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Nearly 100 years after its extinction, the Tasmanian tiger could live again. Scientists want to resurrect the striped carnivore marsupial, officially known as the thylacine, that once roamed the Australian bush.
The ambitious project will harness advances in genetics, ancient DNA recovery and artificial breeding to bring the animal back.
“We strongly advocate that we must first and foremost protect our biodiversity from further extinctions, but unfortunately we are not seeing a slowdown in species loss,” said University of Melbourne professor Andrew Pask. and responsible for its Thylacine Integrated. Genetic Restoration Research Lab, which leads the initiative.
“This technology offers a chance to correct this and could be applied in exceptional circumstances where fundamental species have been lost,” he added.
The project is a collaboration with Colossal Biosciences, founded by tech entrepreneur Ben Lamm and Harvard Medical School geneticist George Church, who are working on an equally ambitious, if not bolder, $15 million project to bring back the woolly mammoth in modified form.
About the size of a coyote, the thylacine disappeared almost 2,000 years ago. everywhere except the Australian island of Tasmania. As the only marsupial apex predator to have lived in modern times, it has played a key role in its ecosystem, but it also made him unpopular with humans.
European settlers on the island in the 1800s blamed thylacines for livestock losses (although in most cases wild dogs and human habitat mismanagement were actually the culprits), and they hunted the shy, semi-nocturnal Tasmanian tigers to the point of extinction.
The last living thylacine in captivity, named Benjamin, died of exposure in 1936 at Beaumaris Zoo in Hobart, Tasmania. This monumental loss occurred shortly after thylacines were granted protected status, but it was too late to save the species.
The project involves several complicated steps that incorporate advanced science and technology, such as gene editing and the construction of artificial wombs.
First, the team will draw up a detailed plan genome of the extinct animal and compare it with that of its closest living relative – a mouse-sized carnivorous marsupial called the fat-tailed dunnart – to identify differences.
“We then take live cells from our dunnart and edit their DNA wherever it differs from the thylacine. We’re basically designing our dunnart cell to be a Tasmanian tiger cell,” Pask explained.
Once the team successfully programmed a cell, Pask said stem cells and breeding techniques involving dunnarts as surrogates would “turn that cell into a living animal.”
“Our ultimate goal with this technology is to restore these species to the wild, where they have played an absolutely essential role in the ecosystem. So our ultimate hope is that you will see them again someday in the Tasmanian bush,” he said.
The fat-tailed dunnart is much smaller than an adult Tasmanian tiger, but Pask said all marsupials give birth to tiny cubs, sometimes as small as a grain of rice. This means that even a mouse-sized marsupial could serve as a surrogate mother for a much larger adult animal like the thylacine, at least in the early stages.
Reintroducing the thylacine to its old habit should be done very carefully, Pask added.
“Any release like this requires studying the animal and its interaction in the ecosystem over many seasons and in large areas of closed land before considering a full reseeding,” he said.
The team hasn’t set a timeline for the project, but Lamm said he believes progress will outpace efforts to bring back the woolly mammoth, noting that elephants take much longer to gestate than dunnarts.
The techniques could also help living marsupials, such as the Tasmanian devil, avoid the fate of the thylacine as they grapple with intensifying bushfires in the wake of the climate crisis.
“The technologies we are developing to eradicate the thylacine all have immediate conservation benefits – right now – to protect marsupial species. Biobanks of frozen tissue from living marsupial populations have been collected to protect against fire suppression,” Pask said via email.
“However, we still don’t have the technology to take that tissue – create marsupial stem cells – and then turn those cells into a living animal. That’s the technology we will be developing in this project.
The way forward, however, is unclear. Tom Gilbert, a professor at the University of Copenhagen’s GLOBE Institute, said there are significant limits to deextinction.
Recreating the complete genome of a lost animal from DNA contained in ancient thylacine skeletons is extremely difficult, and therefore some genetic information will be missing, explained Gilbert, who is also director of the Center for Evolutionary Hologenomics at the Danish National Research Foundation. He studied the resurrection of the extinct Christmas Island rat, also known as Maclear’s rat, but is not involved in the thylacine project. The team won’t be able to recreate the thylacine exactly, but will eventually create a hybrid animal, a modified form of the thylacine.
“We are unlikely to get the full genome sequence of the extinct species, so we will never be able to completely recreate the genome of the lost form. There will always be parts that cannot be changed,” Gilbert said by email.
“They will have to choose what changes to make. And so the result will be a hybrid.
It’s possible, he said, that a genetically flawed hybrid thylacine has health problems and won’t survive without lots of help from humans. Other experts question the very concept of spending tens of millions of dollars on de-extinction attempts when so many living animals are on the verge of extinction.
“To me, the real benefit of any de-extinction project like this is how awesome it is. Doing it feels very justified to me just because it will get people excited about science, nature, conservation,” Gilbert said.
“And we really need that in the wonderful citizens of our world if we are to survive into the future. But… do the stakeholders realize that what they will get will not be the thylacine but an imperfect hybrid? What we don’t need is more people who are disappointed (or) feeling cheated by science.