Mr.Germain Bayon, the study leader, said when he and his colleagues were matching rainfall rates over thousands of years with the degree of chemical weathering in minerals to see how the rocky material breaks down over time, they did not expect such a finding.

Bantu migrations, which happened 3,000 years ago, played a key role that cutting into the forest and helping rain forests into drier grassland. Several archaeological sites and the presence of iron artifacts back up this theory.

The theory, published online this week in the journal Science, is still in argument;however, the assumption that human and human activity may have a great impact on the environment even 3,000 years ago is amazing.  It again reminds us that we have to think first before we act.