100 years after extinction, the Tasmanian wolf can live again. Scientists want to resurrect a striped carnivorous marsupial, officially known as a thylacine, that roamed the Australian bush.
The project will take advantage of scientific advances in genetics, ancient DNA recovery and artificial reproduction to resurrect animals.
“First, we strongly advocate protecting our biodiversity from further extinction, but unfortunately we’re not seeing a slowdown in species loss,” said Andrew Bask, a professor at the University of Melbourne and director of its Integrated Research Laboratory on Thylacine. Genetic recombination, which leads the initiative.
“This technology offers an opportunity to fix this problem and can be used in exceptional situations where the base species have been lost,” he added.
The project is in partnership with Colossal Biosciences, founded by tech entrepreneur Ben Lam and Harvard Medical School geneticist George Church. The company is working on an equally ambitious, perhaps bolder, $15 million project to bring back the woolly mammoth in convertible form.
The size of a coyote, the thylacine disappeared worldwide about 2,000 years ago, except for the Australian island of Tasmania. As the only carnivorous marsupial predator to have lived in modern times, it plays an important role in its ecosystem, although it is not popular with humans.
Europeans who settled the island in the 19th century blamed livestock losses on thylacines (in most cases due to feral dogs and mismanagement of human habitat), and hunted Tasmania’s shy, semi-nocturnal wolves to extinction.
The last thylacine in captivity, named Benjamin, died in 1936 at the Beaumaris Zoo in Hobart, Tasmania, after being exposed to a rare case of extreme weather.
The program involves many complex steps involving advanced science and technology, such as gene editing and creating artificial wombs.
First, the team will create a detailed genome of the extinct animal and compare it to its closest relative, a mouse-sized carnivorous marsupial called the fat-tailed tunnard, to identify differences.
“Then we take live cells from our Dunnard and replace its DNA in all the places where it differs from the thylacine. Basically, we turn the Dunnard cell into a Tasmanian wolf cell,” Bask explained.
Once the team successfully reprograms a cell, Bask said, stem cell and reproductive techniques allow Dunnards to “turn that cell back into a living animal.”
“Our ultimate goal with this technology is to restore these species to the wild, where they played an absolutely vital role in the ecosystem. So our ultimate hope is that one day we’ll see them back in the Tasmanian bush,” he said.
A fat-tailed dunnard is much smaller than an adult Tasmanian wolf, but all marsupials give birth to tiny pups, sometimes as small as a grain of rice, Bask noted. This means that a rat-sized marsupial can serve as a surrogate stomach, at least initially, for very large adult animals such as the thylacine.
Re-introducing the thylacine to its old habits should be done very carefully, Bask added.
“Any release like this needs to be analyzed over large areas of covered land before considering its interaction with animals and ecosystems over multiple seasons and complete remodeling,” he said.
The group has yet to set a timeline for the project, but Lam said he thought progress would be faster than efforts to reintroduce woolly mammoths, noting that elephants take longer to get pregnant than dunnards.
These techniques could help other marsupials avoid the fate of the thylacine, such as the Tasmanian devil, which is endangered by forest fires as a result of the climate crisis.
“The technologies we are developing to resuscitate the thylacine have all the immediate conservation benefits for marsupial species conservation. Biobanks of frozen tissue from living marsupial populations have been collected to protect against fire,” Bask said.
“However, we don’t yet have the technology to harvest this tissue, create marsupial stem cells, and then transplant those cells into a living animal. That’s the technology we’re going to develop as part of this project.”
However, the path forward is not linear and clear. Tom Gilbert, a professor at the GLOBE Institute at the University of Copenhagen, said there are significant limitations to the resurrection of extinct animals.
Reconstructing the complete genome of an extinct animal from DNA in ancient skeletons is a major challenge, meaning some genetic information may be lost, explained Gilbert, who is also director of the Center for Evolutionary Hologenomics at the Danish National Research Foundation.
In turn, Gilbert has studied the resurrection of the Christmas Island mouse, also known as the Maclear mouse, but is not involved in the project. The team cannot reproduce the thylacine exactly, but instead creates a hybrid animal that is a modified version of the thylacine.
“It’s impossible for us to get the complete genome sequence of an extinct species, so we can’t completely recreate the genome of a lost species. There will always be some parts that can’t be changed,” Gilbert said. .
“They have to choose what changes they want to make. So, there will be consequences
A genetically defective thylacine hybrid may have poor health and cannot survive without the help of humans, he said. Other experts question the idea of spending millions of dollars on resuscitation efforts when so many living animals are on the brink of extinction.
“To me, the real benefit of any project like this is its magnitude. It seems to me very reasonable to do it because it will stimulate people’s interest in science, nature, conservation,” Gilbert said.
“And if we’re going to survive in the future, we need that awareness in our world. But…are stakeholders realizing what they’re going to get is not a thylacine, but an imperfect hybrid? What haven’t we done? We need very disillusioned people.” Or feel cheated by science.”