Thinking of popping to your nearest specialist store for some sesame oil, turmeric, or soy? Some things haven't changed in 3,700 years, it turns out...
At least, that's what a growing new field of research, palaeoproteomics, suggests. Human mouths are full of bacteria, which continually petrify and form dental calculus — which can entrap and preserve tiny food particles. These remnants can be accessed and analysed thousands of years later, providing remarkable insight into the dietary habits of our ancestors.
Philip Stockhammer, an archaeologist at the Ludwig Maximilian University of Munich (LMU), has worked with Christina Warinner, a molecular archaeologist at Harvard University and the Max Planck Institute for the Science of Human History, and a team of researchers to apply this new method to the eastern Mediterranean, including the Bronze Age site of Megiddo and the Early Iron Age site of Tel Erani.
“Our high-resolution study of ancient proteins and plant residues from human dental calculus is the first of its kind to study the cuisines of the ancient Near East,” said Warinner, explaining its significance. “Our research demonstrates the great potential of these methods to detect foods that otherwise leave few archaeological traces. Dental calculus is such a valuable source of information about the lives of ancient peoples.”
High-resolution analyses of ancient dental calculus have given us a whole new perspective on the diets of Bronze Age people.
The research team took samples from a range of individuals and analysed which food proteins and plant residues were preserved in their teeth. “This enables us to find traces of what a person ate,” said Stockhammer. “Anyone who does not practice good dental hygiene will still be telling us archaeologists what they have been eating thousands of years from now!”
Of course, it's not quite as simple as looking at the teeth of those who didn't thoroughly clean them nearly four millennia ago and hoping the proteins survived. “Interestingly, we find that allergy-associated proteins appear to be the most stable in human calculus”, remarked Ashley Scott, LMU biochemist and lead author. That might be because of the known thermostability of many allergens. For instance, the researchers were able to detect wheat via wheat gluten proteins, which they independently confirmed with a different method using a type of plant microfossil known as phytoliths.
This substance has previously been used to identify millet and date palm in the same area during the Bronze and Iron Ages but phytoliths are not plentiful or even present in many foods, which is why this research is so exciting — palaeoproteomics means foods that have left few other traces, such as sesame, can now be identified.
Research suggests that the humble banana was eaten throughout the Mediterranean far earlier than first thought.
The method has allowed the team to identify that people at these sites ate, among other things, sesame, turmeric, soy, and bananas far earlier than anyone had realised. “Exotic spices, fruits and oils from Asia had thus reached the Mediterranean several centuries, in some cases even millennia, earlier than had been previously thought,” explained Stockhammer.
The finds mean that we have direct evidence for a flourishing long-distance trade in fruits, spices, and oils, from East and South Asia to the Levant via Mesopotamia or Egypt as early as the second millennium BCE.
More than that, the analyses "provide crucial information on the spread of the banana around the world. No archaeological or written evidence had previously suggested such an early spread into the Mediterranean region,” according to Stockhammer (although the sudden appearance of bananas in West Africa a few centuries later has previously led archaeologists to believe that such a trade might have existed, this is the first evidence).
The team acknowledged that other explanations are possible, including that the individuals concerned had travelled to East or South Asia at some point but there is evidence for other trade in food and spices in the Eastern Mediterranean — for instance, we know Pharaoh Ramses II was buried with peppercorns from India in 1213 BCE.
But it certainly seems like some foods might have been popular in the Mediterranean for much longer than we realised, which might be an interesting thought to accompany you next time you add some spices or bananas to your shopping basket.
2019 has been declared by UNESCO as the Year of the Periodic Table. To celebrate, we are releasing a series of blogs about our favourite elements and their importance to the chemical industry. Today’s blog is about the highly reactive gas, fluorine.
Fluorine wasn’t discovered until the 19th century, and even now very few chemists have seen elemental fluorine. Fluorite – fluorine’s source mineral – was used industrially as far back as the 16th century, but elemental fluorine wasn’t made until much later.
Fluorite is the mineral form of calcium fluoride (CaF2) and can be found in a wide variety of colours – from pastel free, to burgundy, and even purple or golden yellow. Many samples of fluorite can also be seen fluorescing under UV light. Fluorite’s main industrial use is as a source of hydrogen fluoride (HF), a highly reactive acid. It can also be used to lower the melting point of raw materials, such as steel.
Fluorite has been used in industry for hundreds of years and is fluorescent under UV light. Image: Pixabay
In 1886, French chemist Henri Moissan first made elemental fluorine by electrolysing a mixture of potassium fluoride and hydrogen fluoride. He later won the Nobel Prize in Chemistry for his work.
Large-scale production of fluorine first began during World War II, where it was used to separate uranium for the Manhattan Project – the United States’ nuclear weapons development project.
Fluorine is known for its high reactivity. It is the most electronegative element, which means it can react with almost every other element in the periodic table. Despite being difficult to handle, fluorine and fluorine containing compounds have many real-world applications.
Due to its reactivity, elemental fluorine must be handled with great care. Fluorine reacts with water to produce hydrogen fluoride, which is such a powerful acid it can eat through glassware.
Fluorine’s reactivity isn’t all bad – in fact, it has hundreds of applications. One of the most common uses of fluorine is the fluorides in toothpaste.
These fluorides exist usually as tin or sodium fluoride, and when you brush your teeth they react with calcium in the enamel to make it less soluble to acids. This gives some protection to your teeth from acidic foods such as fizzy drinks or juices.
The fluorochemical industry began in the 1930′s and 40′s with DuPont, who commercialised organofluorine compounds on a large scale. They developed Freon-12 (dichlorodifluoromethane) after General Motors showed chlorofluorcarbons (CFCs) could be used as refrigerants. The two companies joined together to market Freon-12, which quickly replaced previously used toxic kitchen refrigerants.
CFCs were found to be creating holes in the ozone layer, contributing to global warming. Image: Pixabay
CFCs were later banned by a number of countries due to the damage they caused to the ozone layer. More environmentally friendly fluorine-based alternatives are now used in refrigeration, including hydrochlorofluorocarbons (HCFCs) and hydrofluorocarbons (HFCs).
DuPont continued to pioneer the industry, when recently hired chemist Roy J Plunkett accidentally discovered polytetrafluoroethylene, also known as the polymer Teflon. Tests of the mysterious white polymer he had generated showed its’ high temperature stability and resistance against corrosion were significantly higher than any other plastic. It only took three years for large-scale production to begin.
Fluorine – Professor Martyn Poliakoff. Video: Periodic Videos
The development of Teflon lead to many other similar fluorine-containing polymers appearing on the market, including PTFE, which is used in breathable rainwear by the Gore-Tex business and was developed by Robert Gore, the son of ex-DuPont employee Bill Gore.
The fluorochemicals industry continues to grow to this day; in 2017 the global market was estimated at $17.6 billion.