Archived Abstracts
Nut-cracking behaviour in wild-born, rehabilitated bonobos (Pan paniscus): a comprehensive study of hand-preference, hand grips and efficiency
Authors: Johanna Neufuss, Tatyana Humle, Andrea Cremaschi, Tracy L. Kivell
There has been an enduring interest in primate tool-use and manipulative abilities, most often with the goal of providing insight into the evolution of human manual dexterity, right-hand preference, and identifying the set of behaviors that make humans unique. Chimpanzees are arguably the most well-studied tool-users among primates, and they are renowned for their complex tool-use and particularly their nut-cracking behavior. Unlike their chimpanzee cousins, bonobos rarely use even simple tools (e.g. dragging branches, leaf sponging) in the wild and have never been observed to crack nuts. Only a few studies have reported tool-use in captive bonobos, including their ability to crack nuts, but details have not been documented before. VIrtually everything we currently know about the bonobo’s manual manipulative abilities derives from a few studies in captivity, mainly using unnatural objects or artificial manipulative tasks. Here, we fill this gap with the first comprehensive analysis of bonobo nut-cracking in a natural environment at the Lola ya Bonobo sanctuary, Democratic Republic of the Congo. Our study demonstrates that bonobos have a much greater ability for the complex tool-use behavior than traditionally believed. The study revealed that bonobos use 15 hand grips for manipulating different hammerstones, 10 of which had not been previously described in the literature, and most often selected the most effective hammerstones. Additionally, bonobos use either the right or left hand exclusively during nut-cracking, with the majority of individuals being right-handed. We show that bonobos are efficient nut-crackers with a skill level that is similar to that of wild nut-cracking chimpanzees.
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