Weighing up the evidence: did Bronze Age Britons use gold as currency?

‘While gold would still have had an intrinsic value... it most likely wasn’t a generally recognised form of currency.’

Last issue we traced the long history of cross-Channel human interactions, stretching far back into prehistory (CA 385). These far-reaching connections have led researchers to compare prehistoric technological capabilities on both sides of the water, and it is known that both Bronze Age Britons and their European counterparts used weights and balances to quantify the weight of some objects. However, new research (published in Antiquity; https://doi.org/10.15184/aqy.2021.54) by Dr Raphael Hermann, a University of Göttingen research associate working on the European Research Council-funded ‘WEIGHTANDVALUE’ project, suggests that such mass-regulation was not applied to objects made of gold, with implications for our understanding of Britain’s Bronze Age economy.

Image: Raphael Hermann/Antiquity Publications Ltd/© The Trustees of the British Museum.

Metrological research (the scientific study of weights and measures) has indicated that some Bronze Age metal items, such as bronze scrap fragments in Europe or silver in the Middle East, were regulated by weight, their masses having been determined according to a system of standardised units using balance scales. Mass-regulation of this kind, which guarantees the weight and value of objects in a way that allows them to be used as currency, was previously said to have been used to quantify gold objects in Britain. Until recently, though, only a limited number of gold artefacts from the British Bronze Age had been subject to metrological analysis. ‘We now know that weighing as a method to quantify things did exist in Bronze Age Britain,’ Dr Hermann said, ‘as evidenced by balance weights and scale beams found in England at Potterne and Cliffs End Farm, but were gold objects, on the whole, regulated by weight?’

To find out, Dr Hermann examined more than 800 gold objects from Bronze Age Britain, including torcs, fasteners, bracelets, rings, and lunulae (crescent-shaped collars made from gold sheet), using a method known as Cosine Quantogram Analysis (CQA). ‘CQA looks at a group of values – for example, the mass values of gold objects – and finds common multiples, so-called “quanta”, that they all share,’ he explained. Essentially, the higher the number of objects that are found to share a given ‘quantum’, the more chance there is that this reflects an actual unit of measurement, which may be interpreted as evidence for mass-regulation.

Given the size of the sample – the largest of its kind to-date – as well as its varied contents, Dr Hermann divided the artefacts into smaller groups for analysis. Frequency Distribution Analysis (FDA) was used to identify two basic mass-based ranges, a ‘light range’ (0g-60g) and a ‘heavy range’ (60g-410g), and once artefacts had been assigned a category they were further grouped by object-class (for example, bar torcs, penannular bracelets and dress fasteners, lunulae, and so on). FDA diagrams (describing the frequency of particular mass values) and CQA graphs (describing common multiples shared across the mass-values of the objects) were then produced for each range and for each class of object found within it. As Dr Hermann explains in his paper, if the gold objects being analysed were mass-regulated, then the CQA graphs would show statistically significant peaks at regular intervals, indicative of a ‘quantal configuration’, while the FDA diagrams would display corresponding data gathered into ‘neat clusters’ at particular mass values.

The study showed that the majority of the objects in the sample were ‘light’, and CQA of the items within this range revealed a number of high peaks, at quanta values of 3.2, 6.2, and 12.1-13.7, while FDA revealed corresponding concentrations of mass values at around 5g, 11-13g, and 25g. It was, however, impossible to conclude from this evidence that the items were mass-regulated as, despite some regularities, the results were not statistically significant by comparison with randomly generated samples. CQA analysis of the heavier items did reveal a statistically significant curve peaking at a quanta value of 77, but FDA analysis of the same artefacts shows that this is merely the result of a concentration of masses around that value rather than a quantal configuration. Analysis of the artefacts by object-class generated similarly irregular, false-positive, and statistically insignificant results. Indeed, some CQA peaks may simply have been describing shared quantal characteristics based on something other than mass-regulation, such as object size. Thus, Dr Hermann did not find convincing evidence for mass-regulation among the gold objects that he investigated, which suggests that Bronze Age Britons had no standard system for regulating the mass of their gold objects.

‘Despite the undoubted attraction of gold and the existence of weighing and measuring in later Bronze Age Britain, objects made of the most precious of the metals apparently were not generally regulated by weight,’ Dr Hermann said. ‘While gold would still have had an intrinsic value and probably could have been used for trading in any number of circumstances, it most likely wasn’t a generally recognised form of currency.’