The capuchin monkeys are New World monkeys of the subfamily Cebinae. They are readily identified as the "organ grinder" monkey, and have been used in many movies and television shows. The range of capuchin monkeys includes some tropical forests in Central America and South America as far south as northern Argentina. In Central America, where they are called white-faced monkeys ("carablanca"), they usually occupy the wet lowland forests on the Caribbean coast of Costa Rica and Panama and deciduous dry forest on the Pacific coast.
The word "capuchin" derives from the Order of Friars Minor Capuchin, who wear brown robes with large hoods. When Portuguese explorers reached the Americas in the 15th century, they found small monkeys whose coloring resembled these friars, especially when in their robes with hoods down, and named them capuchins. When the scientists described a specimen (thought to be a golden-bellied capuchin) they noted that: "his muzzle of a tanned color, ... with the lighter color around his eyes that melts into the white at the front, his cheeks ..., give him the looks that involuntarily reminds us of the appearance that historically in our country represents ignorance, laziness, and sensuality."[1] The scientific name of the genus, Cebus comes from the Greek word kêbos,[2] meaning a long-tailed monkey.
The species-level taxonomy of this subfamily remains highly controversial, and alternative treatments than the one listed below have been suggested.[3] [4] [5] [6]
In 2011, Jessica Lynch Alfaro et al. proposed that the robust capuchins (formerly the C. apella group) be placed in a separate genus, Sapajus, from the gracile capuchins (formerly the C. capucinus group) which retain the genus Cebus.[7] [8] Other primatologists, such as Paul Garber, have begun using this classification.[9]
According to genetic studies led by Lynch Alfaro in 2011, the gracile and robust capuchins diverged approximately 6.2 million years ago. Lynch Alfaro suspects that the divergence was triggered by the creation of the Amazon River, which separated the monkeys in the Amazon north of the Amazon River, who then evolved into the gracile capuchins. Those in the Atlantic Forest south of the river evolved into the robust capuchins. Gracile capuchins have longer limbs relative to their body size than robust capuchins, and have rounder skulls, whereas robust capuchins have jaws better adapted for opening hard nuts. Robust capuchins have crests and the males have beards.
* Rediscovered species.[11]
The oldest known crown platyrrhine and member of Cebidae, Panamacebus transitus, is estimated to have lived 21 million years ago. It is the earliest known fossil evidence of a mammal travelling between South and North America.[12]
Capuchins are black, brown, buff or whitish, but their exact color and pattern depends on the species involved. Capuchin monkeys are usually dark brown with a cream/off-white coloring around their necks. They reach a length of 30to, with tails that are just as long as the body. On average, they weigh from 1.4 to 4 kg (3 to 9 pounds) and live up to 25 years old in their natural habitats, and up to 35 in captivity.
Capuchins prefer environments that give them access to shelter and easy food, such as low-lying forests, mountain forests, and rain forests. They are particularly abundant in Argentina, Brazil, Costa Rica, Honduras, Paraguay, and Peru. They use these areas for shelter at night and food access during the day. The canopy of the trees allows for protection from threats above, and the capuchin monkeys' innate ability to climb trees with ease allows them to escape and hide from predators on the jungle floor. This environment is mutually beneficial for the capuchins and for the ecosystem in which they inhabit. This is because they spread their seed leftovers and fecal matter across the forest floor which helps new plants to grow, therefore adding to the already abundant foliage that shelters the capuchin.
Like most New World monkeys, capuchins are diurnal and arboreal. Capuchins are polygamous, and the females mate throughout the year, but only go through a gestation period once every 2 years between December and April. Females bear young every two years following a 160- to 180-day gestation. The young cling to their mother's chest until they are larger, then they move to her back. Adult male capuchin rarely take part in caring for the young. Juveniles become fully mature within four years for females and eight years for males. In captivity, individuals have reached an age of 50 years, although natural life expectancy is only 15 to 25 years. Capuchins live in groups of 6–40 members, consisting of related females, their offspring, and several males.
The capuchin monkey feeds on a vast range of food types, and is more varied than other monkeys in the family Cebidae. They are omnivores, and consume a variety of plant parts such as leaves, flower and fruit, seeds, pith, woody tissue, sugarcane, bulb, and exudates, as well as arthropods, molluscs, a variety of vertebrates, and even primates.[13] Recent findings of old stone tools in Capuchin habitats have suggested that recently the Capuchins have switched from small nuts, such as cashews, to larger and harder nuts. Capuchins have also been observed to be particularly good at catching frogs.[13] They are characterized as innovative and extreme foragers because of their ability to acquire sustenance from a wide collection of unlikely food, which may assure their survival in habitats with extreme food limitation.[14] Capuchins living near water will also eat crabs and shellfish by cracking their shells with stones.[15]
Capuchin monkeys often live in large groups of 10 to 35 individuals within the forest, although they can easily adapt to places colonized by humans. The Capuchins have discrete hierarchies that are distinguished by age and sex.[16] Usually, a single male will dominate the group, and he will have primary rights to mate with the females of the group. However, the white-headed capuchin groups are led by both an alpha male and an alpha female.[17] Each group will cover a large territory, since members must search for the best areas to feed. These primates are territorial animals, distinctly marking a central area of their territory with urine and defending it against intruders, though outer areas may overlap. The stabilization of group dynamics is served through mutual grooming, and communication occurs between the monkeys through various calls.[18] Their vocal communications have various meanings such as creating contact with one another, warning about a predator, and forming new groups. The social experience of the capuchins directly influences the development of attention in society. They create new social behaviors within multiple groups that signify different types of interactions. These include; tests of friendship, displays against enemies, infant and sexual intimacy.[19] This creates social rituals that are designed to test the strength of social bonds and a reliance on social learning.[20]
Capuchin females often direct most of their proceptive and mating behavior towards the alpha male. However, when the female reaches the end of her proceptive period, she may sometimes mate with up to six different subordinate males in one day.[21] Strictly targeting the alpha male does not happen every time, as some females have been observed to mate with three to four different males.[22] When an alpha female and a lower-ranking female want to mate with an alpha male, the more dominant female will get rights to the male over the lower-ranking one.
The capuchin is considered to be the most intelligent New World monkey[23] and is often used in laboratories. The tufted monkey is especially noted for its long-term tool usage,[24] one of the few examples of primate tool use other than by apes and humans. Upon seeing macaws eating palm nuts, cracking them open with their beaks, this monkey will select a few of the ripest fruits, nip off the tip of the fruit and drink down the juice, then seemingly discard the rest of the fruit with the nut inside. When these discarded fruits have hardened and become slightly brittle, the capuchin will gather them up again and take them to a large flat boulder where they have previously gathered a few river stones from up to a mile away. They will then use these stones, some of them weighing as much as the monkeys, to crack open the fruit to get to the nut inside. Young capuchins will watch this process to learn from the older, more experienced adults but it takes them 8 years to master this.[25] The learning behavior of capuchins has been demonstrated to be directly linked to a reward rather than curiosity.[26]
In 2005, experiments were conducted on the ability of capuchins to use money.[27] After several months of training, the monkeys began exhibiting behaviors considered to reflect an understanding of the concept of a medium of exchange that were previously believed to be restricted to humans (such as responding rationally to price shocks).[27] They showed the same propensity to avoid perceived losses demonstrated by human subjects and investors.
During the mosquito season, they crush millipedes and rub the result on their backs. This acts as a natural insect repellent.[28]
When presented with a reflection, capuchin monkeys react in a way that indicates an intermediate state between seeing the mirror as another individual and recognizing the image as self.
Most animals react to seeing their reflections as if encountering another individual they do not recognize. An experiment with capuchins shows that they react to a reflection as a strange phenomenon, but not as if seeing a strange capuchin.
In the experiment, capuchins were presented with three different scenarios:
In scenario 1, females appeared anxious and avoided eye-contact, while males made threatening gestures. In scenario 2, there was little reaction by either males or females.
When presented with a reflection, females gazed into their own eyes and made friendly gestures, such as lip-smacking and swaying. Males made more eye contact than with strangers or familiar monkeys but reacted with signs of confusion or distress, such as squealing, curling up on the floor, or trying to escape from the test room.[29]
See main article: Theory of mind.
The question of whether capuchin monkeys have a theory of mind—whether they can understand what another creature may know or think—has been neither proven nor disproven conclusively. If confronted with a knower-guesser scenario, where one trainer can be observed to know the location of food and another trainer merely guesses the location of food, capuchin monkeys can learn to rely on the knower.[30] This has, however, been repudiated as conclusive evidence for a theory of mind as the monkeys may have learned to discriminate knower and guess by other means.[31] Until recently it was believed that non-human great apes did not possess a theory of mind either, although recent research indicates this may not be correct.[32] Human children commonly develop a theory of mind around the ages 3 and 4.
Capuchin monkeys are clever and easy to train. As a result, they are used to help people who are quadriplegics in many developed countries. They have also become popular pets and attractions for street entertainment, and are hunted for meat by local people.[6] Since they have a high reproductive rate and can easily adapt to their living environment, loss of the forest does not negatively impact the capuchin monkey populations as much as other species, although habitat fragmentation is still a threat.[33] Natural predators include jaguars, cougars, jaguarundis, coyotes, tayras, snakes, crocodiles and birds of prey. The main predator of the tufted capuchin is the harpy eagle, which has been seen bringing several capuchin back to its nest.[34]
Easily recognized as the "organ grinder" or "greyhound jockey" monkeys, capuchins are sometimes kept as exotic pets. Sometimes they plunder fields and crops and are seen as troublesome by nearby human populations. In some regions, they have become rare due to the destruction of their habitat.
Capuchins have been used as service animals, and were once referred to as "nature's butlers" by the AARP.[35] Helping Hands, a nonprofit organization, trained capuchin monkeys to assist quadriplegics as monkey helpers in a manner similar to mobility assistance dogs.[35]
In 2010, the U.S. federal government revised its definition of service animal under the Americans with Disabilities Act (ADA). Non-human primates are no longer recognized as service animals under the ADA.[36] The American Veterinary Medical Association does not support the use of nonhuman primates as assistance animals because of animal welfare concerns, the potential for serious injury to people, and risks that primates may transfer dangerous diseases to humans.[37] In 2021, Helping Hands (the organization that provided helper monkeys to disabled persons) rebranded, changing its name to Envisioning Access and replaced the use of monkeys with a focus on new assistive technologies.[38]
Capuchin monkeys are the most common featured monkeys in film and television, with notable examples including: Night at the Museum (and its sequels), Outbreak, Monkey Shines, (and its sequels), Zookeeper, George of the Jungle, and The Hangover Part II. Ross Geller (David Schwimmer) on the NBC sitcom Friends had a capuchin monkey named Marcel. Crystal the Monkey is a famous monkey actress.