Chimpanzees treat each other’s wounds with medicinal plants

Researchers studying chimpanzees in Uganda have documented something amazing – these apes can not only treat their own injuries with medicinal plants, but also provide health care for injured community members.

The finding, published Wednesday on the ecological and evolutionary boundaries, suggests that prosocial health care for our closest relatives may be more extensive than previously recognized, which may illuminate the evolutionary roots of human medical practice.

The amazing world of chimpanzees first aid

Deep in Budongo Forest in Uganda, a chimpanzee named Ko carefully picks leaves from Argomuellera Macrophylla plants, chews its stem skin, and methodically applies the chewed material to the wounds in the knee. In another observation, a teenage woman mimics her mother’s wound care technique, folding and chewing her medicine leaves, and then gently wiping her mother’s injuries.

“Our research helps to elucidate the evolutionary roots of human medicine and health care systems,” explains Dr. Elodie Freymann of Oxford University who led the study. “By documenting how chimpanzees recognize and utilize medicinal plants and provide care for others, we can gain an in-depth understanding of the cognitive and social basis of human health care behavior.”

Forest medical tool kit

The team documented 41 cases of medical behavior in two chimpanzee communities (Sonso and Waibira), utilizing thirty years of observation, video evidence and direct field research. They identified several different wound treatment techniques:

• Direct wound licking, remove debris and potentially apply antibacterial compounds in saliva
• Lick your fingers and press the wound
• Leaves fall off and leaves are used as a compression for injury
• Chew the plant material and apply it directly to the wound
• Hygiene behaviors, including cleaning the genitals with leaves after mating

Many plants selected by chimpanzees have known medicinal properties. The researchers identified several species, including several species with antibiotics, antifungal and anti-inflammatory properties. These same plants have traditionally been used by local human communities to treat wounds and infections.

Nursing staff go beyond kinship

Perhaps most notable is the discovery of seven “prosocial care” cases – one animal treats another’s wounds or helps remove dangerous thieves. Despite some care provided between relatives, more than half of the unrelated community members were involved.

“These behaviors add to evidence from other locations that even without direct genetic advantage, chimpanzees appear to recognize people who need or suffer and take deliberate action to mitigate the situation,” Freman said.

The study did not find patterns in which individuals are more likely to give or receive care – men care for women, men and men of all ages are involved in providing assistance.

Adapt to threats

Budongo chimpanzees face unique health challenges. Although there are no natural predators, they suffer a high degree of human injury. It has been observed that approximately 40% of individuals in the SONSO community are trapped by traps set against other animal hunters.

Will these elevated risks affect the development of their health care behaviors? Researchers believe that just like predation stress, it may enhance social cohesion, and that artificial threats may promote more frequent prosocial care.

The team observed a variety of situations where chimpanzees tried to help eliminate dangerous snares from others – an act that requires awareness of problems, understanding solutions and taking action to help struggling community members.

The evolution of empathy and medicine

What drives chimpanzees to risk exposure to infection by treating other people’s wounds? The researchers point out that sympathy is a characteristic shared with humans and seems to be based on the basis of selflessness.

Chimpanzee health care is not limited to relatives’ discovery raises fascinating questions about the evolution of medicine. Can these behaviors represent the original form of the institutionalized medical system that humans later developed?

Although the team acknowledges some limitations in their research, including differences in the ways in which humans observe habits, their work provides compelling evidence that the roots of human medical practices may penetrate deep into our evolutionary past.

As Dr. Freymann and colleagues continue their research, they want to better understand which social and ecological factors affect when and why chimpanzees provide care. This understanding may have an impact not only on evolutionary science, but also on the conservation efforts to protect these outstanding animals and the medicinal plant resources they depend on.

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