Study: Orangutans survived 'squeeze' event

ZURICH, Switzerland, Nov. 23 (UPI) -- Orangutans in Borneo are descended from a small number of ancestors who survived a population "bottleneck" about 176,000 years ago, Swiss researchers say.

Scientists at the University of Zurich say a genetic analysis of the species suggests a global cooling trend could have created the bottleneck, defined as a period in which animal numbers shrink but eventually expand again when conditions improve, ScienceNews.org reported Monday.

The Earth experienced a serious period of cooling about 190,000 to 130,000 years ago, anthropological geneticist Natasha Arora says, and while Borneo itself wasn't iced over, rain forests where orangutans live might have shrunk during this time, threatening the orangutan population within it.

Orangutans today live only on Borneo and Sumatra in two distinct species, both of which show a genetic suggestion of a bottleneck event.

"Something really important happened" roughly 170,000 years ago, Lounes Chikhi, a population geneticist in Toulouse, France says.

At least one other primate may have had a similar history to Borneo's orangutans, species Pongo pygmaeus, he says.

"There is a strange parallel with human evolution," Chikhi says.

Geneticists say that for modern humans, the time to a most recent common ancestor is 170,000 years ago.

"What happened between 150,000 and 200,000 years ago that influenced both Homo sapiens and Pongo pygmaeus?" Chikhi asks.