Bringing back to life an enigmatic marsupial

Few men on Earth know as much about the thylacine as Professor Andrew Pask. He is so enthralled by the longlost marsupial, also known as the Tasmanian tiger, that he’s leading the effort for its de-extinction.

Through a potent cocktail of ingenuity, audacity and genetic engineering, he is creating a gene-by-gene instruction manual on how to do exactly that, in a laboratory at the University of Melbourne.

It is work that places him in the vanguard of a small but dedicated club of bioscientists working diligently in different parts of the world to bring back from oblivion extinct species that include the woolly mammoth and the dodo. Remarkably, it is no longer a question of whether such a feat will be achieved, but when – and by whom.

Professor Andrew Pask

Professor Andrew Pask examining a preserved thylacine skull in the Tiegs Museum, the University’s zoology collection located at the Parkville campus.

Professor Pask’s work happens in the University’s TIGRR (Thylacine Integrated Genomic Restoration Research) Lab where a team of 40 professionals – specialists in the fields of morphology, developmental biology, evolution, stem cell biology, genetics, genomics, bioinformatics and conservation – are working to bring back the apex predator (one residing at the top of the food chain).

It’s heady stuff. What was once considered science fiction is now science fact.

And to think, this endeavour all started as a sort of side hustle for Professor Pask, who found himself beguiled by the thylacine, the last of which is believed to have died in a Hobart Zoo in the 1930s.

“I couldn’t get government funding for a research project because, 20 years ago, such a project was seen as pie in the sky,” he recalled. But he persevered, finding a little bit of money here and there, and gleaned from other research projects.

From folklore to reality

Professor Pask managed to extract DNA from a baby thylacine – a pup taken from its mother’s pouch after she was killed in Tasmania in 1909 – which had been stored in the Melbourne Museum. Importantly, it had been preserved in alcohol, which maintained its DNA integrity.

“We put the DNA into a mouse to see if it could work again and it did,” he recalled. “It was then just a matter of scale and money to bring back the thylacine.”

Touched by the researcher’s passion and disturbed by the way the thylacine had been hunted to extinction, the Wilson Family Trust gifted Professor Pask’s research $5 million over 10 years.

This gift started the TIGRR Lab and encouraged Colossal Biosciences, an American-based biotech company, to invest another $14 million to expand the Lab.

“We came across Professor Pask’s incredible work, believe it or not, via some YouTube clips,” said Russell Wilson. “We realise that we are on the verge of a great breakthrough in science through improvements in technology and its application to the genome.”

The donation from the Wilson family and access to groundbreaking technology at the Dallas-based biotech company was transformative, notes Professor Pask.

“Having that level of investment meant that, for the first time, we could tell the world that we were working to bring back the thylacine,” he explained. “I will be forever grateful to Russell and his family.”

Past destruction, future promise

Long before the efforts to bring it back from the dead, the thylacine was part of Australian wildlife folklore. It was hunted to extinction on mainland Australia around 3000 years ago, but a population survived in Tasmania. Ultimately, they too were wiped out by hunters who believed, mistakenly, that the tigers were sheep killers.

However, the thylacine was critical to the environment because, as an apex predator, it helped control the spread of disease throughout the animal kingdom, and it also supported stabilisation of ecosystems.

Indeed, the loss of animals like the thylacine may represent humankind’s most destructive influence on nature. The emergence of the Tasmanian devil facial tumour is a good example of trophic downgrading – in which ecosystems break down following the loss of top-level predators such as the thylacine.

The thylacine’s extinction gave birth to the legend. Although the last known one died in 1936, there have been 900 reported ‘sightings’ of the marsupial since.

Indeed, Professor Pask’s laboratory was for a long time regularly sent Ziplock bags filled with poo that members of the public were convinced were the faeces of thylacines.

"It was always dog poo. There are a lot of wild dogs in Tasmania and even I couldn’t tell one from a thylacine at 10 metres," he said.

It’s a bit like the Loch Ness monster. The sightings keep the memory of the thylacine alive. Professor Andrew Pask

Professor Pask’s energies are sharply fixed on the future rather than the past, on creating a new chapter in the thylacine’s story. The DNA recovered from the pup stored at the Melbourne Museum provided the team with the material needed to attempt to sequence the entire genome blueprint of the extinct animal.

“It’s an enormous job to sequence through that genome and put the pieces of the puzzle back together,” Professor Pask explained. “It’s very challenging to rebuild these extinct genomes.”

The research journey has been exciting and exacting. Professor Pask and his team have now established that the fat-tailed dunnart, a mouse-like marsupial, is key to resurrecting the thylacine. It is ideal for breeding in captivity and will make a good surrogate.

The team is now filling in some of the gaps in the thylacine genome and has started to edit the dunnart genome to create the thylacine. “We have made about 10 edits and there are hundreds of thousands still to edit,” he explained.

“The technology to do this is getting better. It could take us 10 years to do all the necessary edits but if the tools improve – and they are likely to – that timeline will be cut drastically.”

Ecosystems more broadly stand to benefit

Genomes are rich sources of information, offering all kinds of insights into a marsupial’s past. They have discovered, for example, that the thylacine was becoming inbred towards the end of its existence. By engineering the genome, Professor Pask’s team will be able to create a healthier population.

Finding a home for them will not be a problem since their entire ecological niche still exists in Tasmania, as does the food chain it needs to survive.

One of the most exciting aspects to the current research is its promise for animal conservation.

Every tool we are drawing on to bring back the thylacine is an important tool for animal conservation.Professor Andrew Pask

“We need these tools to reverse the mistakes we have made over time. Australia’s record is abysmal – we hold the record for the most mammal extinctions.”

Being able to edit the DNA of marsupials will make it possible for scientists to engineer in features such as better immune health for some restricted populations.

“We can, for example, think about engineering a resistance to devil facial tumours for our Tasmanian devils, or try to engineer in cane toad toxin resistance for quolls.”

When he emigrated from the UK as a 10-year-old, Professor Pask was captivated by Australia’s magical animal kingdom. 38 years later, that magic endures.

“I care about what I do,” he said. “I always say, I’m the luckiest scientist alive. Working on the Tasmanian tiger and helping marsupials – I can’t think of anyone as fortunate as me.