Common chimpanzee

Common chimpanzee
Common chimpanzee ( Pan troglodytes )
Systematics
without rank: Old World Monkey (Catarrhini) Superfamily : Human (Hominoidea) Family : Apes (Hominidae) Subfamily : Homininae Genre : Chimpanzee ( Pan ) Type : Common chimpanzee
Scientific name
Pan troglodytes
( Blumenbach , 1775)

The Common Chimpanzee , also Common Chimpanzee or just chimpanzee called ( Pan troglodytes ) is a primate of the family of great apes (hominids). Together with the bonobo (dwarf chimpanzee) it forms the genus of chimpanzees ( Pan ). Both species are the most biologically close relatives of humans. The chimpanzee is more robustly built than the bonobo and has a larger range that extends over large parts of central Africa.

anatomy

Replica of a female chimpanzee skull, Rostock Zoological Collection

Common chimpanzees reach a head body length of 64 to 94 centimeters, like all great apes they are tailless. Standing, they reach heights of between 1 and 1.7 meters. Males reach a weight of 34 to 70 kilograms and are therefore significantly heavier than females, who reach between 26 and 50 kilograms. Animals in captivity can get heavier and weigh 80 kilograms. The fur is black or dark brown in color.

The arms are significantly longer than the legs, the span between the outstretched arms is half the height of the animal. The hands are characterized by the long fingers and the comparatively short thumbs, the first toe of the feet can be opposed, as is the case with most primates .

The face is hairless. It is generally lighter than that of the bonobo, and young animals also have a lighter face than adults, but there are also regional differences. The head of the chimpanzee is characterized by the outstanding, round ears, the bulges above the eyes and the protruding snout. The size of the canines is strongly sex-dimorphic (in males they are significantly larger).

Karyotype and genome

The genetic information of the common chimpanzee is organized within the cell nucleus into 24 pairs of chromosomes , two of which are sex chromosomes . The full genome was first analyzed in 2005; it consists of 3,349,642,171 base pairs . The exact number of genes is still unknown. Bonobos and common chimpanzees have mixed with each other several times in the course of their development, as studies on the genome of both species show.

distribution and habitat

Distribution of the common chimpanzee with four subspecies:
1. Western chimpanzee ( Pan troglodytes verus )
2. Nigeria chimpanzee ( P. t. Vellerosus , also P. t. Ellioti )
3. Central African chimpanzee ( P. t. Troglodytes )
4. Eastern Chimpanzee ( P. t. Schweinfurthii )

The common chimpanzee range extends in a wide belt through central Africa . It ranges in West Africa from Senegal on the south-east of neighboring countries into the western part of Ghana over Nigeria , Cameroon , Gabon , the Republic of Congo , to the southeast of the Central African Republic , the south-western border regions of South Sudan and the north and east of the Democratic Republic of Congo until the western regions of Uganda and Tanzania . In the Democratic Republic of the Congo barely überquerbare forms Congo River , the southern border of its range, south of it live the bonobos. Human settlement has reduced the habitat of these animals and divided them into a large number of smaller spots.

These animals are more flexible about their habitat than other great apes. They occur in tropical rainforests , in dry savannahs and in mountainous regions up to 3000 meters above sea level.

Chimpanzee in the rainforest

Way of life

Movement and activity times

Common chimpanzees can forage both on the ground and in trees, but most of the time they do so in trees. On the ground, like all African great apes , they move in a four-footed ankle gait , which means that they prop themselves on the second and third phalanges. In the branches they either climb with all four limbs or move around hanging on the arms ( suspensory ). As a rule, chimpanzees are diurnal. When they sleep they make a nest out of twigs and leaves. This nest is mostly on trees at a height of 9 to 12 meters and is usually only used once. In particular in the rainy season, they sometimes rest during the day, for which they also build nests.

Social behavior

Within the large group

The social structure of the chimpanzees is described as a "fission fusion organization" ("separating and merging"). This means that they live in large groups made up of 20 to 80 animals, which often split up into subgroups - for example to search for food - and then come together again, especially to sleep. For example, adult animals often hunt for food alone or join forces with others to form a short-lived, temporary subgroup. These subgroups are very flexible and usually include four to eight animals, significantly fewer than the bonobo . The composition and size of the subgroups is very variable and also differs from population to population.

Strong and older males lead and defend the whole large group. The males develop a distinctive rank structure. Various rituals such as loud screams, drumming on tree trunks, demonstrations of strength - they shake branches or throw stones - and demonstratively fast running or jumping serve this purpose. They invest a lot of time and energy to improve their rank within the group. To this end, they form coalitions, among other things, but this can also be a deception, a sham alliance. Hunting small mammals and guarding territorial boundaries, both of which are carried out by males, also serve this purpose. Mutual grooming ( comfort behavior ) is also very pronounced in the males and supports social communication.

In contrast, females are often more solitary and develop a less conspicuous hierarchy. However, there is still a hierarchy, as shown by the fact that higher-ranking females are more likely to have offspring. In general, females have little interaction with other females other than their daughters. This is also because the females leave their birth group when they reach sexual maturity, while the males stay with their group for most of their lives.

The interactions between males and females are variable and are described in more detail in the section on mating behavior .

Outside the large group

A large group usually has a specific home area. This is 5 to 40 square kilometers in forests, but significantly larger in savannas with 120 to 560 square kilometers. Small groups of males often patrol the borders of the territory. Animals that do not belong to their own large group are usually treated very aggressively. The persecution of individual foreign animals is sometimes so brutal that the word " war " was used for it. (see also → Gombe Chimpanzee War ). Even non-fertile females are not spared. These warlike attacks, in which common chimpanzees sometimes invade foreign territory without provocation and chase and kill the animals there, are unknown except for them and for humans among primates .

Tool use

Common chimpanzees have been repeatedly observed using tools . They use chewed leaves as sponges to scoop water out of tree holes, blades of grass and sticks are processed and inserted into termite mounds so that the insects can eat them. Stones or branches serve as a hammer and anvil to crack nuts, and branches are used as hooks to pull fruit-bearing branches. Sticks and stones are used as projectiles in hunting and defense. Recently, it was also observed that they worked and sharpened wooden sticks as skewers to use in order Galagos to hunt. There is no indication that you are working on stones, but keep particularly suitable stones or store them in a safe place where you can find them again if necessary.

The individual populations differ markedly in the type and frequency of tool use, and no single use occurs in all populations. So far, cracking nuts by means of stones has only been observed in the western subspecies; this practice is unknown in the animals in the east of the distribution area. Finds from the Taï National Park in the Ivory Coast show that this practice has been used for at least 4,300 years. A study published in February 2019 describes a population of the East African chimpanzee ( P. t. Schweinfurthii ) living in the north of the Democratic Republic of the Congo , which uses sticks of various types (short, long, thick or thin) to collect different species of ants or the honey from Prey on stingless bees . Nuts and other hard fruits as well as the nests of tree termites and the shells of African giant snails ( Achatina ) and jointed turtles ( Kinixys ) are opened by knocking them on tree trunks or stones. It is also noteworthy that these chimpanzees prefer not to sleep in trees but on the ground.

The use of tools, like building nests every evening, is not an instinctive activity, but is learned by the younger animals through observation of experienced animals.

Self-medication

As observed by the great ape researcher Richard Wrangham in 1972 in a Tanzanian national park, chimpanzees have developed various methods of getting rid of parasites . For this purpose, the rough, sharp-edged leaves of certain plants are torn off, carefully folded up and swallowed whole. The leaves of around 30 tree species are eligible. Faecal examinations showed that the leaves are excreted undigested, along with numerous large intestinal parasites. The rough leaf structure is believed to scrape the worms off the intestinal walls. In addition, there is the laxative effect of the tannins contained in various leaves . The laxative effect of the tannins contained in the very bitter pulp of the Vernonia amygdalina shrub , which grows in western Tanzania and is eaten by chimpanzees when required, also serves to ward off parasites .

Self-medication is also not an innate, but an acquired or learned behavior that is only passed on by some populations. Female chimpanzees who are newly immigrating to such a horde and are not familiar with this behavior learn it from the members of the horde through imitation.

communication

Head of a chimpanzee

Common chimpanzees communicate with one another using a variety of sounds and postures. The most common sound is the "pant-hoot" call, which is used to establish contact with distant group members. In addition, they also use a food call, a barking gasp to draw the attention of other animals to a source of food, screeching or roaring roars when hunting or a plaintive "Wraaa call", which serves as an alarm signal. Panting in and out is an equivalent to human laughter .

Facial expressions and postures also serve for interaction. Submission is signaled by crouching or presenting the bottom. Angry or excited animals stand on two legs, bristle their fur and press their lips together. Big grins are often a sign of nervousness or fear. The spectacular display behavior of these animals includes loud roars, fast running around, throwing stones or pulling large branches.

food

Common chimpanzees are omnivores, but plants make up the focus of their diet. The most important food components are fruits and nuts (45 to 76%) and leaves (12 to 45%). The food is supplemented by flowers, seeds and animal prey, so insects are regularly consumed. They also occasionally hunt mammals such as small artifacts and smaller primates such as red colobus monkeys , galagos, and even baboons . The hunt is mostly done by adult males and has a very strong social component. Males share the meat with other group members in an attempt to improve or maintain their position in the group hierarchy.

Reproduction

Young chimpanzee

Mating behavior

Mating can take place all year round, the length of the sexual cycle is around 36 days. The oestrus lasts around 6 to 7 days, during which time the females show a significant swelling . Besides bonobos are the only primates that have this feature; but it also occurs in baboons, for example .

The mating behavior is variable and can take different forms. On the one hand, it can lead to a promiscuous behavior within the large group, so that several males and several females reproduce with one another. It can also be observed that a male mates with a fertile female and then guards it and does not allow other mating partners. Finally, it also happens that a male and a female form a pair for a short time and separate themselves from the large group for several days during their fertile period. The mating success of individual males can be almost doubled by feeding selected females and thus supports the “meat-versus-sex hypothesis” .

Birth and rearing of young

After a gestation period of 230 days on average, the female usually gives birth to a single young, twin births are rare. The birth weight of newborns is around 1.9 kilograms. In the first six months of life, the young animal clings to the mother's fur, later it rides on her back. They are only weaned after 3.5 to 4.5 years, but the young animal usually stays with the mother for a longer period (up to ten years).

A female can give birth to offspring every five to six years unless the cub dies sooner. The sexual maturity occurs at the age of about seven years, due to the group hierarchy, the first reproduction is usually a few years later in females 13 to 14 years and in males 15 to 16 years. Unlike humans or gorillas, chimpanzees do not menopause . It is true that females have cubs less often from the age of 40, but this is solely due to health reasons.

The life expectancy of common chimpanzees is 30 to 40 years in the wild, but rarely over 50 years in captivity.

Common chimpanzees and humans

Research and research history

Jane Goodall conducted pioneering research on wild chimpanzees

It is not known since when the western world knew about the chimpanzee. The Carthaginian navigator Hanno († 440 BC) brought back the skins of three “wild women” from his trip to Africa, probably chimpanzees or gorillas . In 1641 a live chimpanzee came to the Netherlands for the first time . It was discovered by the Dutch doctor Nicolaes Tulpius (1593–1674), who was inspired by Rembrandt's painting “ The Anatomy of Dr. Tulp ”was investigated; the findings were published under the title "Indian Satyr". The English doctor and zoologist Edward Tyson (1650-1708) examined a chimpanzee in 1699 and found a number of similarities between this and humans. Ever since Darwin's and Huxley's works on evolutionary theory , chimpanzees have come into the public eye as close relatives of humans.

In 1915, Rosalía Abreu succeeded in breeding a chimpanzee in captivity for the first time in Cuba . From 1914 to 1920 Wolfgang Köhler studied learning behavior and the use of tools by chimpanzees in Tenerife . In the second half of the 20th century, the way of life and behavior of chimpanzees became the focus of interest. Jane Goodall's research work on wild animals in the Gombe Stream National Park in Tanzania was groundbreaking . In the mid-1960s, a Japanese research team led by Professor Nishida began habituating two groups of chimpanzees in the Mahale Mountains National Park , 150 kilometers south of Gombe Stream National Park . Since the mid-1980s, Dr. Michael Huffmann from Kyoto University discussed medicinal plant use in chimpanzees.

The communication skills of these animals is still the focus of research today. In the 1960s and 1970s, the psychologist Roger Fouts succeeded in teaching several chimpanzees American Sign Language (ASL). Today, the chimpanzee Washoe is considered to be the first non-human being to learn a human language.

David Premack did similar research, but he used symbol cards. In addition, tool use, intelligence and the ability to learn are also examined. Common chimpanzees manage to solve tricky problems (such as getting a fruit out of a sealed container) and pass the mirror test - that is, they recognize themselves in the mirror. In order to be able to draw specific comparisons between humans and these animals, a genome project for chimpanzees was initiated.

The Max Planck Institute for Evolutionary Anthropology was newly founded in Leipzig in 1997 . In the Primatology department headed by Christophe Boesch , social behavior, linguistic learning abilities and reproductive strategies of great apes are examined in comparison to humans.

Keeping and use

Humanization of a chimpanzee for entertainment purposes around 1910 in East Africa

Chimpanzees are also used as objects of entertainment, usually without proper housing

This close relationship between chimpanzees and humans clearly determines their relationship with these animals. Expressive facial expressions and often amazingly human-like behavior make the common chimpanzee the most popular and best-known of all great ape species . These animals can be seen many times in the zoo, in the circus, on posters or in TV programs (e.g. Daktari , Our Charly ). Common chimpanzees are sometimes kept as pets , the best known being " Bubbles ", Michael Jackson's monkey .

These animals play an important role in research and science. There are diseases that, apart from humans, can only be examined in chimpanzees. For example, chimpanzees can be infected with HI or hepatitis viruses, but they do not develop hepatitis or AIDS . With some symptomatic treatment options for these diseases now available, the number of chimpanzees used for biomedical research is steadily declining. In some countries (including Austria) there are now laws that prohibit the use of great apes for biomedical research. Since the long life expectancy and the practice of not euthanizing disused laboratory chimpanzees, mixed with the breeding efforts of the last decades, has resulted in an excess of chimpanzees from European and American laboratories, there are now also sanctuary for former laboratory chimpanzees (Stichting Aap in the Netherlands; Monkey World in Great Britain; HOPE in Austria and Chimp Haven in the USA).

Chimpanzees were also used in space travel. On 31 January 1961, the chimp was Ham as part of the Mercury program of NASA with the Mercury-Redstone 2 (MR-2) into space. He survived the 16-minute flight. In another experiment, on November 29, 1961, the chimpanzee Enos flew through space with the Mercury Atlas 5 for three hours and 20 minutes.

threat

Common chimpanzees are considered threatened in the wild. The main reason for this is the destruction of their habitat by deforestation, which has led to their range becoming more and more restricted and severely fragmented. The populations in West Africa are particularly affected. But they are also hunted for their meat ("bushmeat") or because they sometimes devastate plantations. While in the past live animals were often caught in order to use them for animal experiments or to make pets, the live catch has declined today. The Washington Convention on Endangered Species (CITES) completely bans the trade in chimpanzees.

The IUCN lists the species as endangered and fears a further decline in populations. The two more western subspecies are therefore more threatened than the animals in the east of the distribution area.

Estimates of population size are difficult to make. It is possible that several million common chimpanzees were still alive at the beginning of the 20th century; this number has fallen dramatically. An estimate from 1999 puts the total population at 150,000 to 235,000, other sources assume fewer than 100,000 animals. The WWF published the following figures in 2009: 21,000 to 56,000 West African chimpanzees, 70,000 to 117,000 Central African, 76,000 to 120,000 East African and only 5,000 to 8,000 Nigerian chimpanzees, for a total of between 172,000 and 301,000 individuals. In 2019, an estimate for West African chimpanzees resulted in a population of around 53,000 individuals, with a confidence interval (95%) of 17,577 to 96,564 individuals.

Western chimpanzee population

The following figures, based on different studies, are from 1998 to 2010.

Country	Stock (minimum)	Stock (maximum)
Guinea	8,100	29,000
Sierra Leone	3,000	10,400
Liberia	?	7,000
Mali	1,600	5,200
Ivory Coast	800	1,200
Guinea-Bissau	600	1,000
Ghana	300	500
Senegal	200	400
Burkina Faso	0	some
Nigeria	0	?
Togo	0	0
Benin	0	0

Systematics and subspecies

Kladogramm the apes ; Pongo stands for orangutans , Pan for chimpanzees

The common chimpanzee ( Pan troglodytes ) forms the genus of chimpanzees ( Pan ) together with the bonobo or dwarf chimpanzee . It is estimated that the two species separated between 1.8 and 0.8 million years ago. The genus of chimpanzees is within the family of apes the (Hominidae) Schwestertaxon of people represents.

Four subspecies are distinguished within the common chimpanzees:

• The West African chimpanzee or real chimpanzee ( Pan troglodytes verus ) is widespread in western Africa (from Senegal to Ghana ). Outwardly, it is characterized by a pink face that only gradually turns dark. This subspecies differs significantly from the other subspecies in terms of skull structure and molecular structure, so that some authors list it as a separate species ( Pan verus ).
• The Nigerian-Cameroon chimpanzee ( Pan troglodytes ellioti ) was recently recognized as a subspecies. It is the rarest subspecies and lives in eastern Nigeria and western Cameroon .
• The Central African chimpanzee or Tschego ( Pan troglodytes troglodytes ) is characterized by a darker face than the other subspecies. It is distributed from southern Cameroon via Gabon and the Republic of the Congo to the west of the Democratic Republic of the Congo and is by far the most common subspecies.
• The East African chimpanzee or long-haired chimpanzee ( Pan troglodytes schweinfurthii ; its name goes back to the German explorer Georg Schweinfurth ). Schweinfurth was one of the first to describe regional differences between chimpanzees in the west and east of the African continent. That is why the East African chimpanzee bears his name. He lives from the Central African Republic and the north of the Democratic Republic of the Congo to the western parts of Uganda and Tanzania . This subspecies differs from the other representatives of this species by a bronze-colored face and a longer fur.

• 

  Distribution area of ​​the western chimpanzee
  ( P. t. Verus )

• 

  Distribution area of ​​the Nigeria chimpanzee
  ( P. t. Ellioti )

• 

  Distribution area of ​​the Central African chimpanzee
  ( P. t. Troglodytes )

• 

  Distribution area of ​​the eastern chimpanzee
  ( P. t. Schweinfurthii )

The "giant chimpanzee" or "bili chimpanzee", sometimes postulated as a separate species or subspecies, has turned out to be a representative of the eastern subspecies ( P. t. Schweinfurthii ) after DNA studies .

literature

• Jane Goodall : Reason for Hope Riemann, Munich 2006, ISBN 3-570-50079-9 , ISBN 978-3-570-50079-8 .
• Roger Fouts : Stephen Tukel Mills. Our closest relatives. Learn from chimpanzees what it means to be human . Limes, Munich 1998, Droemer Knaur, Munich 2002, ISBN 3-8090-3013-9 , ISBN 3-426-77420-8 .
• Thomas Geissmann: Comparative Primatology . Springer, Berlin 2002, ISBN 3-540-43645-6 .
• Ronald M. Nowak: Walker's Mammals of the World . Johns Hopkins University Press, Baltimore 1999, ISBN 0-8018-5789-9 .

Web links

Commons : Common chimpanzee ( Pan troglodytes )  - Collection of images, videos and audio files

• Chimpanzee sounds and picture
• Wild Chimpanzee Foundation - Germany e. V.
• Jane Goodall Institute Germany
• Friends of Washoe - official website for chimpanzees communicating with ASL (American Sign Language)
• Pan troglodytes in the endangered Red List species the IUCN 2006. Posted by: Butynski et al. , 2000. Retrieved May 10, 2006.
• Rehabilitated laboratory chimpanzees
• Summary of the chimpanzee genome (Engl.)

Individual evidence

1. ↑ MapViewer entry
2. ^ Initial sequence of the chimpanzee genome and comparison with the human genome . In: Nature . 437, No. 7055, September 2005, pp. 69-87. doi : 10.1038 / nature04072 . PMID 16136131 .
3. ↑ M. de Manuel, M. Kuhlwilm u. a .: Chimpanzee genomic diversity reveals ancient admixture with bonobos. In: Science. 354, 2016, p. 477, doi : 10.1126 / science.aag2602 .
4. ↑ Jane Goodall Institute: Chimpanzees - Conflicts, War and Peace ( Memento June 10, 2008 in the Internet Archive )
5. ↑ RM Nowak: Walker's Mammals of the World. Baltimore 1999, p. 624.
6. ^ Jill D. Pruetz, Paco Bertolani: Savanna Chimpanzees, Pan troglodytes verus, Hunt with Tools. In: Current Biology. Volume 17, No. 5, 2007, pp. 412-417, doi: 10.1016 / j.cub.2006.12.042
7. ↑ See also: Mathias Osvath and Elin Karvonen: Spontaneous Innovation for Future Deception in a Male Chimpanzee. In: PLoS ONE. Volume 7, No. 5, 2012: e36782, doi: 10.1371 / journal.pone.0036782 .
8. ^ Julio Mercader et al .: 4300-year-old chimpanzee sites and the origins of percussive stone technology. In: PNAS . Volume 104, No. 9, 2007, pp. 3043-3048, doi: 10.1073 / pnas.0607909104
   mpg.de of February 13, 2007: The Chimpanzee Stone Age. West African chimpanzees have been cracking nuts with stone tools for thousands of years.
9. ↑ Thurston C. Hicks, Hjalmar S. Kühl u. a .: Bili-Uéré: A Chimpanzee Behavioral Realm in Northern Democratic Republic of Congo. In: Folia Primatologica. 90, 2019, p. 3, doi : 10.1159 / 000492998 .
10. ↑ Jean Marie Pelt: The secrets of medicinal plants. Knesebeck, Munich 2005, ISBN 3-89660-291-8 , p. 17f.
11. ^ Numbers according to T. Geissmann: Comparative Primatology. Berlin 2002, p. 301.
12. ↑ lust of the flesh. Female chimpanzees copulate more often with food suppliers. In: Spektrumdirekt. Report on April 8, 2009.
13. ↑ CM Gomes, C. Boesch: Wild Chimpanzees Exchange Meat for Sex on a Long-Term Basis. In: Public Library of Science One. 2009, Vol. 4, Iss. 4, item e5116.
14. ↑ Reproduction: No menopause in chimpanzees . ( Spektrum.de [accessed on March 18, 2017]).
15. ↑ CE Finch: Evolution of the human lifespan and diseases of aging: Roles of infection, inflammation, and nutrition. In: PNAS 2009 Internet publication before printing doi: 10.1073 / pnas.0909606106 .
16. ^ Sanctuary for exotic animals
17. ^ Ape Rescue Center, UK
18. ↑ Home Of Primates Europe
19. ↑ American sanctuary for former laboratory chimpanzees
20. ↑ RM Nowak: Walker's Mammals of the World. Baltimore 1999, p. 625.
21. ↑ Chimpanzee habitat. In: janegoodall.de. Jane Goodall Institute eV Germany , 2008, archived from the original on June 3, 2008 ; Retrieved March 5, 2016 . 
22. ↑ Stefan Ziegler, Frank Barsch: The disappearance of the great apes. In: WWF Magazin. No. 3, 2009, p. 13, ( online at: schattenblick.de ; last accessed on September 28, 2013).
23. ↑ Background information on chimpanzees (Pan troglodytes). (PDF; 128 kB) In: wwf.de. WWF Deutschland & TRAFFIC Europe-Germany, April 2007, accessed on March 5, 2016 . 
24. ↑ Stefanie Heinicke et al .: Advancing conservation planning for western chimpanzees using IUCN SSC APES - the case of a taxon-specific database. In: Environmental Research Letters. Online publication from March 26, 2019, doi: 10.1088 / 1748-9326 / ab1379
25. ↑ Sierra Leone National Chimpanzee Census August 2010. Tacugama Chimpanzee Sanctuary, 2010, p. 95.
26. ↑ One of the last strong holds for Western chimpanzees. Max Planck Society, April 9, 2014.
27. ^ Evidence for a Complex Demographic History of Chimpanzees
28. ↑ Jutta Hof, Volker Sommer: Apes like us: portraits of a kinship. Ed. Panorama, Mannheim 2010, ISBN 978-3-89823-435-1 , p. 110.
29. ↑ Emma Young, Adrian Barnett: DNA tests solve mystery of giant apes. In: New Scientist. No. 2558, 2006, ( online preview ).

This version was added to the list of articles worth reading on June 6, 2007 .