Reverse-engineering the Stone Age Inside the hands-on lab of an experimental archaeologist Beyond flint-knapping and tossing spears with atlatls, Kent State University's Metin Eren has a vision for his field's future. Jennifer Ouellette Jan 2, 2025 7:00 am | 0 Metin Eren has spent more than 20 years honing his flint knapping skills. Credit: Jennifer Ouellette Metin Eren has spent more than 20 years honing his flint knapping skills. Credit: Jennifer Ouellette Story textSizeSmallStandardLargeWidth *StandardWideLinksStandardOrange* Subscribers only Learn moreBack in 2019, we told you about an intriguing experiment to test a famous anthropological legend about an elderly Inuit man in the 1950s who fashioned a knife out of his own frozen feces. He used it to kill and skin a dog, using its rib cage as a makeshift sled to venture off into the Arctic. Metin Eren, an archaeologist at Kent State University, fashioned rudimentary blades out of his own frozen feces to test whether they could cut through pig hide, muscle, and tendon.Sadly for the legend, the blades failed every test, but the study was colorful enough to snag Eren an Ig Nobel Prize the following year. And it's just one of the many fascinating projects routinely undertaken in his Experimental Archaeology Laboratory, where he and his team try to reverse-engineer all manner of ancient technologies, whether they involve stone tools, ceramics, metal, butchery, textiles, and so forth.Eren's lab is quite prolific, publishing 15 to 20 papers a year. The only thing were limited by is time, he said. Many have colorful or quirky elements and hence tend to garner media attention, but Eren emphasizes that what he does is very much serious science, not entertainment. I think sometimes people look at experimental archaeology and think its no different from LARPing, Eren told Ars. I have nothing against LARPers, but its very different. Its not playtime. Its hardcore science. Me making a stone tool is no different than a chemist pouring chemicals into a beaker. But that act alone is not the experiment. It might be the flashiest bit, but that's not the experimental process.It takes years to develop the practical hands-on skills required to do research in experimental archaeology, and this influences how Eren chooses his students. Eren himself is a master flint-knapper, deftly producing all manner of Stone Age blades from chert. One of his students was a musician who decided to study the pitches and octaves produced from the percussive aspects of flint-knapping."We look for people with unique skillsmusic, woodworking, tattooingbecause those are things we cant teach in a four-year undergrad or a two-year masters program," he said. "They come in with the skills, we teach them the science. These students didnt think that their more utilitarian skills were academically valuable, and suddenly theyre publishing in the scientific literature. Metin Erens experimental archaeology lab features a ballistics range, stone-weapon creation, and pottery-making. Eren comes from a long line of medical professionals, but Im not a big fan of blood, he said. History and science were more his forte growing up in northeast Ohio, and in high school, he asked the curator of the Cleveland Museum of Natural History, Brian Redmond, if he could join Redmonds dig. This was usually reserved for grad students, but Redmond consented, and Eren racked up hours of practical fieldwork before college, where he naturally majored in archaeology. He joined the lab of the late Ofer Bar-Yosef as a freshman.He soon became interested in experimental archaeology. He would hear archaeologists describing how a given artifact probably worked or what it meant to the culture, and Eren would wonder how they knew that, given the dearth of evidence. This was the spark that ignited his interest in experimental archaeology. It was Bar-Yosef who encouraged Eren to learn flint-knapping skills. In the process, Eren figured out a new method by which to measure how stone tools were resharpened and tested his hypothesis. That work turned into his first published peer-reviewed paper while still a junior in college.For graduate studies, he chose Southern Methodist University near Dallas, Texas, specifically to work with David Meltzer. It was during his first post-doc at the University of Kent in Canterbury, England, that he met biological anthropologists Stephen Lycett and Noreen von Cramon-Taubadel, who ignited his corresponding interest in evolutionary theory within the context of his archaeological pursuits. And he continued to refine his flint-knapping skills under mentors Bruce Bradley and the late Robert J. Patten.Flint-knapping is equal parts art and science, which I learned firsthand as Eren guided me while making a Stone Age hand axe out of the random chunks of chert Eren keeps in buckets in his lab. It requires striking very specific areas of the target chunk with a rock with just the right amount of force to chip off shards. These shards, in turn, can be used as sharp edges for cuttingand they are very sharp indeed. Goggles and a leather pad for one's lap are among the crucial safety implements when flint-knapping. Even so, injuries are common and can be severe, as detailed in a 2023 paper.Physicists have been studying how cracks propagate for decades; Eren's 25+ years of flint-knapping experience allows him to precisely predict which parts to strike to chip off what he needs so that the axe can take shape. The task becomes more challenging in the later stages, when one is trying to chip off smaller and smaller shards to refine the shape. Eren typically switches to using bone when it comes to fine-tuning the edges.I can make a knife out of a rock Using bone instead of a rock to fine-tune the edges. Jennifer Ouellette Using bone instead of a rock to fine-tune the edges. Jennifer Ouellette Voila! A replica Acheulean hand axe. Jennifer Ouellette Voila! A replica Acheulean hand axe. Jennifer Ouellette My first attempt at a Stone Age hand axe wasn't quite as impressive. But it worked! Jennifer Ouellette My first attempt at a Stone Age hand axe wasn't quite as impressive. But it worked! Jennifer Ouellette Voila! A replica Acheulean hand axe. Jennifer Ouellette My first attempt at a Stone Age hand axe wasn't quite as impressive. But it worked! Jennifer Ouellette Even the shards can be used as handheld cutting tools. Jennifer Ouellette Buckets of rocks, antlers, and chunks of chert for future flint-knapping. Jennifer Ouellette Achievement unlocked! Experimental archaeology is not without its challenges, particularly when one's area of expertise is the Stone Age. Theres so much that doesnt preserve, said Eren. Sure, he can make a stone blade and use it to cut things, but there are no surviving examples of, say, a wooden handle that may (or may not) have been attached.And if there was such a handle, How long was it? What wood was it? Did they finish it in any way? What adhesive did they use?" said Eren. "These are all variables that dont preserve but that influence the function of that knife. It's inherently difficult to determine precisely how accurate their experiments really are because of this, which he has dubbed the Poltergeist of the Unpreserved, because it haunts me as an experimental archaeologist.Another key concept is what Eren calls "the Prevalence of Equifinality." Say a Clovis point is found near a mammoth in a position in between the ribs. Many archaeologists would conclude that the Clovis point killed the mammoth; it serves as the proverbial smoking gun. That might seem like a reasonable interpretation, except now we know that Clovis points also functioned as knives, said Eren. So its also possible that the mammoth was already dead, and people just used the point to butcher the animal. Two processes, hunting and scavenging, are yielding the same archaeological results.In the 1980s, an archaeologist named George Frison famously went to Zimbabwe and threw spears tipped with Clovis points into (dead) elephants to see where they penetrated. Not only were the points remarkably effective at penetrating the hides and rib cages of the elephants, but when he studied the resulting microscopic striations on the points, other Clovis points found at different sites also showed the same striations, suggesting that the points were definitely used for hunting purposes.Then a student from Zimbabwe came to Erens lab and wanted to test Frison's findings. So they made a batch of replica Clovis points attached to spears, but they threw them into the grass rather than into dead elephants. They ended up with the exact same microscopic striations. So maybe a point found near a mammoth had been used to kill the mammoth, or maybe it was used to skin an already dead mammoth or hunt a rabbit two weeks beforeit just happened to be there, lying in the grass, when the mammoth died and decayed on top of it. Butchering a Bison with Clovis points and tools. That said, Frison was correct that Clovis points are remarkably effective toolsnot just for hunting but for butchering. Eren's lab recently collaborated with five hunters affiliated with MeatEater (an outdoor lifestyle company). They have a popular podcast and YouTube channel, as well as a former Netflix series. Eren wanted to test how well Clovis points and large handheld shards worked for butchering, and the MeatEater crew obliged by using Eren's tools to butcher a bison, capturing the experience for their YouTube series (see video above).While the Clovis points needed frequent sharpening and broke easily, the hunters were surprised at how well they functioned as butchering tools. They gained a greater appreciation for the ingenuity of their Stone Age counterparts and were listed as co-authors on a paper published earlier this year describing the results of the experiment.Target practiceMost of Eren's students (and the occasional visiting journalist) get the chance at some point to throw point-tipped spears at a hunting target outside on campus, using an attached atlatl or spear-thrower. This ingenious handheld rod-shaped device employs leverage to launch a dart or spear. Versions have been developed by several different ancient cultures, including Aztec, Maya, Greek, Roman, and Australian aboriginal designs.And as Eren's colleague Michelle Bebberan expert in ceramics and pottery (who also participated in the frozen feces study)discovered in 2023, the atlatl is essentially the great equalizer between women and men. She noticed that her male students struggled more than female students to pick up the crucial whip action required because they were so accustomed to relying on strength and turned it into a blind test. She found that, unlike the javelin, the atlatl equalizes the velocity of female- and male-launched projectiles. It's not even exclusively a gender difference, according to Bebber, since children, older men, or injured men would also have benefited from its use.Although throws made with the atlatl are faster, the javelin has more kinetic energy because of its higher mass. Eren also experimented with throwing from different heights, renting a scissor lift for the purpose. "We wanted to understand how much more velocity and kinetic energy does gravity lend to these projectile weapons as you get higher," said Eren. Eren's lab regularly makes replica spears for target practice. Jennifer Ouellette Eren's lab regularly makes replica spears for target practice. Jennifer Ouellette A handy target. Jennifer Ouellette A handy target. Jennifer Ouellette Eren demonstrates proper form when throwing a spear with an atlatl. Jennifer Ouellette Eren demonstrates proper form when throwing a spear with an atlatl. Jennifer Ouellette A handy target. Jennifer Ouellette Eren demonstrates proper form when throwing a spear with an atlatl. Jennifer Ouellette Eren's shots are the ones that hit the mark. Mine? Not so much. Jennifer Ouellette Eren displays different kinds of tipped spears. Jennifer Ouellette A closer look at the different heads. Jennifer Ouellette Running a ballistics test with the spears. Jennifer Ouellette He found that the javelin increased not only in velocity but kinetic energyalmost a 200 percent increase in impact energy by 9 meters in height. But the atlatl decreased as the height increased. "If you are throwing down, the lever is deactivated," Eren explained. "And because the darts are so light, they have higher velocity when traveling horizontally, but once the lever is deactivated, the wind can make it go sideways, producing more drag. That had never occurred to us, that the atlatl actually has a major cost if you are firing downward.This might explain why Neanderthals, for example, never developed a version of the atlatl. They often hunted in hilly areas and would have gained more advantage from a thrown javelin. "They did the evolutionarily optimal thing," said Eren.Eren also conducts a variety of controlled ballistics tests in the lab. He has a crossbow apparatus set up in the lab designed to shoot short distances at a target. One such study was designed to test a 1970s hypothesis about whether some stone blades once had some sort of wood or bone backing on the flat, dulled edge (as opposed to the sharp cutting edge), which would have increased adhesion.Eren's lab members shot backed and unbacked specimens of this stone tool hacked into wooden shafts with the crossbow and measured how well they stuck together. It didnt quite go as planned. The backed specimens, which were supposed to stick better, all blew off, like stone rain, said Eren. That experiment, plus a second round of tests, clearly demonstrated that backing does not increase adhesion relative to non-backing.More recently, Eren has ventured into forensics, publishing his first paper on bullet ricochet marks earlier this year. He was inspired by ancient fossilized footprints at White Sands National Park that date back to 22,000 to 24,000 years old. There is an ongoing debate as to whether the footprints were made by humans. (Eren falls on the skeptical side of the debate.) He was pondering those footprints while practicing at the shooting range and noticed all the ricochet marks on the wall and floor from less skilled shooters. He found himself wondering what caliber of gun had produced them and soon realized there hadnt been any forensic studies on whether one could distinguish between bullet ricochet marks. Colleague Michelle Bebber specializes in ceramics and pottery, complete with an in-lab kiln. Jennifer Ouellette Colleague Michelle Bebber specializes in ceramics and pottery, complete with an in-lab kiln. Jennifer Ouellette Pottery projects in the works. YouTube/Kent State Pottery projects in the works. YouTube/Kent State Colleague Michelle Bebber specializes in ceramics and pottery, complete with an in-lab kiln. Jennifer Ouellette Pottery projects in the works. YouTube/Kent State A few replicas of ancient pottery. Jennifer Ouellette A few replicas of ancient pottery. Jennifer Ouellette Bebber's replica Jomon vase. Jennifer Ouellette Bebber's replica Jomon vase. Jennifer Ouellette A few replicas of ancient pottery. Jennifer Ouellette Bebber's replica Jomon vase. Jennifer Ouellette Most criminals are terrible shots," said Eren. "They dont practice. And ricochet marks are present at crime scenes quite often while the casings arent. So he conducted a controlled ballistics experiment with large sample sizes of five different calibers and shot the guns at different angles and distances into cement (a common urban material). He then used digital software to determine the outlines of the ricochet marks, followed by machine learning to see if one could distinguish between calibers. The answer was clear: You cant. Or at least Eren couldnt, and his conclusion ably demonstrated the scientific value of null results.The bigger pictureThese aren't just isolated academic questions for Eren. While archaeology has its roots in discovery-based science, Eren firmly believes the field needs a theoretical framework to transform it into a question-based science. He's particularly interested in cultural evolution, particularly how technology and culture evolve. "Culture is operationally defined as socially transmitted information," he said. "Chimps have culture, birds have culture. This isnt a unique thing to humans, but were very egotistical, and we like to think were special."In fact, most of the books in Eren's office concern evolutionary theory. Over the last 20 years, weve been undergoing a synthesis of culture and evolutionary theory," Eren said. "Its been shown time and again that culture evolves via Darwinian evolutionabsent the gene. For that, you only need three ingredients: variation, inheritance, and some kind of sorting mechanism.Experimental archaeology is well suited to testing such a theoretical framework. Its very difficult to talk about evolution and how phenomena evolve if you dont understand how stuff works, said Eren. If you dont understand whether this change in this variant is functional or not, you cant distinguish between drift and selection, which is the basis of evolutionary theory."This, for Eren, is the central conflict. "Any evolutionary science that deals with the past will always remain inference," he said. "Archaeologists have this tendency to pick their one pet thing and then impose it on all the variation that we see. What we really need to do is lean completely into evolution and biology and realize there could be multiple sources of variation that are influencing the things that we dig up out of the ground. And our job is to figure out how they interact to create that phenotype of the artifacts.Eren also sees a great need for more replication studies in his chosen field, even for that infamous frozen feces paper, which was primarily meant to bring the question out of the world of myth and legend and into the realm of science. "Imagine if youre a geneticist studying fruit flies and you do one study and nobody repeats it," he said. "There is a tradition in archaeology and anthropology where something is published and then its just gone, when really that should be the beginning.In my opinion, experimental archaeology is the future of the field," said Eren. "The archaeological record itself is a finite resource. We already have 200 years of excavated data in museums. So what do we do when all the sites are gone? Its this: experimental archaeology. Weve been digging stuff up for 200 years, and we barely have an understanding of how any of it works.Jennifer OuelletteSenior WriterJennifer OuelletteSenior Writer Jennifer is a senior reporter at Ars Technica with a particular focus on where science meets culture, covering everything from physics and related interdisciplinary topics to her favorite films and TV series. Jennifer lives in Baltimore with her spouse, physicist Sean M. Carroll, and their two cats, Ariel and Caliban. 0 Comments