Two news articles (BBC News and Live Science) are reporting a new archaeological find from Julio Mercader et al., who has discovered a deposit of stone tools at the Noulo site in Ivory Coast of West Africa. This site is known exclusively for being prehistoric chimpanzee settlement, and the find is dated to be 4,300 years old.
“The stones were much bigger than anything a human could use comfortably and bore the residue of nuts that modern chimpanzees like to snack on.”
The age of the tools was determined by radiocarbon dating the charcoal from the same ground layers the stone tools were in. The discovery represents the oldest evidence of tool use by our closest evolutionary relative.
Chimps stone tool usage has been going on for sometime; they have been observed using similar tools for the past few centuries. The origins of this behavior was thought to come from imitation, where chimps mimicked human’s using hammers and various tools. These stones now suggest the contrary, where now there is evidence that chimpanzees developed this behaviour on their own, or even that stone tool use was a trait inherited from our common ancestor. The age of these stone tools show us now that,
“chimpanzee material culture has a long prehistory whose deep roots are only beginning to be uncovered.”
I wonder something more globally than how and where this behavior came about, actually how does this finding change the concept of “man the tool maker?” While chimps don’t necessarily make these tools, they do select for stones that are more effective in cracking nuts. So how does this change Homo habilis‘ legacy and how we have, for the most part, ignorantly assumed australopithecines incapable of stone tool selection?
Julio and his teams’ report will be published soon in a February 2007 PNAS paper titled, “4300-year-old chimpanzee sites and the origins of percussive stone technology.” In the meantime you can check out the press releases issued by his co-author Christoph Boesch and also photos from the dig where you can see Julio and Chris excavating the tools:
Oh yes, this discovery is not entirely new, Julio Mercader published a similar albeit more preliminary discovery in 2002, “Excavation of a Chimpanzee Stone Tool Site in the African Rainforest.” You may wanna have a read at that before the paper in PNAS gets published.
“Chimpanzees from the Taï forest of Côte 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.”
I’ve cross posted this to Anthropology.net for more exposure.