Researchers from the Queen's University Belfast have found evidence of human intervention in the tropical forests of Southeast Asia.

Forests located in Sumatra, Java, Thailand, Vietnam, and Borneo, which were previously believed to be unaffected by humans, were in fact shaped by men for at least 11,000 years.

Although it is extremely challenging to find evidence of human activity in rainforests, due to the fact that traditional archeological techniques of locating and studying sites are difficult to carry out in the forest, the researchers found out that reviewing pollen samples and published paleoecology researches may suggest human activities in the area.

They isolated pollen samples from three islands in the Southeast Asia in which they found evidence of regular intervention in the vegetation of these forests as early as the end of the last ice age.

Chris Hunt, lead author of the study and a paleoecologist at Queen's University Belfast, said in a university press release, "It has long been believed that the rainforests of the Far East were virgin wildernesses, where human impact has been minimal. Our findings, however, indicate a history of disturbances to vegetation."

"While it could be tempting to blame these disturbances on climate change, that is not the case as they do not coincide with any known periods of climate change. Rather, these vegetation changes have been brought about by the actions of people," he added.

The researchers found evidence that proves the existence of humans in the Kelabit Highlands in Borneo. They also found out that human inhabitants in the area used to clear the land to plant food-bearing crops. "Pollen samples from around 6,500 years ago contain abundant charcoal, indicating the occurrence of fire," Hunt said.

Natural occurring fires would be followed by species of weeds and trees that can grow in charred land, however, the evidence that the researchers found showed that the charred grounds were usually followed by food-bearing trees, which clearly suggests that the people who used to live there regularly cleared the forest vegetation in order to plant food-bearing crops in their place.

The study was published in the Jan. 24 issue of the Journal of Archaeological Science.