Wild orangutan treats wound with pain-relieving plant

Even though there is evidence of certain self-medication behaviors in animals, so far it has never been known that animals treat their wounds with healing plants. Now, biologists from the Max Planck Institute of Animal Behavior, Germany and Universitas Nasional, Indonesia have observed this in a male Sumatran orangutan who sustained a facial wound. He ate and repeatedly applied sap from a climbing plant with anti-inflammatory and pain-relieving properties commonly used in traditional medicine. He also covered the entire wound with the green plant mesh. Thus, medical wound treatment may have arisen in a common ancestor shared by humans and orangutans.

While sick and avoidance behavior can be regularly observed in non-human animals, self-medication in the form of ingestion of specific plant parts is widespread in animals but exhibited at low frequencies. The closest relatives to humans, the great apes, are known to ingest specific plants to treat parasite infection and to rub plant material on their skin to treat sore muscles. Recently a chimpanzee group in Gabon was observed applying insects to wounds. However, the efficiency of this behavior is still unknown. Wound treatment with a biologically active substance has so far not been documented.

In a study published in Scientific Reports, cognitive and evolutionary biologists from the Max Planck Institute of Animal Behavior, Konstanz, Germany and Universitas Nasional, Indonesiareport evidence of active wound treatment with a healing plant in a wild male Sumatran orangutan. The study, led by Caroline Schuppli and Isabelle Laumer, took place at the Suaq Balimbing research site in Indonesia, which is a protected rainforest area home to approximately 150 critically endangered Sumatran orangutans. "During daily observations of the orangutans, we noticed that a male named Rakus had sustained a facial wound, most likely during a fight with a neighboring male," says Isabelle Laumer (MPI-AB), first author of the study.

Three days after the injury Rakus selectively ripped off leaves of a liana with the common name Akar Kuning (Fibraurea tinctoria), chewed on them, and then repeatedly applied the resulting juice precisely onto the facial wound for several minutes. As a last step, he fully covered the wound with the chewed leaves.

Says Laumer: "This and related liana species that can be found in tropical forests of Southeast Asia are known for their analgesic and antipyretic effects and are used in traditional medicine to treat various diseases, such as malaria. Analyses of plant chemical compounds show the presence of furanoditerpenoids and protoberberine alkaloids, which are known to have antibacterial, anti-inflammatory, anti-fungal, antioxidant, and other biological activities of relevance to wound healing."

Observations over the following days did not show any signs of the wound becoming infected and after five days the wound was already closed. "Interestingly, Rakus also rested more than usual when being wounded. Sleep positively affects wound healing as growth hormone release, protein synthesis and cell division are increased during sleep," she explains.

Like all self-medication behavior in non-human animals, the case reported in this study raises questions about how intentional these behaviors are and how they emerge. "The behavior of Rakus appeared to be intentional as he selectively treated his facial wound on his right flange, and no other body parts, with the plant juice. The behavior was also repeated several times, not only with the plant juice but also later with more solid plant material until the wound was fully covered. The entire process took a considerable amount of time," says Laumer.

"It is possible, that wound treatment with Fibraurea tinctoria by the orangutans at Suaq emerges through individual innovation," says Caroline Schuppli, senior author of the study. "Orangutans at the site rarely eat the plant. However, individuals may accidentally touch their wounds while feeding on this plant and thus unintentionally apply the plant's juice to their wounds. As Fibraurea tinctoria has potent analgesic effects, individuals may feel an immediate pain release, causing them to repeat the behavior several times."

Since the behavior has not been observed before, it may be that wound treatment with Fibraurea tinctoria has so far been absent in the behavioral repertoire of the Suaq orangutan population. Like all adult males in the area, Rakus was not born in Suaq, and his origin is unknown. "Orangutan males disperse from their natal area during or after puberty over long distances to either establish a new home range in another area or are moving between other's home ranges," explains Schuppli. "Therefore, it is possible that the behavior is shown by more individuals in his natal population outside the Suaq research area."

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Great apes playfully tease each other

Babies playfully tease others as young as eight months of age. Since language is not required for this behavior, similar kinds of playful teasing might be present in non-human animals. Now cognitive biologists and primatologists from the University of California Los Angeles (UCLA, US), the Max Planck Institute of Animal Behavior (MPI-AB, Germany), Indiana University (IU, US), and the University of California San Diego (UCSD, US) have documented playful teasing in four species of great apes. Like joking behavior in humans, ape teasing is provocative, persistent, and includes elements of surprise and play. Because all four great ape species used playful teasing, it is likely that the prerequisites for humor evolved in the human lineage at least 13 million years ago.

Joking is an important part of human interaction that draws on social intelligence, an ability to anticipate future actions, and an ability to recognize and appreciate the violation of others' expectations.

Teasing has much in common with joking, and playful teasing may be seen as a cognitive precursor to joking.

The first forms of playful teasing in humans emerge even before babies say their first words, as early as eight months of age.

The earliest forms of teasing are repetitive provocations often involving surprise.

Infants tease their parents by playfully offering and withdrawing objects, violating social rules (so-called provocative non-compliance), and disrupting others' activities.

In a study recently published in the Proceedings of the Royal Society B, scientists from the University of California Los Angeles, the Max Planck Institute of Animal Behavior, Indiana University, and the University of California San Diego(Isabelle Laumer, Sasha Winkler, Federico Rossano, and Erica Cartmill) report evidence of playful teasing in the four great ape species: orangutans, chimpanzees, bonobos and gorillas.

"Great apes are excellent candidates for playful teasing, as they are closely related to us, engage in social play, show laughter and display relatively sophisticated understandings of others' expectations," says Isabelle Laumer (UCLA/MPI-AB) a post-doctoral researcher and the first author of the study.

The team analyzed spontaneous social interactions that appeared to be playful, mildly harassing, or provocative.

During these interactions, the researchers observed the teaser's actions, bodily movements, facial expressions, and how the targets of the teasing responded in turn.

They also assessed the teaser's intentionality by looking for evidence that the behavior was directed at a specific target, that it persisted or intensified, and that teasers waited for a response from the target.

The researchers found that orangutans, chimpanzees, bonobos and gorillas all engaged in intentionally provocative behavior, frequently accompanied by characteristics of play.

They identified 18 distinct teasing behaviors. Many of these behaviors appeared to be used to provoke a response, or at least to attract the target's attention.

"It was common for teasers to repeatedly wave or swing a body part or object in the middle of the target's field of vision, hit or poke them, stare closely at their face, disrupt their movements, pull on their hair or perform other behaviors that were extremely difficult for the target to ignore," explains UCLA and IU professor Erica Cartmill, senior author of the study.

Although playful teasing took many forms, the authors note that it differed from play in several ways.

"Playful teasing in great apes is one-sided, very much coming from the teaser often throughout the entire interaction and rarely reciprocated," explains Cartmill.

"The animals also rarely use play signals like the primate 'playface', which is similar to what we would call a smile, or 'hold' gestures that signal their intent to play."

Playful teasing mainly occurred when apes were relaxed, and shared similarities with behaviors in humans.

"Similar to teasing in children, ape playful teasing involves one-sided provocation, response waiting in which the teaser looks towards the target's face directly after a teasing action, repetition, and elements of surprise," Laumer explains.

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Killing remains a threat to Bornean orangutans

University of Queensland research has found despite considerable conservation efforts, the illegal killing of critically endangered orangutans on Borneo may be an ongoing threat to the species.

PhD candidate Emily Massingham from UQ's Faculty of Science managed a team of researchers which visited 79 villages across the Bornean orangutan range in Kalimantan, conducting face to face interviews with 431 people.

"Our study builds on previous research which indicated killing was one of the key reasons for orangutan population decline, alongside habitat loss," Ms Massingham said.

"The aim of our project was to understand whether orangutans have been killed in recent times, to look at whether conservation projects are effectively preventing killing, and to gain insights into community perceptions and the motivations behind it.

"It has been almost 15 years since the previous study, and we did not find a clear decrease in killings despite Indonesia's commendable efforts to reduce habitat loss.

"Thirty per cent of villages reported orangutans had been killed in the last 5 -10 years, despite the practice being both illegal and taboo -- which also makes it hard to get an accurate picture of the true scale."

Ms Massingham said Borneo's orangutan population had decreased by 100,000 in recent decades, with current estimates suggesting fewer than 100,000 animals remain.

"Our findings did not indicate that conservation projects are reducing killing, highlighting an urgent need to improve the collective approach to orangutan conservation," she said.

"Killing by humans needs to be addressed, as our findings suggest it may still be occurring and poses a real threat to the species."

Ms Massingham said orangutans have long lifespans and breed slowly, so are particularly vulnerable to population declines driven by the death of adult apes.

"Our interviews revealed some of the situations which lead to the killing or displacement of individual orangutans," she said.

"They include protecting crops and taking infant apes to keep as pets."

The researchers outlined recommendations that could improve future conservation efforts.

"Working with communities and collaborating across disciplines and projects will be key," Ms Massingham said.

"Conservationists need to work closely with individual villages to understand their needs and perspectives, identify the social drivers of killing of orangutans and implement solutions that reduce human-orangutan conflict."

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How orangutans respond to novelty in the wild

Humans like to discover. Presented with something we've never seen before, most of us will be compelled to explore and learn more about it. The same can't exactly be said for our closest living relatives -- the great apes. Although decades of studies have shown that captive chimpanzees, gorillas, and orangutans will eagerly explore unfamiliar objects in a laboratory, great apes have rarely been observed in these encounters in the wild. As such, almost nothing is known about how great apes respond to novelty in the natural habitats in which they evolved. Now, a team from the Max Planck Institute of Animal Behavior (MPI-AB) has succeeded in measuring the behavior of wild orangutans in their first encounter with an unfamiliar object. The experiments, conducted in an Indonesian rainforest, uncovered a mix of social, environmental, and age factors that made orangutans more likely to explore. Published in Scientific Reports, the study reveals the conditions that spark curiosity in orangutans, and sheds light on how our own curious natures might have evolved.

The team studied orangutans at a long-term monitoring site, Suaq Balimbing, in Sumatra. Orangutans at the site have been habituated over decades to the presence of humans, thus offering scientists a rare opportunity to observe wild great apes at close range. Caroline Schuppli, director of the Suaq Project and the study's first author, became interested in how wild orangutans would react when presented with something unfamiliar.

"Curiosity is a trait that has driven the exceptional ability of humans to learn and innovate," says Schuppli, a group leader at MPI-AB. "If we want to know how the trait evolved in us, we have to study it in our closest living relatives."

Curiosity, which describes an individual's motivation to learn about the unknown, has been studied before in great apes; however, due to the logistical difficulties of studying wild animals, almost all tests have occurred in captivity. "We know that apes are very curious to explore when they are in the safe and controlled conditions of a zoo," says Schuppli. "But these results tell us little about what really triggered or suppressed curiosity over our evolutionary history."

About ten years ago, Schuppli and collaborators first attempted to assess curiosity in wild orangutans with an experiment inspired by captive studies. They roamed Suaq, peppering the forest with foreign objects for the orangutans to find: a bright red flag; plastic flowers and fruits; a stuffed toy. The results were stark. "They hardly ever came near any of the items," she remembers. "You could see them making huge circles in the forest to avoid the experiment."

Schuppli realized that testing orangutans' reaction to novelty in nature would require reimagining the past paradigm. "The challenge was figuring out how to entice them with something that was novel, but also familiar enough not to scare them off," she says. Over the years Schuppli perfected just such an object: a piece of tree trunk with a natural hole filled with local forest honey. The tree hole and food were familiar, but deploying these in an unusual way represented a novel foraging situation. With a team of local and international scientists, Schuppli hoisted the experimental log into trees about 10 meters from orangutans -- and watched what happened.

During the trials, the orangutans spent on average 30 minutes in the vicinity of the novel log. During this time, they explored the novel log by intensively observing it over extended periods of time and approaching it closely. Overall, however, orangutans rarely touched the branch directly; and when they did, they often used a tool, such as a stick to do so. "The orangutans were pretty cautious," says Tri Rahmaeti, a team member from Universitas Nasional in Indonesia and co-author on the study. "The honey reward could have easily been scooped out of the log using a finger, but they still preferred to use a tool so they didn't have to make physical contact."

But there were significant differences in the behaviors. Using statistical techniques, the team uncovered traits of individuals and features in the environment that amplified exploration. Young orangutans were far more likely than adults to observe and approach. And, orangutans were more likely to approach the log if they saw another individual heading that way too. The habitat also seemed to play a role: in areas with abundant food, orangutans observed more but approached less.

Says Schuppli: "On the one hand, the results confirmed our hunch that orangutans in the wild are not that keen to explore new objects. This could be because in nature, orangutans live very long lives in stable habitats where novelty is rare. So, the potential risk of approaching something unknown doesn't outweigh the potential reward."

"On the other hand, the experiment showed that there is flexibility in the behavior. Orangutans have the potential to be curious about novelty in nature, but only under certain conditions. And by experimentally testing this in a wild population, we pinned down the conditions."

Of these conditions, Schuppli finds the social factor most illuminating. "Orangutans are the least social of all great apes, and yet we find that the presence of association partners increases their curiosity," she says.

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Orangutans instinctively use hammers to strike and sharp stones to cut, study finds

Untrained, captive orangutans can complete two major steps in the sequence of stone tool use: striking rocks together and cutting using a sharp stone, according to a study by Alba Motes-Rodrigo at the University of Tübingen in Germany and colleagues, publishing February 16 in the open-access journal PLOS ONE.

The researchers tested tool making and use in two captive male orangutans (Pongo pygmaeus) at Kristiansand Zoo in Norway. Neither had previously been trained or exposed to demonstrations of the target behaviors. Each orangutan was provided with a concrete hammer, a prepared stone core, and two baited puzzle boxes requiring them to cut through a rope or a silicon skin in order to access a food reward. Both orangutans spontaneously hit the hammer against the walls and floor of their enclosure, but neither directed strikes towards the stone core. In a second experiment, the orangutans were also given a human-made sharp flint flake, which one orangutan used to cut the silicon skin, solving the puzzle. This is the first demonstration of cutting behavior in untrained, unenculturated orangutans.

To then investigate whether apes could learn the remaining steps from observing others, the researchers demonstrated how to strike the core to create a flint flake to three female orangutans at Twycross Zoo in the UK. After these demonstrations, one female went on to use the hammer to hit the core, directing the blows towards the edge as demonstrated.

This study is the first to report spontaneous stone tool use without close direction in orangutans that have not been enculturated by humans. The authors say their observations suggest that two major prerequisites for the emergence of stone tool use -- striking with stone hammers and recognizing sharp stones as cutting tools -- may have existed in our last common ancestor with orangutans, 13 million years ago.

The authors add: "Our study is the first to report that untrained orangutans can spontaneously use sharp stones as cutting tools. We also found that they readily engage in lithic percussion and that this activity occasionally leads to the detachment of sharp stone pieces."

From Science Daily