern North Dakota, which currently spans 1,000,000 acres (400,000 ha). The wolves currently live in a 2,000-acre (810 ha) ecological preserve in an undisclosed location in the United States.

Author George R.R. Martin, the creator of Game of Thrones, was invited to see the dire wolves, and commented, "Maybe I was remembering a past life, when I ran with a pack in the Ice Age. … Whatever the reason, I have to say the rebirth of the direwolf has stirred me as no scientific news has since Neil Armstrong walked on the moon."

See also

• Dire Wolf Project – The first attempt at recreating the dire wolf through backbreeding
• List of resurrected species
• Woolly mouse – Another genetically modified animal from Colossal Biosciences