One Life: Chimpanzees

14 July 2021

Chimpanzees are our closest living relatives, sharing more than 98 percent of our genetic blueprint, and just like us, they live in complex social societies. They have individual personalities, communicate via an extensive array of facial expressions and vocalisations, make and use tools, and experience a range of complex emotions such as empathy and grief. Chimps can even outsmart humans on some memory tasks. 

Complex social lives

Chimpanzees live in social communities ranging from 20 to 150 individuals, with subgroups of individuals within the community. Each individual chimpanzee develops personal relationships with others in their group which last a lifetime.

Understand and help each other

Older chimpanzees generally prefer spending more time with, and grooming, chimps they have developed mutual friendships with over the years, understanding each other and how their close friends are feeling.

Bonded individuals demonstrate complex cooperation, not just helping each other out but using coordination and an understanding of partnership to achieve shared goals. For example, Ivory Coast chimpanzees hunt cooperatively to catch red colobus monkeys, coordinating their actions to increase their chances of success. The meat is much prized and its subsequent sharing strengthens male alliances and familial bonds.

Develop friendships with those that they can trust

Trust is a defining element of genuine friendship. We trust friends with crucial resources or important secrets, and chimpanzees show a comparable pattern and extend trust selectively toward those individuals they are closely bonded with. 

Trust is demonstrated in chimpanzee friendships. Researchers tested trust by observing the interactions of 15 chimpanzees living at Sweetwaters Chimpanzee Sanctuary. Based on friendly interactions among chimp pairs, they identified each chimpanzee's closest "friend" and a "non-friend. They then asked the chimps to play a trust game, both with their friend and with their non-friend. In the game, chimps had a choice between pulling a "no-trust rope" and a "trust rope." When the no-trust rope was pulled, the first chimp got immediate access to a food that he or she didn't like especially well. When the trust rope was pulled, the other chimp got immediate access to a much more tempting food item and the option to send a treat back to the first chimp (or not). In other words, the trust rope offered the potential for a win-win, but only if chimp one trusted chimp two enough to send something back. 

Each chimp played the game 12 times with his or her friend and another 12 times with his or her non-friend. The results showed much greater trust between friends than non-friends. Chimpanzees were significantly more likely to voluntarily place resources at the disposal of a partner, and thus to choose a risky but potentially high-payoff option, when they interacted with a friend as compared to a non-friend. 

Have a sense of fairness

Altruism or selflessness is the principle or practice of concern for the welfare of others, even at a risk or cost to ourselves. Chimpanzees are altruistic, they care about the welfare of others, and will help other members of their communities to obtain resources even when there is no direct benefit to themselves. 

For example, they are known to share both food and hunting tools with other chimps

Chimpanzee researchers in Senegal, have witnessed 41 cases of chimpanzees willingly transferring either wild plant foods or hunting tools to other chimpanzees, ensuring that all members within their community have access to essential resources for survival. 

Have a moral compass

Individuals often quarrel when living together, following these incidents chimpanzees will often reconcile with each other to ensure that the group can live peacefully. Third party individuals are also known to help ensure that there is peace and order in their group by ‘policing’ conflicts and intervening where possible.

This is a morally motivated behaviour, intervening impartially in a conflict to guarantee the stability of the group. The third party individual exhibits prosocial behaviour based on community concern. The willingness  to intervene impartially is greatest if several individuals are involved in a dispute as such conflicts particularly jeopardize group peace. It is primarily high-ranking males or females or animals that are highly respected in the group that intervene in a conflict. As with humans, there are also authorities among chimpanzees.

Great mums

Parental care is mum’s responsibility and is critical to the survival and emotional health of young chimps. Chimpanzee  mums provide food, warmth, protection, and the opportunity to learn life skills.  Mum and baby are in constant contact for the first 30 days of life, and newborns are helpless to survive without such maternal support. 

Infants will venture a small distance from their mothers at around 2 years of age and are weaned between 4 and 6, becoming independent between 6 and 9 years of age, but maintaining a lifelong bond with their mum.

Chimps are ‘adopters’

If a mother tragically dies during childbirth or whilst the infant is still dependent, the infant is unlikely to survive, or is unlikely to develop the social skills needed to live within such a complex society, unless adopted by a family member. 

Adoption of infants has been observed in captive chimpanzees. This includes the adoption of  ‘Boon’ by a female named ‘Zombi’ in 2015 at the Monarto Zoo in Australia, following the death of his mother ‘Soona’. After Boon was born, a male within the group was reported to have picked up Boon and cared for him whilst Soona sat with Zombi until she passed away. Zombi then collected Boon from the male and subsequently provided him with the care he would have received from his mother.

It is believed that adoptions by closely related females are also likely to happen within wild populations. Adult chimps may carry orphans, share their food and their nest at night, and protect them from aggression, helping to fill the essential role that their mothers would have played in their lives.

Chimps that are orphaned when they are old enough to survive are also put at a distinct disadvantage. Due to this, orphaned chimpanzees are known to be less socially competent than chimpanzees who were reared by their mothers. 

Orphaned chimpanzees engaging in social play, are known to have shorter play bouts which result in aggression more often than in chimpanzees which have been raised within social groups. Since social play comprises a complex context in which signals about intentions need to be communicated, it seems that orphaned chimpanzees have missed out on valuable lessons that they are likely to receive from their mother to prepare them for challenges that are very important for successful group-living.

Fortunately, recent studies suggest that non-dependant orphans also have the ability to recover over time from this early life stress.

Learn from their elders

Infants and juveniles benefit from the close relationship with their mothers in terms of food, warmth, protection, and the opportunity to learn skills. They also watch and learn from other older group members to find food, and learn how to use tools. Learning socially with skills and knowledge being transferred between generations.

Care for their disabled

Individuals born with disabilities rarely survive unless they have the support of a society which is willing to provide additional care above and beyond the care normally provided. 

Researchers in Tanzania have observed a chimpanzee mother caring for her disabled infant in the wild. The infant exhibited symptoms resembling Down syndrome, and the mother's care for her infant's disabilities and allomothering of the infant by its sister helped it to survive for 23 months in the wild.

Are ‘self-aware’

Chimpanzees are self-aware, they have a sense of being an independent agent and can anticipate the impact of their actions on the environment around them, in much the same way as we can. An ability once thought to be uniquely human.

Excellent tool users

Chimpanzees are proficient tool makers and users, shaping and using sticks to fish for termites, to dip for ants, and to extract honey. They use leaves as sponges to soak up drinking water, and even use stone or wooden hammers to crack open nuts.  

Male chimpanzees will also throw branches and stones during displays, or leaf-clip to solicit attention from females.

Great communicators

Visual and vocal communication are important to chimpanzee society with a suite of facial expressions, postures, and sounds that function as signals during interactions between individuals and groups. Chimpanzees have particularly expressive, hairless faces and facial expressions play an important role in close-up communication between individuals.

Body position and stance also convey information to others. Submissive positions include extending the hand, crouching, and bobbing while aggressive positions usually involve an individual trying to appear larger than he is by swaggering bipedally, hunching his shoulders, and waving his arms. Adult chimpanzees will also drum on the trunks of trees, by beating their hands and feet against large trees, for a dramatic display.

Vocal communication also conveys a wide variety of emotional states and intentions and often serves to affect the behaviours of those that hear the calls. Over 30 different chimpanzee vocalizations have been identified. A chimpanzee will whimper or cry when they are feeling distressed and laugh when they feel excitement. When young chimpanzees play they will emit a laughter, similar to that heard in young children. 

A very important vocalization is the "pant-hoot," these are individualistic vocals, and are the most commonly heard call of adult individuals used to signify food enjoyment, social excitement, and sociability feelings.

Have language and regional dialects

Chimpanzee vocalisations are used in a sophisticated manner; in many cases they are known to carry specific messages such as indicating the presence of fruits or the location of the trees which contain the fruits.  

They also have regional dialects and they are capable of learning dialects from other groups to enable them to fit into a new society, learning to mimic the grunts of new companions over time, allowing for better communication between formerly different social groups.

Have tantrums

Researchers studying the interactions and communications among chimpanzees at Central Washington University’s Chimpanzee and Human Communication Institute, found that they used a unique mixture of communication methods and would increase and alter their communication style based on the attention they were receiving. 

Like a child seeking the attention of a parent whose concentration is momentarily elsewhere, the chimpanzees would intensify their vocalizations and resort to poking, prodding and even foot stomping if they were not being heard

Have the cognitive capacity to cook

Wanting to eat cooked food requires an understanding of the transformation of a food item into a new form by the act of cooking. 

Chimpanzees have demonstrated the cognitive capacity to understand this transformation process and have shown the ability to choose not to eat favoured uncooked food items straight away but to place them into a ‘cooking device’ to receive the transformed cooked food item instead. Therefore, aside from control of fire, chimps possess all the requisite cognitive skills to engage in cooking.   

Highly intelligent

Metacognition occurs when individuals monitor what they know and don't know, when they seek information they need to know and when they respond to a question with high confidence or low confidence. Confidence measures are one clear means of looking at how humans monitor their own knowledge states. 

Chimpanzees in behavioural research settings have demonstrated they share with humans the capacity for metacognitive monitoring, which reflects a form of cognitive control that underlies intelligent decision-making.

Have excellent memories

Chimpanzees have incredible short term memories which helps them to survive in the wild, where they often must make rapid and complex decisions. 

This short term memory ability has been clearly demonstrated by a Japanese researcher with a Chimpanzee named Ayumu. Using a touchscreen and rewards for correct responses, Ayumu is presented with the numbers 1 to  9 randomly on a screen and these then disappear. Ayumu is able to recall the exact sequence and location of each number. Ayumu has also learnt numbers 1 through 19 and is able to touch each one in ascending order. This is a memory skill that very few people possess.

Chimpanzees have cultures

Chimpanzees have cultural traditions exhibiting highly distinctive behavioural differences between different populations. These behavioural differences include 39 different patterns of tool-use, grooming, and courtship behaviours. 

Behaviours are classified as culture if intergenerational transmission of behaviour occurs through social or observational learning to become a population level characteristic. 

While some behaviours are species typical, such as nest building, others are far from uniform across chimpanzee populations. Termite or ant fishing are seen only in some populations while nut cracking behaviour is seen only in West African chimpanzees. One group of chimpanzees in Uganda have developed the technique of using leaf sponges to collect water from tree holes, and this has not been seen in any other groups. 

Chimpanzees in Bossou, Guinea have learned how to break and deactivate dangerous snares, and they are passing this information  down through generations, in the same way that human parents pass on skills to their children.

Different groups of chimpanzees may have the same tools to hand, but each group may  develop their own techniques and behaviours unique to them. 

Chimpanzee cultures are disappearing

Sadly, these chimpanzee cultures are disappearing. Where humans are encroaching onto chimpanzee habitats and changing the landscape, the chimps are reverting to more basic survival skills. The loss of these skills can be damaging to the chimpanzees though, as many are associated with accessing different foods. 

Researchers from Germany have spent 10 years observing 144 groups of chimpanzees in Africa to find out what is happening to their cultural traditions. They found that the chimp groups who were living close by to humans were performing fewer cultural behaviours. Researchers suggest that this may be due to the encroachment upon habitat, isolating groups of chimpanzees, and impacting upon social learning. 

Chimpanzees can suffer too

Humans can respond to traumatic events by developing mental illnesses such as post-traumatic stress disorder (PTSD) or depression. Humans are not alone in this, as chimpanzees can also suffer from these illnesses too. 

Researchers have found that chimpanzees who have suffered traumas such as being separated from their mother, forced into social isolation, or having been experimented on, displayed the signs of PTSD and depression, in a similar way to humans. This has important implications for how they are treated, as chimps can suffer just like us. 

Grieve the loss of their family members

Grief is a multifaceted response to loss, particularly to the loss of someone or something that has died, to which a bond or affection was formed. Although conventionally focused on the emotional response to loss, it also has physical, cognitive, behavioural, social, and philosophical dimensions. 

Chimpanzees demonstrate emotional responses to the deaths of their family members which are interpreted as grief.

Chimpanzees really are amazing animals

Many chimpanzees live in poor living conditions, often socially isolated in substandard zoos and private collections around the world. Many hundreds are also used in circuses and in the tourism industry, forced through fear and punishment to perform meaningless tricks or to have their photograph taken with tourists. Chimpanzees are wide-ranging social animals with diverse physical, social, behavioural and psychological needs. Poor captive facilities and the use of chimpanzees in entertainment causes chimpanzees to suffer unnecessarily, and may cause them severe mental illnesses. 


Chimpanzee conservation

The main threats to the chimpanzee are habitat loss and hunting for bushmeat. The relative severity of these threats differs from region to region, but the two are linked. Degradation of forests through logging, mining, farming, and other forms of land development is contributing to the decline of primate species throughout tropical Africa. Remaining habitat patches are often small and unconnected, leaving chimpanzee populations isolated. This may be why chimpanzees are losing their cultural traditions.

In many areas, poaching for meat and live infants is common, as is unauthorized logging, mining and farming. Logging activities improve access to formerly remote forest areas, leading to increased hunting pressure.

'Bushmeat' has always been a primary source of dietary protein in Central and West African countries. However, in recent years, hunting for bushmeat, once a subsistence activity, has become heavily commercialized and much of the meat goes to urban residents who can afford to pay premium prices for it.

The effect of the bushmeat trade on chimp populations has yet to be evaluated, but a study in the Congo showed that the offtake was 5-7%, surpassing the annual population increase. In addition, apes are often injured or killed in snares set for other animals. Infant chimpanzees are frequently taken alive and sold in the cities as pets.

1.Gruber, T., Reynolds, V. & Zuberbühler, K. The knowns and unknowns of chimpanzee culture. Commun. Integr. Biol.3, 221–223 (2010).

2.Ohashi, G. & Matsuzawa, T. Deactivation of snares by wild chimpanzees. Primates.52, 1–5 (2011).

3.Heinicke, S. et al. Characteristics of Positive Deviants in Western Chimpanzee Populations. Front. Ecol. Evol.7, 16 (2019).

4.Ferdowsian, H. R. et al. Signs of mood and anxiety disorders in chimpanzees. PLoS One6, e19855 (2011).

Read more: