The dire wolf has not been seen in over 10,000 years. However, hybrid grey wolves have been genetically modified to replicate the dire wolf, thanks to the biotechnology startup Colossal Biosciences.
Colossal scientists were able to decipher the dire wolf genome with the help of genetic engineering and ancient, preserved DNA. Using this, they rewrote the genetic code of the common gray wolf to match it and used domestic dogs as surrogate mothers. This process yielded three pups, two males named Romulus and Remus and their 2-month-old sister Khalessi, during three separate births between last fall and this winter. This marked the first de-extinction of a species whose gene pool vanished a long time ago.
The Dire wolf is not the only animal that Colossal scientists want to bring back. Their “de-extinction wish list” includes the woolly mammoth, the dodo bird, and the Tasmanian tiger. In March, the company announced that they were able to create a woolly mouse, a mouse with the accelerated fat metabolism of a mammoth (by copying mammoth DNA).
However, this idea of de-extincting certain species is not favored by everyone. Scientific history has shown newly introduced species becoming invasive, bringing danger to native species in that region. Along with that, genetic engineering is still in its infancy, and it is not clear what problems can arise in the cloned animals through this process. However, the cloning process can be difficult on the surrogate mother.
“There’s a risk of death. There’s a risk of side effects that are severe,” says Robert Klitzman, professor of psychiatry and director of the bioethics master’s program at Columbia University. “There’s a lot of suffering involved in that. There are going to be miscarriages.”
There are not many genetic changes between a living species and an extinct one. A wolf has 19,000 genes, but to create a dire wolf, only 20 edits in 14 genes are sufficient. The dire wolf genome was extracted from a 13,000-year-old tooth found in Sheridan Pit, Ohio, and a 72,000-year-old ear bone found in American Falls, Idaho.
Cloning typically requires a tissue sample from a donor and isolating a single cell, but in the dire wolf case, the isolated cell came from a donor gray wolf’s blood. The selected cells are known as endothelial progenitor cells, which form blood vessel lining. The scientists were then able to rewrite 14 key genes to match the dire wolf, and the edited nucleus was transferred into denucleated ovum. The scientists procured 45 engineered ova, which developed into embryos. Those embryos were then inserted into two surrogate mothers, who processed to a full-term pregnancy. This led to the birth of the two male pups. The same procedure was repeated with another group of embryos and surrogate mothers, giving birth to Khalessi. This allowed the company to produce replicas of the dire wolf from grey wolves with the help of engineered genes.
Since their births, the wolves have lived on an ecological preserve in the U.S., a location that is kept secret to protect the animals. The preserve is surrounded by a ten-foot fence and includes a veterinary clinic, an extreme-weather shelter, and natural dens to satisfy the need for a secure retreat.
“I think they are the luckiest animals ever,” says Beth Shapiro, Colossal’s Chief Science Officer. “They will live their entire life on this protected ecological reserve, where they have all sorts of space.”
