Editing Capuchin monkey (section)

== Intelligence ==
[[File:Cebus robustus (Crested capuchin monkey).jpg|thumb|right|[[Crested capuchin]] (''Sapajus robustus'')]]

The capuchin is considered to be the most intelligent New World monkey<ref>{{cite web |url=http://www.monkeyjungle.com/amazonian.htm |title=Black-faced Capuchin |work=Amazonian Rainforest |publisher=Monkey Jungle |access-date=2008-10-13}}</ref> and is often kept in captivity. The tufted monkey is especially noted for its long-term tool usage,<ref>{{cite web|title=Saving the monkeys|url=https://spie.org/membership/spie-professional-magazine/journal-of-applied-remote-sensing-saving-monkey-habitat|publisher=SPIE Professional|access-date=1 January 2016}}</ref> one of the few examples of primate tool use other than by [[ape]]s including humans. Upon seeing [[macaw]]s eating [[Oil palm|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.<ref>{{cite journal |title=Substrate and Tool Use by Brown Capuchins in Suriname: Ecological Contexts and Cognitive Bases |author=Boinski, S. |author2=Quatrone, R. P. |author3=Swartz, H. |name-list-style=amp |year=2008 |volume=102 |issue=4 |pages=741–761 |doi=10.1525/aa.2000.102.4.741 |journal=American Anthropologist}}</ref> The learning behavior of capuchins has been demonstrated to be directly linked to a reward rather than curiosity.<ref>{{Cite journal|last1=Edwards|first1=Brian J.|last2=Rottman|first2=Benjamin M.|last3=Shankar|first3=Maya|last4=Betzler|first4=Riana|last5=Chituc|first5=Vladimir|last6=Rodriguez|first6=Ricardo|last7=Silva|first7=Liara|last8=Wibecan|first8=Leah|last9=Widness|first9=Jane|date=2014-02-19|title=Do Capuchin Monkeys (''Cebus apella'') Diagnose Causal Relations in the Absence of a Direct Reward?|journal=PLOS ONE|volume=9|issue=2|pages=e88595|doi=10.1371/journal.pone.0088595|issn=1932-6203|pmc=3929502|pmid=24586347|bibcode=2014PLoSO...988595E|doi-access=free}}</ref>

In 2005, experiments were conducted on the ability of capuchins to use money.<ref name="anderson.ucla.edu">{{cite journal|last1=Chen|first1=M. Keith|last2=Lakshminarayanan|first2=Venkat|last3=Santos|first3=Laurie R.|title=How Basic Are Behavioral Biases? Evidence from Capuchin Monkey Trading Behavior|journal=Journal of Political Economy|date=2006|volume=114|issue=3|pages=517–537|doi=10.1086/503550|url=http://www.anderson.ucla.edu/faculty/keith.chen/papers/Final_JPE06.pdf|citeseerx=10.1.1.594.4936|s2cid=18753437}}</ref> 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).<ref name="anderson.ucla.edu"/> They showed the same propensity to [[loss aversion|avoid perceived losses]] demonstrated by human subjects and investors.

During the mosquito season, they crush [[millipede]]s and rub the result on their backs. This acts as a natural [[insect repellent]].<ref>{{Cite journal |title=Seasonal Anointment with Millipedes in a Wild Primate: A Chemical Defense Against Insects? |journal=Journal of Chemical Ecology |volume=26 |issue=12 |year=2000 |doi=10.1023/A:1026489826714 |pages=2781–2790 |author=Valderrama, X.|bibcode=2000JCEco..26.2781V |s2cid=25147071 |display-authors=etal}}</ref>

=== Self-awareness ===
{{Further|Self-awareness}}

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:
# 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.

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.<ref>{{cite journal | author=de Waal, F. B. | author2=Dindo, M. | author3=Freeman, C. A. | author4=Hall, M. J. | name-list-style=amp | title=The monkey in the mirror: Hardly a stranger | journal=[[Proceedings of the National Academy of Sciences]] | volume=102 | issue= 32| year=2005 | pages= 11140–7| pmid=16055557 | doi=10.1073/pnas.0503935102 | pmc=1183568| bibcode=2005PNAS..10211140D | doi-access=free }}</ref>

=== Theory of mind ===
{{Main|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.<ref>{{cite journal | last = Kuroshima | first = Hika |author2=Fujita, Kazuo |author3=Fuyuki, Akira |author4=Masuda, Tsuyuka |date=March 2002 | title = Understanding of the relationship between seeing and knowing by tufted capuchin monkeys (''Cebus apella'') | journal = Animal Cognition | volume = 5 | issue = 1 | pages = 41–48 | doi = 10.1007/s10071-001-0123-6  | pmid = 11957401 | s2cid = 10783449 | issn = 1435-9448 }}</ref> 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.<ref>{{cite journal|author=Heyes, C. M. |year=1998 |title=Theory Of Mind In Nonhuman Primates |journal=Behavioral and Brain Sciences|doi=10.1017/S0140525X98000703 |volume=21 |issue=1 |pmid=10097012 |pages=101–14 |s2cid=6469633 |url=http://discovery.ucl.ac.uk/117063/1/download.14pdf.pdf }}</ref> Until recently it was believed that non-human [[hominidae|great ape]]s did not possess a theory of mind either, although recent research indicates this may not be correct.<ref>{{cite web|last=Jabr|first=Ferris|title=Clever critters: Bonobos that share, brainy bugs and social dogs|url=http://blogs.scientificamerican.com/observations/2010/06/08/clever-critters-bonobos-that-share-brainy-bugs-and-social-dogs/|publisher=Scientific American|date=8 June 2010}}</ref> Human children commonly develop a theory of mind around the ages 3 and 4.