Tool-use and cognition in Darwins´s finches
Zusammenfassung der Projektergebnisse
One of the fundamental issues in the study of human and animal cognition concerns the factors that drove the evolution of intelligence. The ability to use tools has played a long-standing role in this debate. In this project, we aimed to investigate whether the use of tools evolved in conjunction with enhanced cognitive abilities in the physical domain, using a comparative approach. Alternately, tool-use might have evolved along with enhanced general learning abilities or without a cognitive adaptation related to tool-use. To distinguish between these scenarios, we compared general learning and physical cognitive abilities in a toolusing bird species, the woodpecker finch (Cactospiza pallida) and a closely related non-tool-using species, the small tree finch (Camarhynchus parvulus). Both species belong to the famous group of Darwin's finches, the poster children of adaptive radiation who are also impressive in the range of their unusual foraging techniques. If tool-use evolved with enhanced specialized cognitive abilities, we would expect woodpecker finches to outperform small tree finches in the physical tasks but not necessarily in the general learning tasks. Since not all woodpecker finches use tools (in areas where food is abundant, they do not develop tool-use) we were also able to investigate whether tool-use affects the development of cognitive abilities in ontogeny by comparing the task performance of tool-using and non-tool-using woodpecker finches. Birds received two general learning tasks and four tests of physical cognitive abilities. Examples of these tasks include one general learning task which required finches to figure out how to open a box with a transparent lid and a physical task where individuals had to learn to choose between two canes, only one of which was in line with a food reward, so that pulling the tool extracted the reward. Contrary to our prediction, we found no evidence that woodpecker finches are better at solving physical tasks than small tree finches. In one of the general learning tasks and most of the physical tasks, small tree finches performed equally to or better than woodpecker finches. Therefore, the hypothesis that tool-use in woodpecker finches evolved in conjunction with enhanced physical cognition must be rejected. Indeed, the competency of small tree finches in these tasks indicates that enhanced general learning abilities and flexibility preceded the evolution of tool-use. Finally, we did not find a significant difference in performance between tool-using and non-tool-using woodpecker finches in any of the tasks, indicating that tool-using experience does not necessarily hone specialized cognition.
Projektbezogene Publikationen (Auswahl)
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2010. The tale of the finch: adaptive radiation and behavioural flexibility. Philosophical Transactions of the Royal Society B: Biological Sciences, 365, 1099-1109
Tebbich, S., Sterelny, K. & Teschke, I.
