Like humans, their wounds are cured. They lick them, they plug them with their hands, they apply plants with healing properties and even make leaves and stems before using them as a plaster. A work that includes 30 years of observations and published by the scientific journal shows that they also have hygiene behaviors after intercourse or defecate. Previous studies had already demonstrated similar practices in other species of, such as orangutans or gorillas, but chimpanzees also cure others, something very close to human altruism.
In the (Uganda) they have been studying chimpanzees for more than 30 years. With patience, primatologists have achieved that members of two different communities have become accustomed to their presence, leaving them to approach a very little meters. In the Sonso community, studied since 1990, 68 identified copies have lived. Meanwhile, in Waibira, with the presence of scientists since 2011, the population exceeds hundred. Fruit of this work was the finding, last year, that these apes would ingest the bark of some trees with.
“The Chimpanzees communities of this article are the same as those of the previous one,” says Oxford University and first author of the research, Elodie Freymann. “On this occasion, instead of analyzing the plants that these chimpanzees consume as a possible medicine when they are sick or with parasites, I focus on the forms of external care (healing of wounds and injuries, withdrawal of traps, hygiene behaviors …),” he adds. In addition, “in the other work, we focus only on self -care, self -medication. Now, we also report prosocial behaviors, aimed at others,” completes. To his own observations on the field for eight months of field work, Freymann joins the study and analysis of the newspapers of his colleagues who have been in Budongo since 1990.
Since 1993, almost 50 cases of priests have registered. The majority, 34 of them, with the wounded chimpanzee being. But there are several in which they cured other members of the group. It is very likely that the total figure was much larger, but at the beginning of the investigations these behaviors will not be registered systematically. In fact, in the four months that Freymann was in Sonso, in the summer of 2021, he could observe 12 cases of wounds. All injuries were due to violence within the group, two of them occurred during two infanticides in which the aggressor was injured in one of them and the mother in the other.
In Waybira, Freymann registered four wounds in another four months of stay. The most serious was caused by a trap. “I observed a Pavelaa young female, trapped in a wire trap. He was around his foot and seemed quite recent. Unfortunately, he did not survive and did not see her again after that day, “he says. Made of nylon or wire, humans place them to hunt antelopes, but they also catch the chimpanzees. In fact, 40% of the members of the Sonso community have scars of one of these traps.
“When the chimpanzees are trapped in traps, their mobility is drastically affected. They often lose a limb, other times they die,” Feymann laments. “When a chimpanzee is trapped, it usually disappears and moves away from the group for a while, especially if it has limited mobility. This can have serious social consequences for them, in addition to representing a risk to their health,” he adds. “I returned to Budongo a few weeks ago and Sonso’s alpha male had hooked on one of them. This made it difficult for him to maintain control of the group,” says the researcher. During his stay he failed to see them, but in the Diario de Sonso, several cases are collected in which scientists observed how a chimpanzee helped another to free themselves from a trap.
The work collects how wounds are cured. The first and most common of behaviors is to lick the injury. In addition to cleaning it to avoid infections, saliva could have antimicrobial properties, as studies with other animals have demonstrated, although not in chimpanzees. Another behavior is to take your fingers to your mouth and then put them on the wound. The two most elaborate are the direct application of leaves or chew them and then apply them on the laceration. The interesting thing is that they do not use any plant. The study includes four different species, all with recognized or supposed properties. This is the case of the sheets of the Pseudospondias microcarpaused in several countries in Central Africa for the treatment of various pathologies. The leaves of the Argomuellera macrophylla They are used by chimpanzees to treat their wounds, but in ivory coast humans take their sap as purgative and to treat ascites.
Although it was not the objective of this work, it also records several cases of other behaviors more related to hygiene. Thus, several animals have been recorded cleaning the genital area with leaves after two events: intercourse or doing their needs.
In the last year, several works have been announced that show how three of the four great apes use plants to treat their wounds or diseases. The image of applying a plaster in a wound on his face, which had disappeared in less than three weeks, is exceptional, but because it is difficult to observe these animals in a natural state. Other orangutans have been seen eating ginger leaves, used as medicine in Southeast Asia.
As for the gorillas, the ethnopharmacologist of the Bernhard Nocht Institute of Tropical Medicine (Germany), Fabien Schultz, is finalizing a work they have been doing since 2019 in the National Park of the Impenetrable Selva of Bwindi, which remain. These species have coevolved with their pathogens, so they have had to develop defense behaviors. But there is something that has not been observed neither in gorillas nor in orangutans and yes among chimpanzees: cure others. On bonobos, although there are no direct observations, given its greatest empathy than that of chimpanzees, there are many possibilities that they also have these prosocial behaviors
Susana Carvalho, associate director of Paleoantropology and Primatology of (Mozambique), acknowledges that among primatologists there has been much debate about altruism, reciprocity and cooperation in chimpanzees. “Many researchers argue that chimpanzees lack a behavior of helping others if they do not obtain a reward. However, longitudinal studies are lacking on the subject, and some captivity have shown that chimpanzees spontaneously help others, even without rewards and despite their high cost,” he recalls. Hence the importance of this work in which it appears as a senior author.
For Carvalho, the care of the wounds of others should among the chimpanzees should lead to review the study of the roots of prosociality. “Probably, we share with the chimpanzees a longer evolutionary story regarding altruism of what we had considered before,” he writes in an email. In his opinion, he could have originated in similar contexts, where the care of others became fundamental for the survival and health of the group, justifying the care of unrelated individuals. “Therefore, its origins could be more related to the care of others than with sharing objects,” he ends.
