Martin Franziska, Niemitz Carsten
Department of Human Biology and Anthropology, Freie Universität Berlin, Berlin, Germany.
J Comp Psychol. 2003 Dec;117(4):371-9. doi: 10.1037/0735-7036.117.4.371.
In this article, the side preferences of feeding-related trunk movements of free-ranging Asian elephants (Elephas maximus) were investigated for the first time. It is hypothesized that a functional asymmetry of the trunk is necessary to perform skillful feeding movements more efficiently. This might be connected with a corresponding hemispheric specialization. Video recordings of 41 wild elephants provided frequencies and durations of the following trunk-movement categories: object contact, retrieval, and reaching. In each category, individual side preferences were found. The strength of side preferences varied between the trunk-movement categories and the sexes. Mean durations of retrieval and reaching correlated negatively with the strength of side biases. Comparing the side preferences in the unpaired trunk with analogous phenomena in other unpaired grasping organs and in primate handedness. the authors discuss possible explanations for the evolution of asymmetries in unpaired grasping organs.
在本文中，首次对自由放养的亚洲象（印度象）与进食相关的躯干运动的侧偏好进行了研究。据推测，象鼻的功能不对称对于更高效地执行熟练的进食动作是必要的。这可能与相应的半球特化有关。对41头野生大象的视频记录提供了以下象鼻运动类别的频率和持续时间：物体接触、取回和够取。在每个类别中，都发现了个体的侧偏好。侧偏好的强度在象鼻运动类别和性别之间有所不同。取回和够取的平均持续时间与侧偏好的强度呈负相关。通过将不成对的象鼻的侧偏好与其他不成对的抓握器官以及灵长类动物的利手的类似现象进行比较，作者讨论了不成对的抓握器官不对称性进化的可能解释。
