The dietary habits of the inhabitants of a settlement are a reflection of its economy. In research into the history of ancient communities, information about what people ate helps interpret available evidence about politics, land use and trade.

Sheila Hamilton-Dyer, Evi Margaritis, Samantha Oxford, Walter Pantano, Martin Millett and Simon J Keay, from institutes of archaeology in the Universities of Cambridge and Southampton, Southampton, Chelmsford, Nicosia and Rome, describe in the journal, Antiquity, published from Durham University, UK, their study of plant, animal and human remains found at a well-known archaeological site. And they explain how the study of eating habits helps reconstruct and verify the commercial and political changes during the period that they cover.

The Portus Project, a detailed archaeological study undertaken by the University of Southampton, began with the mapping, in 1998, of 220 hectares in and around Portus, a large artificial harbour that served ancient Rome. The work continued from 2006 to 2011 with funding by the UK Government’s Art and Humanities Research Council and has brought multi-disciplinary and international attention to research into aspects of the history of Imperial Rome

The harbour of Portus Romae was situated on the northern bank of the mouth of the river, Tiber, which flows through Rome to the Mediterranean Sea in the western coast of Italy. The emperor, Claudius, of the first century AD, built Portus as an alternative to the existing port of Ostia, four km to the south. The object, largely attained, was to protect ships from the southwestern wind that blew at the mouth of the Tiber. The facility consisted of a large harbour basin, enclosed by curving breakwaters, and was connected to the Tiber by two wide canals. While the canals also served to drain the Tiber and save Rome from flooding, Portus itself had elaborate facilities for the reception of ships, handling merchandise and dispatch imports up the Tiber. The harbour even had an artificial lighthouse in the centre. Portus was developed and expanded in the following reign of Emperor Trajan and through the first half of the millennium, it received most of the imports from the Mediterranean for Rome, and exports from the Tiber valley.

The widest of the canals, 90 metres wide, discovered with the help of magnetic anomalies, “was so big that there seems to have been an island in the middle of it,” said a news report of 2010. “The dig, which is being carried out in partnership with Italian archaeologists, is shedding light on the extraordinary trading network that the Romans developed throughout the Mediterranean basin, from Spain to Egypt and Asia Minor… The archaeologists have found evidence that trading links with North Africa in particular were far more extensive than previously believed. They have found hundreds of amphorae, which were used to transport oil, wine and a pungent fermented fish sauce called garum, to which the Romans were particularly partial, from what is now modern Tunisia and Libya,” the news report goes on to say

“Plant and animal remains provide direct evidence for food, traded goods, building materials, fuels and the local environment”, the report in Antiquity says. The authors hence analysed plant and animal remains, from rubbish heaps, and human skeletons from burial grounds. Of plant and animal remains, found in rubbish, the samples were mostly recent, the report says, and earlier periods were underrepresented.

One of the first things observed is that the remains included exotic varieties, like charred black pepper seeds, imported via Egypt from India and containers made from African ostrich egg-shell, clear evidence of extensive maritime trade. There were also remains of exotic animals, like bears, and what appears to be a rib from a crocodile of the Nile. While the exotica were clearly for display in the spectacles of Rome, the focus of the study is on charred grain and the bony remains of larger domestic animals, used for food. As the samples were available only at some locations, however, the food refuse examined is mainly of the daily lives of port workers, rather than households

The plant remains contained ample seeds of grain, preserved, as grain is baked, rather than boiled, but there were little traces of chaff. The absence of chaff suggests that the sources were not nearby cultivation, but came from a distance, the paper says. And there were other indications that the wheat was sourced from different parts of the Mediterranean. It was also seen that the nature of the wheat grains changed from the “freethreshing” kind in the early centuries to the “processed” kind from the midfifth century onwards. This could be a result of a change in maritime networks, and could be related to changes in religious customs, which are recorded, the paper says

An interesting observation arises from the analysis of human remains, in the main cemeteries in the area. While the bones in one cemetery showed signs of manual labour, and were hence of the workers who handled cargo, the other cemetery was for the leisure class. Both classes, however, between the second and mid-fifth centuries, appeared to follow the same kind of diet, rich in animal protein, imported wheat, olive oil, fish sauce and wine. The diet of the local populations, however, changes during the later stages, to more plant protein and lesser imports, more a “peasant diet”.

This, the paper notes, is around 455 AD, the year of the Sack of Rome by the Vandals and the decline of the Roman influence over the Mediterranean. “We are able to observe political effects playing out in supply networks. The politics and the resources both shift at the same time,” the paper says. The change continues until the Gothic wars of the sixth century.

A press release from the University of Cambridge quotes the director of the project, professor Simon Keay, “Our excavations at the centre of the port provide the first archaeological evidence of the diet of the inhabitants of Portus at a critical period in the history of Imperial Rome. They tell us that by the middle of the fifth century AD, the outer harbour basin was silting up, all of the buildings were enclosed within substantial defensive walls, that the warehouses were used for the burial of the dead rather than for storage, and that the volume of trade that passed through the port en route to Rome had contracted dramatically.”