11 Surprising Facts About Chimpanzees

Chimpanzees are great apes and members of the family Hominidae, which also includes humans. Found across western and central Africa, chimps are our closest relatives in the animal kingdom. We share about 98 percent of our DNA with them. Chimps are also endangered with a decreasing population.

Like us, chimps laugh together, form social groups, and use tools to achieve goals. Chimps live for about 50 years in the wild and up to 60 years in captivity. Offspring have strong bonds with their mothers, and maintain close relationships throughout their lives. These gregarious primates nest in the treetops and walk on all fours, and while we’ve been studying them for decades, we are constantly learning new things. From having stable personality traits to keeping their nests extra clean, discover the most remarkable facts about chimpanzees.

1. Chimps and Humans May Share an Ancient Body Language

A 2018 study found that gestures made by chimpanzees and bonobos overlap 90 percent — far more than would be possible by chance. These gestures included flinging hands to shoo an ape or stroking another animal’s mouth to indicate a desire for the other’s food. Humans have been able to discern what many of these gestures mean as well, concluding that the gestures were used by our last common ancestor. This finding was further supported by a study that showed that toddlers share nearly 90 percent of gestures, such as jumping, hugging, and stomping, with chimpanzees.

Chimpanzees have been observed using 58 different gesture types to communicate with each other. A team of researchers studied video footage of wild chimpanzees at Uganda's Budongo Forest Reserve and recorded over 2,000 gestures. Commonly used gestures represented short phrases and meanings, while longer gestures were broken into smaller gestures similar to the way human language includes multiple syllables for longer words.

2. They Warn Their Friends of Danger

Chimps live in dangerous spaces, but fortunately they have each other's backs. These great apes are known for warning their friends, but in a 2013 study, scientists discovered that chimps will adjust their warnings based on the information they perceive that the other chimps have about the threat. Chimps will make alarming vocalizations and gaze at a threat and then back at their group until other chimps take notice. If they believe another chimp is unaware, their vocalizations and gestures become more urgent. The study also found that chimps will give more warnings about threats to chimps who are relatives or friends.

3. They Will Wage War

In 1974, Jane Goodall observed a splintering between a group of apes in Tanzania's Gombe Stream National Park that were once unified. Over the next four years, the chimps fought over territory and deliberately killed one another, including an ambush of six chimps against one. While one group ended up victorious, their expanded territory pushed against the range of a third chimp group, prolonging the conflict. 

Further studies have supported the theory that access to resources — particularly food and mates — are the primary triggers of violence among chimps. Most of the attacks are by male chimps against other males, and they are primarily against members of different communities. The attacks are more common when there is a higher population of males, as well as in areas with a higher population density overall. The research also revealed that the violent behavior was more common among eastern chimps than western chimps.

4. They Emulate Desirable Behavior

Social learning is common in chimps. They not only learn to make tools from one another, but also have been observed picking up fashion tips. In 2010, a Zambian chimpanzee named Julie stuck a stalk of grass in her ear for reasons that have not been determined. The rest of her group followed suit. A group of researchers observed the behavior, but did not find this to be a repetitive action, and couldn’t find a purpose for the ear accessory beyond that it must have looked nice to the other chimps.

5. Chimps Can Catch Human Illnesses

In 2013, an outbreak of respiratory disease occurred in a group of chimps in Uganda's Kibale National Park. Five of the 56 chimps died due to the disease. When the body of a two-year-old chimp was recovered and autopsied, researchers discovered the cause: rhinovirus C, one of the primary causes of the common cold in humans.

Due to their endangered status and susceptibility to infections that occur in humans, in 2020 the IUCN and Primate Specialist Group laid out protective measures and best practice guidelines to protect chimps and other great apes from COVID-19.

6. They Will Eat Just About Anything

For a long time chimps were assumed to be herbivores, but it turns out that they are omnivores that eat both meat and plants. Goodall first observed the creatures eating something other than plants when she saw them extract termites using sticks. Chimps also eat the meat of monkeys, and they strongly prefer red colobus monkeys. In areas where both are present, there are significant declines in the red colobus monkey population. 

While they eat a wide variety of fruits, vegetables, roots, and seeds, they avoid things they find distasteful, including food with smells associated with biological contaminants.

7. Chimps Have Demonstrated Signs of Alzheimer's

A team of researchers analyzed the preserved brains of 20 chimps that died between the ages of 37 and 62, paying specific attention to the regions that are damaged by Alzheimer's. They found that four of the 20 brains contained plaque made of a protein called amyloid-β and tangles of a protein called tau — both indicators of Alzheimer's in humans. All 20 brains showed signs of "pre-tangles." Researchers in this study didn't have records of changes in the chimps' behaviors, including severe dementia, but the presence of the proteins and the plaque suggest that it would have been possible for the chimps to have experienced such changes.

8. They Have Stable Personality Types

In 1973, a group of researchers described the personalities of 24 chimps in Gombe National Park using the Emotions Profile Index (EPI). The index assigns scores based on eight major personalities: trustful, distrustful, controlled, dyscontrolled, aggressive, timid, depressed, and gregarious. Generally, females demonstrated more trusting natures, while males were more gregarious. Outliers existed, however, including one female chimp named Passion who rated very high as distrustful, aggressive, and depressed. Passion and her daughter were also identified as chimps that killed four infants belonging to another female. 

Researchers returned to the park in 2010 to gauge the personalities of 128 chimps using 24 different metrics. They found that personalities remained stable among chimps regardless of whether they had been in the wild or held in captivity.

9. They May Have Rituals

Camera footage of four groups of chimpanzees in West Africa revealed animals that would throw stones at or into certain trees and then leave the rocks there so they could repeat the process. The practice did not appear to have anything to do with foraging or tool use. The authors suggest that the activity may be ritualistic in nature, while acknowledging that the very definition of "ritual" in this case is contested.

The majority of the participants were male, and the throwing activity included a pant hoot vocalization. The significance of the practice itself remains unclear, but it opens up another avenue for understanding chimpanzees.

10. Chimps Keep Their Nests Clean

Did you know that chimpanzee nests are cleaner than our beds? According to a study conducted in Tanzania, chimps’ nests are less likely to harbor bacteria (fecal, skin, or oral) as compared to human beds. The reason: They build a new nest nightly, which prevents bacteria from accumulating. Researchers also noted that they only discovered four individual parasites among a total of 41 nests analyzed. So, chimps are sleeping peacefully in a nearly bug-free, bacteria-free nest.

11. They Are Endangered

Chimpanzees — our closest living relatives — are endangered, and their population is in decline. The greatest threats to chimps are poaching, infectious diseases, loss of habitat, and decreased quality of habitat due to competition with humans. Although the capture, killing, or consumption of chimpanzees is illegal, the greatest threat to their survival is hunting. 

While legally protected within their range, enforcement is weak, and chimp populations need more stringent protection from law enforcement. In order to protect chimps from continued habitat loss due to agricultural projects, better coordinated land use regulation in the chimps’ range is needed to improve their chances for survival. Due to their similarity to humans, another significant risk for chimps is their susceptibility to diseases that also affect humans. Contact with humans, whether due to tourism or research, puts chimps at risk of contracting infectious diseases.