The Tasmanian Tiger, or thylacine, stands as a poignant symbol of extinction, its unique appearance and predatory nature having captivated public imagination. This iconic marsupial, with its distinctive striped back, represents a significant loss to global biodiversity. Despite its disappearance nearly a century ago, the prospect of its return has transitioned from speculative fiction to a tangible scientific pursuit. Modern scientific advancements in genetic engineering have fueled discussions and ambitious projects aimed at potentially bringing this creature back. This endeavor sparks public interest, prompting questions about its feasibility and implications.
The Thylacine’s Extinction
The thylacine ( Thylacinus cynocephalus ) was a large carnivorous marsupial native to mainland Australia, Tasmania, and New Guinea. On the mainland, the species faced extinction around 2,000 to 3,000 years ago, likely due to a combination of climate change, human activity, and competition with dingoes. The Tasmanian population, however, persisted until more recent times, inhabiting eucalyptus forests, grasslands, and coastal scrublands. European colonization of Tasmania marked the beginning of the end for the thylacine, primarily driven by human hunting.
Farmers and settlers, believing thylacines preyed on livestock, initiated widespread hunting. This led to bounty systems, notably the Tasmanian Parliament’s official bounty of £1 per thylacine introduced in 1888, which incentivized their eradication. Beyond hunting, habitat loss from land clearing and the potential spread of disease also contributed to their decline. The last known thylacine, often referred to as Benjamin, died in captivity at the Beaumaris Zoo in Hobart on September 7, 1936. While Benjamin was long considered the last, recent research suggests another female thylacine may have survived slightly longer, also dying at the zoo in 1936.
The Science of De-Extinction
The concept of de-extinction relies on advanced biotechnologies to resurrect species. One primary method is Somatic Cell Nuclear Transfer (SCNT), a cloning technique. SCNT involves taking the nucleus from a somatic (body) cell of the extinct animal and transferring it into an egg cell from a closely related living species. This reconstructed egg is then stimulated to develop into an embryo, which is subsequently implanted into a surrogate mother of the living relative. This approach requires well-preserved cells with intact DNA, making it most feasible for recently extinct species.
Another tool is gene editing, using CRISPR (Clustered Regularly Interspaced Short Palindromic Repeats) technology. CRISPR allows scientists to precisely modify DNA by targeting specific sequences, essentially acting as molecular scissors to cut and edit genetic material. For de-extinction, scientists can sequence the degraded DNA of an extinct species and compare it to the genome of its closest living relative. CRISPR can then be used to introduce specific genes or traits from the extinct species into the living relative’s genome, creating a hybrid organism that exhibits characteristics of the extinct animal. This method is particularly useful when complete, viable cells are not available, relying instead on fragmented ancient DNA.
Current Thylacine Revival Initiatives
Prominent initiatives to bring back the Tasmanian Tiger are led by the University of Melbourne and Colossal Biosciences. The University of Melbourne’s Thylacine Integrated Genetic Restoration Research (TIGRR) Lab, headed by Professor Andrew Pask, partnered with Colossal Biosciences in 2022, a genetic engineering company also involved in Woolly Mammoth de-extinction projects. This collaboration combines the TIGRR Lab’s marsupial research expertise with Colossal’s advanced CRISPR DNA editing and computational biology capabilities.
A major breakthrough for the project involved sequencing the entire thylacine genome from a 110-year-old pickled head, achieving over 99.9% accuracy. This genetic map guides the de-extinction process. Researchers are focusing on the fat-tailed dunnart, the closest living relative, as a potential surrogate. The teams are developing assisted reproductive technologies tailored for marsupials, including methods for creating stem cells, inducing ovulation, and exploring the use of artificial wombs or dunnart surrogates for gestation. Professor Pask has expressed confidence that a thylacine joey could be born within 10 years, while Colossal Biosciences has a more ambitious timeline, aiming for less than six years for the first mammoth calves.
Ethical and Practical Considerations for Revival
Ethically, concerns exist regarding animal welfare, as cloning processes can result in high rates of miscarriage and genetic abnormalities. Some question the morality of creating animals that may experience suffering. There is also a debate about humanity’s responsibility to rectify past extinctions.
Practically, the financial cost of de-extinction projects is high, raising questions about resource allocation. Critics suggest that these funds might be better invested in conserving currently endangered species or protecting existing habitats.
Even if a thylacine could be de-extincted, reintroducing it into the wild presents challenges. The original factors contributing to its extinction, such as habitat loss and disease, might still be present. Their integration into a transformed ecosystem could have unforeseen impacts. Researchers are considering where the animals would be placed and how their impact on the ecosystem would be monitored.