The Web of Life – Monkeys


The term monkey may have originated from a character named Moneke in the 16th century German fable Reynard the Fox. Moneke was the son of Martin the Ape.

There has been long-standing confusion between monkeys and apes, thanks to simple-minded scientists. Into the 1950s, primate evolution was considered a Darwinian progression leading through monkeys to apes to humans. Though all primates evolved from a common ancestor 85 MYA, the evolution of humans has since been found to be considerably more complex than the straight-line descent once imagined.


Monkeys are the most colorful mammals. Their flamboyance accents their social standing. In some monkeys, such as the polygamous mandrill, the dominant male has brilliant colors, while subordinates are somewhat duller.

Monkey color vision acuity evolved to aid foraging, including the ability to discern fruit ripeness and the freshness of shoots. Once evolved, the ability to see red led to incorporating reddish hues into monkey looks, by virtue of female preference.

Sexual dimorphism is somewhat common among monkeys, especially the larger species. Male baboons are typically twice the size and weight of females. In contrast, in the smallest New World monkeys – tamarins and marmosets – the sexes are similarly sized.

Monkeys in the wild have a life span of 18–50 years, depending upon species. Larger monkeys are typically longer lived. Life in captivity shortens life expectancy considerably.

Monkeys have long been a popular meat. Human hunters now kill millions each year, pushing many monkeys toward extinction. Relentless deforestation more slowly kills those that are not hunted, by robbing monkeys of their food supplies as well as a decent place to live. Like many other forest creatures, monkeys will be extinct within a few decades.


Many monkeys are arboreal, though some are ground-dwellers, such as patas monkeys and baboons.

Most monkeys are diurnal. The night monkey is a notable exception. It avoids foraging competition by working the night shift.

The length of monkey limbs varies by lifestyle. Monkeys that scramble nimbly amid branches have relatively short arms and legs, aided by prehensile tails. Monkeys that walk and run have longer limbs. Exceptional jumpers, such as the pygmy marmoset, have longer legs, while tree swingers, such as spider monkeys, have longer arms than their legs.

Monkeys range from the tiny New World pygmy marmoset (13–16 cm, 0.12–0.14 kg) to the colorful and highly sexually dimorphic Old World mandrill (male: 75–95 cm, 19–37 kg (though some grow to 54 kg); female: 55–66 cm, 10–15 kg).


Monkeys are categorized by continent: either Old World (Africa, Asia) or New World (South and Central America). Old World monkeys (Cercopithecids) are more closely related to hominids than New World monkeys (Platyrrhines).

In geological time, the Atlantic Ocean has been a widening gap between Africa and South America, which separated over 65 MYA. Perhaps as late as 40 MYA, simian conquistadors came from the dark continent to the New World.

Old World monkeys spread from Africa into Asia and Europe during the Miocene epoch (23–5.3 MYA).

Old World monkeys differ from New World in several ways. On average, New World monkeys tend to be smaller than Old World. Almost all New World monkeys are arboreal. Old World monkeys have a wider range of habitat and are more terrestrial.

Taxonomy of monkeys has been an ongoing dispute. This is incidental to appreciating the diversity of lifestyles that these intelligent creatures have.


New World monkeys have a different dentition than Old World: an evolutionary matter of diet. Whereas Old World monkeys have 32 teeth, New World monkeys have 36.

New World monkeys are generally frugivores, supplemented by small insects and other invertebrates, though some also eat leaves. Old World monkeys are primarily folivores (leaf eaters), though Old World monkey diet varies; most are nominally omnivores.

Generally, most monkeys are opportunists that will eat anything that is digestible. African mangabeys rely heavily upon fruit and flowers, but they are not above ripping the bark off trees to snatch anything edible that crawls beneath. Mangabeys also hunt for birds’ nests, devouring both eggs and nestlings when found.

Monkeys love fruit, though they can quite wasteful: taking a bite or two before chucking it, as it is often not ripe enough to suit their taste. There is some socially inspired conflict in this.

Monkeys are actually quite adept at discerning just how ripe a fruit is. They prefer to wait for the sweetness that comes with ripening.

But if they wait too long, they may lose the fruit to another. So, they often compromise by picking early and eating only the best part rather than risk losing the whole thing.


Most monkeys live in tropical rainforests. The farther one travels from the equator, the fewer monkeys. This makes sense in light of their diet, which is heavily dependent upon fruit and leaves.

There are exceptions. Baboons are successful savanna residents, as is the ground-dwelling patas monkey, which feeds on insects, gum, seeds, and tubers. The hamadryas baboon lives in the dry, rocky regions of southern Arabia.

Most monkeys live warm climates, though there are exceptions. A few tropical monkeys live well about the snow line of mountains, including the African vervet, the Asian snub-nosed langur, and several species of macaques. The Japanese macaque survives the cold winters of northern Honshū; the only nonhuman primate to live so far north.


With a few exceptions, New World monkey vision is dichromatic (2-color), whereas Old World monkeys are trichromatic (3-color), as are humans.

New World monkey noses are flat, with nostrils to the side. Old World monkeys have human-like down-facing noses.

Unlike Old World monkeys and humans, New World monkeys don’t have opposable thumbs, with one exception. The capuchin, a New World monkey, does have an opposable thumb.

Polygyny (males mating multiple females) predominates with Old World monkeys. In contrast, several New World monkeys are monogamous, with extensive parental care.

Unlike apes, almost all monkeys have tails, as do prosimians. Some tails are quite short, such as the mandrill.

Only the Barbary macaque entirely lacks a tail. This macaque is endemic to the Atlas Mountains of Algeria and Morocco, with a small population on Gibraltar.

New World monkeys have relatively longer tails than Old World monkeys.

The atelid family of New World monkeys are the only primates with a prehensile tail, which is useful as a 5th limb for foraging or climbing. Howler, spider, and woolly monkeys are atelids.

Prehensile tails are not a common animal trait. New World mammals with prehensile tails include the opossum, kinkajou (honey bear), and porcupine. The harvest mouse, tree pangolin (scaly anteater), and bearcat (binturong) are the few Old World mammals with prehensile tails.


Monkeys are typically noisy, with a rich repertoire of communications, including combinations and expressions of considerable nuance. Monkeys are quite sensitive to changes of expression on each other’s faces.

New World monkeys are especially exuberant. It helps keep the group together. Tiny marmosets constantly call to each other, twittering like birds as they scamper through the branches.

Female squirrel monkeys are the top talkers: ceaselessly communicating as they move through the forest. Losing sight of one another results in a call-and-response series of high-pitched peeps. Other squirrel monkey sounds have their own syntax. Females that direct a troop twitter to get others moving. A “chuck” sound is a call reserved for close friends.


Monkeys have an innate sense of fairness and are naturally empathic. Rhesus macaques will not perform an action if they think it will harm a conspecific.

Whatever social finery humans possess they inherited from monkeys. The difference in human social proclivities is some liberation from biologically-bound mores to allow selfishness fuller flower.

Monkeys are gregarious. Groupings vary by species, but all monkeys have social organizations.

All societies are rule-based to some degree, though monkey mores tend to be relatively relaxed in those that live in the trees. For example, African mangabey groups are nominally led by a male who does not exercise much control over group activities. Members come and go frequently.

Ground-dwellers tend to live in controlled societies. Baboons have a patriarchal social system that is tightly managed: members seldom leave their group, and newcomers are not normally welcome.

Security is one evolutionary impetus for social organization. The trees are nominally safer than the ground; hence the difference in liberality between species with different lifestyles.

Baboon and patas monkeys stay safe via discipline among male members who have assigned roles for security detail and other duties. Every member knows its station and its duty to the group.

Such social organization has enveloping effects. Competition for food is frequent. Rules determine who gets the best food. Breeding is controlled in stricter societies.

Monkeys simultaneously compete and depend upon each other. They remember kindnesses and conflicts. A monkey knows who it can depend on and who will stand in its way.

Might makes right in monkey society. Dominant members dole out discipline as deemed necessary: whether physical punishment or reduction in food rations for some duration.

Subordinates are careful to stay on the good side of those above them. A monkey seeks to groom another that it is afraid it would lose a fight with.

Spectators gather round when 2 monkeys fight. Immediately afterwards, a bystander approaches the loser, seemingly to console. Mutual grooming often ensues between the two. More often than not, the loser grooms the bystander for longer than the bystander grooms the loser. The bystander takes advantage of the loser’s diminished sense of self.


Grooming as placation is a mainstay in maintaining close relations. Monkey grooming is analogous to human manners, often with similar social considerations.

Grooming is extensively practiced by females that stay in the same troop their whole lives. They know one another well. Each female is aware of hers and others ranks. Grooming cements bonds.

Males need allies too. A dominant male baboon is less vulnerable to attack by an ambitious upstart with another large male by his side. Learning whom to groom is a necessary skill.

The need for close bonds depends on many factors but food looms large. When there is enough food for all, competition is low. Bonding is less critical in times of plenty. Grooming is occasional.

Scarcity brings struggle. Grooming increases during tense times, to keep friends close, and to curry favor.


Monkeys have a fascinating mix of mental acumen. Monkeys remember where different fruit trees are and when they ripen. This requires spatial mental maps correlated to calendars.

Monkeys manage math, especially quantities. Rhesus monkeys understand the relations of numbers and can perform mental addition.

Sociality is paramount to leading a successful monkey life. A monkey needs to know who belongs and who does not, who is related to whom, the relative ranks of every monkey in the group, and the special grooming relationships group members have with each other. Monkeys have distinct personalities which must be accounted for. A monkey must keep in mind which relationships are valuable to cultivate, and how, and who should be assiduously avoided.

A male bonnet macaque, when challenged by another troop member, will often seek out another male for assistance. The beset macaque will seek an ally that he knows outranks the monkey challenging him. The presence of a higher-ranking male renders the challenger much less eager for a confrontation.

Monkey pettiness has a distinctly human edge. They squabble among themselves. To answer an attack, a monkey may not directly confront the attacker, but instead take revenge on a relative or friend of the other monkey, even though the victim played no part.


Deliberate deception is a monkey trait; something which requires thoughtful anticipation of another’s expectations (theory of mind). Baboons are especially adept at deception.

A juvenile baboon watched an adult female dig a plant bulb from the ground. The youngling scanned the scene; no one else nearby. So, it screamed its lungs out for help. Mom came running. Spotting the other female, she instantly assumed that her precious child had been attacked. The outraged mother went after the puzzled innocent female, who dropped the bulb and ran. The now calm and contented youngster casually picked up the tasty bulb. This was not the only incident observed of this child pulling this trick.

New World Monkeys

There are 5 families of New World monkeys: Callitrichidae, Cebidae, Aotidae, Pitheciidae, Atelidae. Only night monkeys (aotids) are nocturnal; all others are diurnal.


The smallest monkeys are squirrel-sized marmosets and tamarins, with 26 species in 5 genera. Once wrongly thought primitive, they are instead dwarfs, having adaptively shrank.

Pygmy Marmoset

Marmosets and tamarins differ mainly by where they reside. Tamarins live on the northwest side of the Amazon River, marmosets on the southeast side.

Callitrichids are all arboreal; eating insects, fruit, and the exudate (gum or sap) of trees. Marmosets rely heavily on exudates. Some marmosets are obligate exudativores.

Callitrichids live in small territorial groups of 5–6 members. They have a unique social organization among primates: cooperative polyandry. Females mate with more than 1 male, but only 1 female is contemporaneously reproductive. Callitrichids are the only primate group that regularly produces twins: over 80% of the time.

Everyone shares the responsibility of carrying the offspring (alloparenting). Older adolescents help with infant care. Males provide as much parental care as females; sometimes more. From an evolutionary perspective, the uncertainty of fatherhood engenders cooperative parenting.


Capuchin and squirrel monkeys are cebids. They are opportunistic omnivores but confirmed arboreals, rarely traveling on the ground. These small monkeys are gregarious, living in groups of varying sizes, with the smaller species preferring larger groups.


Capuchins are the size of a house cat. They live in a troop of 10 to 40 members: related females and their offspring, along with several males.

Capuchins have a social hierarchy with a dominant male. Some tribes have a dominant female too. Mutual grooming and gossip maintain social order.

Capuchins are opportunistic omnivores, with a diet of fruit, nuts, seeds, buds, insects, spiders, bird eggs, and small vertebrates. Capuchins living near water also enjoy crabs and shellfish which they crack open with stones. On shore, capuchins dig up tubers, roots, and insects using sticks or rocks.

A capuchin prefers an impressively heavy rock for cracking hard-shelled palm nuts. They carry the nut and stone to a suitable flat rocky surface. Stone anvil sites are repeatedly employed, so much so that shallow bowls are worn into the anvil spot from use. Preferred anvil stones are river rocks, carted to the site where the anvils are used, sometimes by several capuchins at a time. 1 of 2 techniques are preferred: repeated pounding, or picking up the stone to chest level, and dropping it on the nut.

Capuchins throw objects, sticks or otherwise, either agonistically or in play.

Capuchins master tool use and construction through trial and error. They use wooden limbs to pound on rotten logs, thumping out grubs. Sticks and twigs are crafted to make a pointed prod for accessing larvae and insects from tree crevices. Capuchins also use stones as cutting tools.

Young capuchins apprentice. It can take years to master advanced tool techniques.

To ward off mosquito bites when the pests are in season, capuchins crush millipedes and rub the residue on their backs as an insect repellent.

As gregarious creatures, capuchins have mastered the social contract of empathy and reciprocity, with a demonstrated sense of fairness in transactions.

Capuchins posses a strong sense of equality. ~ American psychologist Sally Boysen

Capuchins maintain long-term social bonds, especially with relatives. Females form coalitions and have dominance hierarchies.

A male needs male allies to become the dominant male of a group with mature females. The alpha male sires virtually all offspring in a group that are not his direct descendants.

The males who assist the alpha male in gaining and preserving sexual dominion must typically delay breeding until the alpha male’s daughters have matured.

Infanticide by alpha males is the primary cause of infant death. Females socially support the current alpha male, thereby preventing disruptive takeovers that could lead to infanticide. Male offspring of the alpha male enjoy a social advantage as juveniles.

The same selective forces that shaped humans also shaped capuchins, causing both species to share features such as complex political behavior and culturally transmitted social rituals. ~ American primatologist Susan Perry

Capuchins can be trained and are fine actors. Capuchins are best known as the dancing monkey belonging to the organ grinder, though, as that venue has been abandoned, show-biz capuchins have been cast in numerous movies, though always typecast as being up to some monkey business.

When presented with the mirror test, capuchin females pose and make friendly gestures at themselves; their social graces come to the fore. Males look at themselves, then freak: showing confusion or distress. It is bizarre to suddenly see a twin you didn’t know existed, and one who looks like a potential rival.

 Squirrel Monkeys

Squirrel monkeys are considerably smaller and slenderer than their relatively chunky cousins, the capuchin. A squirrel monkey weighs but 1.2 kg versus 4 kg for a capuchin, and the average squirrel monkey is 35 cm, versus 56 cm for a capuchin. But the two often have an ongoing relationship.

Capuchins are messy eaters. They rip the forest apart as they move through the trees foraging. They’ll even grab a small squirrel monkey for a meal upon occasion.

Despite that infrequent danger, capuchins and squirrel monkeys often feed in proximity. Their diet is similar, though squirrel monkeys must content themselves with insect grubs found on branches, as they cannot rip the bark off trees looking for insects like capuchins can.

The big benefit of the capuchin association comes in hanging out on the tree branches below, catching the numerous bits of food that their larger cousins carelessly drop.

Squirrel monkeys, small as they are, band together, often traveling in troops of 40 or more, though sometimes congregating in a herd of 400 to 500 individuals. There is safety in numbers; not only from predators, but also from bullying by larger monkeys that might otherwise try to shove them aside for the finer foraging.

Squirrel monkeys are complex communicators: incorporating 25 to 30 distinct calls (to human ears), with various meanings by context. Some calls are further elaborated or nuanced by postural displays.

Squirrel monkeys also communicate chemically, with scents from different sources: urine, scent glands on their chest, or from their nasal passage. A squirrel monkey may rub its nose on something, or sneeze into its hand to physically transfer that scent. A male can tell whether a female is sexually receptive by restraining her and sniffing her genitals.

 Night Monkeys

Night monkeys are the only truly nocturnal monkey. Their vision has adapted to this lifestyle: monochromatic (no color vision), and better spatial resolution in low light. Night monkeys re-evolved nocturnality from diurnal ancestors.

Night monkeys live near the forest canopy, walking branches on all fours, though they are skilled leapers: capable of crossing canopy gaps as large as 4 meters. Territories are defended by scent marking and vocalizations.

Male and female night monkeys are similarly sized, averaging 34 cm and 1.2 kg, with males slightly taller.

Night monkeys are monogamous, with only 1 infant born each year. A mother carries her infant for only its 1st week. Afterwards, the father is the primary caretaker. If dissatisfied in her marriage, a female divorces her husband and finds another mate.


The 40 species of pithecids include titis, sakis, and uakari monkeys. Pithecids have medium to long fur in a wide range of colors. Many have contrasting color patches, particularly on the face. This helps accentuate facial expressions.

Most pithecids live in the trees of the Amazon forest, from low-lying swamps to mountain slopes. They are generally herbivores: mostly fruit and seeds, though some species sample small insects.

Sakis and titis are monogamous. They live in small family groups.

Uakaris and bearded sakis are polygamous. They live in larger groups, with 8–30 members. Each group has multiple males which establish their own social hierarchy.


Atelids are typically the largest New World monkeys. The atlid family includes the howler, spider, woolly, and the woolly spider monkey, which is the largest New World monkey. Most atlids are arboreal residents in dense rain forests, though some howler monkeys live in drier forests, or in wooded savanna.

 Howler Monkeys

Howler monkeys are large tree dwellers; slow, deliberate leaf eaters. They almost never leap from branch to branch. When they move, they leisurely walk on all fours, or swing slowly, arm over arm, though tree branches. At rest, they hold themselves onto a branch using their strong prehensile tail.

Most howler monkeys live in groups of 6 to 15, though mantled howler monkeys live in larger groups of 15–20. They are territorial.

Howlers live up to their name by the loud calls, which can be heard for kilometers. The point is maintaining territory. Howler groups contend over a new territory via vocal battle. The louder, more persistent group wins. Physical fighting is rare.

 Spider Monkeys

Spider monkeys are about the same size and weight as howler monkeys but are more active and acrobatic. They make spectacular leaps between trees.

Spider monkeys have strong prehensile tales, along with exceedingly long limbs. A spider monkey can hang from a branch by its tail and pick an otherwise unreachable fruit or take a drink from a pond below.

Spider monkeys are largely frugivores, though leaves, flowers, and insects make up part of their diet.

Spider monkeys live in the rainforest canopy, in groups of up to 35 members, though they split up during the day to forage.

Spider monkey society is sexually segregated. Males and females live separately for much of the year.

Males are friendly to each other. They spend hours in mutually grooming and fall asleep hugging. Contrastingly, males are aggressive toward females, attempting to dominate them.

Males typically forage in groups, while females often forage with just their infants. Males may chase females away from fruiting trees, relegating them to less nutritious leaves. Only when food is scarce do males and females forage together.

Spider monkey communications are quite complex. They produce a wide variety of sounds: from a horse-like whinny to barks to prolonged screams. Spider monkeys are one of the most intelligent New World monkeys.

Humans have long hunted spider monkeys as a food source. More recently, logging and land clearing have drastically reduced their forests. Spider monkeys will soon be wiped out.

 Woolly Monkeys

Like spider monkeys, woolly monkeys prefer high elevations, living in cloud forests and mature tropical rainforests. Woolly monkeys are among the largest New World monkeys, with a thick prehensile tail and arms about as long as their legs. As their name implies, woolly monkeys have a thick and woolly fur.

Woolly monkeys live in a troop of 10 to 45 members, though they forage in small groups of 2 to 6, thus reducing food competition among individuals. Woolly monkeys are largely fruit eaters, supplemented by leaves, seeds, flowers and invertebrates.

Each troop is governed by an alpha male. Social hierarchy is by age, sex, and, for a female, her reproductive status. Play establishes bonds and maintains relationships, as well as reinforcing the social hierarchy.

Woolly monkeys are promiscuous. Dominant males get the most mating in, with multiple females. Likewise, females will mate with more than 1 male.

Females leave their natal group upon reaching maturity. With such a promiscuous lifestyle, this is the only way to prevent inbreeding.

Woolly monkeys are complex communicators, using diverse media: visual, vocal, olfactory, and tactile. They may show affection or aggression and everything in between.

Group activities are coordinated. Woolly monkeys maintain marked territories.

Sadly, like spider monkeys, woolly monkeys are highly endangered. Captive prisoners are being kept and bred in a token effort to “ensure” species survival. The cruelty of men knows no bounds, as they show scant sense when it comes to respecting life.

Old World Monkeys

The classification of Old World monkeys is geographically confused. The 2 subfamilies are Cercopithecinae and Colobinae. Cercopithecines are largely African, though macaques are Asian. Colobines are nominally Asian, though colobus monkeys are African.


The colobine subfamily includes 59 species in 10 genera. Most are medium-sized monkeys with long tails. Colobine monkeys include colobus, douc, langur, leaf, lutung, surili, snub-nosed, and proboscis monkeys.

Most colobines are arboreal, though some are more terrestrial. Their habitats range from rain forests, mangroves, mountain forests, to savanna.

Colobines have diverse colorations. In many species, the coloring of juveniles differs considerably from adults.

Colobines are herbivores, with occasional dietary supplements of insects and other small animals. Leaves are a columbine staple. Leaves are hard to digest, so these monkeys have complex stomachs with multiple chambers.

Red colobus monkeys that live on the island of Zanzibar sometimes eat charcoal to help them handle the cyanide in the leaves they eat. Red colobus monkeys are often able to digest plants that are toxic to other primates.

 Proboscis Monkeys

Proboscis monkeys are endemic to the swampy mangrove forests of Borneo. They are among the minority of monkeys that swim. Proboscis monkeys not only swim, they swim well, both on the surface and underwater. Having partly webbed hands helps. Such is swamp life.

Proboscis eat primarily seasonal fruit and leaves; also, flowers, seeds, and insects as supplements.

Proboscis are one of the largest monkey species in Asia. Males average 72 cm, 19 kg; females 57 cm, 9.5 kg. This is not the only dimorphism.

Proboscis males have a particularly pronounced snoot; enough of a nuisance that some have to push it aside to eat. A female’s nose, while peculiarly prominent for a monkey, is much smaller, and upturned.

A male’s cartoonish nose has its compensation. Females find males with the biggest noses most attractive.

Proboscis monkeys have somewhat fluid sociality. A typical family group has 1 adult male, along with some adult females and their offspring. Females in a group have a dominance hierarchy. Mothers often rear their young with some assistance from other females in the group, particularly close relatives.

All-male groups of up to 20 are also common. Some, mostly males, prefer a more solitary life.

Upon reaching maturity males leave their natal group for an all-male group. Females occasionally leave their natal group for any of a variety of reasons: avoiding inbreeding or infanticide, reducing competition for food, or in hope of elevating their social status.

Females solicit mating. Proboscis monkeys also engage in non-reproductive and same-sex mounting.

There is little territoriality in the overlapping home ranges. Groups gather into bands of up to 60 or more and travel together, though individuals only groom and play with those in their own group. Arguments do arise, but proboscis monkeys are generally tolerant of each other.

Proboscis monkeys have a variety of vocalizations, including alarm and threat calls. Males communicate the status of their group by honking. A special honk is used to reassure infants.

Proboscis monkeys prefer to sleep in trees near a river, perhaps for safety, though crocodiles are its main predator.

Proboscis monkeys need large tracts of forest to sustain themselves. Though protected by law, habitat loss and poaching reduced the proboscis population by over half from 1970–2008. By 2010, their numbers in the wild were down to 1,000 or less. National parks and wildlife reserves are their last enclave. Like many other monkeys, proboscis monkeys will soon be extinct.


The cercopithecine subfamily comprises some 71 species in 12 genera. Cercopithecines include baboons, guenons, macaques, mandrills, mangabeys, patas monkeys, and vervet monkeys. Most are omnivorous.

Most cercopithecines live in sub-Saharan and central Africa, though macaques range from far east Asia through northern Africa, with a presence in Gibraltar.

All cercopithecines have cheek pouches which can store food. This differentiates cercopithecines from colobines.

Otherwise, the various species are adapted to the different habitats they inhabit. Arboreal species tend to be gracile: slender, with long tails; while terrestrial species are more robustly built.

 Guenon Monkeys

Guenons are a fairly diverse grouping of monkeys. The beautiful Diana monkey is a guenon. The smallest Old World monkey, the talapoin, is also a guenon, as is the fastest primate of all: the patas.

 Talapoin Monkeys

Talapoins may be found in the swamp forests of central Africa. An adult male talapoin weighs 1.3 kg, while a female averages 0.8 kg. Talapoins are 32–45 cm long, excluding the tail. Typical of small monkeys, talapoins are arboreal, living in troops of 50 to 100.

Talapoins are gregarious, with the typical complement of social behaviors, including play, occasional aggression, and grooming. They are not territorial.

 Patas Monkeys

At the other extreme from talapoins are ground-dwelling patas monkeys. Patas monkeys have considerable sexual dimorphism. Adult males weigh 12.4 kg, 60–87 cm long (excluding tail); females 6.5 kg, 49 cm.

Patas monkeys are adapted for life on the ground, and are the only monkey built for running. These slender monkeys run on all fours at up to 55 km per hour, faster than any other primate, owing to their long forelimbs.

They need the speed. Patas are preyed on by hyenas, jackals, and leopards. Away from sheltering trees, patas monkeys rely on running away from danger.

Patas monkeys typically live in groups of 20–30, though troops with up over 60 members have been seen. Groups are largely segregated by sex.

During most of the year, a female troop has a single adult male. Females lead the group, while the male is lead only in providing vigilant security. Should a predator appear, the male will try to grab its attention and run away from the troop, while the females flee to safety. Other males temporarily join a female troop during breeding season.

Once a male juvenile reaches sexual maturity, around 4 years of age, he leaves his natal group to join an all-male group.

Patas are tolerant of several types of habitat, ranging from savanna and steppe to woodlands, preferring open areas to heavily wooded forests. Patas live in fairly arid areas.

Patas prefer tall trees to short ones, and spend midday there resting, as well as sleeping in the trees. They forage on the ground in the morning and afternoon.


Diana monkeys live in West Africa. Adults weigh 4–7 kilograms. A Diana may live 2 decades.

Dianas live in in the canopy of primeval forests, rarely hitting the ground. They don’t do well in secondary forests. As such, Dianas are gravely endangered by human habitat destruction.

Dianas are omnivorous, eating anything nutritious and nontoxic: fruit, leaves, flowers, insects, and small invertebrates.

A Diana family group may be 5–10 adults, with a single male and a harem of females. Multiple families make up a troop of up to 50. Breeding is year-round, with a 6-month gestation to a birth of a single offspring.

Like vervets, Diana monkeys have a distinct alarm call for each type of predator: leopards, eagles, chimpanzees, and humans. Communication may be coordinated in a call-and-response. For example, a female may answer a male’s call of a leopard alert, though with a different vocalization that females use for the same animal.

Chimps chase Diana monkeys through the treetops, trying to snag one for a meal. Spotting such a wily predator results in deafening silence and retreat. Others in the troop take note and move off silently too.

Diana monkeys have highly distinctive hair, with sharply contrasting portions. This helps a Diana effectively convey body language, including communicative facial expressions.

Diana monkeys have a reputation for perceptive reliability. The tree-dwelling African hornbill isn’t concerned about leopards but is preyed upon by eagles. The hornbill recognizes a diana eagle warning and responds, while ignoring leopard calls.

Red colobus monkeys live in the same neck of the woods as Dianas. Red colobus associate with Dianas for safety, as either is chimp meat if caught.

When the two forage together, both monkeys respond to a Diana warning. The type of vigilance differs between Diana monkeys and red colobus, so there is more overall protection for both when together.


Vervet monkeys reside in sub-Saharan Africa. They sleep in the trees for safety, but spend their days on the ground, playing and feeding.

Vervets have 3 types of predators: snakes, leopards, and raptorial birds, such as martial eagles. Vervets have names for these predators. Chickens and ground squirrels are also known to have different alarm calls for ground and aerial predators.

If a snake is spotted, a distinctive vervet alarm call is made. Nearby vervets stand up to spy the snake. Once several monkeys have seen the snake, they may approach it as a mob, forcing the snake to retreat.

A leopard raises a cry that has vervets leaping up the trees to small branches where a leopard cannot reach. An air attack possibility gets vervets running for cover after a vervet cries out to look out from above.

The vervet predator language is learned by young ones. Infant vervets often make mistakes, raising an alarm to pigeons, warthogs, or other non-threatening creatures.

While infants may be easily scared into alarm, they quickly cotton to the concept of alien approach, whether overhead or on the ground. By observing adult alarm call and response, a juvenile learns the subtleties of proper calling.

Vervets have other verbal communications specific to an individual or social situation. In other words, vervets gossip. The communications are so nuanced that humans have difficulty discriminating vervet-speak.

 Japanese Macaques

Japanese macaques reside in the furthest northern range of all monkeys. They are found on 3 of the 4 main islands of Japan: Honshū, Kyūshū, and Shikoku; but not Hokkaidō, the northernmost island.

Japanese macaques are equally comfortable in the trees and on the ground. Some have learned to swim and to dive into water.

Japanese macaques live 25 to 30 years. They are tough, clever, and learn quickly; typical of the 15 macaque species.

Japanese macaques are omnivores. Their favorite foods are fruits, berries, nuts, and acorns. Flowers, seeds, leaves, and grasses are also good, as are mushrooms. Spiders, insects, larvae, snails, crabs, crayfish, and barnacles provide variety. Some are fond of birds’ eggs when they can be found.

Winter can mean living off tree bark, along with winter tree buds and sprouts. Japanese macaques that live seaside eat the kelp and algae that wash up onto beaches.

Males and females are similarly sized: 60 cm, with the average female 12.3 kg, and 14.6 kg for males. Overall, weight varies between 9 to 18 kg. Males look larger, as they have more muscle and hair on their shoulders and hips.

Japanese macaque troops commonly contain 20 to 100 members. Female Japanese macaques spend their entire life in the same troop. Matrilines develop, albeit at different social strata.

A mother provides all the care for her newborn. As an infant grows, relatives assist. Older siblings pay special attention.

Males sometimes carry, comfort, play with, and protect juveniles. A male may adopt a juvenile that needs attention. Overall, a troop provides a supportive environment for its young, with many willing caregivers.

Males typically emigrate to another troop when they reach maturity, which is between 3 to 7 years of age. The few that stay in their natal troop maintain close ties to their mothers and sisters.

There are separate dominance hierarchies for females and males. Favored males have high social standing. They stay in the central part of the troop with the most dominant female matriline.

The top-ranking male oversees security. The top female leads the troop. The alpha male and alpha female settle disputes between group members.

Males getting ready to leave a troop are relegated to its outer edges, as are males trying to join the group. These peripheral males are low ranking. Low-ranking females sometimes develop friendships with these males.

Many males change troops several times. Some become nomads, joining a troop only during breeding season.

Males compete for females during breading season, but females choose their mating partners. A male’s chances are as much a matter of personality as well as look. Some new males are welcomed, while others are chased away.

As with many monkeys, grooming and play are important facets of macaque social life. Both serve to form and maintain relationships; play more so for the young.

As juvenile male macaques mature, they go off with playmates for longer durations. Young males especially like to play with nearby adult males. In contrast, females stay close to their female relatives, learning by practice on infants their mothering skills.

Home ranges are 5 km2 in the south, and up to 20–30 km2 in the north, where food is scarcer. Troop ranges may overlap.

Neighboring troops try to avoid each other. They let each other know where they are by shaking treetops. Chance encounters are most often trouble-free, but fighting can occur.

  Imo the Innovator

Researchers studying Japanese macaques once doled out sweet potatoes on a sandy beach to entice monkeys into the open. The monkeys would rub the sand off before munching. Then, a 2-year-old, low-ranking female that researchers named Imo, which is the Japanese word for sweet potato, had the insight that washing was a superior technique.

Imo took her taters to a nearby freshwater stream to wash them off. Within a short time, Imo’s friends and family followed her lead, and rinsed their potatoes in the stream. Inside of a decade, spud washing was practiced by 90% of the troop.

Then Imo had another idea: salted potatoes. Imo started washing her potatoes at the seashore.

Again, Imo started a trend that became a tribal norm; over 80% within 5 years. The tradition continued through generations, long after Imo was gone. That troop of Japanese macaques treat themselves to sea-rinsed potatoes whenever they get the chance.

Imo also figured out how to sort wheat from sand by dropping it into water. Whereas sand sinks the wheat floats. This technique also caught on with the tribe.


Deep winter snow in the mountain forest on Honshū makes for mean foraging. One Japanese macaque troop acquired the luxury of bathing in natural hot springs to take the chill off; a learned behavior passed on through generations.

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As with much of the natural world, the lives of Japanese macaques are being degraded by humans, who pave roads and cut down trees. As their habitats shrank, Japanese macaques became regarded as encroaching into human territory: raiding crops and coming into towns. To many Japanese people now, having taken macaque territory, the indigenous monkey has become a pest.

A 1948 national law protecting the species is adhered to in the breach by permits to kill those that pillage on human land. Japanese macaque populations are on an inexorable decline toward extinction.


The largest Old World monkey, baboons live mostly in East Africa, with some in the Middle East. There are 5 species of baboon.

(The chacma baboon is found in southern Africa. The Guinea baboon resides in far western Africa. The hamadryas baboon occupies the heights in the Horn of Africa (the peninsula of central eastern Africa). The olive baboon inhabits in a wide range of north-central African savanna. The yellow baboon lives in the savannas and light forests of south-central and eastern Africa. Baboon classification is controversial. Some contend there are only 2 species: the hamadryas and savanna baboons, which have subspecies.)

4 baboon species prefer the savanna and other semiarid habitat, whereas the hamadryas baboon prefers a scenic view: living on the cliffs and in the hills along the Red Sea; dispersing for day foraging on the ground, but coming home to the cliffs at night, where they sleep and enjoy leisurely meals.

Adult males weigh 15–37 kilos. Baboons have pronounced sexual dimorphism. Females are considerably smaller.

Baboons are stunningly strong. They are built for life on the ground: with long arms that let them walk on all fours, with their shoulders and head held high, allowing them to scan the land without rising on 2 legs.

Baboon hands, much like humans, are adapted to digging up roots and bulbs. Baboon feet are flatter than other monkeys, giving them good ground stability at the sacrifice of tree-climbing agility. Nonetheless, baboons pull themselves into the trees to sleep at night.


Baboons are big eaters. Unsurprisingly, they are opportunistic omnivores, consuming a wide variety of foods.

Grass is a big part of the baboon diet. Baboons also munch nuts, leaves, bark, berries, seeds, flowers, birds, insects, shellfish, hares, and other small mammals, including vervet monkeys.

A small antelope or gazelle is a meaty catch. Baboons may hunt as a group: some acting as drivers of prey, into the trap of others that are waiting.

While baboons don’t make stew, they do appreciate taters. Baboons dig tubers out of the ground, a welcome supplement when seasonal fruit is scarce.


Among savanna baboons, the biggest and fiercest males dominate a troop that may run to hundreds, acting as protectors and mediators in social disputes.

A group within a troop has several adult males, and about twice as many females, along with their offspring.

Females have their own social hierarchy. Offspring generally share the same rank as their mother.

Females live their lives within the same natal group. Young males leave their home troop when they reach sexual maturity.

The olive baboon is named for the color of its coat. It is the widest ranging of all baboons: extending through much of middle Africa almost from coast to coast. Olive baboons inhabit savannas, steppes, and forests.

Though olive baboons have social stratification, choice of collective troop movements are made democratically: majority rules. Such democratic decisions arise only when the conflict in directions involve widely divergent paths; otherwise differing baboons compromise about which way to go.

While savanna baboons have a matrilineal hierarchy, the hamadryas is unusual in having a strictly patriarchal society. Correspondingly, savanna baboon females stay with their natal group. In contrast, hamadryas males have continuing relations.

The hamadryas have an atypical 4-level society: harems, clans, band, and troop. Most social interaction is within the smallest group: a harem is a single dominant adult male and up to 10 adult females, which the male guards. A harem may have a younger subordinate (follower) male, often related to the leader.

2 or more harems often unite into a clan. The dominant males of a clan are commonly close relatives, with an age-related dominance hierarchy at the clan level.

2 to 4 clans form a band of up to 200 baboons. Bands typically travel and sleep as a group.

Bands are insular. Males and females rarely leave a band. Interaction with other bands, particularly by juveniles, is discouraged by dominant males. Bands often have solitary males that are neither harem leader nor follower, but which stay with the band.

Several bands may come together as a troop. Troops often share a cliff-face for sleeping accommodation.

Related males of the same clan respect the social bonds of their kin. Otherwise, males sometimes raid harems in an aggressive takeover of its females. Infant baboons may be taken as hostages during such fights.

Females have a say as to their harem. A female’s preference for her male is heeded by his rival. But the less a female favors her harem male, the more likely a rival will attempt a takeover.

Hamadryas do not have a dominance hierarchy like savanna baboons. The males won’t tolerate it. Aggression among adult hamadryas males precludes male-male bonding and overrides extensive sociality. By contrast, some females are socially active and have strong bonds with the harem male.

Younger follower males may start their own harem by seducing young females into following them. Alternately, a male may take a female by force, though that does not necessarily bode well for a long-term relationship.


Baboons converse with considerable vocabulary and syntax, as well as subtle, and not so subtle, gestures. There are about 3 dozen basic baboon vocal calls, including a wide range of barks, grunts, screams, and alarm calls.

Baboon body language is extensive: staring, lip smacking, and a variety of body poses. Belligerent baboons display degrees of aggression. If a threatening stare doesn’t make the point, a baboon will try an “open-mouth” threat that starts by raising the eyebrows to show the whites of the eyes, followed by baring the teeth. A threatening yawn reveals enormous canine teeth, making an impressive warning display. At higher hostility, a baboon makes his hair stand up, voices verbal threats, and slaps the ground for punctuation.

Cowed baboons put on a fear face to back down: a wide smile that says “don’t hurt me.”

Baboon vocalization can be subtle, with individual styles that reveal emotional state and convey social context. Baboons gossip. Baboons talk about objects and events, indicating their feelings about the subject.

Alarm calls identify predator type. Alligators are referred to differently than lions. Such cries also identify the caller and context: whether of concern or a reported sighting.

Geladas are so closely related to baboons that their exclusion from the baboon genus remains controversial. Geladas vocalize while lip-smacking. These “wobbles,” as they are called, are structurally similar to human speech. Geladas even sound like a human talking, as their rhythmic qualities, determined by opening and closing the mouth, are the same.

Baboons were assessed on their orthographic processing ability: visual memory of words from their spelling (in a character-based language like English, as contrasted to a pictographic system like Chinese). The results were impressive.

Baboons were able to learn not only a specific list of words, but also to predict whether a new letter sequence was a real English word or not. ~ French psychologist Jonathan Grainger


In the alpine grasslands of eastern Africa, geladas tolerate Ethiopian wolves in their midst. Sensing comity, the wolves ignore potential meals of baby geladas in favor of rodents, which are more readily caught when the monkeys are present. This is the onset of domestication. (By contrast, geladas flee when they spot feral dogs, which show no decency toward the monkeys.)

You can have a wolf and a gelada within a metre or 2 of each other and virtually ignoring each other for up to 2 hours at a time. ~ Indian primatologist Vivek Venkataraman


25 MYA, an Old World monkey speciated into the first ape. Tectonic activity in the Great Rift Valley during the late Oligocene may have triggered the evolutionary divergence.