Evolution Research - General Evolution News

Researchers have found evidence that chimpanzees from West Africa were cracking nuts with stone tools before the advent of agriculture, thousands of years ago. The result suggests chimpanzees developed this behaviour on their own, or even that stone tool use was a trait inherited from our common ancestor.

Julio Mercader, Christophe Boesch and colleagues found the stones at the Noulo site in Cote d'Ivoire, the only known prehistoric chimpanzee settlement. The stones they excavated show the hallmarks of use as tools for smashing nuts when compared to ancient human or modern chimpanzee stone tools. Also, they found several types of starch grains on the stones; part of the residue derived from cracking local nuts.

The tools are 4300 years old, which, in human terms, corresponds to the Later Stone Age.

Image caption: Examples of some of the stones that were excavated. Analysis shows they were used by chimpanzees some 4,300 years ago to crack nuts. (Credit: University of Calgary)

Before this study [1], chimpanzees were first observed using stone tools in the 19th century. Now, thanks to this new archaeological find, tool use by chimpanzees has been pushed back thousands of years. The authors suggest this type of tool use could have originated with our common ancestor, instead of arising independently among hominins and chimpanzees or through imitation of humans by chimpanzees.

This study confirmed that chimpanzees and human ancestors share for thousands of years several cultural attributes once thought exclusive of humanity, including transport of raw materials across the landscape; selection and curation of raw materials for a specific type of work and projected usage; habitual reoccupation of sites where garbage and debris accumulate; and the use of locally available resources. Nut cracking behaviour in chimpanzees is transmitted socially, and the new discoveries presented in this study shows that such behaviour has been transmitted over the course of many chimpanzee generations. Chimpanzee prehistory has deep roots!

The study of our living closest relative, the chimpanzee, constantly highlights new aspects of human evolution, and a better protection of this endangered species will guarantee that we can continue uncovering new facets of our past. Relevant finds come from all parts of the African continent, including the rainforest, and not just the classical east African homeland.

Source: Max Planck Institute for Evolutionary Anthropology - "The Chimpanzee Stone Age" February 13th, 2007

[Primatology, Archaeology]

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Video of chimpanzees using stone tools to crack nuts:

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[1] Julio Mercader, Huw Barton, Jason Gillespie, Jack Harris, Steven Kuhn, Robert Tyler, and Christophe Boesch

4300-year-old chimpanzee sites and the origins of percussive stone technology.

Published online before print February 20, 2007
Proc. Natl. Acad. Sci. USA, 10.1073/pnas.0607909104

Archaeological research in the African rainforest reveals unexpected results in the search for the origins of hominoid technology. The ancient Panin sites from Cote d'Ivoire constitute the only evidence of prehistoric ape behavior known to date anywhere in the world. Recent archaeological work has yielded behaviorally modified stones, dated by chronometric means to 4,300 years of age, lodging starch residue suggestive of prehistoric dietary practices by ancient chimpanzees. The "Chimpanzee Stone Age" pre-dates the advent of settled farming villages in this part of the African rainforest and suggests that percussive material culture could have been inherited from an common human-chimpanzee clade, rather than invented by hominins, or have arisen by imitation, or resulted from independent technological convergence.

Also see:

Excavation of a Chimpanzee Stone Tool Site in the African Rainforest
Julio Mercader, Melissa Panger, Christophe Boesch

Science 24 May 2002:
Vol. 296. no. 5572, pp. 1452 - 1455
DOI: 10.1126/science.1070268

Chimpanzees from the Tai forest of Cote d'Ivoire produce unintentional flaked stone assemblages at nut-cracking sites, leaving behind a record of tool use and plant consumption that is recoverable with archaeological methods. About 40 kilograms of nutshell and 4 kilograms of stone were excavated at the Panda 100 site. The data unearthed show that chimpanzees transported stones from outcrops and soils to focal points, where they used them as hammers to process foodstuff. The repeated use of activity areas led to refuse accumulation and site formation. The implications of these data for the interpretation of the earliest hominin archaeological record are explored.

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