Chimpanzees have been spotted using plants to self-medicate – and could lead their human relatives to new drugs.
For many years, scientists have suspected that chimpanzees and other primates could self-medicate by eating particular plants – while recently a remarkable orangutan known as Rakus was seen applying chewed up leaves to his face to treat a facial wound.
To investigate, a team from the University of Oxford turned undercover detectives, and appear to have evidence that chimpanzees really do know how to treat their ailments from nature’s pharmacy, eating specific plants when they’re feeling ill.
The researchers followed 51 wild chimpanzees from two groups in the Budongo Central Forest Reserve in Uganda, closely observing their behaviour, diets, and any particular animals that appeared unwell.
Then they collected plant extracts from different trees and herbs to analyse, including those they saw sick or injured chimpanzees eating that weren’t part of their normal diet.
Laboratory testing revealed the exciting find that almost all of the plants had medicinal properties, suggesting the animals were eating them in order to feel better.
The team found that 88% of the plants inhibited bacterial growth – acting as antibiotics – and 33% had anti-inflammatory properties.
Dead wood from a tree in the Dogbane family had the best bacteria-fighting ability, suggesting the animals were eating it to treat wounds. The same tree is also used by human communities in East Africa to treat a variety of conditions, including bacterial infections, gastro-intestinal issues, snake bites, and asthma.
One male chimpanzee with an injured hand was seen seeking out and eating the leaves of a particular fern with anti-inflammatory properties, while another with a parasitic infection chewed the bark off a cat-thorn tree, something the team had never seen the group do before. Testing showed the bark has both anti-inflammatory and antimicrobial properties.
Dr Elodie Freymann, lead author of the study published in the journal PLOS One, said: ‘The results suggest that chimpanzees seek out specific plants for their medicinal effects.
‘The study is one of the first to provide both behavioural and pharmacological evidence of the medicinal benefits to wild chimpanzees of feeding on bark and dead wood.’
She added: ‘To study wild chimpanzee self-medication you have to act like a detective – gathering multidisciplinary evidence to piece together a case.
‘After spending months in the field collecting behavioral clues that led us to specific plant species, it was thrilling to analyse the pharmacological results and discover that many of these plants exhibited high levels of bioactivity.’
And quite aside from the incredible finding that chimpanzees are even more smart than previously thought, the discovery could lead to better healthcare for humans as the world faces growing bacterial antibiotic resistance and chronic inflammatory diseases.
‘Our study highlights the medicinal knowledge that can be gained from observing other species in the wild and underscores the urgent need to preserve these forest pharmacies for future generations,’ said Dr Freymann.
