SYDNEY, Oct. 8 (Xinhua) -- Now known for its dense tropical rainforests, Southeast Asia was once home to vast grassy savannas which allowed early humans to thrive and gave rise to several species of megafauna.
An Australian-led study released Thursday suggests that the climate-driven disappearance of these ancient grasslands also led to the demise of the region's ancient human inhabitants and large grazing mammals.
"Southeast Asia is often overlooked in global discussions of megafauna extinctions, but it once had a much richer mammal community full of giants now extinct," lead author, Associate Professor Julien Louys from Australia's Griffith University said.
By examining the teeth of living and fossilised mammals, researchers were able to examine the diet of past animals, as well as the climatic conditions at the time they were alive.
"What they showed is that during the early part of the Pleistocene from about 2.6 million years ago, rainforests dominated Southeast Asia. These gave way to more grassland environments, peaking around a million years ago, in which megafauna thrived," Dr. Patrick Roberts from Germany's Max Planck Institute said.
"However, in the past 100,000 years, relatively recently in geological terms, we have seen a return to the much denser rainforests that we see today."
Modelling shows a clear correlation between the resurgence of rainforests and the disappearance of both early humans and most of the giant mammal species from the region -- suggesting their failure to adapt to the new environment.
"It is only our species, Homo sapiens, that appears to have had the required skills to successfully exploit and thrive in rainforest environments," Roberts said.
"All other hominin species were apparently unable to adapt to these dynamic, extreme environments."
The team pointed out that the only remaining hominin species in Southeast Asia, is at risk of wiping out some of the last of the giant mammals -- Asian elephants.
"Rather than benefiting from the expansion of rainforests over the last few thousand years, Southeast Asian mammals are under unprecedented threat from the actions of humans," Louys said.
"By expanding out into vast tracts of rainforest, causing deforestation and overhunting, we're at risk of losing some of the last megafauna still walking the earth." Enditem
