The study, which was published in Science Advances

Understanding how and when hominins developed the capacity to purposefully produce sharp stone flakes is a significant subject that is normally addressed through the analysis of ancient artifacts and fossils. The study demonstrates that the manufacturing of stone tools is not limited to humans and their ancestors. It is not surprising that these macaques utilize tools to prepare nuts because they also use them to access a variety of shellfish. It's interesting because they unintentionally create a sizable archaeological record of their own that is partially identical to some items from early hominins.

The researchers were able to demonstrate that many of the items generated by monkeys fall within the range of those often associated with early hominins by contrasting the inadvertently created stone fragments formed by the macaques with those from some of the earliest archaeological sites. The spectrum of behaviors we identify with sharp-edged flakes in the archaeological record may be affected by the fact that these artifacts can be made through nut-cracking.

The recently discovered macaque stone tools provide new insights into how the first technology may have begun in our earliest ancestors and suggest that its origin may have been connected to similar nut-cracking behavior, which may be much older than the earliest archaeological evidence currently known.

Using stone hammers and anvils to crack nuts, like certain monkeys do today, has been proposed by some as a potential predecessor to the intentional manufacturing of stone tools. The results of this investigation pave the way for future attempts to locate such an archaeological signature. This finding also demonstrates how study into the ancestry and evolution of tool use in our own lineage can be benefited comparing stone tool use of living primates.