My social media feeds this week have been full of headlines about how a trio of genetically engineered dire wolves are the newest advance in the quest to clone extinct animals. The short version is that researchers from Colossal Biosciences altered fourteen genes in the gray wolf (Canis lupus) genome to resemble genes taken from dire wolf (Aenocyon dirus) fossils. The DNA was then inserted into denucleated domestic dog (Canis familiaris) egg cells which were then implanted in domestic dog surrogates.
Three of these eggs resulted in viable pups. Romulus and Remus are six months old, while Khaleesi is two months. The pups are white-furred, heavier-boned than gray wolves, and show wolf-like wariness of humans. But are they true dire wolves?
That’s the real question. You can add in genes from a dire wolf to an extant canid, but that doesn’t make them identical to the extinct species. Moreover, dire wolves are not as closely related to gray wolves as was previously thought; they were recently reassigned to a new genus that reflects their closer resemblance to modern-day jackals. There really isn’t a good analogue to them alive today, particularly when compared to the aurochs, another extinct species, and its domestic cattle descendants.
There have been attempts to backbreed domestic cattle (Bos taurus) to aurochs (Bos primigenius), which went extinct a mere 400 years ago. Heck cattle and the Tauros programme are two examples of efforts to create cattle that more closely resemble their wild forebears. Aurochs backbreeding involves choosing animals that physically resemble the extinct animals, such as having longer faces and legs, curled horns, and dark coloration with a white muzzle. However, just as you can’t make a gray wolf by breeding wolf-like domestic dogs, you can’t make a true aurochs with domesticated cattle.
This gets us into phenotype (appearance and other physical characteristics) vs. genotype (genetic material). We don’t know exactly what dire wolves looked like, beyond their preserved bones, and possibly the genes that gave the three pups their thick, white pelage. We also don’t know how they behaved, and there are no living dire wolves to teach the pups the ways of their world. While we can make some educated guesses based on the behaviors of extant social canids like gray wolves and African painted dogs (Lycaon pictus), we can’t say with full certainty that dire wolves behaved the same way.
Let’s say we could clone extinct animals and somehow make a genotypically perfect dire wolf. The youngest reliably dated dire wolf remains are from about 10,000 years ago. This may seem like a relatively short time, and from a geological perspective it is. But a lot can happen in that time biologically and ecologically–for example, mule deer (Odocoileus hemionus) only appeared as a distinct species 10,000 years ago from hybridization of white-tailed deer (Odocoileus virginianus) and black-tailed deer (Odocoileus hemionus). And while human overhunting likely contributed to the extinction of many species of megafauna at the end of the last ice age 11,000-12,000 years ago, climate change was almost certainly a major factor as well. Given that the planet is heating up even more rapidly due to anthropogenic climate change, would it even be ethical to bring these cold-weather animals back under current conditions?
And, finally, would they still fulfill the same ecological role that they did thousands of years ago? Plains bison (Bison bison bison) and domestic cattle may be related, and share some behaviors, but cattle absolutely are not good replacements for bison. Their grazing patterns and migratory tendencies vary significantly, as does the makeup of their manure, all of which have impacts on local ecology. Some people argue that feral domestic horses (Equus caballus) belong in North America because they may fill a niche left when the last native North American horse, Equus occidentalis, went extinct along with other ice age megafauna. However, once again the landscape has changed significantly in 12,000 years, and niches have shifted in intervening millennia, and so domesticated horses are not the perfect replacement for their extinct counterparts.
This isn’t even getting into the ethics of bringing back an extinct species when there’s no place set for them in the wild. The debate over de-extinction overshadows the grim reality that we are still chewing up wild habitat at unprecedented rates, putting an increasing number of species at risk of extinction–or driving them entirely over the edge. It’s easier to get excited about sexy headlines featuring Jurassic Park-style wild science than the ongoing fight to not only put the brakes on environmental destruction–no small feat–but repair the damage.
All of which is to say while it’s interesting to see the genetic engineering advances represented by the three “dire wolves” now revealed to the world, it doesn’t mean that we’ve brought back an entire extinct species. And really, is the best tactic right now to clone extinct animals? While we could potentially use this technology to clone critically endangered species and reinject preserved DNA from long-dead individuals into the active gene pool, it’s very resource-intensive. And none of this is as important as preserving the habitats that these rare species need to survive. Eye-catching headlines about dire wolves may help raise awareness and funding, but they are not a replacement for the ongoing hard work of conservation.
Very interesting Rebecca. I was wondering about this. I’ve always been concerned about bringing a species back that became extinct due to environmental changes. How would they fit in? Would they be detrimental to species that evolved to replace them? Or simply suffer and continue to go extinct? Evolution is a natural process that benefits the continuation of life overall. No need to mourn the loss of species that no longer fit. Imagine how challenging our human existence would be if T-Rex was still around.
I wonder the same things. Gray wolves have expanded into the apex predator role formerly taken by dire wolves–to an extent, at least, since dire wolves specialized in megafauna prey, whereas gray wolves are comparatively more generalist. (It’s much how coyotes have taken over areas where gray wolves have been extirpated.) Would the reintroduction of dire wolves threaten the recovery of gray wolves?
I think a lot of it comes from wistfulness about something lost so recently in our history, and also the knowledge that our actions likely contributed to their extinction. There’s a lot of “what if we had done things differently?” involved, I think.