Researchers from the Max Planck Institute for Evolutionary Anthropology have discovered artifacts produced by Old World monkeys in Thailand that resemble stone tools, historically identified as being intentionally made by early hominins. Until now, sharp-edged stone tools were thought to mark the beginning of the intentional production of stone tools, one of the hallmarks and unique features of hominin evolution. This new study challenges long-held beliefs about the origins of intentional tool production in our lineage.
The research is based on new analyzes of stone tools used by long-tailed macaques in Phang Nga National Park in Thailand. These monkeys use stone tools to crack the hard-shelled nuts. In the process, the Monkeys often break the hammer and the anvil. The resulting agglomeration of broken stones was large and widespread throughout the land. Moreover, many of these artifacts bear all the same characteristics that are commonly used to identify deliberately made stone tools at some of the oldest archaeological sites in East Africa.
“The ability to intentionally make sharp stone flakes is seen as a crucial point in hominin evolution, and understanding how and when this happened is a huge question that is typically investigated through the study of artefacts and past fossils. Researcher at the Max Planck Institute for Evolutionary Anthropology, Tool production is not unique to humans and our ancestors.” The fact that these macaques use stone tools to process nuts is not surprising, as they also use tools to access various shellfish as well. What is interesting is that they inadvertently produce an archaeological record of their own. It is partially indistinguishable from some hominin artifacts.”
New insights into the evolution of stone tool technology
By comparing the accidentally produced stone fragments made by macaques with those found at some of the earliest archaeological sites, the researchers were able to show that many of the artefacts produced by the monkeys fall within the range of those commonly associated with early hominins. Co-author Jonathan Reeves highlights: “The fact that these artifacts can be produced by cracking nuts has implications for the range of behaviors we associate with sharp chips in the archaeological record..”
The newly discovered stone tools provide new insights into how the first technology emerged in our earliest ancestors and that their origin may be related to similar nut cracking behavior which may be much older than the oldest current archaeological record. Cracking nuts using stone hammers and anvils, similar to what some primates do today, has been suggested by some as a possible precursor to intentional stone tool production. This study, together with previous studies published by our group, opens the door to the ability to identify such an archaeological signature in the future. ,” says Lydia Loncz, senior author of the study and head of the Technological Primate Research Group at the Max Planck Institute for Evolutionary Anthropology. “This discovery shows how living primates can help researchers investigate the origin and evolution of tool use in our lineage.”