Prehistoric currencies, conflict, and climate change

The origins of coinage

It is a very simple idea but an illuminating one: what can we learn by investigating the weight of the earliest metal artefacts, including the contents of the thousands of hoards of bronze scrap known from Europe and Asia? One often-cited explanation is that these hoards represent metalworking resources – material temporarily buried for safety, to be retrieved as needed, melted down, and fashioned into new objects.

Now an EU-funded research project called Weight and Value has come up with an alternative theory: that these hoards represent an early form of coinage, the beginnings of cash-based transactions and the use of weights in assessing commodity values. Led by Professor Lorenz Rahmstorf, at the University of Göttingen, the project has involved weighing huge numbers of artefacts to see whether complete objects and fragments comply with some sort of standardised weight-related system. It seems that they do, and that the system was widely recognised across large swathes of Near Eastern, Mediterranean, and Atlantic territories, echoing what we know about long-distance trade during the late 2nd and early 1st millennia BC.

In a paper in the Journal of Archaeological Science (vol. 129, May 2021), two of the project’s researchers – Nicola Ialongo, of Göttingen University, and Giancarlo Lago, of Rome’s ‘La Sapienza’ University – report on their recent study of 2,500 pieces of bronze derived from swords, axes, and jewellery. The correlation between the weight of the fragments and weights from weighing scales of the same period was so strong that the fragments had clearly been cut to provide pieces of a predetermined weight, being fractions of the standard unit – hence the conclusion that these scraps were used as small change in a cash-based trading system.

A global market

The project’s findings are all the more extraordinary because it seems that the same weight system was used across western Eurasia, implying a global currency market. The quantity of bronze known from hoards is so great that the use of money must have been widespread and the bronze scraps used daily at all levels of the population. Dr Ialongo said: ‘there was nothing “primitive” about pre-coinage money, as money before coins performed exactly the same functions that modern money does now’. She added: ‘it is likely that perishable goods were used as currency long before the discovery of metallurgy, but the real turning point was the invention of weighing technology in the Near East around 3000 BC. This provided, for the first time in human history, the objective means to quantify the economic value of things and services, or, in other words, to assign them a price.’

In an earlier paper, published in Antiquity (vol. 93, issue 371, October 2019), Professor Rahmstorf reported on finds of balance scales from various sites in Britain along with their associated weights, often square or circular in shape and made from stone, bronze, and lead. He compared these with the weights of copper and tin ingots, weapons, and gold objects, including torc fragments. He concluded that a unit of gold weighing 90-95g was the reference point for the value system. This metrical unit is attested independently in Egyptian written sources, recording the deben as the standard measure and the qedet as being one-tenth of a deben. Both are evident in the 149 weights recovered from the late 14th-century BC Uluburun shipwreck near Kas¸, on the southern Anatolian coast. Thirteen of these range in weight from 90.3 to 94.65g, and further weights from the assemblage measure two, three, five, ten, 20, and 80 times the value of the deben.

Climate change and human violence

In a warning of what might occur again in the future, a paper in the journal Nature – Scientific Reports, entitled ‘New insights on interpersonal violence in the Late Pleistocene based on the Nile valley cemetery of Jebel Sahaba’, blames climate change for interpersonal violence among Nile Valley dwellers in the Late Pleistocene. The paper is authored by researchers from the British Museum and the Centre National de la Recherche Scientifique (CNRS), the University of Toulouse, and the French Muséum National d’Histoire Naturelle.

The paper reports on a reappraisal of the human remains from the cemetery at Jebel Sahaba in north-east Africa, the earliest funerary complex in the Nile Valley, dating to at least 13,400 years ago. The research confirms that many of those buried in the cemetery have spear and arrow injuries but, contrary to previous analysis, the violence is now thought not to be the result of a single armed conflict or an episode of organised warfare. Rather, the evidence suggests the violence was frequent, extensive, and intense, with many skeletons displaying multiple lesions, as well as previously undocumented healed injuries, which are indicative of multiple violent events within a lifetime.

Dr Isabelle Crevecoeur, Lead Researcher on the project, said: ‘healed and unhealed lesions, some with embedded lithics, were found on over two-thirds of the 61 individuals buried at the site, regardless of their age or sex, including young children. Most were probably caused by recurrent episodes of small-scale sporadic interpersonal violence such as skirmishes, raids, or ambushes.’

The research team suggests that severe climatic change during the Late Pleistocene created territorial and environmental pressures that triggered the extensive violence demonstrated by the human remains. Dr Daniel Antoine, Acting Keeper of the Department of Egypt and Sudan, and Curator of Bioarchaeology at the British Museum, said: ‘competition for resources due to a shift in the climate was most probably responsible for this frequent conflict’.

The Late Pleistocene period, between about 20,000 and 11,000 years ago, is marked by major climatic variations related to the end of the last glacial period and the beginning of the African wet period. The concentration of archaeological sites (not just Jebel Sahaba but also Wadi Halfa) in a limited area of the Nile Valley at this time suggests that this region may have functioned as a refuge for human populations subjected to hydrological fluctuations and monsoonal changes that engendered climatic and environmental constraints. Environmental and population pressures for access to resources are likely to be the source of this rivalry between human groups experienced by the hunter-fisher-gatherer community that is buried at the Jebel Sahaba cemetery.

Tracking the Green Sahara

Further evidence for climate change in the Late Pleistocene has been published in the journal PNAS by Dr Enno Schefuß of the Centre for Marine Environmental Sciences at the University of Bremen and Dr Rachid Cheddadi of the University of Montpellier. They and their international team of researchers have analysed pollen and leaf material obtained from a sediment core retrieved from Lake Tilsit in the High Atlas Mountains of Morocco. These have enabled the team to identify the types of vegetation and the climatic conditions responsible for the phenomenon known as the Green Sahara when, 14,500 to 5,000 years ago, large areas of North Africa were more heavily populated, and today’s desert was green with vegetation.

Until now, researchers have attributed this phenomenon to the tilting of the Earth on its axis, bringing the tropical summer monsoon further north. Climate scientists now doubt that this would have brought enough rain to explain the permanent vegetation associated with this period in African prehistory. Moreover, the leaf waxes and pollen from Lake Tilsit ‘explicitly reveal that the vegetation was Mediterranean’, says Dr Schefuß. Such plants depend on receiving plenty of rain in winter, and summer monsoon rain would not be sufficient to support them. Instead, Schefuß and his colleagues now believe that, as well as the monsoon moving northward in the summer, there must have been a southward shift of the belt of westerlies in the winter that brought winter precipitation to North Africa. According to Dr Cheddadi, winter rain fell on the northern margin of the Sahara, the summer monsoon watered the southern margin, and there was an area of overlap between the two rain systems that provided water during both summer and winter, albeit rather sparsely.

The implications, says Dr Schefuß, include not only a better understanding of past climate conditions, but also an improvement of the predictions for future climate and vegetation trends in the region, as well as a contribution to archaeological studies of settlement patterns and migration routes. It also helps to explain the evidence from various rock painting sites in the Sahara showing not only hippopotamus and crocodiles, but also – in the Cave of the Swimmers, located on the Gilf Kebir plateau in south-west Egypt, in the Libyan Desert section of the Sahara – people with limbs bent to suggest that they are enjoying a refreshing dip.