Our newest relative

Another great ape has been discovered in Sumatra: the TAPANULI ORANGUTAN. And it’s already in danger, says Richard Smyth.

Another great ape has been discovered

The family Hominidae has a new member. Confirmation arrived this month of a third orangutan species, found in the upland forests of Batang Toru in northern Sumatra. To the roster of great apes – the western and eastern gorillas, chimpanzee, bonobo, Bornean and Sumatran orangutans and, of course, ourselves – we can now add the Tapanuli orangutan, Pongo tapanuliensis. But fewer than 800 are left.

Scientists have known for some time that Tapanuli orangutans differ from those elsewhere on the island of Sumatra. Now research has shown that these differences – genetic, behavioural and morphological – mark out tapanuliensis as a species. The other populations will retain the name Sumatran orangutan, Pongo abelii.

Tapanuli orangutans have frizzier hair. Males also sport a prominent moustache, and their face-pads – called flanges – tend to be less prominent than in either P. abelii or the Bornean orangutan, P. pygmaeus. Like abelii – but unlike pygmaeus – Tapanuli females have wispy red beards. And both sexes have less robust skulls and jaws than their counterparts elsewhere.

The discovery comes at a critical time: both Bornean and Sumatran orangutans are classed as Critically Endangered by the IUCN. Gabriella Fredriksson of the Sumatran Orangutan Conservation Programme expects tapanuliensis to be granted the same status. “The Tapanuli orangutan will become the most endangered great ape in the world, as there are no others with such a small population,” she says.

Plans for hydro-power developments in Tapanuli orangutan habitat have sparked urgent concerns about stewardship of the region. “It seems the politics are focused only on shortterm gain,” says Fredriksson.

Richard Smyth writes about natural history and sets our Crossword – see p121.