Animal Diversity Web

Diversity

Papio can be divided into five species, as outlined by Groves (2001). Papio hamadryas (hamadryas baboons), P. anubis (anubis baboons), P. cynocephalus (yellow baboons), P. ursinus (chacma baboons), and P. papio (Guinea baboons). Some authorities continue to recognize only a single species, Papio hamadryas, which is composed of five subspecies corresponding to the species mentioned above. Species are parapatric, with hybridization often occurring in areas where populations abut. In overall physical appearance, all members of the genus are similar, with variation in coat color (olive, brown, black, yellow, red, gray), and hair length. A mane or ruff of fur may be prominent in males, and varies by species. Size varies by species and geographically, with males weighing from 20 to 31 kg, and females weighing from 10 to 15 kg. Baboons may live in large or small multi-male, multi-female troops, or single male harems. In all species, social behavior is complex and varied. Baboons can be found in a variety of habitat types, including grasslands, woodlands, semi-arid and arid savannas, steppes, alpine woodlands, sub-deserts, gallery forests, and rainforests. This genus is primarily frugivorous, although grasses, leaves, seeds and other plant material are consumed. Animal matter is eaten when available. (Groves, 2000; Groves, 2001; Kummer, 1968; Nowak, 1999; Oates, 1986; Primate Info Net, 2000a; Primate Info Net, 2000b; Primate Info Net, 2002a; Primate Info Net, 2002b; Primate Info Net, 2002c)

Geographic Range

Papio is found in the Ethiopian region, with a mostly continuous distribution in sub-saharan Africa. Isolated populations occur in the north within the Saharan region. P. hamadryas occurs both in the Ethiopian region and in the Palearctic, along the Red Sea coast of Yemen and Saudi Arabia. The Palearctic populations of P. hamadryas have been present for the length of recorded history in the region, but are thought to have been introduced by humans, possibly though a shipwreck, or through importation of these "sacred" baboons sometime during the past 4000 years. (Jolly, 1993; Nowak, 1999; Primate Info Net, 2000a; Primate Info Net, 2000b; Primate Info Net, 2002a; Primate Info Net, 2002b; Primate Info Net, 2002c)

• Biogeographic Regions
• palearctic
  • introduced
  • native
• ethiopian
  • native

Habitat

Baboons inhabit a variety of habitats, including savannas, grasslands, scrublands, steppes, semi-arid woodlands, and sub-deserts, as well as gallery and rain forest areas. Key features of all baboon habitats include stable sources of water, and some type of elevated sleeping site. These sleeping sites are usually large trees or cliffs, where the baboons can spend their nights with reduced threat of predation. Rarely, if ever, have baboons been known to willingly sleep on the ground. (Kummer, 1968; Napier and Napier, 1985; Nowak, 1999; Primate Info Net, 2000a; Primate Info Net, 2000b; Primate Info Net, 2002a; Primate Info Net, 2002b; Primate Info Net, 2002c)

• Habitat Regions
• temperate
• tropical
• terrestrial

• Terrestrial Biomes
• desert or dune
• savanna or grassland
• forest
• rainforest
• scrub forest
• mountains

• Other Habitat Features
• urban
• agricultural

Physical Description

Papio baboons are large members of the family Cercopithicidae, with weights ranging between 10 and 31 kg. Females of all species are about the same size (around 10 to 15 kg) but males are significantly larger. The greatest sexual dimorphism in size occurs within hamadryas and chacma baboon populatons. (Harvey, et al., 1986; Napier and Napier, 1985; Primate Info Net, 2000a; Primate Info Net, 2000b; Primate Info Net, 2002a; Primate Info Net, 2002b; Primate Info Net, 2002c)

The fur ranges in color from yellow to reddish, and from olive-gray to black. Young animals are always distinctly colored, usually having black fur, but in some species brown or brownish-red pelage characterizes young. Males may have a prominent mane. The face is nearly bare, and the palms and soles of the feet are completely so.

The long face has a conspicuous muzzle. The dental formula is (i 2/2, c 1/1, pm 2/2, m 3/3) x 2 = 32. The lower incisors tend to be oriented straight upward, and come into contact with the canines, whereas the upper incisors are packed tightly together, and separated from the canines by a large diastema. The upper canines are long, a feature which is extremely prominent in males. (Groves, 2001; Jolly, 1993; Napier and Napier, 1985; Nowak, 1999)

Baboons have large ischial callosities, which are fused along the midline in males, but separated by the genitals in females. The skin surrounding these callosities tends to be furless and is either red or black, depending upon species. During mid-cycle, the ano-genital skin of females is swollen, and during pregnancy it reddens, making the rump even more conspicuous. (Melnick and Pearl, 1986; Napier and Napier, 1985)

Locomotion is quadrupedal, and appears to be somewhat stiff-legged in most species. The weight is born on the front extremities by the fingers (digitigrade), but the weight is born by the hind feet across the entire sole of the foot (plantigrade). The thumb is relatively long, allowing precision grip and manipulation of objects. The tail is held in an arch, with the particular shape of the arch varying between species. (Napier and Napier, 1985)

• Other Physical Features
• endothermic
• homoiothermic
• bilateral symmetry

• Sexual Dimorphism
• male larger
• sexes colored or patterned differently
• male more colorful
• ornamentation

Reproduction

Reproduction and mating systems of the genus Papio fall into two primary types. The first is polygynadrous or promiscuous mating in multi-male, multi-female troops, found in all species except P. hamadryas. The second is mating within single male social units, typically found in P. hamadryas but occasionally reported for P. anubis, P. cynocephalus, and P. ursinus. (Hrdy and Whitten, 1986; Melnick and Pearl, 1986; Nowak, 1999; Smuts, 1986a; Stammbach, 1986; Walters, 1986)

Within multi-female, multi-male troops, females attract males during a prolonged estrus period through the swelling of their prominently colored ano-genital area. Estrus swellings typically last for many days, during which males may actively compete for access to the female. Papio anubis females are reported to have receptivity of 15 to 20 day during the middle portion of their estrous cycles. Papio ursinus females are receptive throughout their cycle, but copulations peak during the mid portion of the cycle. (Walters, 1986)

Olfactory cues may be present to signal female reproductive receptivity. Papio anubis females produce aliphatic acids, enhance their attractiveness to potential mates. (Walters, 1986)

Certain males, usually mid- to high-ranking older males, are capable of forming stable consortships with females through exclusion of competitors. Younger males often attempt to "steal" females away from older males, but such older males may form coalitions to prevent this. Regardless, the success of a male in copulating with a female is often related to his long-standing relationship with her. Females are more cooperative toward males with whom they frequently associate in a friendly manner during the times when they are not in estrus. Such males will often support a female in her conflicts with other females or males, and will support the female’s offspring in peer conflicts. These males are also more likely to share food with the offspring of their "close" female friends. (Smuts, 1986a; Stein, 1984)

The initiation of copulation follows a somewhat ritualized pattern in baboon species. A female typically presents her hindquarters to a male to signal that she is sexually receptive. Chacma baboon females also raise their eyebrows and flatten their ears while looking at males (Walters, 1987). Males may initiate a copulation by lip-smacking, making a friendly face, or gently shoving a female to entice her to stand. Copulation proceeds in either a single mount (e.g. P. anubis) or a series of mounts (e.g. P. ursinus, P. hamadryas). Information on mating frequencies is spotty, but is known to occur from 1 to 6 times per hour for cycling female yellow baboons, and from 7 to 14 times per hour for cycling female hamadryas baboons. Pregnant females, who generally exhibit a reddening of the perineal skin, do not copulate. (Hrdy and Whitten, 1986; Walters, 1986)

In contrast to the competition for access to females in other baboons, there is little overt competition of this nature in hamadryas baboons. A single male establishs a "harem" of females, which he guards from other males at all times, not just during their estrus periods. Males actively herd their females, keeping the social unit together during foraging. Males actively suppress aggression between females. Although sometimes these one-male units may have another male who acts as a "follower," rarely does the follower male interact with females. (Hamilton III and Bulger, 1992; Kummer, 1968)

In some cases, one-male units are found in other species of baboons, apparently usually a result of demographic stochasticity. When they occur, the male typically engages himself much more strongly in controlling the movements of group females, and intervenes more frequently and to greater effect in the conflicts which arise between females. (Hamilton III and Bulger, 1992)

There are two mechanisms by which hamadryas males typically attract mates. The first is by abducting a young female from her mother. The male cares for the female, grooms her, and carries her if need be, until she reaches maturity, at which time he will mate with her. Females, who typically transfer out of their natal group upon reaching maturity, are generally attracted to males who already have a female, so kidnapping is an effective strategy for males to begin their family unit. The second strategy males adopt is to take-over an existing harem through direct aggression with and displacement of the tenured male. This strategy is complicated by the complex social relationships between males, who may intervene to support brothers, cousins, uncles or fathers in such conflicts. (Smuts, 1986a; Stammbach, 1986)

An interesting correlate of these different mating systems is the schedule of testicular development in young males (Jolly and Phillips-Conroy, 2003). In P. anubis testes continue to grow through the adolescent period until full adult body size is attained, whereas in P. hamadryas testicular growth and development ends when the male is still a sub-adult. This results in distinctly smaller testes in hamadryas baboons than in anubis baboons, as would be predicted by models of sperm competition theory. (Jolly and Phillips-Conroy, 2003)

Another potential correlate of mating systems is the presence of series mounting during copulation, as opposed to single mounting. It is interesting to note that one-male units are most commonly reported for chacma baboons, and like hamadryas baboons, this species exhibits serial mounting during mating. Species where one-male units are less common are not reported to be serial mounters. (Hamilton III and Bulger, 1992; Walters, 1986)

• Mating System
• polygynous
• polygynandrous (promiscuous)

Most members of the genus Papio breed throughout the year, although some populations may breed seasonally. The female cycle length is from 30 to 40 days, and varies by species, age, reproductive history of the female, social situation, and ecological variables. Information on gestation length is spotty. Gestation lasts approximately 180 days in P. anubis, 161 to 175 days in P. cynocephalus, 172 days in P. hamadryas, 187 days in P. ursinus. (Bentley-Condit and Smith, 1997; Melnick and Pearl, 1986; Napier and Napier, 1985)

In most species and populations, there is a birth peak. The timing of this peak varies, but is usually the end of the dry season or beginning of the rainy season. Lactation occurs until 6 to 15 months of age, varying by species, timing of birth, availability of weaning foods, maternal rank, and other variables (Harvey et al., 1987; Bentley-Condit, 1997; Rhine et al, 1988). Young typically weigh approximately 600 to 900 g at birth for P. hamadryas, 1068 g for P. anubis, and 854 g for P. cynocephalus. Newborns have a distinctly colored coat (black, brown or reddish-brown), which they maintain until they are approximately weaning age, when they molt into a fur more typical of adults of the species. (Bentley-Condit and Smith, 1997; Harvey, et al., 1986; Jolly, 1993; Melnick and Pearl, 1986; Rhine, et al., 1988)

With the genus Papio, the interval between births ranges from 12 to 34 months. It is not known whether differences reported in interbirth intervals are due to genetic differences between populations as well as species, or ecological and social differences. (Melnick and Pearl, 1986)

Females may reach menarche between 3 and 6 years of age. This may occur before adult teeth have fully erupted, and before adult body size is attained. Males reach puberty at 4 to 6 years of age. Testicles may mature prior to attainment of adult body size full eruption of canines, as is the case for P. hamadryas, or they may continue to grow until the adult body size is attained, as in P. anubis. (Harvey, et al., 1986; Jolly and Phillips-Conroy, 2003)

• Key Reproductive Features
• iteroparous
• year-round breeding
• gonochoric/gonochoristic/dioecious (sexes separate)
• sexual
• fertilization
• viviparous

Parental care is provided primarily by mothers. Females nurse their young, carry them, groom them, and support them in agonistic encounters with their peers. Infants sleep in contact with their mothers until they are close to a year of age. (Altmann, 1980)

Females other than the mother may attempt to groom or hold newly born infants, and in some cases have been known to kidnap newborns from their mothers. If the infant is not returned promptly to nurse, it could die. This type of behavior therefore, has been interpreted as harassment, rather than as alloparenting. (Altmann, 1980; Bentley-Condit, et al., 2001)

There are interesting patterns of interaction between males and infants, which are sometimes interpreted as parental care. Males will typically use an infant as a buffer against aggression from other males, clinging to an infant if an attack by another male appears imminent. This appears to work because the mother, and her female kin, will become involved in the conflict if the male holding the infant is actually attacked. A potentially attacking male apparently thinks twice about instigating aggression when it might stir up resentment among the females. (Stein, 1984)

Males often have a special relationship with the infants they use in such a fashion. Males groom, carry, and share meat with these infants. They also sometimes intervene in agonistic encounters between the infant and its peers. If a mother happens to die, males have been known to care for orphans whom they have used as agonistic buffers, providing some of the essential functions that the mother normally would. (Stein, 1984)

This behavior may indeed be paternal, since infants typically allow themselves to be used as buffers only by those males who associate closely with their mothers. Since close male associates of a female have greater chances of fathering her offspring, the additional care that the male gives to his "buffer" infants may be going to his likely offspring. (Smuts, 1986a; Stein, 1984; Whitten, 1986)

• Parental Investment
• altricial
• pre-fertilization
  • provisioning
  • protecting
    • female
• pre-hatching/birth
  • provisioning
    • female
  • protecting
    • female
• pre-weaning/fledging
  • provisioning
    • female
  • protecting
    • male
    • female
• pre-independence
  • protecting
    • male
    • female
• post-independence association with parents
• extended period of juvenile learning
• inherits maternal/paternal territory
• maternal position in the dominance hierarchy affects status of young

Lifespan/Longevity

Members of the genus Papio have been reported to live for up to 45 years in captivity. Lifespans of wild animals are more difficult to assess, since even long-term studies of these animals in the wild cannot provide accurate information on the age of animals who immigrate into a community, nor can they track the eventual fate of those animals who emigrate from a community. However, the maximum lifespan in wild populations is probably 30 to 40 years. (Harvey, et al., 1986; Napier and Napier, 1985)

Behavior

Members of the genus Papio all share certain general patterns of behavior which are recounted here. These animals are motile, ranging several kilometers in any one day to find food (Melnick and Pearle, 1987). Social groups always return to one of a limited set of sleeping sites (cliffs or trees) at night to bed down. Patterns of interaction at sleeping sites reflect general patterns of affiliation, and tend to be stable through time. (Bentley-Condit and Smith, 1999; Melnick and Pearl, 1986; Smuts, 1986a; Smuts, 1986b)

In all species except P. hamadryas, the most common social organization is multi-male, multi-female troops. Females are philopatric. There is a stable dominance hierarchy of different matrilines, and in general, a female will have a place in the dominance hierarchy just below her mother. For sisters, dominance is inversely related to birth order. Females can sometimes rise in rank above their mothers where geneologies are small. The acquisition of dominance rank in baboons is due partly to the activities of the mother, who forces subordinates to accept and respect her daughter as dominant to them. (Bentley-Condit and Smith, 1999; Walters and Seyfarth, 1986)

Female relationships within P. hamadryas are less well studied. There does not appear to be a clear-cut pecking order among females in hamadryas baboons, partly because females transfer out of their natal social group. However, females apparently continue to have affiliative relationships with other females, possibly kin, despite their migration into different social groups. (Swedell, 2002)

Within the non-hamadryas baboons, males compete actively for access to females, and have a strong dominance hierarchy themselves. Male dominance is correlated with factors such as age, size and ability to fight, rather than maternal dominance rank. Because males leave their natal troops, they are "free" of inherited dominance relationships. Although any individual adult male is dominant to an individual adult female, interactions between males and females are heavily influenced by coalitions of female kin. Males immigrate into new social groups when they reach adulthood. Their success in these groups can be related to how the females within the group respond to them. (Melnick and Pearl, 1986; Smuts, 1986a)

In hamadryas baboons, there is a complex, four-tiered social system in which males affiliate with their male kin. The basic social unit is comprised of an adult male and his females. Within this group, the strongest social bonds are those between the adult male and any adult female. The male actively suppresses aggression between females, and forces them to maintain proximity to him during daily travel. The animals in these one male units sleep together at night. (Kummer, 1968; Stammbach, 1986; Zinner, et al., 2001)

Each hamadryas one male unit is closely affiliated with a clan, band, and troop. Clans and bands are comprised of male kin, and males within them appear to cooperate socially. Troops, on the other hand, appear mainly to share sleeping sites, and only sleeping sites. (Kummer, 1968)

• Key Behaviors
• terricolous
• diurnal
• motile
• sedentary
• social
• dominance hierarchies

Communication and Perception

Communication between baboons is complex, as would be expected for highly social animals. Baboons are very vocal, and although calls of all species are similar, they may be used in slightly different contexts in each species. Also, different species may produce the same basic vocalizations, yet with slightly different acoustic qualities. Vocalizations reported for Papio include barks, grunts, roars, screeches, yakking, clicking, and ick-ooers. Tactile communication includes a great deal of grooming, as well as social mounting (a form of reassurance), and nose-to-nose contact. Gestures and facial expressions, such as friendly faces and lip-smacking, also play a large role in communication. Some threats are communicated via facial expression or gestures. Olfactory communication may be present, as females are reported to have enhanced attractiveness to males when they are producing aliphatic acids. (Hrdy and Whitten, 1986; Primate Info Net, 2000a; Primate Info Net, 2000b; Primate Info Net, 2002a; Primate Info Net, 2002b; Primate Info Net, 2002c; Walters, 1986)

Social dominance is very important in all baboon species. Human observers calculate the dominance rank of individuals by monitoring the outcome of one-on-one aggressive interactions, and looking at the tendency of one animal to supplant, or displace, another animal. It is likely that there are other cues which communicate dominance between the animals themselves. (Rhine, et al., 1992; Sapolsky and Ray, 1989)

• Communication Channels
• visual
• tactile
• acoustic
• chemical

• Perception Channels
• visual
• tactile
• acoustic
• chemical

Food Habits

Although generally described as frugivorous, baboons will eat just about anything edible, including grasses, forbes, leaves, buds, flowers, seeds, eggs, insects, and meat. All baboons share the unique ability to subsist solely on grasses and forbes, which allows them to exploit savanna habitats not frequented by other monkeys. (Kummer, 1968; Napier and Napier, 1985; Oates, 1986; Primate Info Net, 2000a; Primate Info Net, 2000b; Primate Info Net, 2002a; Primate Info Net, 2002b; Primate Info Net, 2002c)

• Primary Diet
• omnivore

Predation

Baboons are thought to fall prey to several large African predators. Annual rates of predation have been estimated at 1 to 9% of the population for various species and populations.

Some of the predators reported attempting to kill and eat baboons include lions, leopards, and Verreaux’s eagles. Chimpanzees also occasionally hunt baboons. (Cheyney and Wrangham, 1986; Zinner and Pelaez, 1999)

As in many animals, it is often the young who are the most threatened by predators. General patterns of survivorship in baboon infants are correlated indirectly with predation. Certain weather patterns may allow grasses to grow too tall or thick, allowing predators to surprise unwary young. (Cheyney and Wrangham, 1986; Kummer, 1968; Rhine, et al., 1988; Cheyney and Wrangham, 1986; Kummer, 1968; Rhine, et al., 1988)

The genus Papio is known to exhibit several antipredator behaviors. In all species, males may chase members of their social group who have straggled away, bringing them back into the fold, so to speak. Baboons will mob leopards, and have been known to use their tremendous canine teeth to inflict severe damage upon these would-be assailants. (Cheyney and Wrangham, 1986; Melnick and Pearl, 1986; Primate Info Net, 2000a; Primate Info Net, 2000b; Primate Info Net, 2002a; Primate Info Net, 2002b; Primate Info Net, 2002c)

Reports regarding the spatial patterning of animals during troop movements vary. Some authors indicate that males tend to take the lead to protect the rest of the group for potential predators, but other authors assert that there is no consistent organization of individuals during movement. (Cheyney and Wrangham, 1986; Rhine and Tilson, 1987)

• Known Predators

  • lions (Panthera leo)
  • chimpanzees (Pan troglodytes)
  • Verreaux's eagles (Aquila verreauxi)
  • leopards (Panthera pardus)

Ecosystem Roles

Baboons play several important roles in their ecosystems. Because of their frugivorous tendencies, they disperse seeds. They pull forbs to eat their bulbs and eat tubers, contributing to soil aeration. As prey items, they are likely important to several predator species, depending upon the importance of these primates in the diets of the predators. (Cheyney and Wrangham, 1986; Nowak, 1999; Primate Info Net, 2000a; Primate Info Net, 2000b; Primate Info Net, 2002a; Primate Info Net, 2002b; Primate Info Net, 2002c)

• Ecosystem Impact
• disperses seeds
• soil aeration

Economic Importance for Humans: Positive

Baboons are large, active animals. They are therefore of interest to ecotourists. In Saudi Arabia, some local people feed hamadryas baboons, and some populations are reported to feed off garbage found in dumps. Baboons are heavily used in biomedical research. IUCN reports that some baboons are harvested as food by native populations. (Nowak, 1999; Williams-Blangero, et al., 1990)

• Positive Impacts
• food
• ecotourism
• research and education

Economic Importance for Humans: Negative

Baboons are often considered pests. They are known to raid crops in Africa (Strum, 1991)

• Negative Impacts
• crop pest

Conservation Status

CITES lists all baboon species in Appendix II, so international trade in the animals or their parts is in theory regulated by governments.

The IUCN Redlist lists P. hamadryas and P. papio as "Lower Risk/near threatened," with major threats to baboons being habitat loss and degradation due to agriculture, havesting for food and for scientific purposes, as well as continued persecution by indigenous people. Other Papio species are listed as "Lower Risk/least concern," indicating the species are not considered at risk at this time.

• IUCN Red List

  Least Concern
  More information

Other Comments

Among the arguments often presented for considering members of the genus Papio as a single species is the rampant hybridization seen between various forms of baboons. In captivity, hybrids between the following species pairs: P. anubis and P. cynocephalus; P. anubis and P. papio; P. anubis and P. hamadryas; P. anubis and P. ursinus; P. cynocephalus and P. hamadryas; P. papio and P. hamadryas; and P. hamadryas and P. ursinus. (Jolly, 1993; Williams-Blangero, et al., 1990)

In the wild, hybridization has been reported between anubis and yellow baboons, as well as between anubis and hamadryas baboons. However, based upon geographic variation in pelage characteristics, it is likely that hybridization between other forms of baboons also occurs. For example, within P. papio, there is clinal variation in coat color, with eastern populations showing browner pelage, and western populations redder pelage. The brown pelage in the west may be due to introgression of P. anubis genes. Similarly, Jolly (1993) speculates that the typical P. cynocephalus may have arisen through hybridization between Kinda type baboons and gray-footed baboons, with expansion and stabilization of the hybrid population. (Alberts and Altmann, 2001; Jolly and Phillips-Conroy, 2003; Jolly, 1993; Nowak, 1999; Phillips-Conroy, et al., 1992; Williams-Blangero, et al., 1990)

Without detailed information on the flow of genes between populations, it is difficult to speculate on how stable hybrid zones are. Although hybrid animals in wild populations are known to breed, and there does not appear to be any assortative mating by species phenotype within hybrid populations, data on the relative reproductive success of hybrids are lacking. Similarly, data on the reproductive success among the various types of baboons within particular populations are not available. (Jolly, 1993)

In spite of the paucity of evidence, it is relatively easy to speculate on potential barriers to gene flow between hamadryas and anubis baboons. There is some evidence that indicates that male hamadryas baboons and possibly hamadryas-like hybrids, are at a reproductive disadvantage in wild anubis baboon populations. First, differences in absolute testicular size between the two species probably result in lower sperm production in hamadryas males than in anubis males. Given a social setting in which a female mates with multiple males, generating sperm competition, such reduced sperm production would impair a hamadryas males’ chances of fathering offspring. This would be expected even if mating success were equal for the two types of males. However, because of the differences in reproductive strategies between the species, it is also likely that hamadryas males, in their attempts to herd females, expend reproductive effort in a way that does not increase their mating success relative to anubis males. (Jolly and Phillips-Conroy, 2003; Phillips-Conroy, et al., 1992)

Similar difficulties would be predicted for male anubis baboons immigrating into hamadryas territory. Because male hamadryas associate largely with male kin, one might predict that it would be difficult for an anubis male to become associated with a band of hamadryas baboons. Should the anubis male succeed in associating with a hamadryas band, it is unclear how he would fare in establishing a one male unit, or harem, of females given the differences in herding tendency, and the greater tolerance of matings by other males typical of males in multi-male anubis troops. Although males seem able to adjust their behavior facultatively, at least in chacma baboons, it is unclear how these minor changes would translate within the nested social structure of hamadryas baboons. (Hamilton III and Bulger, 1992)

Further investigation of hybridization patterns, behaviors associated with mating, and reproductive success of hybrids are clearly needed in order to make accurate predictions about gene flow between hamadryas baboons and anubis baboons. (Jolly, 1993)

It should also be noted that in itself, the ability to hybridize and produce fertile offspring, although necessary for populations to be considered members of the same species, does not necessarily make two populations members of the same biological species. Marginal hybridization is often seen due to retention of a pleisiomorphic zygostructure. Many cercopithecines are apparently interfertile, although there is little debate that they belong to distinct species. Even anubis baboons are known to occasionally hybridize with geladas, which most primate paleontologists estimate have been separated from the baboon lineage for about 4 million years. (Jolly, 1993)

Contributors

Nancy Shefferly (author), Animal Diversity Web, George Hammond (editor), Animal Diversity Web.

References

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