🌅 Koalas Survived Near-Extinction 100,000 Years Ago

SOURCE

Kovacs et al. (2026)

WHAT TO KNOW

• A new groundbreaking study of koala DNA by researchers at the University of Sydney in Australia suggests the iconic marsupial experienced a dramatic population crash some 100,000 years ago, long before humans arrived on the continent. The study rewrites our scientific understanding of koalas and challenges previous research that suggested koala populations declined only after the arrival of humans.

WHY IT MATTERS

• The researchers found koala populations began a major decline around 100,000 years ago and hit a critical bottleneck sometime around 60,000 years ago, coinciding with a period of intense environmental change during the late Pleistocene age. During that time, the continent that would eventually become Australia repeatedly shifted between cold, dry glacial periods, and warmer, wetter interglacial periods, reshaping the landscape and making it more arid and vulnerable to fire. The authors say the timing suggests climate upheaval was the primary cause of koalas’ decline, not humans.

CONNECT THE DOTS

• The study found all modern koalas descend from a single ancestral population that survived the harsh environmental changes and eventually expanded into five distinct genetic groups between 16,500 and 6,000 years ago. Those five groups went on to form the koala populations still found along the east coast of Australia today.