The Hidden Genetic Clues Behind the Tasmanian Tiger’s Extinction

The thylacine—better known as the Tasmanian tiger—has fascinated people for generations. With its wolf-like head, tiger-striped back, and marsupial pouch, it seemed like an animal assembled from spare parts. But despite its uniqueness, the thylacine vanished in 1936, leaving behind grainy zoo footage and endless speculation about what went wrong.

Most explanations point to familiar culprits: overhunting, competition with dingoes, habitat loss, and disease. But a new study from researchers at IISER Bhopal (Salve et al.) adds a fresh twist to this story. They argue that the seeds of the thylacine’s downfall may have been planted millions of years before the first settlers arrived in Tasmania—hidden deep within its DNA.

When Evolution Takes Away

We often think of evolution as a process of adding new traits—sharper teeth, stronger muscles, keener senses. But evolution also works by subtraction. Genes can break, mutate, or disappear entirely. Sometimes that helps a species adapt (for example, whales losing genes involved in smelling odors on land). But in other cases, gene loss can make a species less resilient when conditions change.

The new study shows that the thylacine had lost several important genes long before humans ever set foot in Australia. Among them:

• SAMD9L, a gene that helps fight viral infections.

• HSD17B13, linked to liver and metabolic health.

• CUZD1, involved in lactation and pancreas function.

• VWA7, connected to immune response and cancer susceptibility.

These losses weren’t accidents of one unlucky animal—the evidence shows they happened in the lineage millions of years ago, between 13 and 1 million years ago.

A Carnivore With Hidden Weaknesses

Intriguingly, the timing of these gene losses matches the thylacine’s evolutionary shift toward hypercarnivory—a lifestyle based almost entirely on eating other animals. This specialization came with bigger body size and sharper predatory skills, but may have made the thylacine genetically fragile.

For example, losing SAMD9L seems to be linked with a meat-heavy diet in many mammals. But this adaptation may have come at a cost: increased vulnerability to diseases. Similarly, the loss of CUZD1 could have made thylacine mothers less efficient at nursing, while the widespread loss of olfactory receptor genes suggests that thylacines relied less on smell than other marsupials—potentially a disadvantage in a world full of scavenging competitors.

Why This Matters Today

This isn’t just about rewriting the thylacine’s obituary. The study makes a bigger point: ancestral gene losses can shape extinction risk. A gene that disappeared millions of years ago might not matter—until climate shifts, new diseases, or human pressures expose the hidden vulnerabilities it left behind.

For conservationists, this is a wake-up call. Looking at endangered species only through the lens of recent genetic diversity might miss deeper evolutionary scars. By mapping out which genes have been lost in a lineage, scientists can get a better sense of what challenges a species may struggle with in the future.

Lessons From the Past

The thylacine’s story shows how extinction isn’t just about what happens in the last few centuries—it’s also about ancient evolutionary trade-offs. Adaptations that once helped the thylacine thrive may have later made it less able to withstand human pressures and environmental change.

By uncovering these long-buried genetic footprints, researchers are opening a new window into the biology of extinction. And in doing so, they are not only solving a mystery from the past, but also giving us better tools to protect the endangered species of today.