From all Possibly the most tragic loss of species that humanity has wiped from the face of the earth is the Thylacine. The thylacine, a wolf-sized marsupial sometimes called the Tasmanian tiger, met its end because the government paid its citizens a bounty for each animal killed. This end came just recently enough that we have photos and film clips of the last of the Thylacines ending their days in zoos. Late enough that in just a few decades, countries would start writing laws to prevent other species from suffering the same fate.
Yesterday, a company called Colossal, which has previously said it wants to bring the mammoth back, announced a partnership with an Australian lab it says is making the Thylacine extinct with a goal of reintroducing it into the wild. A number of features of marsupial biology make this a more realistic goal than bringing back the mammoth, although there’s still work to be done before we even start the debate on whether reintroducing the species is a good idea.
To learn more about the company’s plans for the thylacine, we spoke to Colossal founder Ben Lamm and Andrew Pask, head of the lab he works with.
In a way, Colossal is a way to organize and fund the ideas of Lamm’s partner, George Church. Church has been talking about mammoth eradication for a number of years, fueled in part by developments in gene editing. The company is structured as a startup and Lamm said it is very open to commercializing the technology it is developing while pursuing its goals. “On our road to extinction, Colossal is developing new innovative software, wetware and hardware technologies that can have profound implications for both conservation and human health,” he told Ars. But at its core, it’s about products to develop for which there is obviously no market: species that no longer exist.
The general approach to the mammoth is simple, even if the details are extremely complex. There are many samples of mammoth tissue from which we can extract at least partial genomes, which can then be compared to their closest relatives, the elephants, to find important differences from the mammoth lineage. Thanks to gene editing technology, key differences in an elephant stem cell’s genome can be edited, essentially “mammutifying” the elephant cells. A little IVF later and we have a shaggy beast ready for the subarctic steppes.
Here, too, the details matter. At the beginning of the plan, we had neither created elephant stem cells nor done gene editing, even at a fraction of the scale required. There are credible arguments that the peculiarities of the elephant’s reproductive system make the ‘piece of IVF’ that is required a practical impossibility; if it happens, it will require almost two years of gestation before the results can be evaluated. Elephants are also intelligent, social creatures and there is reasonable debate as to whether it is appropriate to use them for this purpose.
Given these challenges, it may be no coincidence that Lamm said Colossal was looking for a second species to extinct. And the search turned up a project that took a nearly identical approach: the Thylacine Integrated Genomic Restoration Research Lab, based at the University of Melbourne and led by Andrew Pask.
In the bag
As with Colossal’s mammoth plans, TIGRR intends to obtain thylacine genomes, identify the key differences between that genome and related lineages (primarily quolls), and then convert those differences into marsupial stem cells that would then be used for IVF. She, too, faces some significant hurdles, since no one has made marsupial stem cells or cloned a marsupial — two things that have at least been done in placental mammals (though not pachyderms).
But Pask and Lamm pointed out a number of reasons why the thylacine is a far more manageable system than a mammoth. For one thing, the animal’s survival into recent years means there are plenty of museum specimens, and therefore, Pask says, we’ll likely conserve enough genomes to get a sense of the population’s genetic diversity — likely crucial if we have one want to restore stable breeding population.