Stanford University scientists say experiments on ancient Chinese stone tools, including 15,000-year-old hand axes, have solved a longstanding mystery about the critical technological transition from rudimentary hand tools to more versatile ground-edged tools, suggesting these new technologies enabled uses beyond food harvesting.

The research team behind the new analysis said the discovery of ground-edged sickles and knives in Neolithic North China, likely used for fiber production and harvesting, combined with their replica-based experiments, highlights the growing technological capabilities of the transition between Paleolithic and Neolithic peoples.

“The combined experimental and archaeological evidence from the site of Peiligang indicates that the emergence of ground-edged tools marked a significant step in technological specialization from the Late Pleistocene to the Early Holocene,” the researchers write in a paper detailing the work.

Mysterious Technological Transition Hidden in 15,000-Year-Old Stone Tools

According to lead author Ran Chen and colleagues, archaeologists widely regard ground-edged cutting tools like the modern sickle as “technological hallmarks of early agriculture in North China.” However, they note, the functional foundations of this advanced toolmaking capability “remain insuf­ficiently tested.”

The research team also noted that most analyses of the transition from the Upper Paleolithic to the Early Neolithic (ca. 15,000–8,000 BP) in ancient China have viewed tools through “the lens of food production.”

“Within this framework, cutting tools, including early flakes and blades and later ground-edged sickles and knives, are often interpreted primarily as implements for harvesting cereals through cutting stems and leaves,” they explained.

The researchers said these earlier findings made them wonder whether this “food-focused perspective” could have led researchers to miss the broader range of plant resource exploitation possibilities in some of the 15,000-year-old stone tools previously discovered, prompting their replica-based experiments.

“The development of stone tool technology in North China provides a framework for reassessing this long-term relationship between plant use and technological change,” they explained.

Experiments Reveal Ground-Edged Tools Were Multifunctional Implements

To test their hypothesis, Chen and colleagues analyzed 140 stone artifacts previously collected from the Peiligang site in Henan Province, China. This included some 15,000-year-old Upper Paleolithic flaked stone tools and several more advanced Early Neolithic flaked and ground-edged stone tools.

Rather than test irreplaceable artifacts, the study authors created realistic experimental replicas.

Testing the effectiveness of the oldest, most rudimentary stone flake designs and the more technologically advanced ground-edged tools for harvesting seed-bearing grasses, the researchers found little measurable advantage between the two designs.

However, when the researchers compared the 15,000-year-old stone flake tools against ground-edged tools made thousands of years later, they found the more technologically advanced tools were “significantly more efficient at cutting thick-stemmed weeds and fiber-yielding plants.”

“Upper Paleolithic flaked tools were multifunctional implements used for processing diverse plant and animal materials, and Early Neolithic flakes continued to serve similarly flexible roles,” the study authors explain. “In contrast, Early Neolithic ground- edged tools show marked specialization in plant- related tasks.”

More Advanced Tools Emerged Through Broader Functional Demands

When discussing the experimental results, the team noted that their findings were supported by microfiber and starch residues found on some of the ancient tools, suggesting that “ground- edged sickles and knives were used not only for plant foods but also for harvesting and processing fibrous plants.”

“These findings indicate that ground- edged cutting tools emerged through broader functional demands, including fiber production, and potentially vegetation clearance, rather than cereal harvesting alone,” they explained.

Beyond the food-harvesting uses of ground-edged tools, Chen and colleagues said their identification of non-food plant labor like fiber production as an important driver of technological evolution and specialization “reframes the emergence of ground- edged tools as part of a broader technological and economic reorganization in early Holocene East Asia.”

“These findings identify nonfood plant work as an important contributor to the adoption of ground-edged cutting tools and show that tools conventionally linked to early agriculture were shaped by broader demands than food production alone,” they explained.

Finally, the study authors suggested that their analysis of 15,000-year-old Chinese stone tools could “invite renewed attention” to ancient fiber-based economies and nonfood plant use during forager–farmer transitions and in early farming societies beyond China.

The study “Plant fiber exploitation contributed to the emergence of ground-edged cutting tools in North China” was published in Proceedings of the National Academy of Sciences. 

Christopher Plain has spent the last six years as Associate News Editor and Head Science Reporter at The Debrief. Follow and connect with him on X, learn about his novels at plainfiction.com, or email him at christopher@thedebrief.org.

2,000 years ago, ancient Roman engineers were building structures that have withstood the test of time remarkably well, many of which remain standing today. At the heart of their success lies a mystery: what were the secrets of ancient Roman concrete that made these buildings so durable?

Now, MIT researchers are drawing from this curiously durable technology of the ancient world to help them develop modern building materials that can last longer, and potentially even reduce the carbon footprint of modern construction—all while managing to self-repair itself by healing small cracks.

Reverse-Engineering Roman Concrete

The mystery of Roman concrete became a fascination for MIT Associate Professor Admir Masic, who has spent many years now investigating the chemistry and other properties of this durable ancient technology. Based on his research, the material’s longevity isn’t just a product of the ingredients used by its ancient creators: the secret of Roman concrete also has to do with its manufacturing process.

This, according to Masic, seems to be at the heart of the material’s unusual ability to repair itself after cracks begin to form.

In 2023, Masic and his colleagues began looking at samples of lime that were very rich in calcium, which researchers call “lime clasts.” These clasts are ubiquitous throughout concrete found in ancient Roman constructions, although they were long discounted as being the byproducts of imperfections in the mixing process.

However, closer inspection revealed something remarkable about these lime clasts: as cracks form in the concrete, water can gradually enter the material, allowing calcium within the lime casts to dissolve and then recrystallize, effectively sealing the newly formed openings.

Applying Ancient Technology to Modern Engineering

Now, that discovery is propelling the development of modern concrete that incorporates calcium-rich lime clasts, thanks to a partnership between Masic and Italian entrepreneur Paolo Sabatini, who joined forces to develop a commercial version now being produced by Dmat, a company they co-founded in 2021.

Part of the strength of Dmat’s approach is the fact that they have developed additives that can be added to existing kinds of concrete and mortar, rather than requiring builders to acquire new and unfamiliar materials.

“We can now offer an extremely competitively priced, self-healing product that is easy to implement and available worldwide,” Masic recently told MIT News.

“What’s exciting to me is that this material could become the industry standard without requiring companies to change how they operate,” he added.

Increased Structural Lifespan and Environmentally Friendly

Beyond its ability to strengthen the durability of concrete, Dmat’s new technology can also reduce carbon dioxide emissions by up to 40 percent compared to those in traditional concrete. Presently, the new material is already being used in several infrastructure projects in parts of Europe, with eventual plans for expansion into the United States and other countries.

Widespread implementation and scalability like this is important, according to Masic and his colleagues, since large volumes of concrete are produced throughout the world, the production of which accounts for as much as 8% of global carbon dioxide emissions.

Extending the life of structures while simultaneously reducing the emissions associated with their construction would therefore hold significant environmental benefits.

Building the Future with Lessons from the Past

“At Dmat, we like to view concrete as an ecosystem,” Sabatini recently said in a statement. Successfully introducing a new material, he argues, requires considering not merely its chemistry, but cost, transportation, certification, and compatibility with established construction practices.

Notably, Dmat’s approach differs from other examples of modern experimental self-healing concretes, which generally rely on bacteria or polymers. Instead, by placing the focus on ancient techniques used by Roman engineers that long remained overlooked and misunderstood, Masic and his colleagues have developed an innovative new technology with roots that go back almost two millennia.

“There’s something profound about how ancient builders, without our modern chemistry, engineered self-healing material that still stands today,” Masic notes.

“My group research and work with Dmat is to make the modern built environment better by applying the best lessons from the past to today’s challenges,” he adds.

Micah Hanks is the Editor-in-Chief and Co-Founder of The Debrief. A longtime reporter on science, defense, and technology with a focus on space and astronomy, he can be reached at micah@thedebrief.org. Follow him on X @MicahHanks, and at micahhanks.com.

Steel tools were employed in Europe centuries before they became widespread during the Roman Republic era.