Great apes

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Great apes
Representatives of the hominids: Sumatran orangutans (Pongo abelii) and humans (Homo sapiens)

Representatives of the hominids: Sumatran orangutans ( Pongo abelii ) and humans ( Homo sapiens )

Order : Primates (Primates)
Subordination : Dry- nosed primates (Haplorrhini)
Partial order : Monkey (anthropoidea)
without rank: Old World Monkey (Catarrhini)
Superfamily : Human (Hominoidea)
Family : Great apes
Scientific name
Gray , 1825

The apes or hominids , also Germanized hominids , are a family of primates . This summarizes four genera living today with eight recognized recent species :

The great apes also include the fossil ancestors of the eight recent species and their fossil relatives who are not direct ancestors, such as Gigantopithecus and the Neanderthals .

It is only because of the spread of humans ( Homo sapiens ) from Africa that the hominids living today are distributed worldwide. The remaining great apes are restricted to tropical regions in Africa and Southeast Asia and their populations are all endangered.

The closest relatives of the great apes are the gibbons , which are sometimes referred to as "small great apes".

Historical development of the terms hominids and great apes

The positions of the two subfamilies Ponginae and Homininae as well as the four genera living today in the family tree of the great apes (Hominidae). The tribe hominini includes anatomically modern humans ( Homo sapiens ) as well as their fossil ancestors and their fossil relatives (such as the Neanderthals ), who developed after the separation of the line leading to the chimpanzees from the line leading to humans.

As a result of the ever more accurate reconstruction of the tribal history of the great apes, the terms "hominids" and "great apes" have changed. "Hominids" (Hominidae) used to mean anatomically modern humans ( Homo sapiens ) and the fossil closest relatives of humans , while its closest recent relatives - chimpanzees ( Pan ), gorillas ( gorilla ) and orangutans ( Pongo ) - under Exclusion of humans in their own family, the Pongidae ("Pongids", also "great apes" or simply great apes).

This system is outdated due to phylogenetic findings, according to which chimpanzees and gorillas are much more closely related to humans than to orangutans. For this reason, humans and related extinct species are now placed in a common family (Hominidae) with chimpanzees, gorillas and orangutans. The term “great apes”, however, is not precisely defined. Outside of strictly cladistic works and in common parlance, the term great apes is mostly still used as a term for all non-human hominids.


General build and coat

Gorillas are the largest
great apes and the largest living primates

Great apes are the largest living primates. They reach a weight of 25 (female chimpanzees) up to 200 (male gorillas) kilograms and a standing height of around 1 to 2 meters. In all species there is a clear sexual dimorphism : males are often larger and much heavier than females; in orangutans and gorillas they often weigh twice as much as the females. They are robustly built beings that are characterized by a comparatively short trunk with a broad chest . A tail is missing, as in all humans . The wide pelvis , the reduced number of lumbar vertebrae in comparison to quadrupedal mammals and a slight kink of the spine in the area of ​​the sacrum go hand in hand with the partial straightening of the posture, which is most pronounced in humans. This type of locomotion has led to some morphological peculiarities, for example in the structure of the spine (in humans bent double-S-shaped, in other species simply curved) and the pelvis (in humans short and wide, in other species longer and narrower ).

The fur is less dense than that of other primate species, it is reddish-brown in orangutans and black-brown in color in gorillas and chimpanzees. In humans, the coloration is variable, and in most parts of the body it is significantly shorter and thinner and has little pigmentation, but not receded. The reasons for this feature are so far controversial.


Intermembral indices of great apes
human 72
Chimpanzees 102-106
Gorillas 116
Orangutans 139
for comparison:

Together with the gibbons, great apes (with the exception of humans) are among the few primates in which the front limbs are longer than the rear ones. This ratio is given by the intermembral index  - (upper arm + radius) × 100 / (thigh + shin) -, see the table on the right for figures. The long arms of the non-human great apes represent adaptations to a suspensory locomotion (hanging from the branches); the elongated and specialized hind limbs of humans, on the other hand, with their bipedal (two-legged) lifestyle. The shoulder joint is compared with other primates rearwardly moved, accordingly, that is clavicle extended and the shoulder blade is back side - which provides for a great mobility of the upper arms. The arms are very strong, the hands are large, the fingers (except in humans) are curved and the thumb is opposable . As in many primates, the fingers and toes are equipped with nails . In humans, the hands no longer have a locomotor function (necessary for locomotion) and, thanks to their delicate fingers and highly flexible thumb, ensure increased dexterity.

Except in humans, the legs are bent, the big toe is strong and can also be opposed. In humans, the legs are straight and significantly longer than the arms due to the special locomotion. The foot has developed into a curved base, whereby the exposability of the big toe has been lost in the course of evolution.

Head and teeth

Mean brain volumes of recent and extinct great apes in cm 3
Chimpanzees 394
Orangutans 411
Gorillas 506
Australopithecus around 500
Homo erectus 935
Modern man around 1340
Neanderthals around 1400
The skulls of some great apes are characterized by bulges on the cheek or over the eyes

The skull of the apes are compared with those of other primates, relatively large and plump, the cranial cavity holds a relatively large brain  - numbers see table. Several species have conspicuous skull structures, such as bulges above the eyes (gorillas and chimpanzees), sagittal and nuchal ridges (bulges on the top of the head and neck that serve as muscle attachment points, male gorillas and orangutans) or bulges. However, cheek pockets are not available. The eyes are large and directed forward, the ears round and hairless. As in all narrow-nosed monkeys, the nostrils are close together and point forward or downward.

Like all Old World monkeys , great apes have 32 teeth, the tooth formula is I 2- C 1- P 2- M 3. In humans, however, a partial reduction in the last molars (“ wisdom teeth ”) can be observed. The structure of the teeth depends on the diet of the individual species, but what the great apes have in common is the relatively low crown of the molar teeth with the same arrangement of the cusps. The teeth of humans differ from those of the other species in that the canine teeth are small and not developed like a tusk and, moreover, show no sexual dimorphism - in the other species, those of the males are significantly larger than those of the females. Further differences lie in the shape of the dental arch , which is parabolic in humans and U-shaped in the other species. In humans, the diastema ("monkey gap"), a gap between the incisors and canines , is also missing . The modifications of the human dentition may represent an adaptation to the unnatural preparation of the food.

distribution and habitat

With the exception of humans, the range of great apes is now limited to the tropical regions of central Africa ( chimpanzees and gorillas ) and the Southeast Asian islands of Sumatra and Borneo ( orangutans ). The great apes still living today are distinct forest dwellers; their habitat are tropical rainforests and other tropical forest forms; only the common chimpanzee is found in savannah areas . However, fossil finds from Europe show that relatives of early ancestors of today's great apes ( Dryopithecini such as Ouranopithecus macedoniensis ) also colonized Europe up to seven million years ago.

In contrast to the other primates, humans have achieved a worldwide distribution, only the Antarctic was not permanently colonized. A wide variety of habitats (including grasslands, deserts, mountain regions and arctic regions) have been inhabited by them for thousands of years.

It is primarily through deforestation and poaching that humans have brought their closest relatives to the verge of extinction. Since around 1985, their stocks in Africa and Asia have declined by up to 60%.

Way of life

Activity times and movement

Gorilla in the ankle gait

The non-human great apes can be found in the trees or on the ground to different extents, depending on the species. The most pronounced tree inhabitants are the orangutans, while mountain gorillas spend most of their time on the ground. In the trees, great apes either climb with all four limbs or move around in a suspensory manner, sometimes they also walk with their hind legs on the branches. On the ground, these animals usually move on all fours; apart from humans, great apes can only cover short distances on their hind legs. Chimpanzees and gorillas use the ankle gait , which means they put the second and third phalanges on the floor. Orangutans, on the other hand, rely on their fists or the inner edges of their hands.

In contrast, humans are strict ground dwellers. Of all primates, only the jeladas lead a similar, exclusively ground-dwelling way of life. Humans also move on a mandatory bipede , which is unique among mammals. This locomotion is not very fast, but according to more recent findings it saves energy and offers the advantage that the hands are relieved of the locomotion function, thus enabling the development of a differentiated gripping hand.

Like all ancient world monkeys, great apes are diurnal. When they sleep, the non-human apes usually make a nest out of leaves and twigs in the trees. This process usually takes no longer than five minutes, and a new nest is usually built every night. They often stop for a short rest during lunchtime.

Social behavior

Orangutans lead the most solitary life of all great apes

The social structure of the individual genera and species is very different, and there are often different forms of coexistence within one species. One reason for this diversity could be the high intelligence of these animals compared to other primates , which enables greater flexibility in social interactions based on memory and individual partner relationships. In contrast to other primates, however, they rarely have a matrilineal organization (that is, a group of closely related females forms the core of the group), since the females usually leave their birth group.

Orangutans lead a more solitary way of life, although the males, for example, interact with the females whose territories overlap with theirs. Gorillas usually live in harem groups (one male and several females), the dominant males can also be identified by the silver color on their backs. Chimpanzees have a more variable group behavior, which is referred to as the “fission fusion model” (“separating and merging”), which means that short-term subgroups that can be composed flexibly occur again and again. The social structure of humans is variable, in addition to monogamous and polygynous forms, polyandric and promiscuous forms also occur less frequently . A typical or original social structure cannot be specified, as the behavior is strongly cultured. Attempts to fathom the original social behavior of humans on the basis of morphological comparisons (primate species with clear gender dimorphism in terms of weight tend to live in harem groups; on the other hand, primates without differences in size of the canines tend to lead a monogamous way of life) are very doubtful.

Great apes communicate with each other using a variety of sounds with different meanings, facial expressions, gestures and postures. While all of these forms occur in both humans and the rest of the species, a highly complex language as a form of communication is unique to humans.

Tool use

This female gorilla uses a stick to check the water depth and to support herself

There are many forms of tool use among the great apes , whereby not only existing materials are used, but sticks are also specifically processed. In the individual species in the wild, however, the use of tools varies greatly. The most diverse forms can be found in humans, much less in common chimpanzees , and in turn significantly less in gorillas and orangutans. Only the latest studies have shown the use of tools in bonobos . (The behavior of animals in human care, where numerous uses of tools occur in all species.) There are also forms of self-medication , for example gorillas and chimpanzees swallow prickly, tannic leaves that scrape the parasites off the intestinal walls. In Hominini, the oldest known stone tools are about 2.5 million years old, which represents the beginning of the Stone Age - the processing of stones is a process that does not occur in the other great apes.

All these forms are not instinctive activities, but rather actions learned through observation or passed on within the populations. For example, common chimpanzees show different forms of tool use in different regions, and there is no single form that occurs in all populations.


The non-human primates are mainly herbivores, but they also eat carnal food to a different extent. For chimpanzees and orangutans, fruit is the main component of the diet, while gorillas tend to feed on leaves. The consumption of meat is rarely observed in gorillas and orangutans, they occasionally eat insects and other small animals. On the other hand, chimpanzees sometimes hunt vertebrates (such as small ungulates and primates ), but this has a strong social component - making meat available increases the rank in the group hierarchy. Humans, on the other hand, are more adapted to an omnivorous (omnivorous) diet, also due to the structure of their digestive system. They have clearly set themselves apart from the other great apes - and all other animals - in the form of acquisition and processing of food. Presumably this omnivorous diet has at least made it easier for them to greatly expand their range compared to the other great apes and also to penetrate habitats that are otherwise not inhabited by primates .

Reproduction and development

In the left bonobo, a female, the normal swelling can be clearly seen
Young orangutan

The reproductive strategy of the great apes is a pronounced K-strategy , that is, there are long intervals between births and small litter sizes, a lot of energy is invested in raising the individual young, and there is slow individual development with a high life expectancy.

The mating strategies are variable for the individual species and often also within a species and depend on social behavior. In the case of bonobos and humans in particular, in addition to the reproductive purpose, sexual behavior has also gained functions in the social structure of the population that have nothing to do with reproduction. In the case of orangutans, in addition to voluntary mating with resident males, there is also copulation forced by wandering males ("hikers"). With the gorillas, the dominant male usually reproduces with the females in his group. The mating behavior of chimpanzees and humans is extremely variable.

There is no fixed mating season for any species, reproduction can take place all year round. Only in chimpanzees is there a normal swelling that characterizes oestrus . The length of gestation or pregnancy is around 7.5 to 9 months and is longest in gorillas and humans. As a rule, a single young is born, twin and higher multiple births are rare.

Great apes have a very long childhood; they spend a long period of learning with their mother or in a group. In the first months of life, they are carried as active babies by the mother, whose fur they hold on to. They are suckled for several years . In the nonhuman species, the young are finally weaned at the age of 3.5 to 5 years, but afterwards they spend a few more years near their mother. In the non-human species, sexual maturity usually occurs between the ages of 6 and 10 years (a little later for males than for females), and a few years later for humans. Due to the social structures, however, the first reproduction only takes place a few years after the onset of sexual maturity, in non-human species at around 10 to 15 years.

Also due to the long phase of rearing young, great apes have a very low reproductive rate . It is lowest in orangutans, where a female often only raises two or three young in the course of her life. The life expectancy is high relatively: it is highest in humans, where it is about 80 years in some industrialized countries; in individual cases an age of over 110 years is attested. Life expectancy in the wild is 35 to 50 years for non-human species, and significantly higher for animals in human care.

(Non-human) great apes and humans

Research and research history

Depiction of a
great ape from 1833 by Sir William Jardine after a dermoplasty in the Edinburgh Museum

The Carthaginian seafarer Hanno († 440 BC) brought back the skins of three “wild women” from his trip to Africa, who were referred to as gorillai by the African interpreters . However, it is unclear where exactly Hanno killed the creatures and which animals they really were. It was not until the 17th century that the western world received knowledge of these animals again. In 1641 a live chimpanzee came to the Netherlands for the first time and was examined by the doctor Nicolaes Tulp , in 1699 the doctor Edward Tyson found a number of similarities between a chimpanzee he examined and humans. In the 18th century, Carl von Linné created the systematics of animals that is still fundamentally valid today, in which he classified humans in primates. In 1779 , Johann Friedrich Blumenbach divided this group into the "Bimana" (two-handed, that is, humans) and "Quadrumana" (four-handed, that is non-human primates).

In the 19th century, on the one hand, detailed knowledge of the various species of the great apes was obtained; on the other hand, the theory of evolution was developed, and Thomas Henry Huxley's work "Evidence as to Man's Place in Nature" (1863) consistently involved humans in the evolutionary processes , which should fuel discussions that have lasted for decades as to whether humans really "descend from apes". The last remnant of this systematic special position was only removed at the end of the 20th century, when humans and great apes were united in one family due to their common descent, see the section on systematics .

Animal behavior did not move into the focus of research until the 20th century. The best known are three women who were motivated by Louis Leakey to conduct extensive field studies: Jane Goodall in the chimpanzees, the later murdered Dian Fossey in the mountain gorillas and Birutė Galdikas in the Bornean orangutans. Through this and other work - for example Frans de Waal with the bonobos - a lot of knowledge about the way of life and behavior of great apes in the wild could be gained. Laboratory studies also attempt to research the animals' ability to communicate. Attempts have been made with all genres to teach them sign language or communication using symbol cards, for example by Roger Fouts and David Premack with chimpanzees. In addition, tool use , intelligence and learning ability are examined. Great apes manage to solve tricky problems, such as taking a fruit out of a sealed container. They pass the mirror test , which means they can see themselves in a mirror.

Conservation biology is one of the most recent areas of research - how can the survival of these animals be ensured in view of increasingly scarce habitats? Another focus is genetics , from which one hopes to draw conclusions about the treatment of various diseases and human development. For common chimpanzees, for example, genome sequencing projects are ongoing .

Keeping and use

Great apes are also used as an entertainment object, usually without proper keeping

The close relationship of the great apes to humans clearly determines the relationship to these animals. Expressive facial expressions and often amazingly human-like behavior are responsible for the fact that great apes can often be seen in zoos or circuses. Some species such as common chimpanzees and orangutans are also kept as pets , although species-appropriate keeping is hardly possible.

These animals play an important role in research and science. Because of their close relationship with humans, some diseases and their treatment methods can be researched using animal experiments in great apes. However, like all animal experiments, these methods are controversial and animal experiments on great apes are now banned in some countries, such as Austria, the Netherlands, New Zealand, Sweden, Great Britain and Japan.

The Great Ape Project tries, along with other animal rights activists, to transfer rights reserved for humans to great apes .


All non-human great apes are endangered. The reasons for this lie primarily in the destruction of their habitat by clearing the forests and converting savannahs into pasture or arable land. There is also hunting, which has several reasons. On the one hand, their meat ( bushmeat ) is eaten in some places and, on the other hand, because they sometimes invade plantations; Added to this is the search for domestic animals, which is still being carried out, in which young animals are captured, which is usually associated with the killing of the mother. Since all species are listed in the Washington Convention on Endangered Species (CITES), these practices and the trade in products from these animals are illegal. The IUCN lists the Sumatran orangutan and the western gorilla as " critically endangered " and the other four species as endangered .


The incorporation of humans into the great apes

Humans use more complex tools than any other representative of the great apes.

In the past, orangutans, gorillas and chimpanzees were grouped together in the family of the great apes (Pongidae), while humans and their extinct ancestors were grouped together in the family of the hominidae. This special position was justified with morphological differences and above all with cultural and intellectual peculiarities. With the development of the phylogenetic system in the second half of the 20th century, it was no longer just the anatomy, but rather the lines of development that became relevant for the systematic classification. By comparing the primate genomes it was found that the chimpanzees are the closest relatives of humans and that the gorillas are also more closely related to humans than to the orangutans. The great apes without humans were thus a paraphyletic taxon , i.e. a group that descends from a common ancestral form, but does not include all descendants of this ancestor. Since the phylogenetic system only recognizes monophyletic taxa if possible, that is, groups that descend from a common ancestral form and include all descendants of this ancestor, great apes and humans were combined to form a common taxon; nevertheless, humans and their immediate ancestors were assigned their own subgroup below this taxon ( hominini ).

External system

The closest relatives of the great apes are the gibbons (Hylobatidae), together with them they form the superfamily of the human species or great apes in the broader sense (hominoidea). Their position in the primate family tree is shown in the following diagram:


 Wet-nose primates (Strepsirrhini)

 nosed primates (Haplorrhini)  

 Koboldmakis (Tarsiiformes)


 New World or broad-nosed monkeys  

  Old world or narrow-nosed monkeys 
  Tailed Old World Monkey

  Vervet monkey relatives 

  Human   (Hominoidea)  

 Gibbons (Hylobatidae)


 Great apes (Hominidae)

Template: Klade / Maintenance / Style

Internal system

Cladogram of recent great apes:

  Great apes (Hominidae)  
  Subfamily Ponginae -  
 Orangutans  ( Pongo )  

 Sumatran orangutan  ( Pongo abelii )


 Tapanuli orangutan  ( Pongo tapanuliensis )


 Bornean orangutan ( Pongo pygmaeus ), two or three subspecies

  Subfamily  Homininae  
  Gorillas  ( gorilla )  
  Western gorilla 
( Gorilla gorilla )  

 Western lowland gorilla


 Cross River Gorilla

  Eastern gorilla    ( Gorilla beringei )  

 Eastern lowland gorilla


 Mountain gorilla

  Chimpanzee  ( Pan )  

 Common chimpanzee ( Pan troglodytes )


 Bonobo or dwarf chimpanzee ( Pan paniscus )

  People  ( homo )  

 Modern man  ( Homo sapiens )

Template: Klade / Maintenance / Style

The recent great apes divide into two subfamilies and further into four tribes , each with only one species. Of these, only the genus Homo is (today) monotypical :

The efforts of some researchers to place chimpanzees and sometimes gorillas in the genus Homo due to the slight genetic differences compared to humans have not been taken up in most systematic textbooks due to the historically arbitrary delimitation of genera.

Development history

Research into the development of the great apes was guided by the unanswerable question of where the line between “pre-humans” and “real” humans, the “ missing link ” of both, lies. Fossil can be proven that the humans experienced a heyday in the early Miocene ; Numerous genera developed, of which the gibbons and great apes still living today are only a small, specialized remnant. Since the separation of humans and great apes was once set much earlier than today's researchers do, some genera were prematurely ascribed to the ancestors of the great ape or great ape. Today, genera such as Dryopithecus , Oreopithecus and Proconsul are no longer assigned to the great apes in the narrower sense (Hominidae), but at best to the human species (Hominoidea). Often, however, the sparse finds make a clear assignment difficult even today. The emergence of the great apes as a taxon that can be anatomically differentiated from related groups is dated around 18 to 15 million years ago.

As can be seen above, the separation of the great apes into an Asian and an African line took place much earlier than the differentiation of the African great ape species that still exist today. The orangutans are the only survivors of this Asian line (Ponginae); but there are a number of fossil genera that are also incorporated into the Ponginae. These include, for example, Sivapithecus / Ankarapithecus , the gigantic Gigantopithecus as well as Lufengpithecus and Khoratpithecus .

In the African lineage (Homininae) gorillas, chimpanzees and humans emerged. The line to the gorillas was the first to branch off - the presumed gorilla ancestor Chororapithecus was dated to around 10 million years. The time when humans and chimpanzees separated is estimated to be around 6 million years old. Humans and their immediate ancestors are summarized in the group of hominini . The term "hominids" for this group comes from the time when humans and great apes were kept in two different families. Today this term is also used for the great apes in a general sense. The oldest possible representatives of the hominini include Sahelanthropus and Orrorin , who have been dated to an age of 7 to 6 million years. The oldest finds, interpreted as at least close relatives of the human ancestors, date from the early Pliocene (4.4 to 4 million years ago). These include in particular the species of the genus Australopithecus . The genus Homo finally developed around 2.5 to 2 million years ago , the only survivor of which is anatomically modern humans ( Homo sapiens ).

For more detailed information on the presumed reasons for the emergence of the anatomical peculiarities of humans, see the article Hominization and in human tribal history ; for an overview of important fossil finds see List of Hominine Fossils .


Web links

Commons : Great apes  - collection of pictures, videos and audio files
Wiktionary: Ape  - explanations of meanings, word origins, synonyms, translations

Individual evidence

  1. Geissmann (2003), p. 244 (Hominoidea), 288 ( Pongo ), 294 ( Gorilla ), 299 ( Pan ).
  2. a b Alexander Nater et al .: Morphometric, Behavioral, and Genomic Evidence for a New Orangutan Species. In: Current Biology. Volume 27, No. 22, P3487-3498.e10, doi: 10.1016 / j.cub.2017.09.047
  3. Geissmann (2003), p. 243. Hominoidea ( great apes and humans) .
  4. Figures from Geissmann (2003), p. 246.
  5. Figures from Nowak (1999), p. 613; Maier (2004), p. 573; J. Philippe Rushton: Race, genetics, and human reproductive strategies. Genetic, Social & General Psychology Monographs, Vol. 122 (1996); Alice Roberts: Evolution: The Human Story. Dorling Kindersley, London 2011, ISBN 978-1-4053-6165-1 , p. 153.
  6. Maier (2004), p. 561.
  7. ^ Nikolai Spassov et al .: A hominid tooth from Bulgaria: The last pre-human hominid of continental Europe. In: Journal of Human Evolution. Volume 62, No. 1, 2012, pp. 138-145, doi: 10.1016 / j.jhevol.2011.10.008
  8. of January 11, 2012: Europe's youngest ape discovered.
  9. WWF Magazin 3/2009, p. 9.
  10. Geissmann (2003), p. 310.
  11. Michael D. Sockol, David A. Raichlen, Herman Pontzer: Chimpanzee locomotor energetics and the origin of human bipedalism. In: PNAS . Volume 104, No. 30, 2007, pp. 12265-12269, doi: 10.1073 / pnas.0703267104
  12. Geissmann (2003), pp. 310-311.
  13. ^ Michael A. Huffman: Current evidence for self-medication in primates: A multidisciplinary perspective. In: American Journal of Physical Anthropology. Volume 104, No. 25, 1998, pp. 171-200, doi : 10.1002 / (SICI) 1096-8644 (1997) 25+ <171 :: AID-AJPA7> 3.0.CO; 2-7
  14. Explore the Pan troglodytes genome
  15. Jürgen Nakott: Researchers demand basic rights for great apes . Criticism of zoo keeping. In: Spiegel Online . Spiegel Online GmbH, June 25, 2012, accessed on June 26, 2012 .
  16. Figures according to the IUCN Red List , accessed on July 25, 2007.
  17. simplified from Geissmann (2003), p. 19.
  18. after Wilson & Reeder (2005).
  19. Ulrich Welsch : The fossil history of humans. Part 1: How the first primates became homo. In: Biology in Our Time . No. 1/2007, pp. 42-44
  20. Terry Harrison, Apes Among the Tangled Branches of Human Origins. In: Science . Volume 327, 2010, pp. 532–534, doi: 10.1126 / science.1184703 (alternative full text access: ResearchGate )
  21. ^ Gen Suwa et al.: A new species of great ape from the late Miocene epoch in Ethiopia. In: Nature. Volume 448, 2007, pp. 921-924; doi: 10.1038 / nature06113
  22. David R. Begun: The Age of the Great Apes . In: Spectrum of Science . Dossier 01/2004: Human evolution II. P. 8.
  23. Michel Brunet et al: A new hominid from the Upper Miocene of Chad, Central Africa. In: Nature . Volume 418, 2002, pp. 145-151, doi: 10.1038 / nature00879
  24. B. Senut et al: First hominid from the Miocene (Lukeino Formation, Kenya). In: Comptes Rendus de l'Académie de Sciences. Volume 332, 2001, pp. 137-144.
  25. Geissmann (2003), pp. 314-315.
  26. Maier (2004), p. 573.