1,721,009 research outputs found
Coexistence Between Humans and Capuchins (Sapajus libidinosus): Comparing Observational Data with Farmers' Perceptions of Crop Losses
No full textForaging on anthropogenic food by wildlife is a prevalent form of human-wildlife interaction. Few studies have evaluated the impact of wildlife crop foraging in Neotropical areas where small-scale agriculture is practiced and the habitat has not been heavily altered. Our objectives were 1) to evaluate the perceptions of small-scale farmers living in southern Piaui (Brazil) of the impact of bearded capuchins (Sapajus libidinosus) on their crops and 2) quantify crop losses due to the monkeys and other vertebrates. In 2013, we interviewed 78 residents about the impact of capuchins on their crops. Subsequently, we recorded foraging by vertebrate animals in corn fields, and evaluated farmers' crop losses. The farmers showed a positive attitude toward the capuchins and their perceptions of wildlife behavior were generally accurate. The impact of wildlife varied in relation to the field's location, number of foraging individuals, and time spent foraging, as well as plant growth patterns. Vertebrates consumed between 23 and 100 % of the crops. Capuchins consumed the majority of crop losses, though birds consumed up to a third. The presence of a watchman reduced losses from wildlife by 66 %. In conclusion, although capuchins forage flexibly on anthropogenic crops, in a society relying on subsistence agriculture, their impact is perceived to be moderate overall. Peaceful coexistence between humans and monkeys favors conservation actions targeted toward protection of the capuchins and their habitat, both of which are seriously threatened by industrial agriculture in this region
Stone tool use by adult wild bearded capuchin monkeys (Cebus libidinosus). Frequency, efficiency and tool selectivity
No full textChimpanzees have been the traditional referential models for investigating human evolution and stone tool use by hominins. We enlarge this comparative scenario by describing normative use of hammer stones and anvils in two wild groups of bearded capuchin monkeys (Cebus libidinosus) over one year. We found that most of the individuals habitually use stones and anvils to crack nuts and other encased food items. Further, we found that in adults (1) males use stone tools more frequently than females, (2) males crack high resistance nuts more frequently than females, (3) efficiency at opening a food by percussive tool use varies according to the resistance of the encased food, (4) heavier individuals are more efficient at cracking high resistant nuts than smaller individuals, and (5) to crack open encased foods, both sexes select hammer stones on the basis of material and weight. These findings confirm and extend previous experimental evidence concerning tool selectivity in wild capuchin monkeys (Visalberghi et al., 2009b; Fragaszy et al., 2010b). Male capuchins use tools more frequently than females and body mass is the best predictor of efficiency, but the sexes do not differ in terms of efficiency. We argue that the contrasting pattern of sex differences in capuchins compared with chimpanzees, in which females use tools more frequently and more skillfully than males, may have arisen from the degree of sexual dimorphism in body size of the two species, which is larger in capuchins than in chimpanzees. Our findings show the importance of taking sex and body mass into account as separate variables to assess their role in tool use. (C) 2011 Elsevier Ltd. All rights reserved
Use of stone hammer tools and anvils by bearded capuchin monkeys over time and space: construction of an archeological record of tool use
No full textWild bearded capuchins (Sapajus libidinosus) in the cerrado (seasonally dry savannah-like region) of Brazil routinely crack open several species of palm nuts and other hard encased fruits and seeds on level surfaces (anvils) using stones as hammers. At our field site, their nut cracking activity leaves enduring diagnostic physical remains: distinctive shallow depressions (pits) on the surface of the anvil, and cracked shells and stone hammer(s) on or next to the anvil. A monthly survey of the physical remains of percussive tool use at 58 anvils in our study site over a 36-month period revealed repeated use, seasonal consistency, temporal variation, landscape-scale patterning, appearance of new hammers and transport of existing hammers to new anvil sites. Artefactual evidence of the temporal and spatial pattern of tool use collected in the survey is in correspondence with concurrent direct observation of monkeys using and transporting tools at this site. Shell fragments endure for years above ground, suggesting that they may also endure in the strata around anvil sites. The bearded capuchins provide an opportunity to study the construction of percussive tool sites suitable for archeological investigation concurrently with the behavior responsible for the construction of these sites. We suggest several lines of inquiry into tool sites created by capuchin monkeys that may be useful to interpret the archeological evidence of percussive tool use in early humans. Archeologists should be aware that transported stone materials and artificial durable landscape features may be the result of activity by non-human animals. (c) 2013 Published by Elsevier Ltd
"Vision for action" in young children aligning multi-featured objects: Development and comparison with nonhuman primates
No full textEffective vision for action and effective management of concurrent spatial relations underlie skillful manipulation of objects, including hand tools, in humans. Children's performance in object insertion tasks (fitting tasks) provides one index of the striking changes in the development of vision for action in early life. Fitting tasks also tap children's ability to work with more than one feature of an object concurrently. We examine young children's performance on fitting tasks in two and three dimensions and compare their performance with the previously reported performance of adult individuals of two species of nonhuman primates on similar tasks. Two, three, and four year-old children routinely aligned a bar-shaped stick and a cross-shaped stick but had difficulty aligning a tomahawk-shaped stick to a matching cutout. Two year-olds were especially challenged by the tomahawk. Three and four year-olds occasionally held the stick several inches above the surface, comparing the stick to the surface visually, while trying to align it. The findings suggest asynchronous development in the ability to use vision to achieve alignment and to work with two and three spatial features concurrently. Using vision to align objects precisely to other objects and managing more than one spatial relation between an object and a surface are already more elaborated in two year-old humans than in other primates. The human advantage in using hand tools derives in part from this fundamental difference in the relation between vision and action between humans and other primates
Distribution of potential suitable hammers and transport of hammer tools and nuts by wild capuchin monkeys
No full textSelection and transport of objects to use as tools at a distant site are considered to reflect planning. Ancestral humans transported tools and tool-making materials as well as food items. Wild chimpanzees also transport selected hammer tools and nuts to anvil sites. To date, we had no other examples of selection and transport of stone tools among wild nonhuman primates. Wild bearded capuchins (Cebus libidinosus) in Boa Vista (Piaui, Brazil) routinely crack open palm nuts and other physically well-protected foods on level surfaces (anvils) using stones (hammers) as percussive tools. Here we present indirect evidence, obtained by a transect census, that stones suitable for use as hammers are rare (study 1) and behavioral evidence of hammer transport by twelve capuchins (study 2). To crack palm nuts, adults transported heavier and harder stones than to crack other less resistant food items. These findings show that wild capuchin monkeys selectively transport stones of appropriate size and hardness to use as hammers, thus exhibiting, like chimpanzees and humans, planning in tool-use activities
Physical properties of palm fruits processed with tools by wild bearded capuchins (Cebus libidinosus)
No full textHabitually, capuchin monkeys access encased hard foods by using their canines and premolars and/or by pounding the food on hard surfaces. Instead, the wild bearded capuchins (Cebus libidinosus) of Boa Vista (Brazil) routinely crack palm fruits with tools. We measured size, weight, structure, and peak-force-at-failure of the four palm fruit species most frequently processed with tools by wild capuchin monkeys living in Boa Vista. Moreover, for each nut species we identify whether peak-force-at-failure was consistently associated with greater weight/volume, endocarp, thickness, and structural complexity. The goals of this study were (a) to investigate whether these palm fruits are difficult, or impossible, to access other than with tools and (b) to collect data on the physical properties of palm fruits that are comparable to those available for the nuts cracked open with tools by wild chimpanzees. Results showed that the four nut species differ in terms of peak-force-at-failure and that peak-force-at-failure is positively associated with greater weight (and consequently volume) and apparently with structural complexity (i.e. more kernels and thus more partitions); finally for three out of four nut species shell thickness is also positively associated with greater volume. The finding that the nuts exploited by capuchins with tools have very high resistance values support the idea that tool use is indeed mandatory to crack them open. Finally, the peak-force-at-failure of the piassava nuts is similar to that reported for the very tough panda nuts cracked open by wild chimpanzees; this highlights the ecological importance of tool use for exploiting high resistance foods in this capuchin species
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Selection of Effective Stone Tools by Wild Bearded Capuchin Monkeys
No full textAppreciation of objects' affordances and planning is a hallmark of human technology. Archeological evidence suggests that Pliocene hominins selected raw material for tool making [1, 2]. Stone pounding has been considered a precursor to tool making [3, 4], and tool use by living primates provides insight into the origins of material selection by human ancestors. No study has experimentally investigated selectivity of stone tools in wild animals, although chimpanzees appear to select stones according to properties of different nut species [5, 6]. We recently discovered that wild capuchins with terrestrial habits [7] use hammers to crack open nuts on anvils [8-10]. As for chimpanzees, examination of anvil sites suggests stone selectivity [11], but indirect evidence cannot prove it. Here, we demonstrate that capuchins, which last shared a common ancestor with humans 35 million years ago, faced with stones differing in functional features (friability and weight) choose, transport, and use the effective stone to crack nuts. Moreover, when weight cannot be judged by visual attributes, capuchins act to gain information to guide their selection. Thus, planning actions and intentional selection of tools is within the ken of monkeys and similar to the tool activities of hominins and apes
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
- …
