Smell-Ara Croft: piecing together the scents of ancient history

Smell is a potent sense in the animal kingdom. It helps carnivores hunt their prey, and it helps prey species detect danger. In humans, our olfactory abilities are tightly knitted to the experience of emotion and memory.

That’s because of the brain’s anatomy; smells are processed in a region called the olfactory bulb, which is close to the amygdala and hippocampus – ­the regions associated with emotion and memory. So, smell signals have a quick and direct path to those regions.

And because smell paints such a vivid picture, it could be a powerful way of bringing the past into the present. Only there’s one small problem: we can’t smell history.

That’s why a team of researchers from the Max Planck Institute for the Science of Human History in Jena, Germany, has published a call-to-arms in Nature Human Behaviour, looking for new ways to bring the “smell-scapes” of the past back to life

“Tracking scent in the deep past is not a simple task,” says Barbara Huber, lead author of the paper, “but the fact that history records expeditions of discovery, wars, and long-distance exchange to acquire materials with strong olfactory properties – like incense and spices – reveals how significant scent has been for humankind.”

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Past scents can be recovered from scent archives by extracting molecules using a variety of different methods. With successful detection and identification of the molecular composition of samples, ancient sources of smell can then be identified. Credit: Michelle O’Reilly

Scent would have been deeply involved in all sorts of ancient and historical activities, including ritual, the trade of spices and other aromatic substances, perfumery, and cuisine.

Smells and the other senses have traditionally been overlooked in archaeology, because it’s harder to study them in an empirical way; but understanding how ancient people sensed the world can give a richer view of what their lives were like. In fact, sensory archaeology has been making small but powerful waves in the last few decades.

“Scent is a powerful and underappreciated aspect of human experience,” notes Nicole Boivin, senior author of the study and director of the Department of Archaeology at the MPI Science of Human History. “Smells reach our brain fairly directly and motivate us in critical ways – whether to avoid danger, identify something that is good for us, or remember something from our past, for example.”

It was as recent as 1991 that scientists Richard Axel and Linda Buck first discovered olfactory receptors – smell sensors – in the brains of rats, so the science of smell is relatively nascent. 

With that in mind, how do you reconstruct smells from the deep past? Of course, there’s the universally recognisable smells, like the pong emanating from a Roman latrine. But how do we piece together the smell-scape from an ancient village, or bring an ancient person’s last meal back to life?

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Scent data can be contextualized within the framework of relevant historical texts and visual representations, as well as the archaeological and environmental records. Connecting these different sources of information enables the reconstruction of critical aspects of ancient lifeways and society (indicated by arrows emerging from the blue circle). Credit: Michelle O’Reilly

There are all sorts of approaches scientists can take to reconstruct the smells of the past, many of which are borrowed from the field of molecular biology. Because smells tend to come from organic sources and organic materials decay, many of the sources of certain smells will disappear over time. But miniscule residue in ceramics or in gravesites, for example, can offer olfactory hints; and analysis of these residues in the lab can tell us what they’re made up of, and therefore what they would have smelled like. 

“Using only traces of scented substances preserved in archaeological artefacts and features,” adds Huber, “novel methods are revealing the powerful odours that were a cardinal feature of ancient lived realities, and that shaped human action, thoughts, emotions and memories.”

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