A new member of the hominid family
Skeletal and DNA evidence identifies a third species of orangutan.
Then there were eight. Humans now have seven close relatives, thanks to a team of researchers that has identified a previously unrecognised species of orangutan.
The new member of the great ape family joins the two other species of orangutan, two species of gorilla, chimpanzees and bonobos as our closest animal cousins. The new species, formally named
Pongo tapanuliensis in a paper published in the journal Current Biology, is critically endangered and comprises a single colony of fewer than 800 individuals living in the Batang Toru forest on the Indonesian island of Sumatra.
A team of researchers, led by anthropologist Alexander Nater of the University of Zurich in Switzerland, pursued two lines of evidence to determine if the colony was different enough from the two already acknowledged orangutan species – known as the Bornean and Sumatran – to be defined as a third.
They first used the skull of a specimen killed during what they describe as a “human-animal conflict” to compare head and jaw characteristics with those of 33 adult male orangutans. In so doing, they found “consistent differences” in skull and tooth size between the Batang Toru ape and the other species.
After that, they analysed 37 orangutan genomes. This revealed that not only was
P. tapanuliensis a separate species but also a very ancient one.
The analysis revealed the new species split away from the others about 3.3 million years ago. The Bornean and Sumatran species separated from each other much more recently, about 674,000 years ago.
One of the researchers, anthropologist Colin Groves from the Australian National University in Canberra, says the discovery is significant. “The orangutan is one of our closest living relatives,” he says, “and we’ve now found there is more diversity within orangutans than we knew.”