The state of science journalism keeps getting worse, and the stories about the dire wolf being brought back from extinction make me want to give up writing about science. The dire wolf is still extinct, and the unscientific claims that we brought it back from extinction are utterly false.

This Jurassic Park nonsense, bringing back extinct animals from the past, may seem cool and interesting, but it’s not very scientific. Of course, we cannot bring back 65 million-year-old non-avian dinosaurs — even if we could, the environmental effects would be unpredictable and dangerous. But maybe we could bring back an animal that only went extinct 10,000 years ago.

Let’s figure out what’s going on here. Spoiler alert — we did not de-extinct the dire wolf.

What is a dire wolf?

Dire wolves are large extinct canines (Aenocyon dirus) that lived in the Americas until around 10,000 years ago. They were canines that emerged during the Late Pleistocene, between 129,000 and 11,700 years ago, before becoming extinct around 9,500 years ago. They lived throughout the Americas and likely evolved to hunt down the especially massive megafauna seen during the Ice Age.

Despite its name, the dire wolf is not a wolf, it is in the genus Aenocyon, which is distinct from the genus Canis, which includes dogs, wolves, and Eurasian jackals.

Dire wolves were as much as 25% larger than gray wolves and had a slightly wider head, lighter and thicker fur, and stronger jaws. As hyper-carnivores, their diet comprised at least 70% meat from mostly horses and bison.

The animals looked like large wolves with white coats. They were made famous by the Game of Thrones TV series – the de-extincted female dire wolf was given the name Khaleesi, after a main character in the show. I am not a fan of Game of Thrones, so I’m trusting other people that this is true. I guess this is one of the reasons why these “wolves” are making the headlines.

According to DNA evidence, the last common ancestor between the dire wolf and Canis occurred about 5.7 million years ago. This is an important fact — dire wolves and modern wolves are not that closely related. The dire wolf is more closely related to other canids such as the dhole, African wild dog, and African jackals.

Colossal Biosciences, the biotech company that supposedly brought back the dire wolf (and about whom we will discuss below), claims that the dire wolf and modern wolf share about 99.5% of DNA. However, I could not independently confirm that claim, and if dire wolves and wolves diverged 5.7 million years ago, I am highly skeptical. Nevertheless, when someone throws around that the two species share 99.5% of DNA, it really means nothing in an evolutionary sense.

Since the grey wolf genome is around 2.4 billion base pairs long, a 0.5% difference in DNA still leaves a 12 million base pair difference between the grey wolf and dire wolf.

Did we de-extinct a dire wolf?

Colossal Biosciences, a US biotechnology company that is focused on de-extincting animal species, announced that they made 20 changes to an extant wolf’s genome. Five of the changes were known to produce light coats in grey wolves, which gave the dire wolves’ white color. The other 15 changes were based on dire wolf DNA that had been preserved in fossilized skeletons — these altered the animals’ size, musculature, and ear shape.

To de-extinct the dire wolf, Colossal Biosciences did the following:

• Extracted and sequenced ancient DNA from two dire wolf fossils — a tooth from Sheridan Pit, Ohio, that is around 13,000 years old, and an inner ear bone from American Falls, Idaho, around 72,000 years old.
• Assembled ancient genomes from both fossils and compared them to genomes from living canids, including wolves, jackals, foxes, and dholes.
• Identified gene variants specific to dire wolves.
• Determined that dire wolves had a white coat color, and long, thick fur – aspects of the dire wolf morphology that could not be determined from fossils.
• Performed multiplex gene editing on the genome from their closest living relative, the gray wolf, resulting in edits to 20 sites in 14 genes, with 15 of those edits being extinct variants.
• Screened the edited cell lines via whole genome sequencing and karyotyping.
• Cloned high-quality cell lines using somatic cell nuclear transfer into donor egg cells.
• Performed embryo transfer and managed interspecies surrogacy.

They were able to create two male dire wolves (named Romulus and Remus from the Roman origin myth) and the previously mentioned female, Khaleesi.

But do those DNA changes give us a whole new species of dire wolf? I am unconvinced. Sure, it’s amazing what Colossal Biosciences did to alter the grey wolf genome, but a dire wolf had millions of DNA mutations that are different than a grey wolf.

The definition of a “species” is rather arbitrary and a construct of humans trying to make order of organisms’ family trees. Colossal Biosciences can claim that they made a dire wolf, and they probably could defend it. But I’m pretty certain that 20 changes out of millions is too small to claim that we’ve brought back the dire wolf.

At best, it appears that Colossal Biosciences gave us an altered grey wolf that may look like a dire wolf. It may even behave like one because it is still a wild animal. I sincerely doubt it.

There’s also another issue with what they did. Genes don’t evolve independently of one another. If you place a gene for larger size into the grey wolf, what happens to the rest of the physiology? They didn’t add genes for more robust circulatory and pulmonary systems. Genes have extraordinarily complex interactions with one another, so changing even a few genes could have unpredictable outcomes like the dire wolf dying young.

And this is where so-called science journalists went off the rails. They are using clickbait headlines that want you to believe that we have brought back these animals from extinction. We haven’t.

Colossal Biosciences gave us some really cool science. They inserted some genes from an extinct animal into a modern animal. To me, that is exciting knowledge gained.

But they did not bring back that extinct animal. These cute puppies are not dire wolves, they are a slightly genetically-modified grey wolf.

If someone can extract the full dire wolf genome, somehow find the differences between it and an extant Canis species, and finally, change everything different between the two species, then we would have de-extincted the animal. But we are far from that.

Colossal Biosciences seemed to focus on morphological changes to make a grey wolf look like a dire wolf. However, those millions of other DNA base pair changes probably change a lot more than just morphology — they may have major effects on physiology, behavior, and other attributes.

We have not brought back the dire wolf — we just got a modified grey wolf.

But that doesn’t take away from what Colossal Biosciences did, which is scientifically interesting. They have given us extraordinary data about the dire wolves’ genome in addition to finding what genes may give us hints about the dire wolves’ morphology.

It’s the science journalists who made this more than what it is.

Citations

• McCarty NS, Graham AE, Studená L, Ledesma-Amaro R. Multiplexed CRISPR technologies for gene editing and transcriptional regulation. Nat Commun. 2020 Mar 9;11(1):1281. doi: 10.1038/s41467-020-15053-x. PMID: 32152313; PMCID: PMC7062760.
• Perri AR, Mitchell KJ, Mouton A, Álvarez-Carretero S, Hulme-Beaman A, Haile J, Jamieson A, Meachen J, Lin AT, Schubert BW, Ameen C, Antipina EE, Bover P, Brace S, Carmagnini A, Carøe C, Samaniego Castruita JA, Chatters JC, Dobney K, Dos Reis M, Evin A, Gaubert P, Gopalakrishnan S, Gower G, Heiniger H, Helgen KM, Kapp J, Kosintsev PA, Linderholm A, Ozga AT, Presslee S, Salis AT, Saremi NF, Shew C, Skerry K, Taranenko DE, Thompson M, Sablin MV, Kuzmin YV, Collins MJ, Sinding MS, Gilbert MTP, Stone AC, Shapiro B, Van Valkenburgh B, Wayne RK, Larson G, Cooper A, Frantz LAF. Dire wolves were the last of an ancient New World canid lineage. Nature. 2021 Mar;591(7848):87-91. doi: 10.1038/s41586-020-03082-x. Epub 2021 Jan 13. PMID: 33442059.
• Sinding MS, Gopalakrishnan S, Raundrup K, Dalén L, Threlfall J; Darwin Tree of Life Barcoding collective; Wellcome Sanger Institute Tree of Life programme; Wellcome Sanger Institute Scientific Operations: DNA Pipelines collective; Tree of Life Core Informatics collective; Darwin Tree of Life Consortium; Gilbert T. The genome sequence of the grey wolf, Canis lupus Linnaeus 1758. Wellcome Open Res. 2021 Nov 12;6:310. doi: 10.12688/wellcomeopenres.17332.1. PMID: 34926833; PMCID: PMC8649967.

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