Based on genome sequencing, these two extant Pan species diverged around one million years ago.

While Oken did not give a rationale for his choice, it is generally thought to have been inspired by the name of the Greek god Pan.

The species name troglodytes is a reference to the Troglodytae (literally "cave-goers"), an African people described by Greco-Roman geographers.

[9] The bonobo, in the past also referred to as the "pygmy chimpanzee", was given the species name of paniscus by Ernst Schwarz (1929), a Greek-style diminutive of the theonym Pan used by Cicero.

[29][30] The chimpanzee[dubious – discuss] fossil record has long been absent and thought to have been due to the preservation bias in relation to their environment.

Existing chimpanzee populations in West and Central Africa are separate from the major human fossil sites in East Africa; however, chimpanzee fossils have been reported from Kenya, indicating that both humans and members of the Pan clade were present in the East African Rift Valley during the Middle Pleistocene.

In trees, both species climb with their long, powerful arms; on the ground, chimpanzees usually knuckle-walk, or walk on all fours, clenching their fists and supporting themselves on the knuckles.

The chimpanzee is tailless; its coat is dark; its face, fingers, palms of the hands, and soles of the feet are hairless.

The exposed skin of the face, hands, and feet varies from pink to very dark in both species, but is generally lighter in younger individuals and darkens with maturity.

A University of Chicago Medical Centre study has found significant genetic differences between chimpanzee populations.

This relatively great size is generally attributed to sperm competition due to the polygynandrous nature of chimpanzee mating behaviour.

[48] Corrected for their smaller body sizes, chimpanzees were found to be stronger than humans but not anywhere near four to eight times.

Male chimpanzees typically attain dominance by cultivating allies who will support that individual during future ambitions for power.

The alpha male regularly displays by puffing his normally slim coat up to increase view size and charge to seem as threatening and as powerful as possible; this behaviour serves to intimidate other members and thereby maintain power and authority, and it may be fundamental to the alpha male's holding on to his status.

Lower-ranking chimpanzees will show respect by submissively gesturing in body language or reaching out their hands while grunting.

[57] Chimpanzees make tools and use them to acquire foods and for social displays; they have sophisticated hunting strategies requiring cooperation, influence and rank; they are status conscious, manipulative and capable of deception; they can learn to use symbols and understand aspects of human language including some relational syntax, concepts of number and numerical sequence;[58] and they are capable of spontaneous planning for a future state or event.

Recent research indicates that chimpanzees' use of stone tools dates back at least 4,300 years (about 2,300 BC).

[66][67] Nest-building, sometimes considered to be a form of tool use, is seen when chimpanzees construct arboreal night nests by lacing together branches from one or more trees to build a safe, comfortable place to sleep; infants learn this process by watching their mothers.

[68] A study in 2014 found that the muhimbi tree is favoured for nest building by chimpanzees in Uganda due to its physical properties, such as bending strength, inter-node distance, and leaf surface area.

[74] According to a literature summary by James W. Harrod, evidence for chimpanzee emotivity includes display of mourning; "incipient romantic love"; "rain dances"[Note 1]; appreciation of natural beauty (such as a sunset over a lake); curiosity and respect towards other wildlife (such as the python, which is neither a threat nor a food source to chimpanzees); altruism toward other species (such as feeding turtles); and animism, or "pretend play", when chimpanzees cradle and groom rocks or sticks.

[83] Chimpanzees, as well as other apes, had also been purported to have been known to ancient writers, but mainly as myths and legends on the edge of European and Near Eastern societal consciousness.

[citation needed] The first of these early transcontinental chimpanzees came from Angola and were presented as a gift to Frederick Henry, Prince of Orange in 1640, and were followed by a few of its brethren over the next several years.

The next two decades, a number of the creatures were imported into Europe, mainly acquired by various zoological gardens as entertainment for visitors.

Charles Darwin's theory of natural selection (published in 1859) spurred scientific interest in chimpanzees, as in much of life science, leading eventually to numerous studies of the animals in the wild and captivity.

The most progressive early studies on chimpanzees were spearheaded primarily by Wolfgang Köhler and Robert Yerkes, both of whom were renowned psychologists.

This typically involved basic, practical tests on laboratory chimpanzees, which required a fairly high intellectual capacity (such as how to solve the problem of acquiring an out-of-reach banana).

Yerkes studied chimpanzees until World War II, while Köhler concluded five years of study and published his famous Mentality of Apes in 1925 (which is coincidentally when Yerkes began his analyses), eventually concluding, "chimpanzees manifest intelligent behaviour of the general kind familiar in human beings ... a type of behaviour which counts as specifically human" (1925).

Molecular, microscopic and epidemiological investigations demonstrated the chimpanzees living at Mahale Mountains National Park have been suffering from a respiratory disease that is likely caused by a variant of a human paramyxovirus.

[85] The US Fish and Wildlife Service finalized a rule on June 12, 2015, creating very strict regulations, practically barring any activity with chimpanzees other than for scientific, preservation-oriented purposes.