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Neanderthals, an extinct human species, once dominated Eurasia. But then, about 40 000 years ago, they went extinct – largely replaced by modern humans. But who were the Neanderthals and what happened to them? These are the questions that the EU-funded and European Research Council (ERC) supported PALEOCHAR project set out to answer.
“Traditionally, archaeology has attempted to answer these questions by analysing the tools Neanderthals used and the bones left behind from the animals they ate,” says Carolina Mallol, an archaeologist at the Universidad de La Laguna.
While this approach has produced a great deal of important information, Mallol notes that it is limited in that it only looks at inorganic evidence. “Nowadays, prehistoric archaeology is starting to open the door to the organic world and biomolecular methods are furnishing crucial information about our remote past,” she explains.
As a result, researchers with the PALEOCHAR project decided to take a new approach and study microscopic and molecular organic evidence together. “By studying the organic sedimentary record at such fine scales, we are able to extract information about, for example, the fat content of Neanderthal food, the way they made fire, and what their living spaces looked like,” adds Mallol. “By combining these different sources of information, we aim to provide a more complete picture of the Neanderthal world.”
Combining microscopic and biomolecular techniques
With a focus on identifying the ancient organic residues trapped in archaeological soils and sediments, researchers opted to use a combination of microscopic and biomolecular techniques. “At more than 50 000 years old, these Palaeolithic sites contain relatively low amounts of organic matter,” remarks Mallol. “These state-of-the-art techniques allow us to capture significant amounts of information from small amounts of evidence.”
Researchers specifically targeted organic fire evidence, such as the burnt soil found beneath fireplaces. That’s because when organic matter is burnt at low temperatures it becomes less susceptible to biodegradation, meaning its preservation potential increases.
Furthermore, because it is likely that Neanderthals would have used these fireplaces to cook, researchers also surmised that lipids (fats and waxes) would be found in the burnt soil. “Because lipids have the highest preservation rate among all types of organic matter, fireplaces have the potential to offer a wealth of information,” adds Mallol.
After identifying fire evidence, the PALEOCHAR team used microscopy and biomolecular analytical techniques to investigate the burnt lipids found in the fire-related sediment. “Our work has given us a unique snapshot of living floors, rich in residues from human activity, as well as from soils and vegetation from the surrounding environment,” says Mallol.
New methods for a new field of study
In addition to studying the collected samples, the project also conducted burning experiments to characterise how different lipids behave when subjected to heat. Furthermore, by calibrating and calculating the different factors that could affect the analytical process, the project also contributed to the development of new methods for use in this novel field of study.
“We established a method and put it into practice at a number of Palaeolithic sites around the world,” concludes Mallol. “In doing so, we have provided valuable information about Neanderthal fire traditions, along with insights into the climates and environments in which this population lived.”
Researchers are currently investigating expanding the use of their joint microscopic and biomolecular method to different regions, different time periods and different types of archaeological evidence.