Transcription
That chimpanzee just made a stone tool and that one's hunting with a spear. If this looks like the Stone Age to you, you're not wrong. They've wielded stone tools for thousands of years and some are virtually identical to those crafted by our own ancestors. So, are they truly in the Stone Age or just standing on the edge? Let's find out.
For decades, researchers thought tool use is what separated us from the other animals? What made us human? That was until a revolutionary primatologist conducted a study in the 1960s. Jane Goodall ventured into the remote Gome Stream National Park in Tanzania. One day, she witnessed chimpanzees at a termite mound repeatedly poke stocks of grass into the holes. The termites would bite onto the grass defensively, allowing the chimp to pull them out and eat them. Astonished at her discovery, Goodall told paleo anthropologist Lewis Leaky, who wrote, "Now we must redefine tool, redefine man, or accept chimpanzees as human."
Tools are evolutionary game changers. They unlock resources that would otherwise be impossible to reach. In the case of termite fishing, the stick directly aids chimpanzees in acquiring this food source. But this is far from their only tool. Further research has found that chimpanzees actually use over 20 different tools. One of the most important is their use of stone tools. Stone hammers are used to smash open hard nuts against anvil stones. This lets them consume abundant calories they otherwise would have no chance in eating.
A recent paper looked closely at this behavior and found something fascinating. Using stone tools to open nuts is not present in every population. Chimps in seasonal resource scarce environments exploit nuts more often. But the study also looked closer at the hammers and anvils themselves. They found that they differ regionally and choose a certain hammerstone size depending on the hardness of the nut. The so-called anvils that they smash the nuts against are usually just large flat stones that happen to be near the nut trees. These anvils are fairly distinct archaeologically, and researchers have found evidence that their use goes back at least 4,300 years, meaning that this behavior likely extends far into prehistory. What is also interesting to note is that some populations do not smash nuts at all. Meaning some chimpanzee populations are more technologically advanced than others.
Another important tool that chimpanzees use are spears. Yeah, that's right. They make their own spears by taking off a sturdy stick and biting the tip to form a sharp end. They use these weapons to stab into the burrows of bush babies, which are some of the cutest animals on the planet. They jam the stick into the burrow, killing the animal, and then they use the stick to get the animal out. These spears seem to be used exclusively for hunting animals that they physically cannot get to. They have never been witnessed using them against one another. However, chimpanzees have been documented using sticks and branches to hit each other. They even throw rocks during aggressive encounters. It seems that they have already had their 2001 space odyssey moment.
So, chimpanzees use rocks to crack open nuts. They fish for termites. and they even stab prey with spears. So, have they truly entered the Stone Age? Well, they are far from the only animals to use tools. Orangutans use sticks to fish for insects and honey. You may have even seen this image of an orangutan spear fishing. While it is true that this orangutan was imitating some fisherman he was watching, he was unsuccessful and pretty much just splashed a stick at the water. So, it's not impressive as it might seem. Apparently, after this shot, he ended up stealing a fish that was already hooked by a fisherman. So, I guess that's a win. But plenty of other primates like kapuchin monkeys use stones on a daily basis to open shellfish. Even otter use stones to open shellfish. Crows fish with sticks and octopuses use shells for protection. Tool use is not exclusive to humans nor primates.
So then what set our ancestors apart? Well, our ancestors took stone tools to another level by modifying them. By smashing stones together, they broke off sharp stone edges which could cut. This opened up all kinds of new resources for our ancestors. Just as the termite sticks or spears allow chimpanzees to extract calories out of their environment, sharp stone tools allowed our ancestors to do the same. On the savas where we evolved, carnivores are constantly killing prey and leaving their carcasses with plenty of meat and bone marrow left over. A study looking at zebras killed by lions found that on average 33 lb or 15 kg of meat was left over. That is roughly 20,000 calories in meat alone, not to mention the marrow. This would have met the daily requirements of about 27 early hominins. But to harvest this meat, our ancestors needed the sharp edges of stone to cut through tendons, scrape off meat, and break into the brains and marrow. This was one of humanity's biggest breakthroughs, and it's not far off of what chimpanzees are currently doing in Africa.
The earliest modified stone tools are 3.3 million years old. We don't know who was making them. It was most likely our ancestors or close relatives. But who knows? It could have even been the ancestors of chimpanzees. What we do know is that stone tool use wouldn't catch on until around 2.4 million years ago when hominids started selecting stone that could hold a sharp edge. And then they learned how to produce efficient tools. Here's an example of the kinds of tools that our ancestors were using well over 2 million years ago. It's really just a sharp flake of stone, but it's an incredibly useful tool for cutting through flesh and also pounding through bones and other objects. Though it's extremely simple, it was an evolutionary game changer for our ancestors. Many paleo anthropologists would argue that the intentional development of a cutting edge has to be the lower bound of the stone age. Otherwise, otter and capuchins are also in the stone age.
Chimpanzees have never been documented in the wild creating a sharp stone tool, but they are limited for a number of reasons. First of all, fine grain stones that create sharp edges when broken, such as flint, are not common in the modern range of chimpanzees. Most of the time, it is thick jungle, and the stones they have access to are basically useless for cutting. Our ancestors, on the other hand, lived across open rocky savas that often had sources of quality stone. But just because chimpanzees don't have access to the right raw materials for napping stone, doesn't mean they lack the intelligence to understand it. So researchers had a bold idea. What if we simply taught a chimpanzee how to flintnap?
Meet Kanzi, a language competent bonobo who was taught to flintnap in the early 1990s. Bonobos are a closely related cousin of chimpanzees, often seen as more socially intelligent. Kanzi was especially intelligent. He even learned how to play Minecraft. But it was this video of him flintnapping that honestly blew my mind. They first focused on showing him how to knock off flakes through percussion, which is what I'm doing here. You literally hit one rock against another rock in order to knock off a stone flake. So, now let's watch some incredible close-up footage of Kanzi napping.
Oh, look there. While Kanzi made that's really perfect. Oh, look at that one. Oh, thank you. They would really cut things good. Kanzi was able to knock off flakes consistently and after a while he even came up with his own methods of flintnapping. Instead of using the hammer stone in his hand, he started throwing it at the core. This may have helped him overcome challenges unique to the hands of chimpanzees or to protect his fingers. But how fascinating is it that he invented a new flintnapping technique?
After 2 years of practice, researchers decided it was finally time to put his skills to the test. They gave him an unmodified core of flint and a hammerstone. Nearby was a clear box with fruit inside. It was held shut by a thick nylon cord. In order to get to his reward, he would have to hit off a large sharp flake to cut through the cord. During the trial, knocking off flakes was not a problem for the trained bonobo. However, some of these flakes were too small, so he would try again. He would select the largest flakes and assess their sharpness by looking at the edge and testing it on his tongue. Eventually, he knocked off a large flake and was able to cut open the box. This process was repeated 11 times, producing an abundance of data and artifacts.
Now, here's where it gets really interesting. When researchers analyzed the bonobo-made artifacts, they found something remarkable. Many of them were virtually indistinguishable from the tools that our ancestors made 2 million years ago. The flakes had striking platforms, bulbs of percussion, and sharp, usable edges. The ones he decided to use were the largest and sharpest tools. His method of assessing the sharpness with his tongue may have been the same way our ancestors assessed sharpness, but there were differences, too. Our ancestors usually knocked off flakes at around 80° to consistently produce long flakes. Kanzi's flakes averaged nearly 90°, essentially right angles. This is the maximum angle at which these materials will fracture at all. This tells us that Kanzi did not have quite as complex an understanding of flintnapping as our ancestors did 2 million years ago. And this may also be due to chimpanzee hands not being as dextrous as ours. Our lineage has been napping stone for well over 2 million years. Modern human hands are quite literally evolved to nap stone. It was only in the past 5,000 years or so that most of us stopped. Kzi's flintnapping was impressive, but it was notably worse than say Homo erectus. Either way, it gives us a window into what the earliest sharp stone tools would have looked like. Our minds were already capable of understanding how to create sharp stone edges, and our dextrous hands came later.
In another study conducted 14 years later, Kanzi had clearly become more adept at making and using stone tools. Kanzi and another bonobo used stone to break into logs and dig, both getting a reward if successful. Kanzi used flakes like a drill, rotating them to bore deeper into the log. He used larger flakes as wedges to pry into the logs and even used them to chop. In another part of the experiment, he used flakes as shovels to dig into tough sediment to retrieve food. It's interesting to note that Kanzi was far more successful than the other less trained bonobo, indicating that his training really did pay off and allowed him to access these resources. Kanzi lived on for about a decade doing all kinds of fun scientific studies before sadly passing away in March of 2025.
These studies show that with human interaction or training, bonobos and chimpanzees can produce intentional stone tools, leaving wear patterns comparable to early human artifacts. Such tool production and utilization competencies are extremely similar to the competencies of early humans such as homohabilis and homo erectus. A 2021 study on untrained chimpanzees showed that they did not spontaneously create or use sharp flake stone tools, even when provided with materials, suggesting extensive social learning or training is necessary for this behavior. We know that chimpanzees have to learn how to process nuts with stones and anvils from their relatives who teach them the technique. It's a cultural innovation. In order for wild chimpanzees to start flaking their own stone tools, they would have to have quality stone available to them. And importantly, a reason to create sharp tools. Without direct human intervention, this seems unlikely.
But funny enough, Kabuchin monkeys in Brazil are accidentally achieving what we consider a human milestone. They use stone hammers to open fruits and nuts, but also for a far stranger reason. They smash rocks together to create dust, which they then lick up. Scientists really have no idea why they do this. Maybe it's to help them get some minerals into their diet. Regardless of why they do it, they happen to create stone flakes that are virtually identical to early human tools in Africa. These stone flakes have been found in Brazil in layers dating back over 50,000 years ago. At first, it was thought that humans were in the region tens of thousands of years before we thought. But it now seems it was actually capuchin monkeys leaving a seemingly human signature. So, ironically, capuchin monkeys have unintentionally entered the stone age before our closest relatives.
So, are chimpanzees in the stone age? Kind of, but not really. They've been hunting with spears and cracking nuts with stone hammers for thousands of years. And Kzi proved that bonobos can flintnap when taught. Yet, wild individuals have never made a cutting tool on their own. At least as far as we know. Not because they lack the cognitive capacity, but because they lack the necessity. The story of our own species likely mirrors this pattern. We exploited carcasses with sharp stone tools to get access to an entirely new food source. During severe droughts or food scarcity, tool using apes had a much better chance at surviving. This feedback loop favored an increasing reliance on tools and fundamentally shaped what we became. tool use likely became non-negotiable for our survival. Chimpanzees do not face these same circumstances. They simply need a reason, and let's hope they never get one.
Well, that was a fun one. I still can't believe these videos of chimpanzees flintnapping. I legitimately know humans who are worse at flintnapping. What topic should I cover next? Comment down below, hit that like button, and most importantly, subscribe. All right, I'll see you in the next one.