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The bonobo (; ''Pan paniscus''), also historically called the pygmy chimpanzee and less often, the dwarf or gracile chimpanzee, is an
endangered An endangered species is a species In biology, a species is the basic unit of biological classification, classification and a taxonomic rank of an organism, as well as a unit of biodiversity. A species is often defined as the largest group ...
great ape The Hominidae (), whose members are known as great apes or hominids (), are a taxonomic family In , family (from la, familia) is a of people related either by (by recognized birth) or (by marriage or other relationship). The purpose ...
and one of the two
species In biology, a species is the basic unit of biological classification, classification and a taxonomic rank of an organism, as well as a unit of biodiversity. A species is often defined as the largest group of organisms in which any two individu ...

species
making up the
genus Genus /ˈdʒiː.nəs/ (plural genera /ˈdʒen.ər.ə/) is a taxonomic rank In biological classification In biology, taxonomy () is the scientific study of naming, defining (Circumscription (taxonomy), circumscribing) and classifying gr ...
''
Pan Pan may refer to: Prefix *''Pan-'', a prefix A prefix is an affix which is placed before the stem of a word. Adding it to the beginning of one word changes it into another word. For example, when the prefix ''un-'' is added to the word ''happy ...
''; the other being the
common chimpanzee The chimpanzee (''Pan troglodytes''), also known simply as chimp, is a species of Hominidae, great ape native to the forest and savannah of tropical Africa. It has four confirmed subspecies and a fifth proposed subspecies. The chimpanzee and ...
(''Pan troglodytes''). Although bonobos are not a subspecies of chimpanzee (''Pan troglodytes)'', but rather a distinct species in their own right, both species are sometimes referred to collectively using the generalized term ''chimpanzees'', or ''chimps''. Taxonomically, the members of the chimpanzee/bonobo subtribe Panina (composed entirely by the genus ''
Pan Pan may refer to: Prefix *''Pan-'', a prefix A prefix is an affix which is placed before the stem of a word. Adding it to the beginning of one word changes it into another word. For example, when the prefix ''un-'' is added to the word ''happy ...
'') are collectively termed ''panins''. The bonobo is distinguished by relatively long legs, pink lips, dark face, tail-tuft through adulthood, and parted long hair on its head. The bonobo is found in a area of the
Congo Basin The Congo Basin (french: Bassin du Congo) is the sedimentary basin Sedimentary basins are regions of the Earth Earth is the third planet from the Sun and the only astronomical object known to harbor life. About 29% of Earth's surface ...
in the
Democratic Republic of the Congo The Democratic Republic of the Congo ( french: République démocratique du Congo (RDC) ), also known as Congo-Kinshasa, DR Congo, the DRC, the DROC, or the Congo, and formerly Zaire Zaire (, ), officially the Republic of Zaire (frenc ...

Democratic Republic of the Congo
, Central Africa. The species is
omnivorous An omnivore () is an animal Animals (also called Metazoa) are multicellular eukaryotic organisms that form the Kingdom (biology), biological kingdom Animalia. With few exceptions, animals Heterotroph, consume organic material, Cellular ...
and inhabits
primary Primary or primaries may refer to: Arts, entertainment, and media Music Groups and labels * Primary (band), from Australia * Primary (musician), hip hop musician and record producer from South Korea * Primary Music, Israeli record label Works * ...
and
secondary forest Secondary is an adjective meaning "second" or "second hand". It may refer to: * Secondary (chemistry) Secondary is a term used in organic chemistry to classify various types of compounds (e. g. alcohols, alkyl halides, amines) or reactive intermedi ...
s, including seasonally inundated
swamp forest A swamp is a forested wetland A wetland is a distinct ecosystem An ecosystem (or ecological system) consists of all the organisms and the physical environment with which they interact. These biotic and abiotic components are linked ...

swamp forest
s. Because of political instability in the region and the timidity of bonobos, there has been relatively little field work done observing the species in its natural habitat. Along with the common chimpanzee, the bonobo is the closest extant relative to
human Humans (''Homo sapiens'') are the most abundant and widespread species In biology, a species is the basic unit of biological classification, classification and a taxonomic rank of an organism, as well as a unit of biodiversity. A speci ...

human
s. As the two species are not proficient swimmers, the formation of the
Congo River The Congo River ( kg, Nzâdi Kôngo, french: Fleuve Congo, pt, Rio Congo), formerly also known as the Zaire River, is the second longest river in Africa Africa is the world's second-largest and second-most populous , after in both case ...
1.5–2 million years ago possibly led to the
speciation Speciation is the evolutionary process by which populations evolve to become distinct species. The biologist Orator F. Cook coined the term in 1906 for cladogenesis, the splitting of lineages, as opposed to anagenesis, phyletic evolution within ...

speciation
of the bonobo. Bonobos live south of the river, and thereby were separated from the ancestors of the common chimpanzee, which live north of the river. There are no concrete data on population numbers, but the estimate is between 29,500 and 50,000 individuals. The species is listed as
Endangered An endangered species is a species In biology, a species is the basic unit of biological classification, classification and a taxonomic rank of an organism, as well as a unit of biodiversity. A species is often defined as the largest group ...
on the
IUCN Red List The International Union for Conservation of Nature (IUCN) Red List of Threatened Species (also known as the IUCN Red List or Red Data Book), founded in 1964, is the world's most comprehensive inventory of the global Conservation movement, conser ...
and is threatened by
habitat destruction Habitat destruction (also termed habitat loss and habitat reduction) is the process by which a natural habitat Ibex in an alpine habitat In ecology, the term habitat summarises the array of resources, physical and biotic factors that are pr ...
and human population growth and movement, though commercial poaching is the most prominent threat. Bonobos typically live 40 years in captivity; their lifespan in the wild is unknown, but it is almost certainly much shorter.


Etymology

Formerly the bonobo was known as the "pygmy chimpanzee", despite the bonobo having a similar body size to the common chimpanzee. The name "pygmy" was given by the German zoologist Ernst Schwarz in 1929, who classified the species on the basis of a previously mislabeled bonobo cranium, noting its diminutive size compared to chimpanzee skulls. The name "bonobo" first appeared in 1954, when Austrian zoologist
Eduard Paul Tratz Eduard Paul Tratz (25 September 1888, in Salzburg Salzburg (, ; literally "Salt Castle"; bar, Soizbuag, label=Bavarian language, Austro-Bavarian) is the List of cities and towns in Austria, fourth-largest city in Austria. In 2020, it had a pop ...
and German biologist
Heinz Heck Heinz Heck (22 January 1894 – 5 March 1982) was a Germany, German biologist and director of Hellabrunn Zoo (''Tierpark Hellabrunn'') in Munich. He was born in Berlin and died in Munich. With his brother, Lutz Heck, who was director of the ...

Heinz Heck
proposed it as a new and separate generic term for pygmy chimpanzees. The name is thought to derive from a misspelling on a shipping crate from the town of
Bolobo Bolobo is a town on the in in the western part of the (DRC). It is the administrative center of . As of 2009 it had an estimated population of 31,366. People The predominant tribe is that of the , who originate from upriver and whose was the ...
on the
Congo River The Congo River ( kg, Nzâdi Kôngo, french: Fleuve Congo, pt, Rio Congo), formerly also known as the Zaire River, is the second longest river in Africa Africa is the world's second-largest and second-most populous , after in both case ...
near the location from which the first bonobo specimens were collected in the 1920s.


Taxonomy

The bonobo was first recognised as a distinct
taxon In biology Biology is the natural science that studies life and living organisms, including their anatomy, physical structure, Biochemistry, chemical processes, Molecular biology, molecular interactions, Physiology, physiological mechani ...
in 1928 by German anatomist Ernst Schwarz, based on a skull in the in Belgium which had previously been classified as a juvenile
chimp The chimpanzee (''Pan troglodytes''), also known simply as chimp, is a species of great ape The Hominidae (), whose members are known as great apes or hominids (), are a taxonomic Family (biology), family of primates that includes eight N ...

chimp
(''Pan troglodytes''). Schwarz published his findings in 1929, classifying the bonobo as a subspecies of chimp, ''Pan satyrus paniscus''. Coolidge's paper contains a translation of Schwarz's earlier report. In 1933, American anatomist Harold Coolidge elevated it to species status. Major behavioural differences between bonobos and chimps were first discussed in detail by Tratz and Heck in the early 1950s. American psychologist and primatologist
Robert Yerkes Robert Mearns Yerkes (; May 26, 1876 – February 3, 1956) was an American psychologist, ethologist, Eugenics, eugenicist and Primatology, primatologist best known for his work in intelligence testing and in the field of comparative psychology. Ye ...
was also one of the first to notice major behavioural differences. The first official publication of the sequencing and assembly of the bonobo genome was released in June 2012. The genome of a female bonobo from Leipzig Zoo was deposited with the
International Nucleotide Sequence Database CollaborationThe International Nucleotide Sequence Database Collaboration (INSDC) consists of a joint effort to collect and disseminate database A database is an organized collection of data Data are units of information Information can be thought o ...
(DDBJ/EMBL/GenBank) under the EMBL accession number AJFE01000000 after a previous analysis by the
National Human Genome Research InstituteThe National Human Genome Research Institute (NHGRI) is an institute of the National Institutes of Health The National Institutes of Health (NIH) () is the primary agency of the United States government responsible for biomedical and public healt ...
confirmed that the bonobo genome is about 0.4% divergent from the chimpanzee genome. Bonobos and chimps are the two species which make up the
genus Genus /ˈdʒiː.nəs/ (plural genera /ˈdʒen.ər.ə/) is a taxonomic rank In biological classification In biology, taxonomy () is the scientific study of naming, defining (Circumscription (taxonomy), circumscribing) and classifying gr ...
''
Pan Pan may refer to: Prefix *''Pan-'', a prefix A prefix is an affix which is placed before the stem of a word. Adding it to the beginning of one word changes it into another word. For example, when the prefix ''un-'' is added to the word ''happy ...
'', and are the closest living relatives to humans (''Homo sapiens''). The exact timing of the ''Pan''–''Homo'' last common ancestor is contentious, but DNA comparison suggests continual interbreeding between ancestral ''Pan'' and ''Homo'' groups, post-divergence, until about 4 million years ago. DNA evidence suggests the bonobo and common chimpanzee species diverged approximately 890,000–860,000 years ago due to separation of these two populations possibly due to acidification and the spread of savannas at this time. Currently, these two species are separated by the Congo River, which had existed well before the divergence date, though ancestral ''Pan'' may have dispersed across the river using corridors which no longer exist. The first ''Pan'' fossils were reported in 2005 from the
Middle Pleistocene The Chibanian, widely known by its previous designation of Middle Pleistocene, is an Age (geology), age in the international geologic timescale or a Stage (stratigraphy), stage in chronostratigraphy, being a division of the Pleistocene Epoch withi ...
(after the bonobo–chimp split) of Kenya, alongside early ''Homo'' fossils. According to A. Zihlman, bonobo body proportions closely resemble those of ''
Australopithecus ''Australopithecus'' (, ; ; singular: australopith) is a genus of early hominins that existed in Africa during the Late Pliocene and Early Pleistocene. The genera ''Homo'' (which includes modern humans), ''Paranthropus'', and ''Kenyanthropus'' ev ...

Australopithecus
'', leading evolutionary biologist Jeremy Griffith to suggest that bonobos may be a living example of our distant human ancestors. According to Australian anthropologists Gary Clark and Maciej Henneberg, human ancestors went through a bonobo-like phase featuring reduced aggression and associated anatomical changes, exemplified in ''
Ardipithecus ramidus ''Ardipithecus ramidus'' is a species of australopithecine from the Afar region of Early Pliocene Ethiopia 4.4 million years ago (mya). ''A. ramidus'', unlike modern hominids, has adaptations for both walking on two legs (bipedality) and life in ...

Ardipithecus ramidus
''.


Description

The bonobo is commonly considered to be more gracile than the common chimpanzee. Although large male chimpanzees can exceed any bonobo in bulk and weight, the two species actually broadly overlap in body size. Adult female bonobos are somewhat smaller than adult males. Body mass in males ranges from , against an average of in females. The total length of bonobos (from the nose to the rump while on all fours) is . When adult bonobos and chimpanzees stand up on their legs, they can both attain a height of . The bonobo's head is relatively smaller than that of the common chimpanzee with less prominent brow ridges above the eyes. It has a black face with pink lips, small ears, wide nostrils, and long hair on its head that forms a parting. Females have slightly more prominent breasts, in contrast to the flat breasts of other female apes, although not so prominent as those of humans. The bonobo also has a slim upper body, narrow shoulders, thin neck, and long legs when compared to the common chimpanzee. Bonobos are both terrestrial and arboreal. Most ground locomotion is characterized by quadrupedal knuckle walking. Bipedal
walking Walking (also known as ambulation) is one of the main gait Gait is the pattern of movement Movement may refer to: Common uses * Movement (clockwork), the internal mechanism of a timepiece * Motion (physics), commonly referred to as move ...

walking
has been recorded as less than 1% of terrestrial locomotion in the wild, a figure that decreased with
habituation Habituation is a form of non-associative learning in which an innate (non-reinforced) response to a stimulus A stimulus is something that causes a physiological response. It may refer to: *Stimulation Stimulation is the encouragement of deve ...

habituation
, while in captivity there is a wide variation. Bipedal walking in captivity, as a percentage of bipedal plus quadrupedal locomotion bouts, has been observed from 3.9% for spontaneous bouts to nearly 19% when abundant food is provided. These physical characteristics and its posture give the bonobo an appearance more closely resembling that of humans than the common chimpanzee does. The bonobo also has highly individuated facial features, as humans do, so that one individual may look significantly different from another, a characteristic adapted for visual facial recognition in social interaction. Multivariate analysis has shown bonobos are more than the common chimpanzee, taking into account such features as the proportionately long torso length of the bonobo. Other researchers challenged this conclusion.


Behavior


General

Primatologist
Frans de Waal Franciscus Bernardus Maria "Frans" de Waal (born October 29, 1948) is a Dutch primatologist and ethologist. He is the Charles Howard Candler Professor of Primate A primate ( ) (from Latin , from 'prime, first rank') is a eutherian mammal ...

Frans de Waal
states bonobos are capable of
altruism Altruism is the principle A principle is a proposition or value that is a guide for behavior or evaluation. In law Law is a system A system is a group of Interaction, interacting or interrelated elements that act according to a s ...

altruism
,
compassion Compassion motivates people to go out of their way to help the physical, mental, or emotional pains of another and themselves. Compassion is often regarded as having sensitivity, which is an emotional aspect to suffering. Though, when based on cer ...
,
empathy Empathy is the capacity to understand or feel what another person is experiencing from within their frame of reference, that is, the capacity to place oneself in another's position. Definitions of empathy encompass a broad range of emotional s ...

empathy
, kindness, patience, and sensitivity, and described "bonobo society" as a "
gynecocracy Matriarchy is a social system In , social system is the patterned network of relationships constituting a coherent whole that exist between individuals, groups, and institutions. It is the formal of role and status that can form in a small, ...
". Primatologists who have studied bonobos in the wild have documented a wide range of behaviors, including aggressive behavior and more cyclic sexual behavior similar to chimpanzees, even though bonobos show more sexual behavior in a greater variety of relationships. An analysis of female bonding among wild bonobos by Takeshi Furuichi stresses female sexuality and shows how female bonobos spend much more time in
estrus The estrous cycle (, originally ) is the set of recurring physiological changes that are induced by reproductive hormone A hormone (from the Greek Greek may refer to: Greece Anything of, from, or related to Greece Greece ( el, Ελλ ...
than female chimpanzees. Some primatologists have argued that de Waal's data reflect only the behavior of captive bonobos, suggesting that wild bonobos show levels of aggression closer to what is found among chimpanzees. De Waal has responded that the contrast in temperament between bonobos and chimpanzees observed in captivity is meaningful, because it controls for the influence of environment. The two species behave quite differently even if kept under identical conditions. A 2014 study also found bonobos to be less aggressive than chimpanzees, particularly eastern chimpanzees. The authors argued that the relative peacefulness of western chimpanzees and bonobos was primarily due to ecological factors. Bonobos warn each other of danger less efficiently than chimpanzees in the same situation.


Social behavior

Bonobos are unique among nonhuman apes for a lack of male dominance and relatively high social status of females, due to the latter forming long-lasting, powerful alliances among each other. Different bonobo communities vary from having a hierarchy that ranges from being gender-balanced to outright matriarchal. At the top of the hierarchy is a coalition of high-ranking females and males typically headed by an old, experienced matriarch who acts as the decision-maker and leader of the group. Female bonobos typically earn their rank through age, rather than physical intimidation, and top-ranking females will protect immigrant females from male harassment. While bonobos are often called matriarchal, this is a generalization. It is not unheard of for some communities to have an alpha male who protects the group from predators such as pythons and leopards, and decides where the group travels to, and where they feed. However, these male leaders never harass or coerce the females, and the females can choose to ignore his suggestions if they feel like it. Aggressive encounters between males and females are rare, and males are tolerant of infants and juveniles. A male derives his status from the status of his mother. The mother–son bond often stays strong and continues throughout life. While social hierarchies do exist, and although the son of a high ranking female may outrank a lower female, rank plays a less prominent role than in other primate societies. Relationships between different communities are often positive and affiliative, and bonobos are not a territorial species. Bonobos will also share food with others, even unrelated strangers. Bonobos exhibit paedomorphism (retaining infantile physical characteristics and behaviours), which greatly inhibits aggression and enables unfamiliar bonobos to freely mingle and cooperate with each other. Males engage in lengthy friendships with females and, in turn, female bonobos prefer to associate with and breed with males who are respectful and easygoing around them. Because female bonobos can use alliances to rebuff coercive and domineering males and select males at their own leisure, they enjoy a higher position in their group compared to the females of other simians, and monogamous tendencies even emerge between some of these unions. Aging bonobos lose their playful streak and become noticeably more irritable in old age. Both sexes have a similar level of aggressiveness. Bonobos live in a male philopatric society where the females immigrate to new communities while males remain in their natal troop. However, it is not entirely unheard of for males to occasionally transfer into new groups. Alliances between males are poorly developed in most bonobo communities, while females will form alliances with each other and alliances between males and females occur, including multisex hunting parties. However, in LuiKotale the males are far more gregarious and engage in territorial patrols. There is also a confirmed case of a grown male bonobo adopting his orphaned infant brother. A mother bonobo will also support her son in conflicts with other males and help him secure better ties with other females, enhancing her chance of gaining grandchildren from him. She will even take measures such as physical intervention to prevent other males from breeding with certain females she wants her son to mate with. Female bonobos have also been observed fostering infants from outside their established community. Bonobos are not known to kill each other, and are generally less violent than chimpanzees, yet aggression still manifests itself in this species. Although males are unable to dominate females, with more chivalrous males enjoying more success in attaining high rank and fathering large amounts of young, rank among males is often violently enforced and the alpha status heavily coveted. Male bonobos are known to attack each other and inflict serious injuries such as missing digits, damaged eyes and torn ears. Some of these injuries may also occur when a male threatens the high ranking females and is injured by them, as the larger male is swarmed and outnumbered by these female mobs. Due to the promiscuous mating behavior of female bonobos, a male cannot be sure which offspring are his. As a result, the entirety of parental care in bonobos is assumed by the mothers. However, bonobos are not as promiscuous as chimpanzees and slightly polygamous tendencies occur, with high-ranking males enjoying greater reproductive success than low-ranking males. Unlike chimpanzees, where any male can coerce a female into mating with him, female bonobos enjoy greater sexual preferences, an advantage of female-female bonding, and actively seek out higher-ranking males. Bonobo party size tends to vary because the groups exhibit a fission–fusion pattern. A community of approximately 100 will split into small groups during the day while looking for food, and then will come back together to sleep. They sleep in nests that they construct in trees. Female bonobos more often than not secure feeding privileges and feed before males do, although they are rarely successful in one-on-one confrontations with males, a female bonobo with several allies supporting her has extremely high success in monopolizing food sources. In captive settings, females exhibit extreme food-based aggression towards males, and forge coalitions against them to monopolize specific food items, often going as far as to mutilate any males who fail to heed their warning. In wild settings, however, female bonobos will quietly ask males for food if they had gotten it first, instead of forcibly confiscating it, suggesting sex-based hierarchy roles are less rigid than in captive colonies. Female bonobos are known to lead hunts on
duiker A duiker is a small to medium-sized brown antelope The term antelope is used to refer to many species of even-toed ruminant Ruminants (suborder In biological classification, the order ( la, wikt:ordo#Latin, ordo) is # a taxonomic rank u ...

duiker
s and successfully defend their bounty from marauding males in the wild. They are more tolerant of younger males pestering them yet exhibit heightened aggression towards older males.


Sociosexual behaviour

Sexual activity generally plays a major role in bonobo society, being used as what some scientists perceive as a
greeting Greeting is an act of communication Communication (from Latin Latin (, or , ) is a classical language A classical language is a language A language is a structured system of communication Communication (from Latin '' ...

greeting
, a means of forming social bonds, a means of
conflict resolution Conflict-of-interest editing on Wikipedia, Conflict resolution is conceptualized as the methods and processes involved in facilitating the peaceful ending of Conflict (process), conflict and Revenge, retribution. Committed group members attemp ...

conflict resolution
, and postconflict reconciliation. Bonobos are the only non-human animal to have been observed engaging in tongue kissing. Bonobos and
human Humans (''Homo sapiens'') are the most abundant and widespread species In biology, a species is the basic unit of biological classification, classification and a taxonomic rank of an organism, as well as a unit of biodiversity. A speci ...

human
s are the only primates to typically engage in face-to-face genital sex, although a pair of
western gorilla The western gorilla (''Gorilla gorilla'') is a great ape found in Africa, one of two species of the hominid The Hominidae (), whose members are known as great apes or hominids (), are a taxonomic family In , family (from la, famili ...
s has been photographed in this position. Bonobos do not form permanent monogamous sexual relationships with individual partners. They also do not seem to discriminate in their sexual behavior by sex or age, with the possible exception of abstaining from sexual activity between mothers and their adult sons. When bonobos come upon a new food source or feeding ground, the increased excitement will usually lead to communal sexual activity, presumably decreasing tension and encouraging peaceful feeding. More often than the males, female bonobos engage in mutual genital-rubbing behavior, possibly to bond socially with each other, thus forming a female nucleus of bonobo society. The bonding among females enables them to dominate most of the males. Adolescent females often leave their native community to join another community. This migration mixes the bonobo
gene pool The gene pool is the set of all gene In biology Biology is the natural science that studies life and living organisms, including their anatomy, physical structure, Biochemistry, chemical processes, Molecular biology, molecular inte ...
s, providing
genetic diversity Genetic diversity is the total number of genetic characteristics in the genetic makeup of a species, it ranges widely from the number of species to differences within species In biology, a species is the basic unit of biological classificati ...
. Sexual bonding with other females establishes these new females as members of the group. Bonobo
clitoris The clitoris ( or ) is a female sex organ present in mammals, ostriches and a limited number of #Other animals, other animals. In humans, the visible portion – the glans – is at the front junction of the labia minora (inner lips), ...

clitoris
es are larger and more externalized than in most mammals; while the weight of a young adolescent female bonobo "is maybe half" that of a human teenager, she has a clitoris that is "three times bigger than the human equivalent, and visible enough to waggle unmistakably as she walks". In scientific literature, the female–female behavior of bonobos pressing genitals together is often referred to as genito-genital (GG) rubbing, which is the non-human analogue of
tribadism Tribadism ( ) or tribbing, commonly known by its scissoring position, is a lesbian sexual practice in which a woman rubs her vulva The vulva (plural: vulvas or vulvae; derived from Latin for wrapper or covering) consists of the external sex ...
, engaged in by some human females. This sexual activity happens within the immediate female bonobo community and sometimes outside of it.
Ethologist Ethology is the scientific Science () is a systematic enterprise that Scientific method, builds and organizes knowledge in the form of Testability, testable explanations and predictions about the universe."... modern science is a ...
Jonathan Balcombe Jonathan Balcombe (born 28 February 1959) is an ethologist and author. He is formerly Director of Animal Sentience with the Humane Society Institute for Science and Policy, and Department Chair for Animal Studies with Humane Society University, in ...
stated that female bonobos rub their clitorises together rapidly for ten to twenty seconds, and this behavior, "which may be repeated in rapid succession, is usually accompanied by grinding, shrieking, and clitoral engorgement"; he added that it is estimated that they engage in this practice "about once every two hours" on average. As bonobos occasionally copulate face-to-face, "evolutionary biologist Marlene Zuk has suggested that the position of the clitoris in bonobos and some other primates has evolved to maximize stimulation during sexual intercourse". The position of the clitoris may alternatively permit GG-rubbings, which has been hypothesized to function as a means for female bonobos to evaluate their intrasocial relationships. Bonobo males engage in various forms of male–male genital behavior. The most common form of male–male mounting is similar to that of a heterosexual mounting: one of the males sits "passively on his back
ith The Ith () is a ridge in Germany's Central Uplands which is up to 439 m high. It lies about 40 km southwest of Hanover and, at 22 kilometres, is the longest line of crags in North Germany. Geography Location The Ith is immediately ...
the other male thrusting on him", with the penises rubbing together due to both males' erections. In another, rarer form of genital rubbing, which is the non-human analogue of
frot Frot or frotting (slang Slang is vocabulary A vocabulary is a set of familiar words In linguistics, a word of a spoken language can be defined as the smallest sequence of phonemes that can be uttered in isolation with semantic, object ...
ting, engaged in by some human males, two bonobo males hang from a tree limb face-to-face while penis fencing. This also may occur when two males rub their penises together while in face-to-face position. Another form of genital interaction (rump rubbing) often occurs to express reconciliation between two males after a conflict, when they stand back-to-back and rub their scrotal sacs together, but such behavior also occurs outside agonistic contexts: Kitamura (1989) observed rump–rump contacts between adult males following sexual solicitation behaviors similar to those between female bonobos prior to GG-rubbing. Takayoshi Kano observed similar practices among bonobos in the natural habitat. Tongue kissing, oral sex, and genital massaging have also been recorded among male bonobos. Bonobo reproductive rates are no higher than those of the common chimpanzee. However, female bonobo oestrus periods are longer. During
oestrus The estrous cycle (, originally ) is the set of recurring physiological changes that are induced by reproductive hormone A hormone (from the Greek Greek may refer to: Greece Anything of, from, or related to Greece Greece ( el, Ελλ ...
, females undergo a swelling of the perineal tissue lasting 10 to 20 days. The gestation period is on average 240 days. Postpartum amenorrhea (absence of menstruation) lasts less than one year and a female may resume external signs of oestrus within a year of giving birth, though the female is probably not fertile at this point. Female bonobos carry and nurse their young for four years and give birth on average every 4.6 years. Compared to common chimpanzees, bonobo females resume the genital swelling cycle much sooner after giving birth, enabling them to rejoin the sexual activities of their society. Also, bonobo females which are sterile or too young to reproduce still engage in sexual activity. Mothers will help their sons get more matings from females in oestrus. Adult male bonobos have sex with infants, although without penetration. Infanticide, while well documented in
chimpanzee The chimpanzee (''Pan troglodytes''), also known simply as chimp, is a species of Hominidae, great ape native to the forest and savannah of tropical Africa. It has four confirmed subspecies and a fifth proposed subspecies. The chimpanzee and t ...

chimpanzee
s, is apparently absent in bonobo society. The highly sexual nature of bonobo society and the fact that there is little competition over mates means that many males and females are mating with each other, in contrast to the one dominant male chimpanzee that fathers most of the offspring in a group. The strategy of bonobo females mating with many males may be a counterstrategy to infanticide because it confuses paternity. If male bonobos cannot distinguish their own offspring from others, the incentive for infanticide essentially disappears. This is a reproductive strategy that seems specific to bonobos; infanticide is observed in all other great apes except
orangutan Orangutans are great apes The Hominidae (), whose members are known as great apes or hominids (), are a taxonomic family In human society A society is a Social group, group of individuals involved in persistent Social relati ...

orangutan
s. It is unknown how the bonobo avoids
simian immunodeficiency virus ''Simian immunodeficiency virus'' (''SIV'') is a species of retrovirus that cause persistent infections in at least 45 species of African non-human primates. Based on analysis of strains found in four species of Old World monkey, monkeys from Biok ...
(SIV) and its effects.


Peacefulness

Observations in the wild indicate that the males among the related common chimpanzee communities are hostile to males from outside the community. Parties of males 'patrol' for the neighboring males that might be traveling alone, and attack those single males, often killing them. This does not appear to be the behavior of bonobo males or females, which seem to prefer sexual contact over violent confrontation with outsiders. While bonobos are more peaceful than chimpanzees, it is not true that they are unaggressive. In the wild, among males, bonobos are half as aggressive as chimpanzees, while female bonobos are more aggressive than female chimpanzees. Both bonobos and chimpanzees exhibit physical aggression more than 100 times as often as humans do. The ranges of bonobos and chimpanzees are separated by the Congo River, with bonobos living to the south of it, and chimpanzees to the north. It has been hypothesized that bonobos are able to live a more peaceful lifestyle in part because of an abundance of nutritious vegetation in their natural habitat, allowing them to travel and forage in large parties. Recent studies show that there are significant brain differences between bonobos and chimps. Bonobos have more grey matter volume in the right anterior insula, right dorsal amygdala, hypothalamus, and right dorsomedial prefrontal cortex, all of which are regions assumed to be vital for feeling empathy, sensing distress in others and feeling anxiety. They also have a thick connection between the
amygdala The amygdala (; plural: amygdalae or amygdalas; also '; Latin from Greek language, Greek, , ', 'almond', 'tonsil') is one of two almond-shaped clusters of nucleus (neuroanatomy), nuclei located deep and lateral and medial, medially within the ...

amygdala
, an important area that can spark aggression, and the ventral anterior cingulate cortex, which has been shown to help control impulses in humans. This thicker connection may make them better at regulating their emotional impulses and behavior. Bonobo society is dominated by females, and severing the lifelong alliance between mothers and their male offspring may make them vulnerable to female aggression. De Waal has warned of the danger of romanticizing bonobos: "All animals are competitive by nature and cooperative only under specific circumstances" and that "when first writing about their behaviour, I spoke of 'sex for peace' precisely because bonobos had plenty of conflicts. There would obviously be no need for peacemaking if they lived in perfect harmony." Surbeck and Hohmann showed in 2008 that bonobos sometimes do hunt monkey species. Five incidents were observed in a group of bonobos in Salonga National Park, which seemed to reflect deliberate cooperative hunting. On three occasions, the hunt was successful, and infant monkeys were captured and eaten.


Diet

The bonobo is an
omnivorous An omnivore () is an animal Animals (also called Metazoa) are multicellular A multicellular organism is an organism In biology, an organism () is any organic, life, living system that functions as an individual entity. Al ...
frugivore A frugivore is an animal that thrives mostly on raw fruits or succulent fruit-like produce of plants such as roots, shoots, nuts and seeds. Approximately 20% of mammalian herbivores eat fruit. Frugivores are highly dependent on the abundance and ...
; 57% of its diet is fruit, but this is supplemented with leaves, honey, eggs, meat from small
vertebrates Vertebrates () comprise all species of animal Animals (also called Metazoa) are multicellular A multicellular organism is an organism In biology, an organism () is any organic, life, living system that functions as an indiv ...

vertebrates
such as
anomalure The Anomaluridae are a family of rodent Rodents (from Latin Latin (, or , ) is a classical language belonging to the Italic languages, Italic branch of the Indo-European languages. Latin was originally spoken in the area around Rome, k ...
s,
flying squirrel Flying squirrels (scientifically known as Pteromyini or Petauristini) are a tribe The term tribe is used in many different contexts to refer to a category of human social group. The predominant usage of the term is in the discipline of ant ...

flying squirrel
s and
duiker A duiker is a small to medium-sized brown antelope The term antelope is used to refer to many species of even-toed ruminant Ruminants (suborder In biological classification, the order ( la, wikt:ordo#Latin, ordo) is # a taxonomic rank u ...

duiker
s, and
invertebrates Invertebrates are animals that neither possess nor develop a vertebral column (commonly known as a ''backbone'' or ''spine''), derived from the notochord. This includes all animals apart from the chordata, chordate subphylum vertebrate, Vertebrat ...
. In some instances, bonobos have been shown to consume lower-order
primates A primate ( ) (from Latin , from 'prime, first rank') is a eutherian mammal constituting the Taxonomy (biology), taxonomic order (biology), order Primates (). Primates arose 85–55 million years ago first from small Terrestrial animal, ...
.; Some claim bonobos have also been known to practise cannibalism in captivity, a claim disputed by others. However, at least one confirmed report of cannibalism in the wild of a dead infant was described in 2008. A 2016 paper reported two more instances of infant cannibalism, although it was not confirmed if infanticide was involved.


Genomic and cognitive comparisons to chimpanzees

In 2020 the first whole-genome comparison between chimpanzees and bonobos was published and shows genomic aspects that may underlie or have resulted from their divergence and behavioral differences, including selection for genes related to diet and hormones. A 2010 study found that "female bonobos displayed a larger range of tool use behaviours than males, a pattern previously described for chimpanzees but not for other great apes". This finding was affirmed by the results of another 2010 study which also found that "bonobos were more skilled at solving tasks related to theory of mind or an understanding of social causality, while chimpanzees were more skilled at tasks requiring the use of tools and an understanding of physical causality". Available unde
CC BY 4.0


Similarity to humans

Bonobos are capable of passing the mirror-recognition test for self-awareness, as are all
great apes The Hominidae (), whose members are known as great apes or hominids (), are a taxonomic family In , family (from la, familia) is a of people related either by (by recognized birth) or (by marriage or other relationship). The purpose ...
. They communicate primarily through vocal means, although the meanings of their vocalizations are not currently known. However, most humans do understand their facial expressions and some of their natural hand gestures, such as their invitation to play. The communication system of wild bonobos includes a characteristic that was earlier only known in humans: bonobos use the same call to mean different things in different situations, and the other bonobos have to take the context into account when determining the meaning. Two bonobos at the
Great Ape Trust Great may refer to: Descriptions or measurements * Great, a relative measurement in physical space, see Size File:Comparison of planets and stars (sheet by sheet) (Oct 2014 update).png, A size comparison illustration comparing the sizes of vario ...
,
Kanzi Kanzi (born October 28, 1980), also known by the lexigram Yerkish is an artificial language developed for use by human, non-human primates. It employs a Computer keyboard, keyboard whose keys contain ''lexigrams'', symbols corresponding to ...

Kanzi
and
Panbanisha Panbanisha (November 17, 1985 – November 6, 2012), also known by the lexigrams Yerkish is an artificial language developed for use by human, non-human primates. It employs a Computer keyboard, keyboard whose keys contain ''lexigrams'', sym ...
, have been taught how to communicate using a keyboard labeled with
lexigrams Yerkish is an artificial language A language is a structured system of communication Communication (from Latin Latin (, or , ) is a classical language belonging to the Italic languages, Italic branch of the Indo-European languages. ...
(geometric symbols) and they can respond to spoken sentences. Kanzi's vocabulary consists of more than 500 English words, and he has comprehension of around 3,000 spoken English words. Kanzi is also known for learning by observing people trying to teach his mother; Kanzi started doing the tasks that his mother was taught just by watching, some of which his mother had failed to learn. Some, such as
philosopher A philosopher is someone who practices philosophy Philosophy (from , ) is the study of general and fundamental questions, such as those about Metaphysics, existence, reason, Epistemology, knowledge, Ethics, values, Philosophy of mind, mi ...

philosopher
and
bioethicist Bioethics is the study of the ethics, ethical issues emerging from advances in biology and medicine. It is also moral discernment as it relates to medical policy and practice. Bioethics are concerned with the ethical questions that arise in the ...
Peter Singer Peter Albert David Singer (born 6 July 1946) is an Australian moral philosopher Ethics or moral philosophy is a branch of philosophy that "involves systematizing, defending, and recommending concepts of right and wrong action (philosophy) ...

Peter Singer
, argue that these results qualify them for " rights to survival and life"—rights which humans theoretically accord to all
person A person (plural people or persons) is a being that has certain capacities or attributes such as reason Reason is the capacity of consciously applying logic Logic is an interdisciplinary field which studies truth and reasoning Reason is ...

person
s (See
great ape personhood Great ape personhood is a movement to extend personhood and some legal protections to the non-human members of the great ape family: chimpanzees, bonobos, gorillas, and orangutans. Advocates include Primatology, primatologists Jane Goodall and ...
). In the 1990s, Kanzi was taught to make and use simple stone tools. This resulted from a study undertaken by researchers and Nicholas Toth, and later Gary Garufi. The researchers wanted to know if Kanzi possessed the cognitive and biomechanical abilities required to make and use stone tools. Though Kanzi was able to form flakes, he did not create them in same way as humans, who hold the core in one hand and knap it with the other, Kanzi threw the cobble against a hard surface or against another cobble. This allowed him to produce a larger force to initiate a fracture as opposed to knapping it in his hands. As in other great apes and humans, third party affiliation toward the victim—the affinitive contact made toward the recipient of an aggression by a group member other than the aggressor—is present in bonobos. A 2013 study found that both the affiliation spontaneously offered by a bystander to the victim and the affiliation requested by the victim (solicited affiliation) can reduce the probability of further aggression by group members on the victim (this fact supporting the ''Victim-Protection Hypothesis''). Yet, only spontaneous affiliation reduced victim anxiety—measured via self-scratching rates—thus suggesting not only that non-solicited affiliation has a consolatory function but also that the spontaneous gesture—more than the protection itself—works in calming the distressed subject. The authors hypothesize that the victim may perceive the motivational autonomy of the bystander, who does not require an invitation to provide post-conflict affinitive contact. Moreover, spontaneous—but not solicited—third party affiliation was affected by the bond between consoler and victim (this supporting the ''Consolation Hypothesis''). Importantly, spontaneous affiliation followed the empathic gradient described for humans, being mostly offered to kin, then friends, then acquaintances (these categories having been determined using affiliation rates between individuals). Hence, consolation in the bonobo may be an empathy-based phenomenon. Instances in which non-human primates have expressed joy have been reported. One study analyzed and recorded sounds made by human infants and bonobos when they were tickled. Although the bonobos' laugh was at a higher
frequency Frequency is the number of occurrences of a repeating event per unit of time A unit of time is any particular time Time is the indefinite continued sequence, progress of existence and event (philosophy), events that occur in an apparen ...
, the laugh was found to follow a
spectrographic Chromatography is a laboratory technique for the Separation process, separation of a mixture. The mixture is dissolved in a fluid (gas, solvent, water, ...) called the ''mobile phase,'' which carries it through a system (a column, a capillary tu ...

spectrographic
pattern similar to that of human babies.


Distribution and habitat

Bonobos are found only south of the
Congo River The Congo River ( kg, Nzâdi Kôngo, french: Fleuve Congo, pt, Rio Congo), formerly also known as the Zaire River, is the second longest river in Africa Africa is the world's second-largest and second-most populous , after in both case ...
and north of the
Kasai River The Kasai River (called Cassai in Angola) is a tributary A tributary, or affluent, is a stream or river that flows into a larger stream or main stem (or parent) river or a lake. A tributary does not flow directly into a sea or ocean. Tributar ...
(a tributary of the Congo), in the humid forests of the
Democratic Republic of Congo The Democratic Republic of the Congo ( french: République démocratique du Congo (RDC) ), also known as Congo-Kinshasa, DR Congo, the DRC, the DROC, or the Congo, and formerly Zaire Zaire (, ), officially the Republic of Zaire (frenc ...
. Ernst Schwarz's 1927 paper “''Le Chimpanzé de la Rive Gauche du Congo''”, announcing his discovery, has been read as an association between the Parisian
Left Bank The Rive Gauche (, ''Left Bank'') is the southern bank of the river Seine in Paris Paris () is the Capital city, capital and List of communes in France with over 20,000 inhabitants, most populous city of France, with an estimated populati ...
and the left bank of the Congo River; the bohemian culture in Paris, and an unconventional ape in the Congo.


Ecological role

In the Congo tropical rainforest, the very great majority of plants need animals to reproduce and disperse their seeds. Bonobos are the largest frugivorous animals in this region, after elephants. During its life, each bonobo will ingest and disperse nine tons of seeds, from more than 91 species of lianas, grass, trees and shrubs. These seeds will travel 24 hours in the bonobo digestive tract, which will transfer them over several kilometers (mean 1.3 km; max: 4.5 km), far from their parents, where they will be deposited intact in their feces. These dispersed seeds remain viable, germinate better and more quickly than unpassed seeds. For those seeds, diplochory with dung-beetles (Scarabaeidae) improves post-dispersal survival. Certain plants such as Dialium may even be dependent on bonobos to activate the germination of their seeds, characterized by tegumentary dormancy. The first parameters of the effectiveness of seed dispersal by bonobos are present. Behavior of the bonobo could affect the population structure of plants whose seeds they disperse. The majority of these zoochorous plants cannot recruit without dispersal and the homogeneous spatial structure of the trees suggests a direct link with their dispersal agent. Few species could replace bonobos in terms of seed dispersal services, just as bonobos could not replace elephants. There is little functional redundancy between frugivorous mammals of the Congo, which face severe human hunting pressures and local exctinction. The defaunation of the forests, leading to the empty forest syndrome, is critical in conservation biology. The disappearance of the bonobos, which disperse seeds of 65% of the tree species in these forests, or 11.6 million individual seeds during the life of each bonobo, will have consequences for the conservation of the Congo rainforest.


Conservation status

The
IUCN Red List The International Union for Conservation of Nature (IUCN) Red List of Threatened Species (also known as the IUCN Red List or Red Data Book), founded in 1964, is the world's most comprehensive inventory of the global Conservation movement, conser ...
classifies bonobos as an endangered species, with conservative population estimates ranging from 29,500 to 50,000 individuals. Major threats to bonobo populations include habitat loss and hunting for bushmeat, the latter activity having increased dramatically during the First Congo War, first and Second Congo War, second Congo wars in the Democratic Republic of Congo due to the presence of heavily armed militias even in remote "protected" areas such as Salonga National Park. This is part of a more general trend of ape extinction. As the bonobos' habitat is shared with people, the ultimate success of conservation efforts still rely on local and community involvement. The issue of parks versus people is salient in the Cuvette Centrale the bonobos' range. There is strong local and broad-based Congolese resistance to establishing national parks, as indigenous communities have often been driven from their forest homes by the establishment of parks. In Salonga National Park, the only national park in the bonobo habitat, there is no local involvement, and surveys undertaken since 2000 indicate the bonobo, the African forest elephant, and other species have been devastated by Poaching, poachers and the thriving bushmeat trade. In contrast, areas exist where the bonobo and biodiversity still thrive without any established parks, due to the indigenous beliefs and taboos against killing bonobos. During the wars in the 1990s, researchers and international non-governmental organizations (NGOs) were driven out of the bonobo habitat. In 2002, the Bonobo Conservation Initiative initiated the Bonobo Peace Forest Project supported by the Global Conservation Fund of Conservation International and in cooperation with national institutions, local NGOs, and local communities. The Peace Forest Project works with local communities to establish a linked constellation of community-based reserves, managed by local and indigenous people. This model, implemented mainly through DRC organizations and local communities, has helped bring about agreements to protect over of the bonobo habitat. According to Dr. Amy Parish, the Bonobo Peace Forest "is going to be a model for conservation in the 21st century". The port town of Basankusu is situated on the Lulonga River, at the confluence of the Lopori River, Lopori and Maringa River, Maringa Rivers, in the north of the country, making it well placed to receive and transport local goods to the cities of Mbandaka and Kinshasa. With Basankusu being the last port of substance before the wilderness of the Lopori Basin and the Lomako River—the bonobo heartland—conservation efforts for the bonobo use the town as a base. In 1995, concern over declining numbers of bonobos in the wild led the Zoological Society of Milwaukee, in Milwaukee, Wisconsin, with contributions from bonobo scientists around the world, to publish the Action Plan for ''Pan paniscus'': A Report on Free Ranging Populations and Proposals for their Preservation. The Action Plan compiles population data on bonobos from 20 years of research conducted at various sites throughout the bonobo's range. The plan identifies priority actions for bonobo conservation and serves as a reference for developing conservation programs for researchers, government officials, and donor agencies. Acting on Action Plan recommendations, the ZSM developed the Bonobo and Congo Biodiversity Initiative. This program includes habitat and rain-forest preservation, training for Congolese nationals and conservation institutions, wildlife population assessment and monitoring, and education. The Zoological Society has conducted regional surveys within the range of the bonobo in conjunction with training Congolese researchers in survey methodology and biodiversity monitoring. The Zoological Society's initial goal was to survey Salonga National Park to determine the conservation status of the bonobo within the park and to provide financial and technical assistance to strengthen park protection. As the project has developed, the Zoological Society has become more involved in helping the Congolese living in bonobo habitat. The Zoological Society has built schools, hired teachers, provided some medicines, and started an agriculture project to help the Congolese learn to grow crops and depend less on hunting wild animals. With grants from the United Nations, USAID, the U.S. Embassy, the World Wildlife Fund, and many other groups and individuals, the Zoological Society also has been working to: *Survey the bonobo population and its habitat to find ways to help protect these apes *Develop antipoaching measures to help save apes, forest elephants, and other endangered animals in Congo's Salonga National Park, a UN World Heritage site *Provide training, literacy education, agricultural techniques, schools, equipment, and jobs for Congolese living near bonobo habitats so that they will have a vested interest in protecting the great apes – the ZSM started an agriculture project to help the Congolese learn to grow crops and depend less on hunting wild animals. *Model small-scale conservation methods that can be used throughout Congo Starting in 2003, the U.S. government allocated $54 million to the Congo Basin Forest Partnership. This significant investment has triggered the involvement of international NGOs to establish bases in the region and work to develop bonobo conservation programs. This initiative should improve the likelihood of bonobo survival, but its success still may depend upon building greater involvement and capability in local and indigenous communities. The bonobo population is believed to have declined sharply in the last 30 years, though surveys have been hard to carry out in war-ravaged central Congo. Estimates range from 60,000 to fewer than 50,000 living, according to the World Wildlife Fund. In addition, concerned parties have addressed the crisis on several science and ecological websites. Organizations such as the World Wide Fund for Nature, the African Wildlife Foundation, and others, are trying to focus attention on the extreme risk to the species. Some have suggested that a reserve be established in a more stable part of Africa, or on an island in a place such as Indonesia. Awareness is ever increasing, and even nonscientific or ecological sites have created various groups to collect donations to help with the conservation of this species.


See also

* Basankusu, DR Congo – base for bonobo research and conservation * Bonobo Conservation Initiative * Chimpanzee genome project * Claudine André * Great ape personhood * Great Ape Project *
Kanzi Kanzi (born October 28, 1980), also known by the lexigram Yerkish is an artificial language developed for use by human, non-human primates. It employs a Computer keyboard, keyboard whose keys contain ''lexigrams'', symbols corresponding to ...

Kanzi
* List of apes – notable individual nonhuman apes * Lola ya Bonobo * Koba (Planet of the Apes), Koba, a fictional bonobo and antagonist of the 2014 film ''Dawn of the Planet of the Apes''.


Notes


References


Further reading


Books

* * * * * *


Articles

* * * * * *


Journal articles

* * *


External links


Evolution: Why Sex?

Bonobos: Wildlife summary from the African Wildlife Foundation

Primate Info Net ''Pan paniscus'' Factsheet


– Ted.com
WWF (World Wide Fund for Nature / World Wildlife Fund) – Bonobo species profile


* {{Authority control Bonobos Apes Mammals described in 1929 Primates of Africa Fauna of Central Africa Mammals of the Democratic Republic of the Congo Endemic fauna of the Democratic Republic of the Congo Tool-using mammals Extant Pleistocene first appearances