The dramatic collapse of orangutan populations has been linked to human activity, new genetic evidence shows.

Researchers report that a population crash occurred during the past 200 years, coinciding with deforestation in the same area.

The study focuses on orangutans found in the forests of Kinabatangan Wildlife Sanctuary in Malaysia. Writing in the journal Plos Biology, researchers suggest that the outlook is "bleak" unless urgent action is taken. The team looked at 200 orangutans living along the Kinabatangan river. These animals are confined to fragmented patches of forest. By collecting the orangutans' hair and faeces, the researchers were able to extract DNA to create genetic profiles, which could then be used to study genetic diversity.

Professor Michael Bruford, a senior author on the Public Library of Science journal paper and a conservation biologist at Cardiff University, told the BBC news website of his surprise at the results. "The genetic diversity of the population showed a very strong signal of a massive population decline," he said. "This was interesting because we didn't expect it to show that the decline has happened so recently - within the last 200 years."