Humans, killed off Australia’s big beasts

Humans exterminated an array of weird and wonderful Australian creatures within only 4,000 years of arriving on the continent, according to a study published yesterday that shifted blame away from climate change.

Before the arrival of homo sapiens, Australia boasted 450-kilogramme kangaroos, wombats weighing as much as a rhino, eightmetre lizards, larger-thanhuman birds, and car-sized tortoises.

More than 85 per cent of Australia’s big mammals, birds and reptiles went extinct “shortly” after our species appeared, a team of scientists reported in the journal Nature Communications.

Scientific debate

The cause of the megafauna die-off Down Under some 45,000 years ago has been the subject of much scientific debate.

A study in Proceedings of the National Academy of Sciences in 2013 said Australia’s giant animals were already mostly extinct by the time humans arrived — and pointed the finger at climate change. That study, based on fossil finds, said there was no evidence that a human ever killed a single mega-animal — many of which were herbivores.

The new research, on the contrary, concluded the mass extinction was much more likely caused by “overkill”, specifically the hunting of juvenile animals.

The team based its findings on the remains of ancient megafauna excrement found in a sediment core drilled in the Indian Ocean, off the southwest Australian coast.

The core contains chronological layers of material that was blown or swept from the land into the sea, including dust, ash, and spores from a fungus that thrived in the dung of plant-eating creatures, the University of Colorado at Boulder, which took part in the study, said in a statement.