Chimpanzees: 98.8% Shared DNA With Us

The chimpanzee is the closest living relative of the human species, tied only with its sister species the bonobo.

Pan troglodytes shares roughly 98.8% of its aligned DNA sequence with Homo sapiens , and the split between the human and chimpanzee lineages is estimated to have occurred seven to ten million years ago: recent enough that much of our shared biology, behaviour and cognition remain clearly recognisable on both sides of the family tree.

Understanding chimpanzees is, in a very direct sense, an exercise in understanding the biological scaffolding of humanity itself.

This guide covers every major aspect of chimpanzee biology and behaviour: anatomy, subspecies, habitat, diet, tool culture, social structure, warfare, reproduction, cognition, conservation status and the long and uneasy history between chimpanzees and humans.

Etymology and Classification

The scientific name Pan troglodytes combines the Greek god Pan, a woodland deity associated with wild, goat-legged forms, with the Greek troglodytes , meaning 'cave-dweller', a reference to the Troglodytae, a mythical race of cave-dwellers. The English word 'chimpanzee' was borrowed from the Kongo or Vili language and first appeared in English in 1738, glossed as meaning 'mockman' in a language of 'the Angolans'.

Chimpanzees sit inside the family Hominidae, the great apes, alongside gorillas, orangutans and humans. The genus Pan contains two species: the common chimpanzee ( Pan troglodytes ) covered here, and the bonobo ( Pan paniscus ), restricted to the forests south of the Congo River. Molecular evidence indicates the bonobo and chimpanzee lineages diverged close to two million years ago.

Four subspecies of common chimpanzee are currently recognised:

• Central chimpanzee ( P. t. troglodytes ), centred on Gabon, Cameroon and the Republic of Congo.
• Eastern chimpanzee ( P. t. schweinfurthii ), found from the Central African Republic across the DRC to Uganda, Rwanda and Tanzania. Includes the famous Gombe and Mahale populations.
• Western chimpanzee ( P. t. verus ), west African from Senegal to Ghana, separately classified as Critically Endangered.
• Nigeria-Cameroon chimpanzee ( P. t. ellioti ), the rarest and most range-restricted subspecies, confined to a small area on either side of the Nigeria-Cameroon border.

Despite the long scientific assumption that humans were uniquely separated from the rest of the great apes, molecular taxonomy now places humans so deep inside the Hominidae that some authorities argue chimpanzees and humans should share a genus, a proposal that remains contested but illustrates just how close the evolutionary relationship is.

Size and Physical Description

Chimpanzees are medium-sized great apes, substantially smaller than gorillas and slightly smaller than orangutans. Sexual dimorphism exists but is milder than in gorillas.

Males:

• Standing height: adults average about 1.5 m, exceptionally over 1.68 m
• Weight: averages about 40 kg in the wild, up to 136 kg in captivity

Females:

• Weight: averages about 30 kg in the wild
• Slightly shorter arms and lighter build

Infants at birth:

• Cling to mother's belly fur within hours, ride on her back from several months

The most distinctive structural feature of the chimpanzee body is its arm span, with arms longer than the legs. This elongated upper body is an adaptation for brachiation, swinging through the forest canopy using the arms alone. The shoulder joint rotates through a nearly complete circle, the forearm is long and the hand has long fingers and a short thumb, and the big toe is opposable.

The feet, while adapted for a grip on branches, also support a knuckle-walking gait on the ground in which the animal bears weight on the middle phalanges of the fingers. Chimpanzee muscles are about 50% stronger per unit of weight than human muscles, owing to a higher content of fast-twitch muscle fibres.

The skin under the coat is white, while exposed skin may be white or dark depending on the subspecies, and it can darken with age. The coat is normally black, though it can be brown or ginger and white or grey patches may appear with age.

Their dentition resembles the human pattern, incisors, canines, premolars, molars, but with enlarged canines, especially in males. The chimpanzee brain is roughly one-third the size of the human brain, but the cortical surface is heavily folded and supports a comparable level of cognitive complexity on a smaller absolute scale.

Habitat and Range

Chimpanzees are forest animals at heart, but they are more ecologically flexible than either gorillas or orangutans. Their range spans a broad equatorial belt from Senegal and Guinea in the west through the Congo basin to western Tanzania in the east. They occupy three main habitat types:

• Tropical rainforest. Closed-canopy forest in the Congo basin, west African lowlands and isolated montane pockets. This is the classic chimpanzee habitat.
• Forest-savanna mosaic. Patchy habitat where gallery forests along rivers give way to open woodland and grass. Populations such as the Fongoli chimpanzees in Senegal are famous for adapting to the heat and fire regime of savanna.
• Montane forest. Found in parts of the range at higher elevations.

Chimpanzee home ranges average about 4 km in diameter. Individual communities hold specific territories that they patrol and defend against neighbouring groups.

Diet and Feeding Ecology

Chimpanzees are omnivores with a strong frugivore bias. Fruit is the main food. In a study in Budongo Forest, Uganda, fruit made up 64.5% of feeding time, particularly figs ( Ficus ), Maesopsis eminii , and Celtis gomphophylla . Leaves, seeds, bark, flowers, piths, honey and occasionally soil are also eaten.

Food category	Role in diet	Notes
Ripe fruit	Main food	Dominant when available
Leaves and herbaceous veg	Secondary	Eaten alongside fruit
Seeds and nuts	Minor	Some populations crack open with stones
Insects	Minor	Termites, ants, grubs, bees
Meat	Small portion	Red colobus, bushbabies, small ungulates
Medicinal plants	Occasional	Bark and other woody material, possibly medicinal

Meat-eating is one of the most striking aspects of chimpanzee ecology. Unlike most primates, chimpanzees hunt in coordinated groups, most famously at Gombe and Tai, where red colobus monkeys are the primary prey. Hunts involve individuals taking distinct roles, blockers, drivers, ambushers and the meat is shared among hunting party members and even bystanders.

Self-medication has also been suggested: the consumption of woody material such as bark appears to have a supplemental or medicinal function, and a 2022 study reported that chimpanzees crushed and applied insects to their own wounds and the wounds of other chimpanzees.

Tool Use and Material Culture

Before 1960, tool use was considered a uniquely human trait. That changed in 1960 when Jane Goodall, working in what is now Gombe National Park in Tanzania, observed a male chimpanzee stripping leaves off a twig and using it to fish termites out of a mound.

Today the chimpanzee is known to use one of the richest tool repertoires in the animal kingdom:

• Termite and ant fishing. Scientists use thin flexible probes, frequently hand-modified, that they insert into insect nests.
• Ant dipping. Collecting aggressive driver ants with longer, stiffer sticks while the user avoids getting bitten.
• Nut cracking. Hard nuts placed on a stone or root anvil and struck with stone or wooden hammers. Stone tools attributed to chimpanzees have been dated to about 4,300 years ago.
• Leaf sponges. Chewed leaves dipped into tree hollows to extract rainwater that cannot be reached by mouth.
• Leaf napkins. Leaves used to wipe blood, dirt, or sticky food from the body.
• Spears. At Fongoli in Senegal, chimpanzees sharpen sticks with their teeth and jab them into hollows to kill bushbabies.
• Seat and rain cover. Large leaves folded and used as insulation or shelter.

Crucially, these tool kits differ between chimpanzee communities. The Tai community in Ivory Coast cracks nuts with stone hammers, the Gombe community a few thousand kilometres away does not. These are not genetic differences.

They are cultural traditions learned by young chimpanzees watching adults, then passed on to the next generation.

Chimpanzee culture therefore represents one of the clearest examples of non-human tradition. Learned variations in grooming, tool use and foraging techniques have been documented between groups.

Social Structure

Chimpanzees live in multi-male, multi-female communities of roughly 15 to more than 150 individuals. Communities hold fixed territories and are structured around a dominance hierarchy in which an alpha male, backed by coalition partners, holds the top position.

The social system is described as fission-fusion: the full community rarely assembles at once. Instead, members split into small temporary parties of a few individuals each, merging and splitting throughout the day based on who is feeding where, who is in oestrus and who is allied with whom. This flexibility allows the group to exploit patchy fruit resources that could not support the whole community at a single tree.

Political life within a community is notoriously complex. Adult males form coalitions and counter-coalitions that can overthrow alphas, reward supporters with meat and punish rivals. Primatologists have documented deliberate deception, strategic alliance-breaking and reconciliation behaviours following conflict.

Female mammals build longer-term friendships that often revolve around grooming networks and transfer between communities when mature, a pattern seen rarely among mammals and found in human societies as well.

Grooming is the glue of chimpanzee social life. Hours each day are spent picking through another animal's fur. This is only secondarily about parasites. Primarily, grooming reinforces bonds, defuses tension and builds the coalitions on which political life depends.

Reproduction and Life Cycle

Chimpanzees have a slow reproductive cycle typical of great apes. Females reach adulthood at around 15 years, and males about a year later. Captive chimpanzees have been recorded living over 60 years, and wild ones can possibly live as long. Oestrus is visually conspicuous: the female develops a pronounced pink genital swelling that signals receptivity and triggers intense male interest.

Reproductive statistics:

• Gestation: about 8 months
• Weaning: 4-5 years

Mothers and offspring form extraordinarily close bonds. Infants ride clinging to the mother's belly in the first months, then ride on her back and nurse for four to five years. Even after weaning, sons and daughters often remain socially close to their mother for life, or, in the case of females, until they emigrate to a new community.

Cases of chimpanzee adoption have been documented at several sites. Orphaned chimpanzees are occasionally adopted by adult males, who tend to their needs. These adoptions are hard to explain under simple genetic models and add to the picture of chimpanzees as socially complex beings.

Warfare and Coalition Killing

For most of the 20th century, chimpanzees were portrayed as gentle forest apes. That picture shattered in 1974, when Jane Goodall's team at Gombe watched a group of males from the Kasakela community systematically hunt down and kill members of the breakaway Kahama community. The Gombe chimpanzee war lasted four years and ended with all of the Kahama males killed or missing, effectively ending that community.

Similar patterns have since been recorded at multiple long-term study sites, including at Ngogo in Kibale National Park, Uganda. The characteristic features are:

• Border patrols. Groups of adult males travel silently to the edges of their territory, listening for neighbouring calls.
• Ambushes of lone individuals. If an isolated member of a neighbouring group is detected, the patrolling coalition attacks in force.
• Lethal violence. Victims suffer severe wounds, and many die of their injuries.
• Territorial outcomes. Winning extermination campaigns let the aggressor community expand its range and gain better food and reproductive opportunities.

Whether chimpanzee warfare is analogous to human warfare in a strict sense is a contested question, but the structural similarities, coordinated, lethal, coalition-based intergroup violence aimed at territorial gain, are striking.

Cognition and Emotion

Though chimpanzees show many signs of intelligence, they seem to lack one human ability in particular: language.

Documented abilities include:

• Mirror self-recognition. When marked surreptitiously with dye, chimpanzees who see themselves in a mirror inspect the mark on their own bodies, demonstrating self-recognition.
• Tool manufacture and planning. Chimpanzees show evidence of planning and foresight in making and gathering tools.
• Symbolic learning. Chimpanzees can remember symbols, and many attempts have been made to teach them languages such as American Sign Language, though whether they can acquire language has been questioned by academics such as Noam Chomsky.
• Theory of mind. Subordinate chimpanzees have been found to use the knowledge state of dominant rivals to decide which hidden food to approach, though other experiments have raised the possibility that chimpanzees lack a theory of mind.
• Numerical cognition. Ayumu, a chimpanzee at Kyoto University, performed better than human adults on a short-duration numerical memory test.
• Empathy and mourning. Mothers have been reported to carry around and groom their dead infants for several days, and in one case chimpanzees cared for a dying elder and then attended and cleaned the corpse.
• Laughter. When tickled or during rough play, chimpanzees produce a laughter-like, breathy panting vocalisation.

Whether these abilities constitute 'intelligence' comparable to a human's depends on how the term is defined. They are certainly sufficient to overturn any clean line separating human and non-human minds.

Population and Conservation Status

The IUCN Red List classifies chimpanzees as Endangered with a decreasing population trend. The western subspecies is separately classified as Critically Endangered . Current estimates place the global wild population at roughly 170,000 to 300,000.

Distribution of current population by subspecies (approximate):

Subspecies	Approximate population	Conservation status
Central	About 140,000	Endangered
Eastern	180,000-256,000	Endangered
Western	About 52,800	Critically Endangered
Nigeria-Cameroon	6,000-9,000	Endangered

Primary threats:

• Habitat loss. Logging, palm oil and cocoa plantations, subsistence agriculture and mining fragment chimpanzee habitat and eliminate feeding trees.
• Bushmeat hunting. Commercial hunting for urban bushmeat markets now reaches deep into previously inaccessible forest via logging roads. Adult chimpanzees are shot for meat, the slow reproductive rate means populations cannot absorb significant hunting pressure.
• Illegal pet and entertainment trade. Infants are captured for the exotic pet market.
• Disease transmission. Respiratory diseases are the most common cause of disease-related deaths in the Kasekela community at Gombe.
• Human-wildlife conflict. As agriculture expands into forest edge, chimpanzees crop-raid and are shot or trapped in response.
• Climate change. Shifting rainfall patterns affect fruit phenology, the backbone of the chimpanzee diet.

While protected areas span the entire range, enforcement remains uneven. Community conservation agreements, chimpanzee sanctuaries for orphaned individuals and long-term research facilities all contribute meaningfully, yet the underlying drivers - demand for land, timber, minerals and meat - continue to stay largely intact.

Chimpanzees and Humans

Humans have captured, traded and killed chimpanzees for centuries. From the 19th century onward, chimpanzees were exported in large numbers for medical research, entertainment and the pet trade. Biomedical use peaked in the 20th century, with some hundreds kept in laboratories, especially in the United States. Invasive research on chimpanzees has been phased out in most jurisdictions since the 2010s, and retired research chimpanzees now live out their lives in sanctuaries.

Legal protection is patchy. In range states, chimpanzees are protected by law but enforcement is uneven. International trade is regulated by CITES Appendix I, which prohibits commercial trade in wild-caught individuals.

On the cultural side, chimpanzees occupy a unique position in human imagination. They appear in folklore across their African range, often as figures of cleverness or mischief. Western popular culture has variously cast them as clowns, surrogate children and existential mirrors, each framing saying more about the humans doing the framing than about the animals themselves.

Serious engagement with chimpanzees in popular science, beginning with the work of Jane Goodall and Frans de Waal, has done as much as anything in the last sixty years to erode the notion that humans are a category apart from the rest of the natural world.