Individual differences |
Methods | Statistics | Clinical | Educational | Industrial | Professional items | World psychology |
White-headed Capuchin (Cebus capucinus)
The capuchins are the group of New World monkeys classified as genus Cebus. Their name comes from their coloration, which resembles the cowls worn by the Capuchin order of Roman Catholic friars. Cebus is the only genus in subfamily Cebinae.
The range of the capuchin monkeys includes Central America (Honduras) and middle South America (middle Brazil, eastern Peru, Paraguay).
Capuchins generally resemble the friars of their namesake. Their body, arms, legs and tail are all darkly (black or brown) colored, while the face, throat and chest are white colored, and their head has a black cap. This general pattern varies from species to species, as well as among individuals within a species. They reach a length of 30 to 56 cm (12 - 22 inches), with tails that are just as long as the body. They weigh up to 1.3 kg (2 lb, 13 oz).
Like most New World monkeys, capuchins are diurnal and arboreal. With the exception of a midday nap, they spend their entire day searching for food. At night they sleep in the trees, wedged between branches. They are undemanding regarding their habitat and can thus be found in many differing areas. Among the natural enemies of the capuchins are large falcons, cats and snakes.
The diet of the capuchins is more varied than other monkeys in the family Cebidae. They are omnivores, eating not only fruits, nuts, seeds and buds, but also insects, spiders, bird eggs and small vertebrate. Capuchins living near water will also eat crabs and shells by cracking their shells with stones.
Easily recognized as the "organ grinder" monkeys, capuchins are sometimes kept as pets, even when import of these animals is forbidden and in spite of assertions by some that monkeys are unsuitable as domestic animals. They are also used as service animals to aid paraplegics and people with spinal cord injuries. Zoos and circuses often keep capuchins as well. 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 live together in groups of six to 40 members. These groups consist of related females and their offspring, as well as several males. Usually groups are dominated by a single male, who has primary rights to mate with the females of the group. Mutual grooming as well as vocalization serves as communication and stabilization of the group dynamics. These primates are territorial animals, distinctly marking a central area of their territory with urine and defending it against intruders, though outer zones of these areas may overlap.
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, when they move to her back. Adult male capuchins rarely take part in caring for the young. Within four years for females and eight years for males, juveniles become fully mature. In captivity, individuals have reached an age of 45 years, although life expectancy in nature is only 15 to 25 years.
Capuchins are considered the most intelligent New World monkeys and are often used in laboratories. The Tufted Capuchin is especially noted for its long-term tool usage, one of the few examples of primate tool use other than by apes. Upon seeing macaws eating palm nuts, cracking them open with their beaks, these capuchins 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 capuchins 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.
During the mosquito season, they crush up millipedes and rub the remains on their backs. This acts as a natural insect repellent.
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 reflection as if encountering another individual they don't 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:
- Seeing an unfamiliar, same-sex monkey on the other side of a clear barrier
- Seeing a familiar, same-sex monkey on the other side of a clear barrier
- A mirror showing a reflection of the monkey
With scenario 1, females appeared anxious and avoided eye-contact. 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.
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 neither been 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. This has, however, been refuted as conclusive evidence for a theory of mind as the monkeys may have learned to discriminate knower and guesser by other means.  Non-human great apes have not been proven to develop a theory of mind either; human children commonly develop a theory of mind around the ages 3 and 4.
Some organizations, such as Helping Hands in Boston, Massachusetts, have been training capuchin monkeys to assist quadriplegics in a manner similar to mobility assistance dogs. After being socialized in a human home as infants, the monkeys undergo extensive training before being placed with a quadriplegic. Around the house, the monkeys help out by doing tasks including microwaving food, washing the quadriplegic's face, and opening drink bottles.
- Genus Cebus
- C. capucinus group
- White-headed Capuchin, Cebus capucinus
- White-fronted Capuchin, Cebus albifrons
- Cebus albifrons albifrons
- Cebus albifrons unicolor
- Shock-headed Capuchin, Cebus albifrons cuscinus
- Trinidad White-fronted Capuchin, Cebus albifrons trinitatis
- Ecuadorian Capuchin, Cebus albifrons aequatorialis
- Varied Capuchin, Cebus albifrons versicolor
- Weeper Capuchin, Cebus olivaceus
- Kaapori Capuchin, Cebus kaapori
- C. apella group
- Black-capped, Brown or Tufted Capuchin, Cebus apella
- Guiana Brown Capuchin, Cebus apella apella
- Cebus apella fatuellus
- Margarita Island Capuchin, Cebus apella ?margaritae
- Large-headed Capuchin, Cebus apella macrocephalus
- Cebus apella peruanus
- Cebus apella tocantinus
- Black-striped Capuchin, Cebus libidinosus
- Cebus libidinosus libidinosus
- Cebus libidinosus pallidus
- Cebus libidinosus paraguayanus
- Cebus libidinosus juruanus
- Black Capuchin, Cebus nigritus
- Cebus nigritus nigritus
- Crested Capuchin or Robust Tufted Capuchin, Cebus nigritus robustus
- Cebus nigritus cucullatus
- Golden-bellied Capuchin, Cebus xanthosternos
- Blond Capuchin, Cebus queirozi
- Black-capped, Brown or Tufted Capuchin, Cebus apella
- C. capucinus group
- Groves, Colin (16 November 2005). Wilson, D. E., and Reeder, D. M. (eds) Mammal Species of the World, 3rd edition, 136-138, Johns Hopkins University Press. ISBN 0-801-88221-4.
- de Waal FB, Dindo M, Freeman CA, Hall MJ (2005). The monkey in the mirror: Hardly a stranger. Proceedings of the National Academy of Sciences Epub ahead of print. PMID 16055557.
- Kuroshima, Hika, Kazuo Fujita, Akira Fuyuki, Tsuyuka Masuda (March 2002). Understanding of the relationship between seeing and knowing by tufted capuchin monkeys (Cebus apella). Animal Cognition 5 (1): 41 - 48. ISSN 1435-9448.
- Heyes, C. M. (1998). THEORY OF MIND IN NONHUMAN PRIMATES. Behavioral and Brain Sciences. bbs00000546.