A sexually mature male with cheek flanges, throat pouch, and very long fur.
Why would a sexually mature male orangutan want to look too young to father children? Just ask male dung beetles or goby fish. All these species have two types of males: big, aggressive ones that elaborately woo females and smaller sneaker males who, well, sneak behind the backs of the bigger ones. Both can end up successful fathers.
Male orangutans become sexually mature around age 10, but some will stay in arrested development for up to 20 years, even after fathering children of their own. These immature-looking males don’t have the broad cheek flanges, throat pouches, and long orange hair we normally associate with male orangutans. They also don’t produce the long calls that mature-looking males use to attract mates. Even with none of these secondary sex characteristics, male orangutans can get mates and have children. A previous study that tracked an orangutan population in Sumatra for 27 years found that 6 of 11 new babies were fathered by the immature-looking males.
Welcome to the family of critters with sequenced genomes, orangutans. In Nature this week, scientists unveil the draft DNA sequencing of our great ape cousins—the only great apes that live exclusively in Asia.
The researchers assembled the draft genome of the female Sumatran orangutan (Pongo abelii) using a whole-genome “shotgun” strategy, an old-fashioned approach that cost about $20 million. In addition, the researchers gathered sequence data from five wild Sumatran orangutans and five Bornean orangutans (Pongo pygmaeus) using a faster and thousandfold cheaper next-generation platform. [LiveScience]
What did scientists find in there? For one thing, orangutans share about 97 percent of the their genome with humans, compared to the 99 percent we famously share with chimpanzees. The two orangutan species—inhabiting the Indonesian islands of Borneo and Sumatra—diverged about 400,000 years ago, lead author Devin Locke says. That’s much more recently than scientists had thought.
They also discovered that over the last 15 million years, orangutan DNA changed at a different rate than either ours or chimps’. Orangutans have undergone fewer mutations of the DNA, have a lower gene turnover rate, and have fewer duplicated DNA segments.
Looking through twenty years worth of orangutan observations, researchers believe they have found 18 examples of pantomimes. The study, which appeared today in Biology Letters, supports the claim that we’re not unique when it comes to abstract communication and lends credence to other observations of great ape gesturing, according to lead researcher Anne Russon.
[Orangutans and chimpanzees were already known] to throw an object when angry, for example. But that is a far cry from displaying actions that are intentionally symbolic and referential–the behaviour known as pantomiming. “Pantomime is considered uniquely human,” says Anne Russon from York University in Toronto, Canada. “It is based on imitation, recreating behaviours you have seen somewhere else, which can be considered complex and beyond the grasp of most non-human species.” [New Scientist]
Of the eighteen observed orangutan pantomimes, four took place between orangutans and 14 between a human and an orangutan. If you ever find yourself in the Indonesian jungles, here are some examples of messages that you might expect:
When an orangutan swings through the trees like an acrobat in its rainforest habitat, it’s burning fewer calories than a human couch potato.
A new study by biological anthropologist Herman Pontzer has found that oragutans use less energy, pound-for-pound, than any other mammal–except for that all-time champion of metabolic lethargy, the tree sloth.
“You and I sitting in front of our computers use more energy each day than these orangutans that are walking around, and climbing around and socializing around their big enclosures,” Pontzer says. [NPR]