Breakthroughs sometimes appear in unexpected places. The researchers working on the international push to bring back the thylacine say they found theirs in a bucket at the back of a cupboard in a Melbourne museum.
It contained an astonishingly well-preserved head of the extinct marsupial, also known as the Tasmanian tiger.
“It was literally a head in a bucket of ethanol in the back of a cupboard that had just been dumped there with all the skin removed and that had been sitting there for about 110 years,” Prof Andrew Pask, the head of thylacine integrated genetics. Restoration Research Laboratory (abbreviated as Tigrr) at the University of Melbourne, says.
“It was pretty rotten, an absolutely gruesome sight. People had cut big chunks of it.”
Aesthetics aside, the specimen had a lot going for it. It contained material that scientists thought would be impossible to find, including long RNA molecules essential to reconstructing the genome of an extinct animal. “This was the miracle that happened with this specimen,” says Pask. “It blew my mind.”
A year later, he says it has advanced the work of the team of Australian and American scientists who are trying to revive the species more than expected at this stage. “We’re further along than I thought we’d be and we’ve accomplished a lot of things that we thought would be very challenging and others said would be impossible,” he says.
The plan to ‘exterminate’ the thylacine
The project to bring back the thylacine is run by Colossal, a Texas-based biotech “de-extinction and species conservation” company, which also aims to recreate the woolly mammoth and dodo using genetic engineering techniques.
Led by technology and software entrepreneur Ben Lamm, Colossal has raised $235 million, employs 155 people directly and funds research in 13 labs around the globe. They include the Tigrr laboratory, which operates at the University of Melbourne School of Biosciences.
The thylacine was Australia’s only marsupial apex predator. It once lived across the continent but was restricted to Tasmania around 3,000 years ago. Dog-like in appearance and with stripes across its back, it was widely hunted after European colonization. The last known survivor died in captivity in 1936, and it was officially declared extinct in the 1980s.
Colossal says scientists have made several breakthroughs in their work with the species, putting the company much closer to its goal of returning it to the wild. They include what they say is the highest-quality ancient genome ever produced, with just 45 gaps in a genetic blueprint containing about 3 billion pieces of information.
Lamm says it’s an “incredible scientific leap” that puts the program “on track to eradicate the thylacine,” while other recent breakthroughs will be helpful in protecting critically endangered species. “We are pushing as quickly as possible to create the necessary science to make extinction a thing of the past,” he says.
The soft tissue from the Museums Victoria specimen, which the researchers called “head in a bucket”, contained preserved long sequences of DNA – genetic material that is the same in almost every cell nucleus in a body – but also long RNA molecules. Pask says the latter was crucial and unexpected.
RNA is much less stable than DNA. It varies in different types of tissue and contains what is effectively a readout of the active genes necessary for a particular tissue to function. This meant that researchers were able to obtain information related to the animal’s nose, eyes, tongue and other facial material, giving a picture of what a thylacine could taste and smell, what kind of vision it had and how its brain worked.
Pask says the result is the first annotated extinct animal genome. “It helps us prove that what we’re bringing back is really a thylacine and not a hybrid animal,” he says.
The thylacine researchers aim to take stem cells from a living species with DNA similar to a thylacine, the much smaller fat-tailed duck species, and turn them into the closest approximation of thylacine cells possible using gene-editing expertise developed by George Church, a professor of genetics at Harvard Medical School and Colossal’s co-founder.
A thylacine-like thing – but what comes next?
The announcement of the genetic breakthrough came ahead of an event at the SXSW festival in Sydney on Friday, where Lamm and Pask will talk about their work with actor Luke Hemsworth. The Hemsworth family has backed the project.
Colossal says it has also developed the first artificial reproductive technology to induce ovulation in marsupials, a move that could lead to captive breeding programs for endangered species, and fertilized single-cell embryos and grew them to more than halfway through pregnancy in an artificial womb.
On when a thylacine might be created, Pask says he expects the first “thylacine-like thing” could be born within three to five years, but that he “wouldn’t call it a thylacine.” He says scientists are confident of creating a thylacine’s skull, legs and even stripes, but there are “still other things we still don’t know how to do”.
Other scientists follow with varying degrees of caution and skepticism. Some ask why so much funding and effort goes into bringing back species when thousands that are still alive are on the brink of extinction. Euan Ritchie, professor of wildlife ecology and conservation at Deakin University, says it is an ambitious project and is likely to lead to breakthroughs that could help conservation. But he says there will be other challenges “if-and-when we bring back thylacine-like animals”.
“I think we’ll probably get some thylacine-like animal, but it won’t actually be thylacines. The question is: what comes next?” he says.
“How will they behave in the wild and what effects might they have in the ecosystems? We have no idea how they will behave because there are no living thylacines left and when you can bring back a thylacine-like animal, it has no other thylacine-like animals to learn from.
“It is at least as big a challenge, if not a bigger challenge, than the genetic challenge. As an ecologist, it is the great unknown.”