Variation in the termite fishing of wild chimpanzees

Older chimpanzees more likely to use tools
from TheHindu.com

Age appears to affect the degree to which chimpanzees are prepared to try out new things, at least when it comes to catching termites. Elderly chimpanzees use a greater number of tools, according to an article published in the scientific journal Biology Letters by a group of US researchers.

They discovered that older chimpanzees experimented with tools and used them for tasks apart from catching termites. Younger animals, on the other hand, not only used a smaller range of tools but took more time to get the required result.

Crickette Sanz from Washington University in Saint Louis and David Morgan from the Wildlife Conservation Society in Chicago examined 130 video recordings of chimpanzees. The videos were recorded between 2003 and 2007 in Nouabale Ndoki National Park in the Republic of Congo. Many of the animals were recorded hunting for termites several times.

The region’s chimpanzees are known for their ability to catch termites with several different tools. They are also known to adapt these tools and to show a preference for certain materials. Termites in overground nests are caught by boring a thin branch into one of the nest’s tunnels. A second tool with a brush—like top is then used to fish the termites out. A different method is used for underground nests: the chimpanzees dig a tunnel into the earth through which they then use the brush tool to catch termites.

The researchers discovered that older and younger animals went about employing these two methods in very different ways. Younger chimpanzees used a limited range of tools compared to older animals who also employed different methods of fishing termites from their nest.

If a tunnel became blocked, some of the older chimpanzees would turn the brush tool around and use its other end to remove the blockage. The researchers believe this is an example of how the animals use their knowledge to use certain tools for several functions.

Some chimpanzees also transported tools to termite nests, showing a degree of planning. The researchers say a better understanding of how chimpanzees use tools helps us understand how our human ancestors utilised technology.

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Reference
Sanz C, and Morgan D (2011) Elemental variation in the termite fishing of wild chimpanzees (Pan troglodytes) Biology Letters doi: 10.1098/rsbl.2011.0088

Abstract
Chimpanzee tool behaviours vary dramatically in their complexity and extent of geographical distribution. The use of tool sets with specific design features to gather termites extends across a large portion of central Africa. Detailed examination of the composition and uniformity of such complex tool tasks has the potential to advance our understanding of the cognitive capabilities of tool users and processes underlying the maintenance of technological skills. In this study, we examined variation in chimpanzee tool use in termite gathering from video-recorded sequences that were scored to the level of functionally distinct behavioural elements. Overall, we found a high degree of similarity in tool-using techniques exhibited by individuals in this population. The number of elements in each individual's repertoire often exceeded that necessary to accomplish the task, with consistent differences in repertoire sizes between age classes. Adults and subadults had the largest repertoires and more consistently exhibited element strings than younger individuals. Larger repertoires were typically associated with incorporation of rare variants, some of which indicate flexibility and intelligence. These tool using apes aid us in understanding the evolution of technology, including that of our human ancestors, which showed a high degree of uniformity over large spatial scales.