How we discovered a new species of orangutan in northern Sumatra



File 20171103 26472 gug2mh.jpg?ixlib=rb 1.1
The new species has a smaller head, and a distinctly ‘cinnamon’ colour compared with other orangutans.
Maxime Aliaga, Author provided

Colin Groves, Australian National University and Anton Nurcahyo, Australian National University

We have discovered a new species of orangutan – the third known species and the first new great ape to be described since the bonobo almost a century ago.

The new species, called the Tapanuli orangutan (Pongo tapanuliensis), has a smaller skull than the existing Bornean and Sumatran orangutans, but has larger canines.

As we and our colleagues report in the journal Current Biology, the new species is represented by an isolated population of fewer than 800 orangutans living at Batang Toru in northern Sumatra, Indonesia.

Orangutan populations in Sumatra and Borneo – the new species’ distribution is shown in yellow.
Curr. Biol.

Read more: The lengthy childhood of endangered orangutans is written in their teeth


The existence of a group of orangutans in this region was first reported back in 1939. But the Batang Toru orangutans were not rediscovered until 1997, and then confirmed in 2003. We set about carrying out further research to see whether this isolated group of orangutans was truly a unique species.

On the basis of genetic evidence, we have concluded that they are indeed distinct from both the other two known species of orangutan: Pongo abelii from further north in Sumatra, and Pongo pygmaeus from Borneo.

The Batang Toru orangutans have a curious mix of features. Mature males have cheek flanges similar to those of Bornean orangutans, but their slender build is more akin to Sumatran orangutans.

The hair colour is more cinnamon than the Bornean species, and the Batang Toru population also makes longer calls than other orangutans.

Making sure

To make completely sure, we needed more accurate comparisons of their body dimensions, or “morphology”. It was not until 2013 that the skeleton of an adult male became available, but since then one of us (Anton) has amassed some 500 skulls of the other two species, collected from 21 institutions, to allow for accurate comparisons.

Analyses have to be conducted at a similar developmental stage on male orangutan skulls, because they continue growing even when adult. Anton found 33 skulls of wild males that were suitable for comparison. Of 39 different measurement characteristics for the Batang Toru skull, 24 of them fall outside of the typical ranges of northern Sumatran and Bornean orangutans.

The new orangutans have smaller heads – but some impressive teeth.
Matthew G Nowak, Author provided

Overall the Batang Toru male has a smaller skull, but bigger canines. Combining the genetic, vocal, and morphological sources of evidence, we have confidently concluded that Batang Toru orangutan population is a newly discovered species – and one whose future is already under threat.

Under threat as soon as they’re discovered.
Maxime Aliaga, Author provided

Despite the heavy exploitation of the surrounding areas (hunting, habitat
alteration and other illegal activities), the communities surrounding the habitat of the Tapanuli orangutan still give us the opportunity to see and census the surviving population. Unfortunately, we believe that the population is fewer than 800 individuals.

Of the habitat itself, no more than 10 square km remains. Future development has been planned for that area, and about 15% of the orangutans’ habitat has non-protected forest status.


Read more: Orangutans need more than your well-meaning clicktivism


The discovery of the third orangutan in the 21st century gives us an understanding that the great apes have more diversity than we know, making it all the more important to conserve these various groups.

The ConversationWithout the strong support of, and participation from, the communities surrounding its habitat, the future of the Tapanuli orangutan will be uncertain. Government, researchers and conservation institutions must make a strong collaborative effort to make sure that this third orangutan will survive long after its discovery.

Colin Groves, Professor of Bioanthropology, Australian National University and Anton Nurcahyo, , Australian National University

This article was originally published on The Conversation. Read the original article.

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The lengthy childhood of endangered orangutans is written in their teeth



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A young Bornean orangutan nursing.
Erin Vogel, Author provided

Tanya M. Smith, Griffith University

Orangutan populations in the wild are critically endangered, and one of the things that may hamper their survival is the time they take to rear new offspring. The Conversation

An orangutan mother will not give birth again until she’s finished providing milk to her previous offspring. Nursing can take a long time and vary across seasons, as we found in research published today in Science Advances.

Primate mothers, including humans, raise only a few slow-growing offspring during their reproductive years.

Differences in infant development have a profound effect on how many children a female can have over the course of her life – the key marker of success from an evolutionary vantage point.

Great apes have a high-stakes strategy. Chimpanzee mothers nurse their offspring for five years on average, twice as long as humans in traditional small-scaled societies.

Orangutans have been suspected of having even longer periods of infant dependency, although determining just how long has been a particular challenge for field biologists.

Wild orangutan from Gunung Palung National Park, Borneo, Indonesia with her one month old infant. (Gunung Palung Orangutan Project)

Living high up in dwindling Southeast Asian forests, these apes are adept at evading observers. Their nursing behaviour is often concealed, particularly while juveniles cling to their mother or rest together in night nests.

Maintaining continuous field studies to track their development is expensive, and efforts are hindered by frequent forest fires and devastating deforestation for palm oil plantations.

Teeth tell the story

I have spent the past few decades studying how orangutans and other primates form their teeth. Amazingly, every day of childhood is captured during tooth formation, a record that begins before birth and lasts for millions of years.

Teeth also contain detailed dietary, health and behavioural histories, allowing biological anthropologists an unprecedented window into the human past.

I’ve also teamed up with researchers Manish Arora and Christine Austin, at Icahn School of Medicine at Mt Sinai in New York, who have pioneered methods to map the fine-scaled elemental composition of teeth, as well as primate lactation expert Katie Hinde at Arizona State University.

We have shown in a previous study that tiny amounts of the element barium are an accurate marker of mother’s milk consumption. Like calcium, barium is sourced from the mother’s skeleton, concentrated in milk, and ultimately written into the bones and teeth of her offspring.

Tooth growth creates daily lines (indicated by short white lines), as well as a neonatal line (NL) at birth. Growth starts at the junction between enamel and dentine, and progresses away from the junction and towards the root (arrows).
Christine Austin and Tanya Smith

Once animals start nursing after birth, their teeth show increases in barium values, which begin to decrease when solid food is added to the diet. These values drop further to pre-birth levels when primates stop nursing and are weaned.

We’ve recently used this approach to explore the nursing histories of wild orangutans in collaboration with orangutan expert Erin Vogel at Rutgers University. In order to do so, I borrowed teeth housed in natural history museums from individuals that had been shot many years ago during collection expeditions.

Wild Bornean orangutan mother and suckling 19-month old infant.
Paige Prentice, Author provided

Orangutan teeth show a gradual increase in barium values from birth through their first year of life, a time of increasing consumption of their mother’s milk. After 12-18 months, values decrease as infants begin eating solid foods consistently.

But surprisingly, barium levels then begin to fluctuate on an approximately annual basis. We suspect that this is due to seasonal changes in food availability. When fruit is in short supply, infants appear to rely more on their mother’s milk to meet their nutritional needs.

Light microscope image (left) of a wild orangutan molar contrasted with an elemental map of the same tooth (right) showing the distribution of barium. The timing of barium incorporation was determined from accentuated lines (in days of age on the left), which form during enamel and dentine secretion. Approximately annual bands of enriched barium are apparent in the dentine after the first year, likely due to seasonal increases in mother’s milk intake.
Smith et al. (2017) Science Advances

Hanging around

Another surprising finding is that nursing may continue for more than eight years, longer than any other wild animal.

This information is the first of its kind for wild Sumatran orangutans, as they have been especially difficult to study in their native habitat. Previous estimates from two wild Bornean orangutans suggested that juveniles nurse until about six to eight years of age.

Rather than spending so much time and energy breastfeeding their children, human mothers in traditional societies transition their infants onto soft weaning foods around six months of age, tapering them off milk a few years later.

Humans also benefit from having help such as older siblings and grandparents who lend a hand with childcare and enable women to energetically prepare for having their next child.

Orangutan mothers have it hard by comparison. They live alone in unpredictable environments with limited nutritional resources. In order to survive they use less energy than other great apes, raising their young more slowly.

Wild orangutan mother and 11-month old infant.
Tim Laman, Author provided

Vulnerable orangutans

Female orangutans begin reproducing around age 15 and can live until 50 years old in the most favourable of circumstances. They bear new offspring every six to nine years, producing no more than six or seven descendents over their lifetime.

Having a long nursing period and slow maturation makes orangutan populations especially vulnerable to environmental perturbations.

Recent work has also implicated poor habitat quality and the pet trade as additional factors in their rapidly declining numbers, which is underscored by their critically endangered status.

Research on collections housed in natural history museums provides timely evidence of how remarkable orangutans are, how much information we can retrieve from their teeth, and why conservation efforts informed by evolutionary biology are critical.

Tanya M. Smith, Associate Professor in the Australian Research Centre for Human Evolution, Griffith University

This article was originally published on The Conversation. Read the original article.

Indonesia: 100 Plus Orangutans Estimated Dead


The link below is to an article on Orangutans in Sumatra and the threat posed to them by deforestation, and a fire that has burnt unchecked there as a result of logging.

For more visit:
http://www.google.com/hostednews/ap/article/ALeqM5hPdy1GSpmZzTWIRiAs4h45tvqteQ

Indonesia: Orangutans Under Threat


The link below is to an article on Orangutans in Sumatra and the threat posed to them by deforestation.

For more visit:
http://www.treehugger.com/endangered-species/wild-sumatran-orangutans-could-be-wiped-out-weeks.html