A joint study by Monash University and the University of Colorado - Boulder have found the cause of the extinction of Australia's "megafauna." Apparently, humans are to blame; not climate change. The Christian Science Monitor reported that Australia used to be full of dense forests and massive animals. However, these megafauna got wiped out of the face of the Earth some 45,000 years ago.

The cause for its extinction has long been a source of debate among scientists. The study, led by Monash University and the University of Colorado - Boulder, found that human activity may have played a significant role in the gradual extinction of the large creatures; contrary to previous beliefs that it was caused by fluctuations in the climate.

It was hypothesized that humans hunted the large creatures for food when they first arrived in Australia. Moreover, even though they limited their hunting, it may have been enough to cause the extinction of Australia's megafauna within just a few thousand years.

The study, which was published in the journal "Nature Communications," stated that most of the world's largest animals outside of Africa were wiped out over the past 130,000 years. This was said to have been caused by fluctuations in climate, human hunting and changing habitats.

In Australia, one of the fastest and most intense extinctions happened in that period. 85 percent of large mammal species, which weighed more than 44 kilograms, began to vanish less than 50,000 years ago.

In Monash University's official website, Dr. Sander van der Kaars, lead author and palaeoecologist from the Monash School of Earth, Atmosphere and Environment, said that the demise of the megafauna was not linked to significant changes in climate, vegetation or biomass. Instead, it was driven by "imperceptible overkill" by humans.

The research team studied a continuous and precisely dated sediment core which was collected offshore southwest Australia. According to CU Boulder Today, it allowed the researchers to reconstruct the climate and ecosystems on the continent in the past.

The megafauna in the continent included 1,000-pound kangaroos, 2-ton wombats, 25-foot-long lizards, 400-pound flightless birds and 300-pound marsupial lions, among others.