How Monkeys Are Making Stone Flakes


A month or two ago, while I was listening to the radio before bed I overheard my local NPR station talk about an observation made by scientists/archeologists regarding the creation of stone flakes by monkeys and how they seem to be similar to the flakes that they find at our old sties. Since I started dabbling in the history of stone tools and learning how to create them, I had to check out their article and see what they had to say about the whole phenomenon. I think it is important to really acknowledge this discovery as it may shine some light on how our early ancestors slowly began to use stone tools as our body and brain evolved over time. There is some correlation between our early use of stone tools and what we are observing in this article.

I hope to showcase how interesting this really is for us who are curious about what it means to be human and how far we as a species have come, as well as some of the beginning technological steps/advancements we may be witnessing with other species in the near future. I plan to highlight why this observation is significant and how it correlates to our own history within our own lineage, how the monkeys are creating the stone flake tools, what they are doing with the tools, what this may signal within our own archeological sites, and lastly my prediction on the potential future for further stone tools for the primates based on how our ancestors utilized the stone tools.

1. Why This is Significant

This finding is very interesting and is unlike many that we have seen before, this is because we are now observing the creation of stone flake tools, much like the ones our ancestors utilized as cutting implements in the not so long future. This showcases how our ancestors maybe discovered a use for the flakes over periods of time where the waste lie sprawled everywhere due to the use of the flint/chert/quartzite hammerstone to crack open nuts or other food items, thus causing flakes to break off of their tools as a byproduct.

 NPR writer Nell Greenfieldboyce describes why this this finding is important in respect to human archeology in her article titled, Stone Flakes Made By Modern Monkeys Trigger Big Questions About Early Humans, when she states, “This surprising discovery, described in the journal Science Advances, has archaeologists wondering if they need to rethink their assumptions about some of the stone artifacts produced by early human ancestors over a million years ago.

“You have a bunch of nonhuman primates that are creating objects that look a lot like the kinds of things that we have wanted to exclusively assign to the behavior of humans and human ancestors,” says Jessica Thompson, a paleoanthropologist with Yale University who wasn’t on the team that did this new research. She notes that the manufacture of sharp cutting tools made of stone, which could date as far back to 3.3 million years ago, has long been seen as a key technological innovation in human history, one that’s wrapped up in a host of assumptions about the evolution of unique human traits”.

Greenfieldboyce reiterates what Jessica Thompson says and emphasizes the true potential that these monkeys possess. This is the start of their technological tree once one of them realizes how to fully utilize what is now considered as a byproduct of their normal tool use.  

Thinning flakes from one of my recent points, and a crude biface in the background

2. How it Parallels Our History

The use and creation of stone flake tools are something that had been deemed as to only be observed with early to modern humans. The use of stone tools and flakes are usually correlated with both the advancement of human diets, intelligence, and the ability to change form and function as human evolution needed it to. As our heads got bigger our teeth shrunk and we lost the original function of teeth such as our canine teeth which were used to pull things apart and grab onto objects. This is where the stone tools came in. No longer, would we need to use our teeth to pull apart meat, break nuts, or cut fibers for crafting. From there we used stone tools to create stronger, more efficient tools out of various different materials and shapes. This is what led us to eventually make it to the place that we are today. Sure, this took hundreds of thousands of years, but we eventually made due. Like many things that humans have discovered, we most likely created the stone flakes on accident for some time prior to our actual need for the tools.

3. How They Use The Tools

It is interesting that the monkeys have produced these sharp flakes. Typically, early humans these flakes were used to cut meat or were used for cutting other materials and were even hafted onto sticks and shafts to be used as a spear or arrow, though this was not until later in the advancement of human technology.

Greenfieldboyce describes how the monkeys utilize the tools when she writes, “A small number of chimpanzees in West Africa are known to use rocks as hammerstones, although they don’t leave many flakes behind, perhaps because of the type of stone they use.

And Capuchin monkeys in Brazil have been shown to pound seeds and nuts with stones — something they’ve apparently done for hundreds of years, leaving behind their own archaeological record.

That’s why some researchers have recently called into question some of the earliest evidence in Brazil for when humans might have entered the continent, saying ancient sites from 50,000 years ago could have been created by monkeys instead of people.

The Capuchin monkeys also sometimes deliberately break rocks by pounding them together for unknown reasons (they also sometimes lick or sniff the crushed stone). This activity produces accumulations of sharp-edged flakes that can look like intentionally-made stone tools — even though those monkeys in Brazil never use the broken flakes as a tool, scientists reported in 2016.

Some of the researchers involved in that study have now turned their attention to wild, long-tailed macaques in Thailand. These monkeys routinely use stones as anvils and hammers to crack open the hit the two stones together. This creates broken pieces of stone that collect around the anvil”.

Scientists don’t really know whether or not the monkeys are purposely crafting these stone flakes or if they are merely a product of their other stone tool use by mere chance or coincidence as they try to crack nuts and miss

4. What This Means For Current Arceological Sites

Leading from the previous description of how these primates use stone tools and create these interesting flakes, Greenfieldboyce speaks with archeologist David Braun of George Washington University talks about how this finding could potentially make archeological sites in South America dated back 50,000 years the work of monkeys cracking nuts. This could potentially rewrite the hypothesis that humans have been in North/South America for the past 50,000 years. This raises issues with peer reviewing these studies and trying to be able to distinguish and properly associate the sites with our ancestors.

5. The Potential Future of Stone Tools For Primates

After reading this article it made me think about how time goes on the primates could follow a similar pattern of technological advancements through the creation of more intricate/sophisticated tools as they evolve and undergo physiological changes. To me, it seems that these groups of monkeys are technologically starting to mirror our own origin story in a way that feels eerie. It makes me feel like in the future if humans do end up trashing the planet and moving to Mars or killing ourselves in a blaze of glory that maybe in a few million years a new dominant primate will take our spot. It may seem ridiculous now, but I wish I could see what the world would look like in a scenario like that.


This observation of monkeys creating stone flakes through the use of using hammerstones to break nuts is very important in understanding our own origin. Not only does it showcase how our ancestors might have created the first flake tools and how we ended up using them, but it also showcases that we might not be the only ones who have the potential to use sharp stone tools. Though the monkeys don’t actively create or use these tools, it makes me question how humans began using the tools. Was it because we simply evolved and lost our jaw strength and prominent canine teeth, or was it one of those things that just made our lives easier, thus leading to less of a need for sharp canines and other physiological attributes? This question is much like the age old question “which came first, the chicken or the egg?”; it really makes me wonder how many of the archeological sites that we have found are really from modern monkeys and how this could impact our hypothesis of how and when we got to the Americas.

Works Cited

Greenfieldboyce, Nell. “Stone Flakes Made by Modern Monkeys Trigger Big Questions about Early Humans.” NPR, NPR, 10 Mar. 2023,,Macaques%20use%20stones%20as%20hammers%20to%20smash,items%20like%20shellfish%20and%20nuts.&text=When%20monkeys%20in%20Thailand%20use,tools%20made%20by%20early%20humans.

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