Distance-decay effect in stone tool transport by wild chimpanzees

Area of Science:

• Primate behaviour
• Archaeology
• Landscape evolution

Background:

• Stone tool transport leaves lasting evidence in landscapes.
• Understanding how short-term, undirected behaviors create large-scale patterns is crucial.
• Chimpanzees in Taï National Park are a long-studied model for stone tool use.

Purpose of the Study:

• To investigate the emergence of large-scale stone distribution patterns from short-term transport behaviors.
• To test for a distance-decay effect in chimpanzee hammerstone distribution.
• To explore the relevance of chimpanzee tool transport for understanding hominin landscape formation.

Main Methods:

• Analysis of hammerstones left at chimpanzee Panda nut-cracking sites.
• Testing for a distance-decay effect (material weight decreasing with distance from source).
• Comparison of modern chimpanzee patterns with millennia-old tool sites (Noulo site).

Main Results:

• A significant distance-decay effect was observed for hammerstones up to 2 km from raw material sources.
• This pattern emerged despite chimpanzee tool transport not appearing to be deliberately directed away from sources.
• Ancient tools from the Noulo site exhibited a similar distance-decay pattern.

Conclusions:

• Chimpanzee stone tool transport demonstrates complex short-term planning leading to long-term landscape patterns.
• The Taï chimpanzee model provides a relevant analogy for understanding hominin landscape formation, particularly where discrete material sources and distance-decay effects are present.
• Further research into other stone-tool-using primates, including hominins, is warranted to explore similar landscape-forming processes.