Scientists are bringing back extinct Tasmanian tigers
Can an extinct species be brought back to life? Scientists are taking a ‘giant leap’ in that direction by using gene-editing to resurrect the Tasmanian tiger, a carnivorous marsupial from Australia. It died out nearly a century ago, driven to extinction by human hunters and the introduction of non-native species to their grassland, wetland and forest habitats.
Researchers with the project, a collaboration between the University of Melbourne and the genetic engineering company Colossal Biosciences in Dallas, suggest that this so-called de-extinction could reinstall Tasmanian tigers (Thylacinus cynocephalus) to the wild within a decade, and could help restore balance to beleaguered Australian ecosystems where the animals once roamed. However, such efforts also raise questions about prioritising high-tech solutions for resurrecting animals that humans have already exterminated, while hundreds of species teeter on the brink of extinction today.
Scientists in the Thylacine Integrated Genomic Restoration Research (TIGRR) Lab at the University of Melbourne have already sequenced the thylacine genome from preserved thylacine
DNA and pinpointed which living marsupials are most genetically similar to thylacines. Colossal’s CRISPR gene editing technology will enable the group to take cells from a closely related living marsupial species, the fat-tailed dunnart (Sminthopsis crassicaudata), create a template genome, and then edit it to produce a thylacine genome and grow viable thylacine embryos.
“With this partnership, I now believe that in ten years’ time we could have our first living baby thylacine since they were hunted to extinction close to a century ago,”’ team member Andrew Pask, a professor of epigenetics at the University of Melbourne and leader of the TIGRR Lab, said in a statement. “We can now take the giant leaps to conserve Australia’s threatened marsupials and take on the grand challenge of de-extincting animals we had lost.”
Tasmanian tigers, or thylacines, appeared in Australia about 4 million years ago and were once widespread across the continent. Despite their name, they didn’t look much like tigers; in fact, they were sometimes referred to as ‘long dogs with stripes’ because of their doglike heads and distinctively marked rumps. Thylacines had short ears and legs, and long, rigid tails, and were about the size of an American coyote, about 60 centimetres tall and weighing 17-20 kilograms.
Thylacines vanished from most of the Australian mainland about 2,000 years ago, and an estimated population of about 5,000 were in Tasmania around the time of European colonisation in the 1800s. But by the 1920s, thousands of Tasmanian tigers had been slaughtered by human hunters who mistakenly saw the marsupials as a threat to livestock. The last Tasmanian tiger seen in the wild was killed in 1930, and the last one in captivity – nicknamed ‘Benjamin’ – died in the Hobart Zoo in 1936.
According to researchers with the deextinction project, resurrecting Tasmanian tigers would be a conservation success story; not only because it would restore a species that has been lost to human activity, but for building a lifeline for threatened species across Australia, “developing gestational and genetic rescue technologies for future marsupial conservation efforts,” said Colossal CEO and co-founder Ben Lamm. “With our planet’s biodiversity at risk, we will continue to contribute scientific resources to preserving the species and ecosystems necessary to sustain life.”