Khaleesi would approve: prehistoric wolves from Game of Thrones have been brought back to life in the US

US biotechnology company Colossal Biosciences says it has managed to bring back to life a long-extinct species, the lute wolves, which disappeared more than 12,000 years ago. Last week, the company released a video of the cute white pups, which scientists say are the result of a de-extinction project - recreating extinct species.

Colossal said in an official statement, "For the first time in human history, we have been able to restore a previously extinct species using science."

The project has sparked a lot of controversy in the scientific community. A video of the pups named Romulus, Remus and Khaleesi (after characters from Roman mythology and the TV series Game of Thrones) is being shared on social media, and scientists are debating whether there has been a real "resurrection" of lute wolves - or whether they are just genetically modified grey wolves.

How it works

The Colossal team studied the DNA of two lute wolf fossils - a 13,000-year-old tooth and a skull fragment that is about 72,000 years old. When they compared them to the DNA of modern grey wolves, they found 0.5% differences. These genes, the scientists believe, are linked to the body size, musculature and coat colouring of lute wolves.

Using CRISPR-Cas9 technology, the researchers introduced 20 of these genetic changes into grey wolf blood cells. They then placed the modified nucleus into an egg cell and transplanted the embryo into a surrogate dog.

Scientists have their doubts

Some scientists were sceptical of the claim. "It's like putting a couple of Neanderthal genes into a human being and calling him a Neanderthal," noted molecular biologist Alan Cooper.

Ecologist and wildlife expert Lysette Waites also does not think that we are looking at real direwolves: "This is not recreating an extinct species, but creating an organism with the appearance of a direwolf."

Nevertheless, she recognised that this is an important technological breakthrough.

Why it's important

While Colossal has not recreated the DNA of an extinct species 100%, the goal, according to the company's chief scientific officer Beth Shapiro, is not an exact copy, but a functional analogue. Eventually, the company wants to apply the same approach to dodos and mammoths - and recently even showed mice injected with DNA fragments from these prehistoric giants.

Critics fear that such experiments distract attention from the real causes of animal extinction - habitat loss and climate change. But other scientists see the technology as a chance to restore endangered species, especially if there is such a large financial interest behind the projects - more than $200 million in investment.