Science Notes – Analysing archaeobotany along the A14

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MOLA Headland archaeobotanist Lara Gonzalez Carretero studying the earliest physical evidence of beer-making in Britain. (IMAGE: Highways England, courtesy of MOLA Headland)

We have yet to cover archaeobotany, or palaeoethnobotany, in ‘Science Notes’. This is a shame as, although it is sometimes pushed to the side by more attention-grabbing finds, like human and animal remains, or even shiny materials, it is a fascinating area of archaeological science. Recent news from post-excavation analysis of the excavations for the A14 Cambridge-to- Huntingdon improvement scheme (see CA 339), which recently won the Current Archaeology Award for Best Rescue Project of 2019, is bringing archaeobotany into the spotlight. Archaeobotanist Lara Gonzalez Carretero has discovered that organic samples taken from the site, dating to the Iron Age, are consistent with the by-product of making beer and may represent the earliest evidence for this process in Britain.

Archaeobotany is the study of archaeological plant remains, and its main aim is to understand how humans utilised plants in the past, whether for social, economic, or dietary purposes. This often takes the shape of analysing seeds, grains, and other organic food waste products. It can also be used in burial contexts to examine flora remains, helping to determine at which time of year interment took place – although this is sometimes considered a separate discipline known as palynology, the study of pollen or other spores.

Archaeobotanical samples are usually collected through bulk sampling from specific features of interest on a site. As plant remains are usually preserved through charring, features such as kilns, hearths, or other pits are usually the most fruitful for finding such samples, but, as is often the case with archaeological remains, plants can be preserved in waterlogged conditions as well.

To sift the materials of interest out of a bulk soil sample, the flotation method is most often used. In this process, the entire sample is slowly added to agitated water, causing the heavier material (such as sediments) to sink to the bottom, while the lighter organic material (usually the material of interest, such as charred seeds, grains, charcoal, and so on) rises to the top. The lighter material, or light fraction, is then sieved, dried, and examined under a microscope for identification. Most remains can be identified in this manner, but further analysis may be required.

A scanning electron microscope image of the Iron Age sample from the A14 excavations that hinted at beer-making. (IMAGE: Highways England, courtesy of MOLA Headland)

It was during this microscopic phase of analysis of the A14 samples that Lara identified a rather unusual specimen: a porous, porridge-like material that contained large fragments of grain rather than the fine flour that is used to make bread.

As Lara described it, ‘I knew when I looked at these tiny fragments under the microscope that I had something special. I was able to see the cereal ingredients (wheat and barley), but the microstructure of these remains had clearly changed through the fermentation process, and there were air bubbles typical of those formed in the boiling and mashing process of brewing. It’s like looking for a needle in a haystack, but, as an archaeobotanist, it’s incredibly exciting to identify remains of this significance and to play a part in uncovering the fascinating history of the Cambridgeshire landscape.’

Found in an Iron Age context, possibly dating back to 400 BC, these traces are a rather exciting discovery. As Dr Steve Sherlock, the Highways England archaeologist who lead the A14 project, highlighted, ‘It’s a well-known fact that ancient populations used the beer-making process to purify water and create a safe source of hydration, but this is potentially the earliest physical evidence of that process taking place in the UK.’

The find was not much of a surprise to beer historians: this region has been known for beer production for centuries. Roger Protz, lecturer and author of more than 20 books on beer, said: ‘East Anglia has always been of great importance to brewing as a result of the quality of its barley. Known as maritime barley, it is prized throughout the world. When the Romans invaded Britain, they found local tribes brewing a type of beer called curmi. As far as is known, it was made from grain, but no hops were used: hops didn’t come into use in Britain until the 15th century, and there was much opposition to hops from traditional brewers, who used herbs and spices to balance the sweetness of the malt.’

This article appeared in CA 350.

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