The Dire Wolf of Theseus
With Colossal Biosciences claiming to have re-created the Pleistocene dire wolf species, we should consider some skeptical objections to their claim
Recently, we were welcomed with the news that an Ice Age creature had been brought into this world. This was a ferocious, hairy beast not unlike the ice age creatures driven into extinction by climate change and human action. This was … the humble woolly mouse. Maybe not the biggest or most exciting news, but this was still adorable. It was followed not long after by the announcement that the same scientists had recreated the Dire Wolf, a large wolf referenced in role playing games and fantasy novels. The hope is that they can soon go further by creating the great white (furry) elephant of the Pleistocene, the woolly mammoth
Who are these scientists, and how are they re-creating long-dead species from a time when the earth was covered in glaciers, and a time when there may have been a few tens of thousands of us wandering this earth? This is coming from Colossal Biosciences, a biotech firm aiming to de-extinct endangered species by modifying existing species using CRISPR technology. CRISPR allows biologists and geneticists to make targeted and specific changes to a genome to modify its genotype (its genetic information) and therefore its phenotype (its physiological and instinctive characteristics).
The news that they had created a Dire Wolf was big news. These creatures have plagued the world of tabletop and virtual roleplaying games alike, and have featured in G.R.R. Martin’s fantasy world of Westeros (full disclosure, despite being a huge fantasy nerd I’ve never read the books or watched the show). Martin himself excitedly tweeted out the images, and Colossal Biosciences shared a sound of the dire wolf howling.
It’s easy to understand the appeal. One can imagine a fantasy author like Martin, a game developer, or a dungeon master reading about these Ice Age terrors and wanting to incorporate them into his world while, deep down, wishing such great terrors still prowled our forests (though hopefully not the ones we frequent in our evening strolls). The world is surely more magical, even if also a bit more dangerous, with terrifying megafauna walking upon it.
Yet it is perhaps important to be skeptical of the claims around this discovery. Colossal Biosciences is a private firm and naturally wants investment and interest from the wider public to make their firm viable. If they can attract an audience with a narrative of repopulating the earth with the species we’ve driven into extinction, then they will naturally do so. Thus, they have a clear incentive to claim that they have restored the ancient dire wolf.
Naturally, there is some grounds for skepticism. If the company is to be believed, and I know no reason not to trust them about this at least, they used CRISPR to modify specific genes of the wild grey wolf with the genes of dire wolf samples. By analyzing samples from dire wolf fossils, the biologists were able to pick up some central identifying markers unique to the dire wolf. They were also able, it seems, to deduce the function of these genes in terms of making the wolves bigger, bulkier, stronger, and hairier. Thus, these wolves have some dire wolf genes for all intents and purposes. Presumably they at least look similar and are just as terrifying to encounter deep in the forest when you’re alone.
Yet are they a dire wolf? To explore that question, we can begin with the most famous thought experiment in Western mereology (the part of philosophy that looks at the relation of parts and wholes). This thought experiment goes back to the tale of Theseus, who sailed from Athens to Crete to fight the Minotaur before sailing home. Theseus was the great Greek hero identified with Athens. The ship he supposedly sailed had been painstakingly and ritualistically maintained by the Athenians to undergo sacred journeys to the island of Delos commemorate the epic exploits of Theseus (Theseus fled to Delos after his adventure in Crete). The ship was made of wood and textiles, like all ships of its era, and when the wood was sufficiently rotten it was carved out and replaced with new planks. It must be remembered that the journey of Theseus, if it has any historical basis, occurred centuries prior to the heyday of the city, and this ritual was referenced as still occurring in Plato’s dialogues (in fact, Socrates’s execution was delayed because the ship had not yet returned from Delos, and did not execute people while the pilgrimage was still occurring). Consequently the Athenians had to maintain this ship by replacing any parts that were too rotten for the ship to be seaworthy. Eventually, they presumably would have changed all the parts of the vessel.
The example of Theseus’s ship created an interesting problem of identity. Assuming the ship really was sailed by Theseus, was it actually the same ship? After all, over the centuries every plank of wood, every nail, every oar, and every sail would have decayed and been replaced. In fact, much if not all of the ship would have been replaced many times over. Even if we can imagine some few parts of the ship would remain the same (perhaps a few pieces here and there held up better with the elements), the vast majority of the ship is new. Had all those same new parts been used to make a new boat, we would not have considered it the “Ship of Theseus”. Why ought we call it the “ship of Theseus” if these same parts had all been used to replace rotten parts of the original boat? In other words, what makes a ship the “Ship of Theseus” if not the parts that constitute it? If we do think it is a new boat, at what point does the ship stop being the “Ship of Theseus” and become something else?
The example of the dire wolf is a Ship of Theseus in reverse. We have the grey wolf, which is most definitely a different species from the dire wolf. We have some genes of the dire wolf, and know which bits of the genome of the Grey Wolf to modify to create those dire wolf genes. We have inserted those specific genes into the grey wolf, but does that turn our grey wolf into a dire wolf? Maybe? Lets consider the thought experiment again. Let’s say we discover the ruins of the ancient Ship of Theseus somewhere off Athens. We dredge it up and find unsurprisingly that it is no longer a functional boat, but some of the important bits are still workable. We take a modern replica of a Greek trireme and install those pieces from the Ship of Theseus. Have we recreated the Ship of Theseus? How many parts from the original Ship of Theseus would we have to stick into our modern galley before it becomes a new Ship of Theseus?
It seems to me that what we would have is no longer either the Ship of Theseus or a replica of a Greek trireme (the trireme was a later invention of the Phonecians and would have been quite structurally different from the earlier ship Theseus sailed). It seems to me we’d have something altogether new - a kind of hybrid type of ship that has some features of the Ship of Theseus.
Perhaps then this “dire wolf” species that has been engineered is neither a gray wolf nor a dire wolf but something new. Perhaps we can call it “dire wolf beta” (except that might have other connotations, but I digress). That is much less exciting than re-creating a “pure” dire wolf, but it may be the best we can do.
Of course, if you’re a movie geek, you’ll notice that the plot to Jurassic Park is effectively that. As an explainer video in the movie tells the characters (in perhaps one of the best cases of an exposition dump in any Hollywood Movie), the park used DNA from frogs and spliced those samples with DNA from dinosaur blood discovered in fossilized amber. From this, they were able to create tyrannosarus rexes, velociraptors, triceratops, and sauropods to name a few. Yet were these really dinosaurs? On some level, they’re simply frogs with dinosaur characteristics!
What is a species anyways? Before Darwin, species were generally taken to be static categories organized around a particular biological plan and set of ends, as Aristotle and Aquinas explained. There is a particular form of “wolf”, and matter is organized into that form to constitute specific wolves (this is Aristotle’s idea of hylomorphism, or matter organized into a particular form). Darwin’s Origin of Species challenged this notion, and led to a new definition of species that is largely conventional. Every species has many varieties, and these varieties change slowly over many generations. This generational change leads to the emergence of new species in geological time, but what we call a new species or simply a variety of another species is entirely based on scientific convention and not anything intrinsic to the wolves themselves. We see different species of wolves as groups of animals that live separately and have different lifestyles. It makes sense to organize them into different species because that makes the world we live understandable. As Darwin explains in his Origin of Species:
Hence, in determining whether a form should be ranked as a species or a variety, the opinion of naturalists having sound judgment and wide experience seems the only guide to follow. We must, however, in many cases, decide by a majority of naturalists, for few well-marked and well-known varieties can be named which have not been ranked as species by at least some competent judges.
That varieties of this doubtful nature are far from uncommon cannot be disputed. Compare the several floras of Great Britain, of France, or of the United States, drawn up by different botanists, and see what a surprising number of forms have been ranked by one botanist as good species, and by another as mere varieties. Mr. H.C. Watson, to whom I lie under deep obligation for assistance of all kinds, has marked for me 182 British plants, which are generally considered as varieties, but which have all been ranked by botanists as species; and in making this list he has omitted many trifling varieties, but which nevertheless have been ranked by some botanists as species, and he has entirely omitted several highly polymorphic genera. Under genera, including the most polymorphic forms, Mr. Babington gives 251 species, whereas Mr. Bentham gives only 112—a difference of 139 doubtful forms! Among animals which unite for each birth, and which are highly locomotive, doubtful forms, ranked by one zoologist as a species and by another as a variety, can rarely be found within the same country, but are common in separated areas. How many of the birds and insects in North America and Europe, which differ very slightly from each other, have been ranked by one eminent naturalist as undoubted species, and by another as varieties, or, as they are often called, geographical races!
Often, species are distinguished by biologists when animals or plants are no longer able to breed with one another, of if they do breed they create infertile offspring. Horses and donkeys are understood to be different species because when they mate, they produce mules which are neither horses nor donkeys but more importantly are infertile. Yet this definition is itself flawed as there are animals that can breed with each other but don’t because they’re not sexually interested in each other, or sometimes produce viable offspring and sometimes do not (as with lions and tigers). Hermaphroditic species often cannot breed with other creatures, meaning by this definition, every individual hermaphrodite is its own species which makes no sense. In the case of extinct species like the dire wolf, there is no way to empirically know for sure that they could not breed with other species of wolf because it is unobservable (we might find fossilized remains of a dire wolf hybrid with other wolf species, but we’d have no way to know whether they could breed with other wolf species where we lack such fossil evidence, and it would be hard to prove whether that wolf was a hybrid or a new species since … they’re just fossils!). Thus, the definition of “species” remains conventional as it can be modified depending on particular biological, paleontological, and taxonomic realities.
We do not know whether the “dire wolf beta” can breed with grey wolves (at least, there’s no published evidence I’m aware of that Colossal Biosciences has tried) and we may never know whether or not they can breed with the original ice-age dire wolves. Yet we do know that our new dire wolves are entirely disconnected from the original blood line and only have certain genes selected based on the tastes and intentions of the genetic scientists who created them. What’s worse, they still mostly have a grey wolf genome and the scientists at Colossal do not know if there are any other important dire wolf genes that they overlooked.
Thus, it seems most sound to conclude that these dire wolves are some new species created in a laboratory - neither grey wolf nor ice age dire wolf. Any species that is un-extincted in this way will suffer the same problem. When they recreate the woolly mammoth, they will have much more genetic material to work with since we’ve found so many mammoths in ice, but still they will need to create the mammoths by splicing elephant DNA with the mammoth genes.
Consequently, we should probably be skeptical of the marketing from Colossal Biosciences. That doesn’t mean their discovery isn’t cool or interesting, or that a Pleistocene Park isn’t possible or not exciting. It just means you can’t really recreate an old species with a few genes spliced into a modern animal. And maybe that’s ok.