September 30, 2023

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Colossal Biosciences and the Art of De-Extinction: Bringing Back the Tasmanian Tiger and the Woolly Mammoth

“Dead as a dodo.” That old saw is spoken to emphasize something so far gone it will never return. But it may well be time to retire that evergreen adage if Colossal Biosciences has its way. The cutting-edge biotechnology and genetic engineering firm is on the verge of de-extincting species that have long disappeared from Earth — and someday, that may include dodos.

Right now, geneticist Andrew Pask is heading a team of pioneers reviving the iconic woolly mammoth and the thylacine, a tigerlike marsupial commonly known as the Tasmanian tiger.

“De-extinction tech isn’t just about bringing back the thylacine; it’s about preventing other animals from becoming extinct,” Pask explained to the BBC.

Modern Science Revives Ancient Beasts

In 2012, scientists Emmanuelle Charpentier and Jennifer A. Doudna unveiled a gene-editing tech called CRISPR-Cas9, for which they won a Nobel Prize. This technology has paved the way to de-extinction, an ambitious undertaking embraced by Colossal Biosciences, which was co-founded by renowned Harvard geneticist George Church and Ben Lamm, a serial tech entrepreneur. 

In Australia, the company has partnered with Pask, the head of the Thylacine Integrated Genetic Restoration Research (TIGRR) Lab at the University of Melbourne. Pask and Colossal will be working together to bring back the Tasmanian tiger. 

“The great thing about the thylacine is that as it was such an important marsupial, every major museum wanted one in their collection, so there are hundreds of samples around the globe, and some are exceptionally preserved,” Pask told the BBC.

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A ‘Tiger’ in Colossal Biosciences’ Tank

The thylacine was ubiquitous in Australia. When European settlers arrived Down Under, however, they drove the native animal to extinction because it was perceived as a threat to livestock. These unique marsupials were driven out of mainland Australia 2,000 years ago but continued to thrive on the Australian island of Tasmania until the 1920s. 

“European settlers came to Australia and brutally obliterated the animal,” said Pask. 

Colossal and Pask have obtained a DNA sample from the baby of a thylacine that had been shot. The thylacine had been carrying a baby in its pouch, which the shooters immediately preserved in alcohol. 

Despite a good sample, the company still has many steps to cover before a live thylacine can walk the Earth again. This is because over time, DNA starts to deteriorate, either from exposure to UV light or due to bacteria. When it breaks down, it’s difficult to piece together the puzzle that is the DNA sequence.

Fortunately for Colossal, the closest phenotype of the thylacine is still alive — the fat-tailed dunnart. As the two species share 95% of their DNA, scientists will be able to sequence a thylacine DNA that’s quite close to the original species. 

“All of those technologies are in place, but nobody’s done it on this scale before because the DNA-editing technology wasn’t good enough or quick enough. But now it’s come such a long way that we do have that tech, and we have had a significant investment to try and make this work,” explained Pask.

Colossal is also working on bringing back the woolly mammoth. Reviving the massive pachyderm has been a long-time interest of Colossal’s co-founder Church. 

The method for resurrecting the woolly mammoth is similar to that of the thylacine. The scientists at Colossal will splice the DNA of the woolly mammoth into the DNA of the Asian elephant. As with the thylacine and the dunnart, the woolly mammoth and the Asian elephant are phenotype relatives. The intention for bringing back the woolly mammoth is to fight climate change. The hybrid between the Asian elephant and the woolly mammoth will be introduced to Pleistocene Park. The woolly mammoth will help create long-gone grasslands and slow the thawing of the permafrost, thereby preventing the release of carbon that occurs as permafrost melts. 

“Back-breeding” is another process scientists can use to revive extinct species. However, the problem with this method is that it’s not possible with animals that died too long ago. Efforts are being made to revive the auroch — an ancestor of modern domesticated cattle that was common throughout Europe — using this method. The auroch was as tall as a modern elephant. Since it went extinct in the 1600s, its genes persist in modern cattle, which is what makes back-breeding this species possible.

Some skeptics have been critical of the efforts of Colossal Biosciences and others conducting de-extinction projects, questioning whether they’re factoring in the unintended consequence that may occur as a result of the de-extinction. However, Archer has a simple response for the critics: “I think the ethical issue here was the impropriety of humans making these animals extinct in the first place.”

This project isn’t being pursued because scientists have taken a fancy to one extinct animal or the other. Reviving the thylacine or the mammoth will pave the way for the de-extinction of other animals that fell prey to human impropriety. 

“We have so many bushfires in Australia, and with rising global temperatures, we are going to see more adverse weather events in the decades to come,” said Pask. “What Australia has been doing is collecting tissues from marsupials in those areas that are most at risk and freezing them. This means that if a bushfire came along, once the vegetation grew back you could repopulate that area with that species.”