Going ape: new orangutan species identified in Sumatra
02 Nov 2017 - 18:53
By Will Dunham / Reuters
WASHINGTON: Scientists have identified a new species of great ape on the Indonesian island of Sumatra, finding that a small population of orangutans inhabiting its Batang Toru forest merits recognition as the third species of these shaggy reddish tree dwellers.
Researchers said on Thursday these orangutans boast genetic, skeletal and tooth differences from the two other species of orangutan, meriting recognition as a unique third species. That would bring to seven the number of great ape species worldwide aside from people, alongside Africa’s eastern and western gorillas, chimpanzees and bonobos.
Scientists are worried about the future of the newly identified species, one of humankind’s closest relatives. They have labeled the species the Tapanuli orangutan, with the scientific name Pongo tapanuliensis.
“There are no more than 800 individuals remaining across three fragmented forest areas,” said conservation biologist Matthew Nowak of the Sumatran Orangutan Conservation Programme.
In addition to threats like hunting by humans, Nowak said, “Significant areas of the Tapanuli orangutan’s range are seriously threatened by habitat conversion for small-scale agriculture, mining exploration and exploitation, a large-scale hydroelectric scheme, geothermal development and agricultural plantations.”
Orangutan means “person of the forest” in the Indonesian and Malay languages, and it is the world’s biggest arboreal mammal. Orangutans are adapted to living in trees, with their arms longer than their legs. They live more solitary lives than other great apes, sleeping and eating fruit in the forest canopy and swinging from branch to branch.
“It’s pretty exciting to be able to describe a new great ape species in this day and age,” said University of Zurich evolutionary geneticist Michael Krützen, adding that most great apes species are listed as endangered or critically endangered.
“We must do everything possible to protect the habitats in which these magnificent animals occur, not only because of them, but also because of all the other animal and plant species that we can protect at the same time.”
Orangutans long were considered a single species, but were recognized as having two species in 1996, one in Sumatra and one in Borneo.
The new species lives south of what was the known range for Sumatran orangutans. This population was unknown to scientists until two decades ago. In addition to genetic differences from the other species, the researchers said the skeleton of a Tapanuli orangutan that died after being wounded by villagers showed differences in tooth and skull shape.
The research was published in the journal Current Biology.
The discovery of new species makes them immediately the world's most endangered great ape, researchers said.
"It's the first declaration of a new great ape species in about 100 years," Ian Singleton, co-author of the study and director of the Sumatran Orangutan Conservation Programme, told AFP.
But in 1997 researchers at the Australian National University discovered an isolated population of the great apes in Batang Toru, south of the known habitat for Sumatran orangutans, and scientists began to study the group to see if it was a unique species.
Researchers studied the DNA, skulls and teeth of 33 orangutans killed in human-animal conflict before concluding that they had indeed discovered a new species, giving it the scientific name Pongo tapanuliensis.
Outwardly the Tapanuli orangutan bears a closer resemblance to its Bornean counterpart, with cinnamon-coloured fur that is frizzier than its Sumatran relative. It also has a "prominent moustache", according to the findings published in the journal Current Biology.
Its skull and bone structure are slightly different from its relatives and so is its behaviour, with the long calls of male orangutans lasting on average 21 seconds longer with a greater number of pulses.
Scientists believe the three types of orangutans share a common ancestor but began to diverge into different species about 3.4 million years ago.
"The Batang Toru orangutans appear to be direct descendants of the initial orangutans that had migrated from mainland Asia, and thus constitute the oldest evolutionary line within the genus Pongo," said co-author Alexander Nater of the University of Zurich.
The Tapanuli orangutan species became isolated from its Sumatran relatives about 10-20,000 years ago, Nater added, eventually settling in the Batang Toru forest.
But its tiny population is under severe threat from mining, agricultural encroachment, illegal logging and a proposed hydroelectric dam, which would flood up to eight percent of its habitat.
The authors of the study said conservation measures need to be urgently implemented.
"Orangutans reproduce extremely slowly, and if more than one percent of the population is lost annually this will spiral them to extinction," co-author Serge Wich, professor at Liverpool John Moores University, said.
Both Sumatran and Bornean orangutans are listed as critically endangered by the International Union for Conservation of Nature (IUCN).
The Sumatran orangutan population is estimated to be just under 15,000, while about 54,000 orangutans are thought to live in Borneo, according to the IUCN.
Rampant logging and the rapid expansion of palm oil plantations have been blamed for destroying their jungle habitat. The primates have also been attacked by villagers who view them as pests and targeted by poachers to be sold as pets.