We can learn a lot from 'Pongo' family

We can learn a lot from 'Pongo' family

Just as Asia's only great ape faces its greatest crisis, scientists have released important new findings on the species.

The latest research has found that the major differences in appearance, behavior and genetics of orangutans in Sumatra and Borneo warrant their reclassification as separate species -- the Bornean Pongo pygmaeus and the Sumatran Pongo abellii.

Previously they were regarded as subspecies of the same species.

"Sumatran orangutan females give birth, on average, once every nine years, while females in eastern Borneo average six years, with western Borneo females somewhere in between," said Carel van Schaik, a professor of biological anthropology at Duke University in the United States.

"The shorter birth-interval for eastern Borneo is probably as a result of them having a slightly higher adult mortality. This is probably due to the fact that orangutans in eastern Borneo have harsher climatic conditions to deal with. They have less fruit and long periods of time when there are only leaves to eat," said Professor van Schaik.

"If you go into the leaf-eating business, there are risks that you'll poison yourself," he added

As well, scientists now regard Bornean orangutans as forming three separate subspecies, with distinct differences even within subspecies in different areas.

"Within Borneo there are all these big rivers which separate them and they are clearly separate populations. They are biologically different, and what is more for me as an anthropologist, is that we see all kinds of cultural differences between orangutan populations."

One example is how different populations perform their "kiss- squeak", the distress signal orangutans send to each other or to a predator.

"As researchers recording orangutan behavior in the forest canopy, we used to just write down 'kiss-squeak', but we've just recently realized that in some places they kiss-squeak on the flat of their hand, to enhance the sound, while in other places they shape their hand like a trumpet and turn it as they squeak.

"In other places they kiss on leaves, but sometimes it's a single leaf and sometimes they strip a whole bunch of leaves. Then they stretch out their hand and rain the leaves down on you.

It enhances the message that this animal is not a happy puppy, right?"

"Now this shows that the animals are incredibly 'copying- oriented'. Like us, they have role models that they emulate and they say 'OK this is how one does it here, I'll do it that way too.'"

Professor van Schaik believes studying such behavioral differences will help us understand the evolution of human culture and intelligence.

"We are just another great ape, and yet we are so vastly different from the others. What caused that? The best way to look at that, because our ancestors are gone of course, is to look at all the variability among the great apes we still have.

"What causes that variability, what brings all that out in the great apes? (If we answer those questions) maybe we can extrapolate from that toward humans. We might learn a lot about our own history by studying the orangutans, but we need a lot of populations. You can't study that in one population. So even if by some miracle one population is saved in perpetuity, we will still lose that opportunity to study our own past."

Professor van Schaik says the orangutan faces what he calls, 'the redwood problem', based on President Reagan's comment 'If you've seen one redwood you've seen them all.'

"If you apply that to the orangutans you think - I've looked at one orangutan, now I know them all. It turns out you don't know them at all because orangutans show incredible variability within and across their subspecies," said Professor van Schaik.

But these new classifications could soon be meaningless as species and subspecies alike near extinction. There are fewer than seven thousand Sumatran orangutan left, and the subspecies in East Kalimantan, the black orangutan, has only a few fragmented populations remaining.

"Just imagine that you have to tell children," said Professor van Schaik, "'this is the orangutan, it used to live in these forests. People sort of figured out what they did but they didn't quite learn everything there was to learn before they went extinct. And now you'll have to live in a world without them.'"

"If we let a species become extinct that's so intelligent, so genetically close to us, so charismatic, then what do the buffaloes have to hope for, what do the birds have to hope for?" said Dr Willie Smits, Chairman of Borneo Orangutan Survival (BOS) Foundation.

"And eventually that whole net is going to collapse - what do we humans have to hope for ourselves? So the orangutan are a big warning flag for what is so us to come."

-- Jacqueline Mackenzie