Chimpanzees not only heal their own wounds but also provide first aid to others.

▲ Social grooming between two chimpanzees in Budongo Forest. Photo by Europa Press

Europa Press

La Jornada Newspaper, Friday, May 16, 2025, p. 6

Madrid. Scientists studying chimpanzees in the Budongo Forest, Uganda, have observed that these primates not only heal their own wounds, but also care for others.

This information could shed light on how our ancestors began to heal wounds and use medicines.

While chimpanzees have been observed elsewhere helping other community members with medical problems, the persistent presence of this behavior at Budongo may suggest that chimpanzee medical care is much more widespread than previously thought and is not limited to caring for close relatives.

Our research helps shed light on the evolutionary roots of human medicine and healthcare systems , said Dr. Elodie Freymann of the University of Oxford, first author of the paper published in Frontiers in Ecology and Evolution .

By documenting how primates identify and use medicinal plants and provide care to others, we better understand the cognitive and social underpinnings of human healthcare behaviors .

Scientists studied two chimpanzee communities in the Budongo Forest: Sonso and Waibira. Like all chimpanzees, members of these communities are vulnerable to injuries, whether caused by fights, accidents, or traps set by humans.

The researchers spent four months observing each community, in addition to drawing on video evidence from the Dictionary of Great Apes database, records with decades of observational data, and a survey of other scientists who had witnessed chimpanzees being treated for illness or injury.

Plants with medicinal properties

All the plants the chimpanzees used for external care were identified; several were found to have chemical properties that could improve wound healing and were used in traditional medicine.

During their direct observation periods, the scientists recorded 12 injuries at Sonso, all likely caused by conflicts within the group. At Waibira, five chimpanzees were injured: one female by a trap and four males in fights. The researchers also identified more instances of grooming at Sonso than at Waibira.

This is likely due to several factors, such as possible differences in the stability of the social hierarchy or greater observation opportunities in the more habituated Sonso community, Freymann said.

The researchers documented 41 instances of caregiving in total: seven involving assistance to others (prosocial) and 34 involving self-care. These instances often included diverse caregiving behaviors, which could be addressing different aspects of an injury or reflecting a chimpanzee's personal preferences.

Wound care in chimpanzees encompasses several techniques: direct licking of the wound, which removes debris and potentially applies antimicrobial compounds in saliva; finger licking followed by pressure on the wound; leaf rubbing; and chewing plant materials and applying them directly to the wound , Freymann explained.

All the chimpanzees mentioned in our tables showed recovery from injuries, although, of course, we do not know what the outcome would have been if they had done nothing about it.

We also documented hygiene behaviors, such as cleaning the genitals with leaves after mating and cleaning the anus with leaves after defecation, practices that could help prevent infections.

Of the seven instances of prosocial care, the researchers found four instances of wound treatment, two of assistance with trap removal, and one in which one chimpanzee assisted another with hygiene. The care was not provided preferentially to one sex or age group. On four occasions, care was provided to genetically unrelated individuals.

Europa Press

La Jornada Newspaper, Friday, May 16, 2025, p. 6

Madrid. Tool use has been widely documented in a wide range of species in the animal kingdom, primarily among vertebrates, and now a notable example has been added in the world of insects.

Researchers from China Agricultural University, Xishuangbanna Tropical Botanical Garden (XTBG) of the Chinese Academy of Sciences, and the Institute of Zoology have described how the assassin bug, Pahabengkakia piliceps ( P. piliceps ), uses resin from the nests of stingless bees to lure them into the predator’s optimal hunting position. This is the first comprehensive evidence of an invertebrate predator using tools to exploit the collective defenses of social insects.

Stingless bees deposit a sticky, pungent resin around the entrances to their nests to deter intruders. When predators like ants or geckos become trapped, guard bees swarm to immobilize them. But assassin bugs use this defensive mechanism against bees.

Researchers observed that the assassin bug deliberately collects resin with its front and middle legs to cover them with the sticky material. The resin's amplified chemical signal attracts guard bees to the assassin bug's location. In this way, the resin not only doesn't repel the predator, but acts as a beacon, drawing the bees within striking distance.

This is a sophisticated manipulation of prey behavior , said Wang Zhengwei of XTBG. The bug not only avoids detection, but actively provokes attacks to create opportunities .

Through controlled field trials, the researchers showed that resin-coated assassin bugs achieved a predation success rate of 75 percent. This rate dropped to less than 30 percent for resin-free bugs. Critically, they found that applying resin to non-hunting body parts (e.g., the abdomen) also offered a relative benefit, confirming that resin viscosity was not the key to predatory success. Instead, chemical analyses revealed that the insects' handling of resin increased emissions of volatile compounds, which are irresistible to protective bees.

As a specialized predator, P. piliceps is completely dependent on stingless bees for its survival and reproduction. This dependence likely drove the evolution of its unique tool-using behavior among predatory insects to improve their hunting efficiency, indicating a link between tool use and dietary specialization across the animal kingdom.

The study challenges assumptions that complex tool use requires advanced cognition, highlighting how ecological specialization can shape seemingly intelligent behaviors. “Unlike vertebrates, insects like P. piliceps offer a practical system for exploring the evolution of tool use in animals,” Wang said.