Koala Decline: Climate, Not Humans, Started It

Genetic analysis has rewritten the timeline of koala population history, revealing a major decline started approximately 100,000 years ago. Researchers mapped the koala's population changes over the last century, concluding that climate shifts, not early human presence, initiated the species' first significant collapse.

This period of decline bottomed out around 60,000 years ago during the last ice age. Drying conditions likely fragmented koala populations, with only a remnant eastern group persisting. Today's five east coast koala groups are believed to have descended from this remnant.

The findings offer vital insights for conservation. Understanding koalas' past resilience to climate-driven bottlenecks can help assess their current capacity to adapt. This knowledge is critical for making informed decisions to protect them from contemporary threats such as habitat destruction, disease, and bushfires.