Koala DNA Reveals Ancient Ice Age Population Crash

A groundbreaking DNA study from the University of Sydney and Texas A&M has unveiled that Australia's koala population experienced a severe crash approximately 100,000 years ago. This significant decline occurred long before humans inhabited the continent and was primarily driven by dramatic prehistoric climate shifts during the Ice Age. These environmental changes included intense cold and dry spells, interspersed with warmer periods, leading to widespread drought.

Researchers precisely calculated the koala mutation rate, finding it to be about half that of humans. This crucial finding allowed for a more accurate mapping of the koala's genetic timeline. The data indicates that koala numbers began to plummet around 100,000 years ago, reaching a critical bottleneck approximately 60,000 years ago. During this time, arid conditions expanded, isolating koala populations.

Only a small group of koalas, predominantly in eastern Australia, managed to survive the extreme conditions of the late Pleistocene. As the climate eventually warmed between 16,500 and 6,000 years ago, these survivors expanded their range along the east coast. This ancient recovery laid the foundation for the distinct genetic clusters observed in modern koala populations. However, the species, listed as endangered in 2022 across Queensland, New South Wales, and the Australian Capital Territory, now faces contemporary threats from habitat loss and disease.