It is suspected that human observers can influence chimpanzee behaviour. For this reason researchers sometimes prefer camera traps and remote microphones rather than human observers.
Chimpanzee vs. bonobo , Japan Anatomical differences between the common chimpanzee and the
bonobo are slight. Both are
omnivorous adapted to a mainly
frugivorous diet. However, sexual and social behaviours are markedly different. The common chimpanzee has a troop culture based on beta males led by an
alpha male, and highly complex social relationships. The bonobo, on the other hand, has
egalitarian,
nonviolent,
matriarchal,
sexually receptive behaviour. Bonobos frequently have sex, sometimes to help prevent and resolve conflicts. Different groups of chimpanzees also have different cultural behaviour with preferences for types of tools. The common chimpanzee tends to display greater aggression than does the bonobo. The average captive chimpanzee sleeps 9 hours and 42 minutes per day. Contrary to what the scientific name (
Pan troglodytes) may suggest, chimpanzees do not typically spend their time in caves, but there have been reports of some of them seeking refuge in caves because of the heat during daytime.
Chimpanzees Social structure Chimpanzees live in large multi-male and multi-female
social groups, which are called communities. Within a community, the position of an individual and the influence the individual has on others dictates a definite
social hierarchy. Chimpanzees live in a leaner hierarchy wherein more than one individual may be dominant enough to dominate other members of lower rank. Typically, a dominant male is referred to as the
alpha male. The alpha male is the highest-ranking male that controls the group and maintains order during disputes. In chimpanzee society, the 'dominant male' sometimes is not the largest or strongest male but rather the most manipulative and political male that can influence the goings on within a group. 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. Female chimpanzees will show deference to the alpha male by presenting their hindquarters. Female chimpanzees also have a hierarchy, which is influenced by the position of a female individual within a group. In some chimpanzee communities, the young females may inherit high status from a high-ranking mother. Dominant females will also ally to dominate lower-ranking females: whereas males mainly seek dominant status for its associated mating privileges and sometimes violent domination of subordinates, females seek dominant status to acquire resources such as food, as high-ranking females often have first access to them. Both genders acquire dominant status to improve social standing within a group. Community female acceptance is necessary for alpha male status; females must ensure that their group visits places that supply them with enough food. A group of dominant females will sometimes oust an alpha male which is not to their preference and back another male, in whom they see potential for leading the group as a successful alpha male. The mating system within each community is
polygynandrous, with each male and female possibly having multiple sexual partners.
Intelligence 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; and they are capable of spontaneous planning for a future state or event.
Tool use In October 1960,
Jane Goodall observed the use of tools among chimpanzees. Recent research indicates that chimpanzees' use of
stone tools dates back at least 4,300 years (about 2,300 BC). One example of chimpanzee tool usage behavior includes the use of a large stick as a tool to dig into termite mounds, and the subsequent use of a small stick altered into a tool that is used to "fish" the termites out of the mound. Chimpanzees are also known to use smaller stones as hammers and a large one as an anvil in order to break open nuts. In the 1970s, reports of chimpanzees using rocks or sticks as weapons were anecdotal and controversial. However, a 2007 study claimed to reveal the use of spears, which common chimpanzees in
Senegal sharpen with their teeth and use to stab and pry
Senegal bushbabies out of small holes in trees. Prior to the discovery of tool use by chimpanzees, humans were believed to be the only
species to make and use tools; however, several other
tool-using species are now known.
Nest-building 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. The nest provides a sort of mattress, which is supported by strong branches for a foundation, and then lined with softer leaves and twigs; the minimum diameter is and may be located at a height of . Both day and night nests are built, and may be located in groups. 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.
Altruism and emotivity Studies have shown chimpanzees engage in apparently
altruistic behaviour within groups. Some researchers have suggested that chimpanzees are indifferent to the welfare of unrelated group members, but a more recent study of wild chimpanzees found that both male and female adults would adopt orphaned young of their group. Also, different groups sometimes share food, form coalitions, and cooperate in hunting and border patrolling. Sometimes, chimpanzees have adopted young that come from unrelated groups. And in some rare cases, even male chimpanzees have been shown to take care of abandoned infant chimpanzees of an unrelated group, though in most cases they would kill the infant. According to a literature summary by James W. Harrod, evidence for
chimpanzee emotivity includes display of
mourning; "incipient
romantic love"; "rain dances"; 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. Research into the chimpanzee brain has revealed that when chimpanzees communicate, an area in the brain is activated which is in the same position as the language center called
Broca's area in human brains.
Aggression Adult common chimpanzees, particularly males, can be very aggressive. They are highly territorial and are known to kill others of their species.
Hunting Chimpanzees also engage in targeted hunting of smaller primates, such as the
red colobus and
bush babies. Males who acquire the meat may share it with females to have sex or for grooming.
Puzzle solving In February 2013, a study found that chimpanzees solve puzzles for entertainment. ==Chimpanzees in human history==