Radu Iovita, New York University – Did Neanderthals Use Glue? Researchers Find Evidence that Sticks

On New York University Week: New discoveries by archaeologists are changing our view of Neanderthals.

Radu Iovita, associate professor of anthropology, glues it all together.

Radu Iovita is an archaeologist researching how ancient humans used technology to disperse through diverse environments and adapt to the harsh climatic changes of the last Ice Age.

He has conducted fieldwork in Europe and Central Asia, most recently in Kazakhstan, where his team discovered 95 previously uncharted cave and rockshelter sites. In New York, his lab research focuses on forensic reconstructions of how stone tools were used. To this end, the team has been developing novel, AI-supported methodologies for classifying microscopic patterns of abrasion on stone tool edges that indicate different materials worked with the tools. Prior to joining NYU, Iovita was a Senior Researcher at the Leibniz Zentrum für Archäologie and a Group Leader at the University of Tübingen in Germany. He obtained his Ph.D. from the University of Pennsylvania, his M.Phil. from Cambridge University, and his A.B. from Harvard University.

Did Neanderthals Use Glue? Researchers Find Evidence that Sticks

Many animals make and use tools, but the way we humans use technology is a true outlier in its complexity. Yet it’s hard to know when and how during human evolution complex technology appeared, because early tools don’t come with user manuals. Instead, scientists have to reconstruct these details from traces left on them. In my lab, we use microscopic traces on stone tools to figure out how they were used in the past.

Glues are ideal for answering this question. They imply multi-part tools and their own properties may reveal their makers’ hidden know-how.

It turns out that glues have a long history. Archaeologists have found traces of birch tar on Neanderthal tools spread out over Eurasia. Birch tar is different from other glues, because it doesn’t occur naturally. It has to be distilled from heated birch bark in anaerobic conditions, that is, without air. Initially, these discoveries stirred up a lot of speculation about how smart their makers were, but together with colleagues from Tübingen, Germany, we showed that one can obtain tar simply by placing a stone next to a birch bark fire and scratching it off.

Does that mean that Neanderthals weren’t as smart as we thought?

Not necessarily.

Last year, together with the same colleagues, we found traces of an even more advanced glue on several stone tools from one site in France. They all featured a bitumen and ochre mixture, a first for Neanderthals. Microscopic traces of abrasion all over the tools’ surface and the mechanical properties of the glue mixture both point to one surprising conclusion: the glue wasn’t used to bind the tool to a handle, but rather, to make the handle itself.

These findings show how archaeology can reveal the secrets of our earliest technologies.

Read More:
Schmidt, P., Blessing, M., Rageot, M., Iovita, R., Pfleging, J., Nickel, K.G., Righetti, L., Tennie, C., 2019. Birch tar production does not prove Neanderthal behavioral complexity. Proc Natl Acad Sci USA 201911137. https://doi.org/10.1073/pnas.1911137116

Schmidt, P., Iovita, R., Charrié-Duhaut, A., Möller, G., Namen, A., Dutkiewicz, E., 2024. Ochre-based compound adhesives at the Mousterian type-site document complex cognition and high investment. Science Advances 10, eadl0822. https://doi.org/10.1126/sciadv.adl0822