How Have Monkeys Rewritten History?

Humans and monkeys have a common ancestor. It’s not quite the “humans evolved from monkeys” tale that misconceived folklore would have you believe, but it’s based on sound evidence from decades of research. As time goes on, we’re piecing together the puzzle even more. But a new discovery might have thrown a spanner in the works, or more aptly a ‘tool-like flake’.

A landmark event

Years and years of wide-ranging research has given us a timeline of milestones through evolution. One of these, which is particularly prominent, is the development of tools. Until now, we believed that flakes of stone resembling tools were evidence of an advanced species.

The creation of a tool, however simple, requires some degree of planning, advanced (human-like) cognition, as well as a high level of hand co-ordination. It’s this which lead archaeologists and historians to assume tools marked a point where humans began to diverge from their ape ancestors. If we could trace the date of tools, we could trace the date when humans began to develop.

“Our understanding of the new technologies adopted by our early ancestors helps shape our view of human evolution. The emergence of sharp-edged stone tools that were fashioned and hammered to create a cutting tool was a big part of that story,” explains Oxford’s Dr Michael Haslam, leader of the project.

Capuchin monkeys

However, when scientists from Oxford, UCL and Sao Paolo observed Capuchin monkeys, they found something a bit contradictory. The monkeys picked up stones and used them to hammer other embedded rocks. It’s thought to be a practice to remove nutrients from the stones, but it actually caused their hammer stones to fracture and flakes to break off. Do you see where this is going?

Collecting and analysing the fragments of broken stone, the scientists found a lot of them to have surprisingly smooth fractures. These were the kind of features we had previously assumed to be uniquely human creations. Their findings support the idea that the tool-like flakes were actually produced by a wider range of hominins, rather than just primitive humans.

Separated by the function

Despite these findings, there is still evidence of how the humans used the tools. Archaeologists assert that this is what separates the hominins from monkeys. How do we know? Lithic microwear analysis allows scientists to study the traces of wear on the tools we discover. However, new, innovative methods could prove to be more effective with such limited materials, as discussed in ‘Surface Tomography and Metrology in the Quest to Understand Prehistoric Man: An Application of Laser Scanning Confocal Microscopy’.