Full text
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| Author(s): |
Bianca de Oliveira Fonseca
Total Authors: 1
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| Document type: | Master's Dissertation |
| Press: | São Paulo. |
| Institution: | Universidade de São Paulo (USP). Instituto de Psicologia (IP/SBD) |
| Defense date: | 2012-03-27 |
| Examining board members: |
Eduardo Benedicto Ottoni;
Briseida Dogo de Resende;
Michele Pereira Verderane
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| Advisor: | Eduardo Benedicto Ottoni |
| Abstract | |
Experiments with captive, semi-free and wild tufted capuchin (Sapajus sp) groups in tasks involving the selection of tools to crack encapsulated fruit seem to show that these primates can distinguish functional from non-functional tools, and also choose, among functional tools, the most efficient ones. In the present study, we investigate these choices in a semi-free group by means of experiments analyzing the potential preferences for hammer stones of a particular weight and the effects of costs and benefits associated with their transport and handling, to verify whether these preferences are modified as a function of the transport distance to their place of utilization (the anvils) or of the toughness of the available nuts. We found a preference by juveniles for heavier hammers than the ones chosen by adults, which may point to a compensation by the former, since they are smaller and weaker, and heavier hammers require less strikes to crack nuts open. Individual choices seem to indicate the influence of factor such as body size and nut cracking experience on hammer choice. ix Besides weight, the costs of transporting the tools to their utilization sites seem to be the most relevant variable examined affecting the average weight of the chosen hammers: when these had to be carried to the anvils, the subjects selected lighter hammers, as compared to when hammers were made available near the anvils. The precise transport costs did not seem to be taken into account, though, since the transport distance (5m x 10m) did not affect choices. The choice of hammers of a given weight were also not significantly affected by the palm nut species made available, either Syagrus Romanzoffiana (smaller), or Atallea dubia (bigger) (AU) | |
| FAPESP's process: | 09/03223-5 - Selection and transport of tools to crack open nuts by semifree-ranging capuchin monkeys (Cebus apella): experimental manipulation of costs, quality of "hammers" and the distance between "hammers" and "anvils". |
| Grantee: | Bianca de Oliveira Fonseca |
| Support Opportunities: | Scholarships in Brazil - Master |