Scientists are trying to reconstruct the smells of the distant past
Smells hover just below the level of our consciousness, evoking emotions and memories that shape the way we perceive and navigate the world. At the same time, according to scientists, the sense of smell is a sense that has been unfairly ignored in most attempts to understand the past. Nowadays, a growing number of researchers want to reconstruct ancient scents and use them to learn more about how people used to live.
Scientists are undertaking new research projects to understand how the past smelled and to determine what modern scents should be preserved for posterity, CNN tells.
“It's a very lifelike feeling. Smell was also very important in the past, and it was probably even more important because in the past, not everything was so thoroughly cleaned,” says Barbara Huber, a doctoral researcher in archeology at the Max Planck Institute for Geoanthropology in Jena, Germany.
The challenge of finding scents of the past is how to capture an ephemeral phenomenon: archaeologists usually find and study things that we can touch, and these are the artifacts we come across in museums. Odor compounds are naturally volatile — as soon as their source disappears, they also disappear, evaporating into the air. And most smells come from biological materials — plants, food, human and animal bodies, — which decompose quickly, explains Barbara Huber.
Despite these challenges, Huber notes that several new and powerful biomolecular approaches are helping scientists decipher ancient scents.
Scientists can study the invisible biomolecular residues left on incense burners, perfume bottles, cooking pots and food storage jars, using methods such as chromatography, the process of separating components in a mixture, and mass spectrometry, which can detect different compounds by calculating the weight of different molecules.
The most informative biomolecules, according to Barbara Huber, are lipids — fats, waxes and oils, — which are insoluble in water. They are often found embedded in porous pottery after being used in items such as lamp fuel or aromatic ointments that people once applied to their bodies or to corpses. Lipids are also found in faeces.
Barbara Huber also studies secondary metabolites, organic compounds produced by plants and left over from plant products used in the past, including resins, flavored woods, herbs, fruits, and spices. Compounds can reveal the ingredients and aroma of incense, medicines, and foods.
Ancient DNA sequencing and proteomics, the study of proteins found in things like calcified plaque, have revealed amino acids that signal conditions like disease gums associated with bad breath.
But as Barbara Huber's research shows, collecting these olfactory cues is often just the beginning. In her work, Huber studied incense burners found at the archaeological site of Tayma, Saudi Arabia's oldest site dating back 5,000 years, to try to reconstruct the «olfactory landscape» ancient oasis.
She found secondary metabolites that indicated the use of aromatic resins containing frankincense, myrrh, and pistachios in private buildings, tombs, and temples, respectively. Huber then worked with a perfumer to try and recreate the scents, revealing what these places might have smelled like thousands of years ago.
“The resins looked really similar… but when you burn them, they have a completely different smell. So, for example, incense had a really rich smell — very balsamic — and you could really feel that maybe it was used to somehow properly clean houses to avoid bad smells or something like that,” explains Huber.
Sean Coughlin, a researcher of ancient and medieval thought at the Czech Academy of Sciences, is trying to recreate the perfume that Cleopatra herself may have used, based on recipes recorded in ancient Egyptian texts and inscriptions on the walls of temples.
“The problem is very simple. Usually, when you follow a recipe, you kind of know what you're going to get. When you replicate a historical recipe, you don't have a goal,» Coughlin said.
«What we're really trying to do is use organic chemistry to be able to tell us something about the process, because that we think that this process would determine the range of possible flavors”, he added.
One perfume recipe that Coughlin studied, known as Mendesian, indicated that ancient perfumers heated oil for 10 days and 10 nights before adding woods like cinnamon and resins like myrrh.
“It was a big mystery to us, – he said. – If you've ever cooked butter for 10 days, it stinks. But after his team heated the oil in test tubes for 12 days, Coughlin found that the method accelerated the oil's natural rancidity process, removing any foul-smelling compounds and ultimately allowing the perfume to last longer.
“There is also a stage, after heating the oil but before preparing the perfume itself, in which they add lightly scented substances such as roots, wine and resins. Our hypothesis is that they not only masked the unpleasant odor (adding a pleasant aroma), but also absorbed the unpleasant smell of the oil,” the researcher explained.
According to Coughlin, most modern perfumes use ethanol, a type of alcohol, although some delicate natural fragrances still require the use of oil or fat, which must be refined in some way.
But today's chemists still owe a lot to ancient perfumers, he added. They pioneered many of the methods still used in modern science, such as distillation and liquid fractionation techniques.
Similarly, researchers are now taking steps to preserve currently available odors in order to give future generations an idea of our time and more recent past.