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Everything you ever wanted to know about capuchinsЕ.

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American Journal of Primatology 68:419–424 (2006)
Everything You Ever Wanted to Know About Capuchinsy
Review of The Complete Capuchin: The Biology of the Genus Cebus by D.M.
Fragaszy, E. Visalberghi, and L.M. Fedigan. Cambridge, United Kingdom,
Cambridge University Press, 2004, 356 pp, $50.00, paperback.
In courses on animal or primate behavior, teachers often pay lip service
to the ideal of integrating ultimate (adaptive) and proximate (mechanistic)
explanations for the behavior of a given organism. In practice, however, we often
emphasize one aspect over the other, depending on our training, research venue
(field or laboratory), and what resonates best with our students. Few animal
species have received as much attention from both field and laboratory studies
as have the capuchin monkeys. They are thus one of a few excellent model
systems we can study to try to understand how and why a given animal does what
it does.
The Complete Capuchin is a comprehensive and authoritative, yet very
readable book that will allow scientists of any background to quickly gain a
balanced and broad overview of both kinds of explanations for the fascinating and
complex array of behaviors shown by capuchin monkeys. In addition, it provides
up-to-date information on many aspects of capuchin biology, enabling advanced
graduate students and practicing researchers to review the latest advances and
quite a lot of unpublished (or soon-to-be published) information in their areas of
interest, especially for work in captivity. In short, this book is essential reading
for anyone who is interested in learning about capuchins or studying capuchin
behavior, and it is highly recommended for anyone who is interested in an
integrative view of the behavior of any primate. It not only reports accurately the
essence of a vast array of studies on both captive and wild capuchins, but often
succeeds in synthesizing this information into a clear picture of exactly what we
do and do not understand about these complex animals. For researchers like me,
who are familiar with wild capuchin monkeys, this book presents a wonderful
synthesis of the rationales and methods of captive studies that explore the
psychological mechanisms that support and define many of the behaviors I have
seen in wild capuchins over the decades.
The book is well organized and illustrated. Each chapter starts with a short
vignette that illustrates a particular example of the behaviors or themes covered
in that section. The descriptions of experiments are well illustrated with diagrams
of the experimental apparatus or procedure involved. Many important behaviors,
gestures, and facial expressions are shown in lovely original drawings by Stephen
Nash. My only peeve with the presentation is that the typeface is woefully small
(9-point font for general text, and 8-point font for figure legends).
DOI 10.1002/ajp.20235
Published online in Wiley InterScience (
r 2006 Wiley-Liss, Inc.
420 / Media Review
The book starts with a Prologue that examines the interface between
capuchin monkeys and humans. Capuchin monkeys have been collected as
curiosities, admired for their seeming intelligence, kept as pets, hunted for food,
reviled as crop-raiders, laughed at by legions of amused onlookers in zoos and
circuses, bred for biomedical research, and appreciated for their help as trained
assistants to quadriplegics. Sadly, two subspecies of capuchins monkeys are
threatened by human destruction of their forest habitat.
The bulk of the book is divided into three major parts: ‘‘Capuchins in
Nature,’’ ‘‘Behavioral Biology,’’ and ‘‘Behavioral Psychology.’’ The third part
takes up about half the book, a result of the authors’ greater familiarity with the
detailed studies of behavioral mechanisms revealed in captivity. ‘‘Capuchins in
Nature’’ reviews in three chapters the taxonomy and biogeography, behavioral
ecology, and community biology of this group. The taxonomic structure of this
genus has been revised three times in recent years, resulting in somewhere
between 7 and 12 species of what formerly had been considered four distinct
species. In recognition of the fact that most published studies used the older, fourspecies taxonomy, the authors of The Complete Capuchin retained the traditional
taxonomy in their exposition. Regardless of the long-term acceptance of the
current taxonomic revisions, this book does an excellent job of drawing together
the criteria, distributions, and history that define each currently recognized
subspecies of capuchin. The chapter on taxonomy ends with a thorough
consideration of the conservation status of each species and subspecies, as well
as a summary description of zoo holdings.
The chapter on behavioral ecology is relatively brief, but does an excellent job
of accurately describing what has been published regarding the ecology and
ranging of wild capuchin monkeys. There is a summary of home range size and
use patterns among the three main species, and emphasizes the adaptability of
ranging patterns to the demands of food distribution and critical resources, such
as water. The spatial structure of individuals within a group is described briefly,
although much more space could be devoted to it, as capuchins are among the
best-studied of all primates in terms of spatial structure and its determinants.
The section on time budgets neatly weaves together general principles of
primate diet and time allocation with a few detailed examples from capuchin field
studies. The following sections succinctly summarize the ecology of sleeping-site
choice and seasonal variation in diet and ranging patterns, including some
synthetic discussion about the causes of variation in response to seasonal food
scarcity. The next section on diet is less satisfying. A couple of references on diet
choice are missing, as is any mention of the critical role of very short gut passage
times (2 hours) in constraining capuchin diets. Instead, the focus is on the
extraordinary manipulative skills of capuchins, which become the topic of
extended discussion later in the book.
Although in the wild such ‘‘clever’’ foraging activities are used in only a small
percentage of substrates, they are what distinguish foraging by capuchins from
that exhibited by the rest of the monkeys in the New World. The section on
dietary variability properly points out the difficulty of distinguishing cultural
traditions from differences in food availability and profitability in explaining
between-group differences in diet. Within-group variation in foraging techniques
is plausibly related to sex and age differences, although oddly there is no mention
at all of the effects of social rank on foraging substrate choice or access.
The section on food competition is a brilliant short essay on the current
thinking about the costs and benefits of increasing group size in primates, with
detailed examples from various capuchin species. Again social rank is nearly
Am. J. Primatol. DOI 10.1002/ajp
Media Review / 421
entirely neglected as an explanation for variation in diet among individuals,
although much is known about this aspect for several of the Cebus species. This
odd omission might be taken as evidence by researchers of Old World primates
that such hierarchies are of little importance in capuchins, but this is certainly
not true in general. Unlike sections of the book that are devoted to captive
studies, this and the other chapters on wild capuchins provide few if any previews
of exciting results of unpublished or soon-to-be-published works. Because vast
stores of interesting but rare behaviors of wild capuchins have never been
published, I was occasionally frustrated by the omission of patterns that I or my
colleagues have seen but never found the reason or time to document in print.
The chapter on community ecology pulls together the diverse literature on
capuchin monkeys as predators, prey, and seed-dispersers. Capuchins are notable
for their predilection for capturing and consuming small vertebrate prey.
Although they share this preference with other species in their family, capuchins
take it to a higher level, systematically and sometimes cooperatively hunting for
birds, squirrels, and especially nests of many species (both birds and mammals).
The resulting prey often end up in hands other than those of the original owner,
mostly through tolerated scrounging rather than active sharing. The authors
describe the more prominent role of males in detecting predators and giving
alarm calls, but do not mention that the alarm calls are differentiated into at least
two types corresponding to terrestrial and aerial predators.
The roles of Cebus monkeys as pollinators, seed dispersers, and seed
predators are described along with a concise overview of the relevant theory.
There follow brief sections on capuchins as niche constructors (remodeling the
plant architecture of their habitat), crop raiders, and hosts for parasites. The
chapter ends with the relationship of capuchins to other primate species in their
ecological communities, ranging from competition among distinct species of
capuchins and niche partitioning among sympatric primate species to the
formation of sometimes remarkably stable mixed-species associations (usually
between squirrel monkeys and tufted capuchins).
The final chapter in this section on capuchins in the wild is on life history and
demography. It points out the complex of characters that have made capuchins so
attractive as study organisms in captivity, including their very large brain size
(adjusted for body mass), and slow development and late maturation coupled with
exceedingly long life spans (more than 50 years in captivity). There are excellent
table summaries of the most reliable and recent demographic data from both the
wild and captivity, as well as age-sex compositions of study groups across the
distribution of the genus. Brief comments summarize the scarce data on birth
seasonality, dispersal patterns, and long-term group dynamics. Notably absent in
this section is any mention of infanticide, which has been observed in all
intensively studied Cebus populations.
The middle section of the book, oddly entitled ‘‘Behavioral Biology,’’ is
composed of three chapters on physical characteristics and development. The first
chapter details the salient traits of the capuchin tribe: prehensile (albeit fullyfurred) tail, very dexterous hands with a precision grip, and a relatively large and
convoluted brain. There follows a lucid explanation of the odd polymorphic color
vision system shared by capuchins and nearly all diurnal New World primates, in
which highly variable alleles at one sex-linked locus provide a majority of females
with functional three-color vision (similar but not identical to that of humans)
while all males are left with only two-color vision. Like many other New World
monkeys, female capuchins possess a prominent external clitoris, which can make
it difficult to distinguish the sex of young animals. The chapter finishes with a
Am. J. Primatol. DOI 10.1002/ajp
422 / Media Review
graphic description of mutual fur-rubbing behavior, a communal anointing of
smelly fruit or animal matter, often accompanied by drooling. It appears to act as
a deterrent to mosquitoes, but it seems clear that the monkeys are enjoying the
process as well as the purpose!
The next chapter, on development, summarizes a scattered literature on
physical growth and behavioral maturation in capuchins. Capuchin babies are
relatively precocial compared to most mammals, but quite altricial compared to
many other monkeys. Growth and development are relatively slow, with sexual
maturation typically delayed until at least 4 years of age in females. Although
male capuchins are sexually mature at about age 4, they continue to grow notably
until age 8 and do not usually reach a dominant breeding position until age 10 or
later, if ever. One of the prominent puzzles regarding capuchins (as well as other
primates) is why they develop so slowly. Evidence on foraging skills does not show
much improvement beyond the age of 2–3 years. Social skills may continue to
improve with age, but the evidence is scant. Perhaps slow development is part of a
general strategy to increase the possibility of individual learning and adjustment
to environmental variation, as the authors argued earlier for the benefits of
having such a large relative brain size.
The final chapter in this section, on motor skills, begins the transition to a
focus on detailed studies of manipulative mechanisms in captive capuchins, a
theme that dominates the remaining half of the book. Their manipulative skills
are not unique but are well developed even among primates, and are mostly used
in the service of acquiring food. Like many other primates, they grab food directly
off the surface of natural substrates and open small or weak substrates (e.g., dead
leaves) to search for food within. Where capuchins really stand out, however, is in
their ability to search within relatively hard or difficult substrates (e.g., dead
branches up to 20 cm thick, palm nuts that would break a human’s teeth, tough
bamboo stalks 8 cm in diameter, and termite and bee nests). Their actions are not
stereotyped but are characterized by great variation in form and duration, as well
as the ability to combine arm motions with objects, objects with each other, and
sometimes even three objects at a time, such as when they use tools (e.g., a
hammer, anvil, or food item). The chapter describes in fascinating detail a variety
of studies on capuchin motor skills, ranging from their ability to control a cursor
with a joystick to the extent and meaning of ‘‘handedness’’ in these animals.
The last half of the book is on behavioral psychology. It is hardly surprising
(given the world-class expertise of the authors in this area) that this is by far the
most detailed, up-to-date, and synthetic part of the work. Many unpublished
studies appear here and provide a richness to the narrative that is less evident in
other parts of the book. The first three chapters cover memory and perception,
exploration and problem-solving, and tool use. The final three chapters are on
social structure and interactions, sexual behavior, and social learning. Each
chapter covers the topic well, serving as an excellent entry to the literature for
those wanting to learn or refresh their knowledge about these subjects as they
pertain to capuchins. The authors do not attempt to judge the merits of
contradictory results in the published literature, but leave them as puzzles for
curious future researchers to resolve. For instance, different studies of apparently
similar vocalizations in different species, or even different populations of one
species of capuchin have led to quite distinct interpretations of the ‘‘function’’ of
the call.
Undoubtedly, the most difficult to understand aspect of any animal’s
behavior is its mental state–what it perceives, what it knows and remembers,
and how it organizes its knowledge. In this category arise a series of paradoxes
Am. J. Primatol. DOI 10.1002/ajp
Media Review / 423
between what careful experiments in captivity suggest capuchins can know, and
problems they appear to be able to solve routinely in the wild. For instance, a
careful set of experiments appears to demonstrate that capuchin monkeys cannot
recognize or remember patterns of changing pitch of sounds in a series. Yet
among the most common vocalizations given by tufted capuchins are several
distinct kinds of ‘‘whistle series,’’ which differ from each other largely (to human
ears) in the pattern of rising (or not) pitches of the individual notes. These wild
capuchins either recognize these patterns or they use some other cue entirely to
distinguish the various whistle series.
The chapter on capuchin problem-solving is loaded with details on how they
manipulate single and multiple objects for fun or profit, including cooperating
with other monkeys. With respect to cooperation, the authors are careful to point
out simple alternative explanations for what can appear to be psychologically
complex behaviors. This is a welcome antidote to the tendency to label capuchin
behaviors with human counterparts that may not reflect what the capuchins
understand, or that would require a sense of social ‘‘contract’’ that has yet to be
demonstrated in any nonhuman species. It is clear that capuchins are rather
tolerant toward other group members, including non-kin, compared to some Old
World primates. Indeed, juveniles are often seen near or even nursing from
females who are not their mothers, and infants are frequently carried by
individuals other than the mother in both captivity and the wild. Although
capuchins in the wild are quick to reinforce status and priority at contested food
sources, they allow other individuals to get close enough to ‘‘steal’’ tidbits of food
from the owner. It remains a puzzle why capuchins should be relatively relaxed
about status compared to macaques and other monkeys that share a femaleresident social system.
The chapter on tool use by capuchins is the best example of synthesis in the
book. It pulls together a significant body of captive studies on tool use with recent
described and still unpublished reports of habitual tool use by wild capuchins. For
those primatologists who are unwilling to grant ‘‘tool user’’ status to any non-ape,
this chapter is mandatory reading. The authors start by defining what they mean
by tool use, and provide a taxonomy of the component parts. They then review the
large body of captive experiments and synthesize the conditions that appear most
likely to lead to tool use by capuchins. It is clear that tool use by capuchins is not
derived from insights into the properties or uses of tools as such.
Capuchins are active, curious, manipulative animals that are highly
motivated to pursue high-quality food rewards. They are persistent in using
objects to pound or probe in the vicinity of such food rewards, and sooner or later
they get lucky and one sequence of manipulations helps them to acquire an
otherwise inaccessible food. Where capuchins excel is in recalling the set of
actions that led to such a success, even out of hundreds of failed attempts. Given
their demonstrated ability to use tools in captivity, why has tool use gone virtually
unreported in wild capuchins, despite some decades-long field studies? The
authors argue convincingly that tool use in the wild requires a special
combination of circumstances: necessity (a harsh lean season), availability of
foods that are difficult to attain without tools, the presence of potential tools
(usually rocks), and a low enough risk of predation that capuchins are willing
to spend significant amounts of time on the ground.
The need for a low predation risk is less obvious and is rarely mentioned in
the literature, but it is the only condition that would appear to prevent tool use
from being acquired in my own study population of tufted capuchins in
Argentina, where the winter season is harsh, rocks are abundant, and the same
Am. J. Primatol. DOI 10.1002/ajp
424 / Media Review
palm species focused on by other tool-using populations of wild tufted capuchins is
one of the most common species of tree. However, in Argentina the forest has a
dense understory and contains five species of terrestrial cats. The capuchins in
our population are demonstrably nervous and very wary about coming to the
ground, typically remaining on the ground for only seconds before racing back up
a tree trunk. Perhaps necessity is the mother of invention, but a lack of ground
predator risk is the father.
The chapter on social structure has unusually insightful discussions about
whether capuchins are female-bonded in the same sense as Old World monkeys,
and if so, why. The authors conclude that while capuchins do not follow the
macaque/baboon model precisely, their social structure is much more similar to
that model than to those of other New World monkeys. Apparent variations in the
degree of female cooperation and philopatry among capuchin species and
populations have not yet been studied systematically, but could offer some
important insights into the origins of female–female social bonding. The authors
bring up the possibility that infanticide avoidance affects the social structure of
capuchins, but so far the evidence is sparse and incomplete.
The chapter on capuchin sexual behavior is noteworthy for the detail with
which it presents the behavioral descriptions, approaching a true ethogram. The
authors describe in detail for tufted capuchins the remarkable active and persistent
courtship by female capuchins of preferred males, the initial apparent indifference
of the male toward the female, and the complex postcopulatory displays.
The final chapter, on social learning, highlights the curious combination of
intelligence and seeming stupidity that characterizes capuchins. It is clear that
capuchins are quite tolerant of approaches and close observation by other group
members, conditions that should promote the transmission of social traditions
within a group over time. Yet repeated experiments have failed to show anything
but generalized dispositions to favor or avoid certain situations based on the
responses of others. A charming vignette at the start of the chapter describes how
one capuchin watches another use a stick as a tool to poke a peanut out of a tube.
Despite observing this 50–70 times, the observer is clueless about the use of the
stick, although well educated about the value of the peanut!
The brief Epilogue does not accomplish what a truly concluding chapter
should aspire to: a survey of the major unresolved questions, areas of ongoing
dispute, and most exciting research opportunities available with these interesting
and unique animals. In particular, some of the striking behavioral differences
between wild capuchin species are glossed over yet beg for an explanation.
Conversely, other described species differences may be biased by the fact that
some forms have rarely been studied in captivity, and others rarely in the wild.
Although captive studies are revealing about behavioral potentials, the ecology
and demography of captive populations are so different from their wild
counterparts that direct comparisons between populations residing in these
different ‘‘habitats’’ may confound species and environmental differences.
Despite these minor shortcomings, The Complete Capuchin is an intelligent
and thorough exploration of everything that is currently known about capuchin
monkeys. This book offers a gold mine of information to anyone who is interested
in these adaptable creatures.
Charles H. Janson
Department of Ecology and Evolution
Stony Brook University
Stony Brook, NY 11794-5245
Am. J. Primatol. DOI 10.1002/ajp
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