<?xml version="1.0" encoding="UTF-8"?><xml><records><record><source-app name="Biblio" version="7.x">Drupal-Biblio</source-app><ref-type>17</ref-type><contributors><authors><author><style face="normal" font="default" size="100%">Christophe Boesch</style></author><author><style face="normal" font="default" size="100%">Hedwige Boesch</style></author></authors></contributors><titles><title><style face="normal" font="default" size="100%">Possible causes of sex differences in the use of natural hammers by wild chimpanzees</style></title><secondary-title><style face="normal" font="default" size="100%">Journal of Human Evolution</style></secondary-title></titles><keywords><keyword><style  face="normal" font="default" size="100%">Chimpanzees</style></keyword></keywords><dates><year><style  face="normal" font="default" size="100%">1984</style></year></dates><urls><web-urls><url><style face="normal" font="default" size="100%">http://www.sciencedirect.com/science/article/pii/S004724848480055X</style></url></web-urls></urls><volume><style face="normal" font="default" size="100%">13</style></volume><pages><style face="normal" font="default" size="100%">415 - 440</style></pages><language><style face="normal" font="default" size="100%">eng</style></language><abstract><style face="normal" font="default" size="100%">&lt;p&gt;The wild chimpanzees of the Tai National Park, Ivory Coast, present an important sex difference in nut-cracking behavior: Adult females more frequently perform the two most difficult techniques, coula cracking in the tree and panda cracking. Adult females are more efficient than males in all the three nut-cracking techniques for one or the other measure of efficiency (number of hits/nut and number of nuts opened/min). The analysis of 5 hypotheses which may explain these differences, stresses the role of the difference of sociability and sexual dimorphism between the sexes, both negatively affecting the nut-cracking techniques and performance of the adult males. We shall discuss the role of these factors on the evolution of the division of labor and food-sharing in the chimpanzee and in early hominids.&lt;/p&gt;
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