This week, it was disclosed that Tom Brady had his dog duplicated. The ex-quarterback disclosed that his Junie is genuinely a clone of Lua, a pit bull mix that passed away in 2023.
Brady’s revelation comes after announcements from celebrities such as Paris Hilton and Barbra Streisand, who also notably cloned their pet dogs. However, some are convinced there are more beneficial uses for cloning technologies.
While the pampered pets of the affluent may capture this week’s headlines, cloning technologies are also being utilized to enhance the genetic diversity of inbred species and potentially revive other animals from extinction.
Cloning itself is not a new concept. The first mammal cloned from an adult cell, Dolly the sheep, was born in the 1990s. This technology has been employed in livestock breeding over the years.
Consider you have an exceptionally large bull, or a cow with an especially high milk yield. Such animals are quite valuable. You could selectively breed for those traits. Alternatively, you could clone the initial animals—effectively generating genetic twins.
Researchers can take certain cells from the animals, freeze them, and keep them in a biobank. This allows the potential to clone them in the future. It’s feasible to thaw those cells, extract the DNA-containing nuclei, and insert them into donor egg cells.
Those donor egg cells, which originate from another animal of the same species, have their own nuclei extracted. It’s a matter of exchanging the DNA. The resulting cell is stimulated and cultivated in the lab until it begins to resemble an embryo. It is then implanted into the uterus of a surrogate animal—which ultimately gives birth to a clone.
There are a select few companies offering pet cloning services. Viagen, which claims to have “cloned more animals than anyone else on Earth,” will clone a dog or cat for $50,000. This is the company that cloned Streisand’s pet dog Samantha, twice.
This week, Colossal Biosciences—the “de-extinction” company that claims to have revived the dire wolf and produced a “woolly mouse” as a precursor to bringing back the woolly mammoth—announced its acquisition of Viagen, but stated that Viagen “will continue to operate under its current leadership.”
Pet cloning is a contentious issue, for several reasons. The companies themselves note that, while the cloned animal will be a genetic twin of the original, it won’t be identical. One concern is mitochondrial DNA—a minuscule fraction of DNA situated outside the nucleus and inherited from the mother. The cloned animal may acquire some of this from the surrogate.
Mitochondrial DNA is unlikely to significantly affect the animal itself. More crucial are the numerous factors believed to influence an individual’s character and demeanor. “It’s the classic nature-versus-nurture debate,” states Samantha Wisely, a conservation geneticist at the University of Florida. After all, identical human twins are never exact replicas of one another. Anyone who clones a pet with the expectation of a direct reincarnation is likely to find themselves disillusioned.
Furthermore, some animal welfare organizations oppose the practice of pet cloning. People for the Ethical Treatment of Animals (PETA) referred to it as “a horror show,” and the UK’s Royal Society for the Prevention of Cruelty to Animals (RSPCA) argues that “there is no justification for cloning animals for such trivial purposes.”
Yet there are alternative uses for cloning technology that could be considered less trivial. Wisely has been long interested in increasing the genetic diversity of the highly endangered black-footed ferret, for instance.
Currently, there are about 10,000 black-footed ferrets that have been bred in captivity from just seven individuals, according to Wisely. Such a level of inbreeding is detrimental to any species—it tends to leave animals vulnerable to health issues. They are less capable of reproducing or adapting to environmental changes.
Wisely and her team were able to access frozen tissue samples from two additional ferrets. Together with colleagues at the non-profit Revive and Restore, the group successfully created clones of those two individuals. The first clone, Elizabeth Ann, was born in 2020. Since that time, additional clones have been born, and the team has started breeding the cloned animals with the descendants of the other seven ferrets, according to Wisely.
This same method has been utilized to clone the endangered Przewalski’s horse, utilizing decades-old tissue samples preserved by the San Diego Zoo. It is too early to determine the effects of these initiatives. Researchers are still assessing the behavior and survivability of the cloned ferrets and their offspring.
Even this methodology is not without its critics. Some have noted that cloning by itself will not avert the extinction of any species. After all, it does not tackle the habitat destruction or human-wildlife conflict that initially led to the peril of these animals. And there will always be those who criticize individuals who clone animals as “playing God.”
Despite her involvement in cloning endangered ferrets, Wisely expresses that she would not pursue cloning her own pets. She presently cares for three rescue dogs, one rescue cat, and “geriatric chickens.” “I cherish them all,” she states. “But there are numerous rescue animals that need homes.”
This article first appeared in The Checkup, MIT Technology Review’s weekly biotech newsletter. To receive it in your inbox every Thursday, and read articles like this first, sign up here.
