Nature's Pharmacy: How Budongo Chimpanzees Use Medicinal Plants to Heal

Redacción HC
21/06/2024

In the dense forests of Budongo, Uganda, wild chimpanzees appear to be doing something extraordinary: self-medicating with plants. A study published in PLOS ONE in June 2024 has provided compelling evidence that these great apes are not just passive foragers but active consumers of plants with antibacterial and anti-inflammatory properties, especially when sick or injured.

Led by Elodie Freymann, Catherine Hobaiter, and colleagues from institutions like the University of Oxford and the Budongo Conservation Field Station, the research combines behavioral observation with laboratory pharmacology. The result is one of the strongest cases yet for zoopharmacognosy—the phenomenon of animals using natural substances to treat their own ailments.

Do Chimpanzees Know How to Heal Themselves?

For years, scientists have observed chimpanzees eating bark, wood, or specific leaves that seem to serve no nutritional purpose. Could these behaviors represent intentional self-medication?

To explore this question, researchers monitored chimpanzee behavior over 116 days across two communities. They carefully recorded instances when individuals consumed parts of plants like bark, dead wood, or pith—materials typically avoided unless under duress. These actions often occurred when the chimpanzees were visibly wounded, lethargic, or recovering from illness.

This behavioral data formed the basis for a deeper analysis: Do the plants chosen by chimpanzees contain bioactive compounds with medicinal effects?

Testing the Plants: In Vitro Evidence of Healing Power

The team collected 17 plant resources from 13 species identified through these behavioral observations. In the lab, they extracted compounds using solvents like methanol, ethyl acetate, and n-hexane, and tested them against dangerous, antibiotic-resistant bacteria (including ESKAPE pathogens) and for anti-inflammatory activity via the COX-2 enzyme pathway.

The Results Were Striking:

• 88% of extracts (45 out of 51) showed antibacterial effects, inhibiting bacterial growth by at least 40% at 256 µg/mL.
• Alstonia boonei (dead wood) and Khaya anthotheca (bark/resin) were the most potent, with minimum inhibitory concentrations (MICs) of just 32–64 µg/mL against Enterococcus faecium and Staphylococcus aureus.
• Anti-inflammatory activity was also observed. Extracts from Khaya anthotheca and Christella parasitica demonstrated strong inhibition of COX-2, with IC₅₀ values as low as 0.55 µg/mL.
• Syzygium guineense showed moderate antimicrobial activity against Pseudomonas aeruginosa.

This robust pharmacological evidence supports the idea that chimpanzees are not just ingesting these plants by chance—but potentially as treatment.

Behavioral and Pharmacological Evidence Align

What makes this study especially persuasive is the overlap between observed behavior and laboratory-confirmed bioactivity:

• Wounded individuals were observed gnawing on A. boonei dead wood—later shown to have strong anti-inflammatory and antibacterial effects.
• A chimpanzee recovering from illness consumed Christella parasitica, a fern with significant COX-2 inhibition.

These case studies reinforce the hypothesis that chimpanzees use certain plants as medicinal remedies—a behavior that may be culturally transmitted or rooted in instinct.

Why This Matters: Evolution, Medicine, and Conservation

1. Ecological Intelligence and Animal Medicine

This study strengthens the concept of zoopharmacognosy, demonstrating that animals may possess—or develop—knowledge about medicinal plants. It challenges long-held assumptions about the exclusivity of human medicine and opens new lines of inquiry into how non-human species learn, remember, and share therapeutic knowledge.

2. Pharmaceutical Potential of Forest Flora

Plants like Khaya anthotheca and Alstonia boonei are now strong candidates for drug development, especially in the fight against antibiotic-resistant bacteria. The study's approach—letting animal behavior guide the search for bioactive compounds—could streamline pharmaceutical discovery by focusing on ecologically relevant leads.

3. Urgency of Biodiversity Conservation

The forest isn't just a home for chimpanzees—it's a pharmacy in danger. Deforestation and habitat loss threaten the very ecosystems where these discoveries are made. Protecting wild habitats like Budongo isn't just about conservation—it's about preserving biomedical potential that could benefit both animals and humans.

4. Future Research Directions

The authors recommend:

• Monitoring health outcomes in chimpanzees post-consumption to verify clinical effects.
• Isolating and characterizing active compounds using biochemical methods.
• Studying the social transmission of medicinal knowledge within chimpanzee communities.
• Expanding research to other species and habitats to assess the generality of these findings.

A Glimpse Into Nature's Pharmacopoeia

This study blends field observation, pharmacology, and ecology to provide one of the clearest demonstrations yet of self-medication in wild primates. It reveals how deeply intertwined animal behavior is with ecosystem function—and how much we stand to learn by paying close attention.

As scientists, conservationists, and policymakers consider the future of tropical biodiversity, Budongo's chimpanzees remind us that some of the best medicine is still growing wild.

Topics of interest

History Biodiversity