Last week it was announced that a new species of orangutan has been
discovered in a remote region of northwestern Sumatra, which is a
remarkable breakthrough in modern biology. Following an expedition to
the remote mountain forests in South Tapanuli in 1997, scientists have
been puzzling for years over the genetic peculiarity of a tiny
population of orangutans there as they appeared to have subtle
differences to the other orangutan species on the island, the Sumatran
Orangutan.
Named
as the Tapanuli Orangutan, they are the first great ape species to have
been discovered since the Bonobo nearly a century ago. After years of
ongoing research, scientists studied 37 individuals from the region and
in 2017 they have now been classified as a new species. Looking into a
few subtle differences between the Tapanuli Orangutan and both the
Bornean Orangutan and the Sumatran Orangutan, this tiny population
differs from both.
First looking into their DNA, it was
discovered that they were genetically isolated from the Sumatran
Orangutan over 3 million years ago and oddly enough only genetically
split from the Bornean Orangutan 700,000 years ago. Researchers then
began to study the calls of the males. Male Orangutans have a booming
call that can travel up to 1km through the forest that is used to both
intimidate other males in the area and to attract females. The calls of
the Bornean and the Sumatran Orangutans differ from one another and the
Tapanuli Orangutan is the same, with a higher pitch than the Sumatran
Orangutans also inhabiting the island.
The final breakthrough
with unravelling this biological mystery lies in the subtle differences
in the shape of the skull which varies in all three orangutan species.
Tapanuli Orangutans also have frizzier hair, smaller heads and flatter
faces than Sumatran Orangutans.
Found in the tropical and
subtropical broadleaf forests in a isolated mountainous region, south of
Lake Toba in northwestern Sumatra, Tapanuli Orangutans are already one
of the most Critically Endangered great ape species in the world with a
population size of just 800 individuals all found within an area of just
1,000 square kilometres.
