By Robert Clark, TIME contributor
Two young wolves named Romulus and Remus are engaging in typical puppy behavior: playing, wrestling, and exploring. However, these 6-month-old pups stand out due to their remarkable size and demeanor. Despite their youth, they already measure almost 4 feet in length, weigh 80 pounds, and have the potential to reach 6 feet and 150 pounds. Unlike typical puppies, they do not exhibit the usual affection towards humans, instead keeping their distance and retreating if approached. Even their handlers struggle to get close to them without evoking a reaction. These behaviors are reminiscent of wild lupine traits, as Romulus and Remus are not ordinary canines but rather dire wolves, a species that has been extinct for over 10,000 years.
Once widespread across North and South America, dire wolves have not been sighted for millennia. However, Colossal Biosciences, a pioneering company, has managed to revive this ancient species using advanced genetic engineering techniques. By decoding the dire wolf genome and modifying the genetic makeup of gray wolves to match it, Colossal successfully brought the dire wolf lineage back to life. Romulus, Remus, and their sister Khaleesi were born through surrogate domestic dog mothers, marking a groundbreaking achievement in de-extinction efforts.
In a confidential wildlife facility in the United States, TIME met with Romulus and Remus in March, ensuring the secrecy of their location to safeguard these reawakened creatures. Colossal Biosciences, founded in 2021 and employing a team of 130 scientists, has ambitious plans beyond the dire wolf resurrection. They aspire to revive other extinct species such as the woolly mammoth, the dodo, and the thylacine. By leveraging genetic engineering, the company aims not only to restore lost biodiversity but also to prevent the extinction of endangered animals by enhancing their resilience to environmental challenges.
Colossal’s approach has sparked both excitement and skepticism within the scientific community. While some view these endeavors as reminiscent of a circus sideshow, the company argues that their technology holds the key to preserving Earth’s genetic diversity and combating the looming threat of species loss. By resurrecting ancient creatures like the dire wolf and mammoth, Colossal seeks to equip humanity with the tools to shape the future of wildlife and mitigate the impacts of climate change.
Beth Shapiro, Colossal’s chief science officer, emphasizes the transformative role of genetic engineering in shaping the evolutionary trajectory of species. With the planet facing a loss of 30% of its genetic diversity by 2050, Colossal advocates for genetic interventions as a crucial strategy to safeguard biodiversity. By applying their knowledge from de-extinction projects, the company aims to support the conservation of endangered species and address pressing environmental challenges.
As humanity stands at a crossroads in determining the fate of Earth’s wildlife, Colossal presents itself as a pivotal player in reshaping the
A moral good, but also a moral imperative, is seen as a way for humans to reconcile with nature, especially after driving many species to the brink of extinction. According to Shapiro, in order to ensure a future that is abundant in biodiversity and thriving with human life, we must explore the potential of using our intelligence to undo some of the harm we have caused to the world. The reintroduction of the woolly mouse and dire wolves marks the initial steps in this direction, although not everyone is in agreement. Throughout scientific history, there have been instances of newly introduced species becoming invasive, leading to unintended consequences when humans interact irresponsibly with other animals. For example, an exotic pet escaping and harming native species, or a toad brought in to control beetles causing harm to marsupials. Additionally, genetic engineering, despite advancements, still faces challenges such as health issues in cloned animals and risks for surrogate mothers.
Colossal’s scientists remain optimistic about their work, believing it holds great potential. Matt James, the company’s chief animal officer, emphasizes the significant impact of their research, recalling a poignant moment when the cloned dire wolf pups responded to a familiar song in a way not heard for thousands of years. The genetic changes required to revive an extinct species are surprisingly minimal, with just a few edits in key genes resulting in significant physical and behavioral differences. The analysis of the dire wolf genome involved studying samples from ancient remains, a meticulous process that required careful extraction and examination.
Overall, while the process of cloning raises ethical and practical concerns, the team at Colossal Biosciences sees their work as a promising opportunity to restore lost biodiversity and reconnect with our natural world.
A new method of cloning involves removing the nucleus from an ovum of a donor animal, allowing it to develop into an embryo, and then implanting it into a surrogate mother’s womb. The resulting baby is an exact genetic replica of the original donor. This technique was used to create the first cloned animal, Dolly, in 1996, and has since been employed to clone various animals like pigs, cats, deer, horses, mice, goats, gray wolves, and over 1,500 dogs.
In a less invasive approach, Colossal conducted dire wolf cloning by isolating endothelial progenitor cells (EPCs) from the blood of a gray wolf rather than a tissue sample. These cells were then genetically modified to match those of the extinct dire wolf, without directly splicing ancient dire wolf DNA into the gray wolf’s genome. The modified nucleus was transferred to a denucleated ovum, resulting in the development of embryos that were later implanted into surrogate mothers who gave birth to Romulus and Remus on Oct. 1, 2024, and Khaleesi on Jan. 30, 2025.
Throughout their pregnancies, the surrogate mothers were cared for at Colossal’s facility, receiving regular monitoring and ultrasounds. The pups were born via planned cesarean section to minimize birthing risks, and were cared for post-birth by a dedicated team. Following a brief period of nursing, the pups were bottle-fed to ensure proper care and development. The successful cloning of dire wolves has been seen as a significant advancement in the field, with potential implications for de-extinction and rewilding efforts.
The dire wolves currently reside in a protected 2,000-acre ecological preserve in the U.S., the location of which is kept confidential by Colossal to safeguard the animals. The company’s success in cloning these creatures has bolstered confidence in their ability to further advance de-extinction and rewilding initiatives.
The enclosed 2,000-acre sanctuary is safeguarded by a 10-foot fence and includes a smaller six-acre area housing a veterinary clinic, an extreme-weather shelter, and natural dens where the resident wolves can find solace and security. An attentive team of veterinarians oversees the well-being of the animals day and night. The wolves are nourished with a diet comprising beef, horse, and deer meat, as well as liver, offal, and puppy chow to ensure they receive essential nutrients. Initially, when they were young, the meat was served pureed, mimicking how a mother regurgitates food for her offspring. As they grew, whole meat was provided, allowing the wolves to tear into their food as they would in the wild. They have not displayed any inclination to hunt live prey within their enclosure, as live prey is not supplied. Paige McNickle, the manager of animal husbandry at Colossal, states, “We have not observed any attempt by them to hunt live prey, which we do not provide. However, if I were a deer, I would steer clear of their preserve.” The wolves, raised from infancy, are not suited for life in the wild; hence, they will spend their days on this protected ecological reserve, offering them ample space to roam. The team aims to study these animals throughout their lives to comprehend how genetic modifications may impact unforeseen factors. Shapiro expresses admiration for the wolves, considering them incredibly fortunate to live in such a sanctuary. The woolly mammoth project is progressing swiftly, with woolly mice gestating in just 20 days and wolf pups taking a mere 65 days to develop. The genetic alteration for the mammoth will involve editing around 85 genes, such as those responsible for cold tolerance. Ancient mammoth DNA will not be utilized; rather, elephant genes will be modified to mimic mammoth characteristics. Colossal reports having edited 25 genes thus far and anticipates having embryos ready for implantation by the end of 2026, aiming for a calf to be born in 2028. Despite being named mammoths, the engineered woolly offspring will primarily be elephants with some mammoth DNA to exhibit key mammoth traits. Shapiro acknowledges potential ethical dilemmas surrounding the presence of these reimagined creatures in the world. Ultimately, the emerging question revolves around the implications of reintroducing such species and the responsibilities that come with it.
Dire wolves at Colossal may be lucky in terms of the care and love they receive, but their lives are limited. Wolf packs can range from two to over 15 members, with hunting territories spanning from 50 to 1,000 square miles. The three dire wolves at Colossal are showing wild behaviors despite their semi-captive environment, which could make reintroduction to the wild challenging. Safety protocols are in place to prevent any risks with human interactions.
The possibility of reintroducing dire wolves beyond the preserve raises questions, as these wolves specialized in hunting large Ice Age mammals. This specialization may have contributed to their extinction once their prey disappeared. In contrast, gray wolves are more adaptable hunters, capable of catching a variety of prey. The challenges of reintroducing mammoths are also significant, as these social animals require vast territories to roam and complex social interactions.
Colossal’s mission extends beyond reviving extinct species to also focus on conservation efforts for endangered species like the red wolf. The red wolf population declined due to habitat loss and predator-control programs, highlighting the importance of conservation alongside de-extinction efforts.
The Fish and Wildlife Service implemented a captive-breeding program to rescue a species and maintain its vital role in the ecosystem by controlling deer populations to prevent overgrazing. This also helps manage smaller prey populations like raccoons and opossums that threaten native birds. Despite efforts that led to 250 individuals being released in North Carolina, fewer than 20 survive today, with many lost to poaching and car accidents.
Colossal is working to reverse this decline by announcing the cloning of four red wolves, a crucial step in strengthening the species. With a dwindling number of individuals, the red wolf population faces a genetic bottleneck, which can result in infertility and inherited defects. To combat this, scientists are exploring ways to introduce new DNA to refresh the gene pool.
Traditionally, species like the red wolf were identified by their physical characteristics, but recent research by Colossal scientists uncovered canid populations along the coasts of Louisiana and Texas with both coyote genes and red wolf ghost alleles. Using this genetic reservoir, they successfully cloned red wolves, including the first Ghost Wolf, with plans to further enhance the genetic diversity of the red wolf species.
The cloned red wolves currently reside in a separate fenced area within a 2,000-acre preserve alongside dire wolves and will not be reintroduced into the wild. However, future red wolves might be rewilded pending assessments of the clones’ health and fitness. Colossal is in talks with North Carolina to implement conservation strategies aimed at rescuing and accelerating the recovery of the red wolf.
James, a spokesperson for Colossal, emphasizes the importance of restoring the lost genetics of the world’s most endangered wolf through cloning and genetic engineering. Similar scientific approaches could also aid in saving the northern quoll, a marsupial native to Australia threatened by the invasive cane toad. Through efforts to revive extinct species like the thylacine, innovative solutions may help protect vulnerable wildlife populations facing extinction.
The Tasmanian tiger, a member of the marsupial family that also includes the quoll, is part of a genetic study that has identified a single change in a single nucleotide—a fundamental component of DNA and RNA—that could provide a 5,000-fold resistance to the neurotoxin of cane toads. “We, as a species, introduced the cane toad, leading to the unintended consequence of endangering not only the quoll but other marsupials as well,” remarks Lamm. “This singular genetic alteration could potentially create super quolls that thrive on consuming cane toads. These are the types of victories that genetic technologies can achieve.”
While Colossal has seen success in its endeavors, with the creation of the woolly mouse and dire wolves marking significant milestones, the intricacies of genetic engineering pose challenges. According to experts like Alison van Eenennaam from the University of California, Davis, the phenomenon of pleiotropy—where one gene influences multiple traits—can lead to unforeseen consequences for survival.
Even if Colossal manages to perfect gene editing, the process of gestating the desired offspring may present further hurdles, as cloning in livestock often results in more failures than successes. The potential risks of de-extincted animals reintegrating into the modern ecosystem also loom large, as seen in the case of the invasive cane toads.
Despite these concerns, Colossal remains undeterred, thriving not only as a scientific entity but also as a successful business. With a valuation of $10.2 billion and ventures like Breaking and Form Bio, the company is carving out a niche in the market by leveraging its innovative technologies.
Cellular and genetic engineering have numerous applications in the biomedical field, including the treatment and prevention of diseases. According to Lamm, the value of genome-engineering technologies alone amounts to tens of billions of dollars. While Colossal is currently a prominent player in this field, it is not the only one. Revive & Restore, a conservation organization based in California, offers funding for global projects related to de-extinction, biodiversity enhancement, and the protection of endangered species. Another organization, Rewilding Europe, supports scientists in their efforts to conserve and restore species throughout Europe, such as the bearded vulture, Iberian lynx, marbled polecat, imperial eagle, and auroch—the extinct predecessor of domestic cattle. Despite their contributions, these groups are smaller in scale compared to Colossal. In 2024, Rewilding Europe allocated 20 million euros to support rewilding initiatives across the continent, while Revive & Restore, established in 2012, has raised $40 million for similar conservation projects. Lamm views these organizations as collaborators rather than competitors in their mutual conservation objectives.
Young animals Romulus, Remus, and Khaleesi are unaware of the scientific advancements that led to their births and the hope they symbolize. During TIME’s visit, Romulus and Remus frolicked in their enclosure, nibbling on bark while observing humans from a distance. McNickle noted the distinct personalities of the pups—Romulus displayed bravery by exploring independently at a young age, while Remus was more reserved, following Romulus’ lead. As they matured, Remus became bolder, venturing into new territories before Romulus. The future status of potential dire wolf mating and reproduction, either naturally or controlled, remains uncertain. Handlers can monitor female estrous cycles, separate animals when necessary, or use contraceptive measures until any hereditary concerns are addressed. The MHA Nation tribes have expressed interest in hosting dire wolves on their North Dakota lands, a concept that Colossal is investigating.
If Colossal achieves its goal of preserving endangered species and reintroducing ancient creatures to the world, Romulus, Remus, and Khaleesi will leave a lasting legacy. As humans continue to dominate the planet, threatening the existence of countless other species, Colossal aims to reverse this trend, even if only to some extent. In the words of James, recalling a quote attributed to Teddy Roosevelt, the right action must be taken promptly, rather than doing nothing at all. For more inquiries, contact Jeffrey Kluger at jeffrey.kluger@time.com.
