The plummeting numbers of orangutans in the wild has been linked, via DNA evidence, directly to human influence, according to a new study. The BBC reports that researchers studied genetic diversity in orangutans in a Malaysian forest and found that a shrinking of the animals’ gene pool coincides directly with the clearing of the forest in the same area, 200 years ago.

According to one of the researchers, “The genetic diversity of the population showed a very strong signal of a massive population decline.”

Orangutans, a species of great ape, number only 50,000, according to the United Nations. They live in southeast Asia, in Borneo, Malaysia, and Indonesia. The scientists on the genetic study worry that declining genetic diversity among populations of the animals living in fragmented forest areas – isolated islands in seas of deforestation – could suffer from inbreeding, which would further hurt the orangutans’ chances for survival.

Photo credit: Orangutan Foundation