BY ZACHARY ROMANO
If it can be mapped, GIS, can be used to conduct analysis. A group of scholars used this fact to develop an innovative new application of GIS to understand stone tool use behaviors in chimpanzees during nut-cracking season. The team conducted a study in Guinea on the variation in stone tool use among these primates and GIS was used to analyze the spatial patterning of wear on the tools at the end of the season. The study could successfully identify distinct, spatial differences in active and passive tool use and exhibited the reliability of this method.
Researchers from Italy were one of the first to develop an accurate GIS technique for assessing the use of tools in chimpanzees. Nearly 47 experimental sessions were conducted, which called for the purposeful placement of nut piles and numbered stone tools within the study area. The chimpanzees nut-cracking behavior was video-recorded and the battered tools were later analyzed. Preliminary morphometric GIS analysis allowed the researchers to identify the basic topography of the surface and to classify whether the tool was used for nut cracking or the wear was caused by something else.
For enhanced precision, this method quantified indices for two important physical features: polish, or the flat sheen on a rock, indicative of intensive tool use, and depression, or indentation, a key feature of nut cracking activity. Human artifacts found in assemblages from as early as the Late Stone Age to the Holocene era were also analyzed within this framework and were directly compared to the patterns on the chimpanzee tools. If similarities were seen, this would provide evidence to the evolution of humans from primates. This has opened the door for GIS methods to be used when studying human evolution. Moreover, it builds off the Human Genome Project where the rich dataset allowed researchers to map the geographic movement of genetic markers out of Africa, which is one of the predominant theories for human evolutionary migration patterns. These genetic markers indicated the general path and branching points of early humans as they left the African continent after the last Ice Age.
A) VIEW OF THE EXPERIMENTAL AREA IN THE FOREST OF BOSSOU, GUINEA. RESEARCHERS RECORD THE NUT-CRACKING BEHAVIOR EVERY YEAR, USING SEVERAL VIDEO CAMERAS WHILE STAYING BEHIND A SCREEN OF VEGETATION, C. 20M DISTANCE FROM THE WILD CHIMPANZEES USING TOOLS. B) FEMALE USING A STONE HAMMER AND ANVIL TO CRACK OPEN NUTS. NOTE THE ASSORTMENT OF STONES ON THE RIGHT SIDE WHICH IS PROVIDED BY THE RESEARCHERS, ALONG WITH THE PILES OF NUTS. FROM ENITO-CALVO A, CARVALHO S, ARROYO A, MATSUZAWA T, DE LA TORRE I (2015).
Data from the experiments showed that there are in fact unique patterns associated with both active and passive tool use. The GIS portion of the analysis was also blind in that the researcher only had a 3D visualization of the tools’ surface and not the actual artifact. These results were compared to the behavioral data collected and indicated that the presence of marks concentrated on the center rather than the edges of a tool were thought to potentially be explained by chimpanzees who had not mastered the technique of nut cracking. Conversely, the intensive wear on the side of a stone would indicate a more sophisticated use of the tool. Such a potential finding offers a foundation for further analysis. Although the behavioral conclusions are still ongoing, due to the lack of research precedents with this method, the chimpanzee study has provided evidence in favor of morphometric analysis for archaeology and its ability to offer significant results.
More:
Benito-Calvo A, Carvalho S, Arroyo A, Matsuzawa T, de la Torre I (2015) First GIS Analysis of Modern Stone Tools Used by Wild Chimpanzees (Pan troglodytes verus) in Bossou, Guinea, West Africa. PLoS ONE 10(3): e0121613. doi:10.1371/journal.pone.0121613
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