The Tasmanian Tiger, or Thylacine (Thylacinus cynocephalus), was a unique, dog-like carnivorous marsupial that once roamed across Australia and New Guinea, with its last wild refuge being Tasmania. Its distinctive dark stripes earned it the “tiger” moniker, and it was the world’s largest marsupial predator until its extinction. The species was driven to extinction primarily by human hunting, habitat loss, and disease following European settlement. The last known individual died in captivity in 1936. Today, “de-extinction” seeks to reverse that loss, using biotechnology to create a proxy of the Thylacine and return a functional apex predator to the Tasmanian ecosystem.
The Scientific Blueprint for Revival
The process of de-extinction begins with constructing a complete genetic instruction set by obtaining a high-quality reference genome from preserved Thylacine specimens. Scientists compare this ancient genome to that of the species’ closest living relative, the fat-tailed dunnart. This comparison identifies the specific genetic differences that must be edited into the dunnart’s DNA to transform its cells into those of a Thylacine.
Gene editing technology, specifically CRISPR, is used to precisely make thousands of necessary changes in the living cells of the surrogate species. Once a viable, genetically engineered Thylacine cell is created, it must be developed into an embryo. This requires pioneering marsupial-specific assisted reproductive technologies (ART), which are less developed than those for placental mammals.
The final biological step is gestation, where the embryo needs a host to grow before birth. Scientists are pursuing two main options: transferring the engineered embryo into a surrogate mother, such as the dunnart, or growing the embryo in an artificial uterus. Since marsupial young are born at an early, almost embryonic stage, this short initial gestation period offers a unique advantage for artificial development.
Current Progress and Project Milestones
Significant progress has been made by the collaboration between Colossal Biosciences and the University of Melbourne’s TIGRR Lab. Researchers have successfully sequenced the Thylacine genome, assembling a blueprint that is over 99.9% accurate and complete to the chromosomal level. This milestone provides the necessary foundation for the genetic engineering work.
Initial gene editing efforts have begun, with researchers achieving over 300 unique edits in a single dunnart cell. This work focuses on implementing the changes that define the Thylacine’s unique characteristics. Parallel efforts are focused on solving the reproductive challenge, leading to breakthroughs in marsupial ART.
The teams have successfully induced ovulation in the dunnart, a crucial step for in-vitro fertilization previously unachieved in this species. They have also cultured fertilized single-cell marsupial embryos over halfway through their short gestation period within an artificial uterus device. These combined advancements are rapidly pushing the project into practical application.
Why Predicting a Timeline Is Difficult
Setting a firm date for the Thylacine’s return is complicated by substantial biological and technological hurdles. While early projections suggested a first birth within a decade, the sheer number of genetic edits required remains a major bottleneck. Scientists estimate that thousands of edits are needed to fully differentiate the dunnart genome into a functional Thylacine genome.
The development of marsupial-specific reproductive technology is an ongoing challenge. Though initial success with artificial culturing is promising, reliably creating a full-term, healthy embryo and successfully introducing it into a host remains unperfected. The long maturation period of marsupials means that even after a successful first birth, it will take several years to determine if the resulting animal is reproductively viable and capable of thriving.
The ultimate goal is not a single animal, but a self-sustaining, genetically diverse population, which requires scaling up the process significantly. Each step, from perfecting the gene edits to ensuring the health of the resulting offspring, must be validated and made repeatable hundreds of times. This necessity for replication, combined with the unpredictable nature of biological engineering, makes any precise timeline a speculative projection.
Ecological and Reintroduction Challenges
Creating a viable Thylacine proxy in a lab is only the first part of the challenge; the second is ensuring its successful return to the wild. After its extinction, the Tasmanian ecosystem adapted to the absence of this apex predator, leading to an imbalance known as a trophic cascade. Reintroducing the Thylacine is expected to restore equilibrium by controlling smaller, invasive mesopredators and restoring natural prey dynamics.
The modern Tasmanian environment presents challenges the original Thylacine did not face, including new diseases and pressure from feral and introduced species. A comprehensive assessment is required to ensure that the protected habitat remaining is adequate to support a population of large carnivores without causing unforeseen negative impacts on current native species.
The logistical and political process of rewilding an extinct species is immense, requiring public acceptance and collaboration with government agencies and Indigenous partners. Before any animals are released, a robust plan must monitor the Thylacine’s impact on the ecosystem and manage its interactions with livestock and humans. The goal is to return a functional animal that can survive, reproduce, and fulfill its role, not just a genetic curiosity.