Do Orangutans Use Nature's Pharmacy?Insights from the Rainforests of Borneo

by Georgia Allen

Deep within the peat-swamp forests of Central Kalimantan, Indonesian Borneo, wild orangutans navigate one of the most complex and biodiverse ecosystems on Earth. Alongside finding food, avoiding dangers, and raising their young, they may also be doing something remarkably familiar to us: using the natural resources around them to maintain their health.

For decades, researchers have documented examples of animals consuming unusual plants or substances when unwell, a behaviour known to us as self-medication, or zoopharmacognosy. From chimpanzees swallowing rough leaves to expel parasites to birds incorporating aromatic plants into their nests, the natural world is increasingly revealing that humans are not alone in turning to nature for remedies.

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Recent discoveries have raised exciting questions about whether orangutans may also possess this ability. As the first study to investigate whether orangutans combine medicinal food resources in non-random ways, our research opens up exciting new avenues for understanding how these combinations may contribute to health and wellbeing.

Using 20 years' worth of behavioural observations, we investigated the diets of Bornean orangutans to explore whether some of the plants they consume may have synergistic medicinal properties when eaten together.

To do this, we combined long-term feeding records with ethnobotanical knowledge from experienced local field staff and botanical experts who have worked in the forest for over a decade. Their knowledge of how local communities use these plants provided valuable insight into the potential medicinal properties of species eaten by orangutans.

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A substantial proportion of the plant species consumed by orangutans had recognised medicinal uses among local communities. These included plants traditionally used to treat gastrointestinal disorders, inflammation, infections, fever, and skin conditions. Many of these species also contain compounds that previous scientific studies have identified as having antimicrobial, antioxidant, or anti-inflammatory properties.

One particularly interesting example is Fibraurea tinctoria, locally known as Liana Kuning ("yellow vine"). This climbing plant is widely used in traditional medicine across Southeast Asia to treat ailments including fever, inflammation, diabetes and infections. It has also recently attracted international attention after a wild Sumatran orangutan was observed chewing the leaves and applying the resulting paste to an open facial wound, which subsequently healed without signs of infection. We found that Bornean orangutans in Sebangau also regularly consume this species with other medicinal species, suggesting it may represent an important medicinal resource across orangutan populations.

Our findings suggest not only that orangutans are regularly exposed to a rich natural "pharmacopoeia", but also that they consume certain medicinal species together significantly more often than would be expected by chance. This non-random pattern raises the intriguing possibility that orangutans may deliberately combine these resources to enhance or complement their medicinal properties.

Further research into the medicinal properties of these highlighted combinations could have important practical applications not only for behavioural science but also for conservation.

As tropical forests continue to be lost and degraded, orangutans are losing more than simply food resources and nesting sites. They may also be losing access to plant species that play important roles in maintaining their health and wellbeing. This has important implications for conservation interventions such as translocations and rehabilitation efforts. Understanding how orangutans use natural resources to maintain their health may help inform dietary management, habitat enrichment, and rehabilitation practices, ensuring rescued individuals have access to plant species that could support recovery before they are reintroduced into the wild. If orangutans have learned to use particular medicinal resources, or have acquired this knowledge over generations through social or individual learning, those same resources may not be present in the habitats to which they are translocated to. Conserving biodiverse forests therefore means protecting not only species, but also the ecological relationships and behavioural knowledge they support.

The research also highlights the importance of collaboration between scientific research and local ecological knowledge. The expertise of local field teams and communities, built through generations of experience living alongside these forests, remains invaluable for understanding tropical ecosystems and the species that depend upon them.

Our research provides an important step towards understanding the complex relationship between orangutans and the medicinal resources within their forest environment. Yet, exciting questions remain: how do orangutans recognise and select these resources? Do these combinations change in response to illness or injury? And could this knowledge help improve the care and rehabilitation of rescued orangutans?

As research continues, the forests of Borneo may reveal that orangutans have long been engaging with nature’s pharmacy in ways we are only beginning to understand.