Geologically, however, a millennium and a half is the blink of an eye. The Roman Empire was a bubble that grew on the surface of the pond and then burst. During this time the physical environment of the Roman world—its landforms and climate in particular—hardly changed. New crops and methods of agriculture spread, but they had only a little impact on the landscapes Rome ruled over. Had Romulus been transported seven centuries forward
at his death (rather than taken up into heaven) he might well have been amazed at what his heirs had achieved, but he would not have been puzzled at how they did it. All this is hard to imagine today, living as we do at the end of two centuries of accelerating technological change, change that is having major impacts on the entire biosphere and moves now at a pace hard to adjust to psychologically even in our own brief lifetimes. This chapter explores the long-term stability of the ancient world and the slow secular changes against which the whole of Rome’s imperial story was played out.
The Environment in Classical Antiquity
Let us begin with the visible. The coastline of the Mediterranean 3,000 years ago was hardly different from what it is today. Slight changes can be spotted around the mouths of the larger rivers: the harbour of Ephesus is now a few miles from the coast, and half of Ostia, the port of Rome, has been washed away. Just off Pozzuoli in the Bay of Naples, a series of luxurious villas lie just a few metres under water. So does the great harbour of Alexandria. But these are marginal changes in highly susceptible locations. Sea levels did begin to rise gradually at the end of antiquity, but the only regions where this had a marked impact were low-lying areas such as the Fenland of eastern England and the areas around the Rhine mouth in the Netherlands, where late antique villages are built on low mounds,
terpen
, for protection against floods. Unsurprisingly, the ancients had no sense of geological time or incremental environmental change. There was almost no ancient science of seismology, and the explanations suggested for earthquakes were underground counterparts of those developed for meteorology.
1
A few writers were so committed to this steady-state idea of the world that they believed marble would, eventually, grow back from where it had been quarried.
2
Their world was eternal; the gods had wandered in the same forests and mountains they knew.
The Mediterranean is, in fact, shrinking, as the African tectonic plate moves northward. But this is happening very slowly. Tectonic movement generates vulcanism in Sicily, the Lipari Islands, and Campania, and earthquakes in central Italy, central and southern Greece, and western Turkey. There are extinct volcanoes in other parts of the Roman world—around Rome, for example, in central France, and southern Scotland—but the ancients had no memory of their eruptions. Volcanoes and earthquakes occurred in antiquity more or less where they occur most often today. Etna,
into which the philosopher Empedokles reputedly threw himself, Vesuvius, which buried Pompeii and Herculaneum, and Santorini, which did the same for the Bronze Age city of Akrotiri, remain active today, indeed the most spectacular volcanoes of the Mediterranean world. Major earthquakes have struck in recent memory at the Isthmus of Corinth, where Poseidon the Earthshaker had his greatest sanctuary; in Aegean Turkey, the cities of which received five years’ remission of tribute in
AD
17 from the Emperor Tiberius to help them rebuild themselves after a devastating quake; and in central Italy, where a series of quakes in the middle of the first century
AD
perhaps inspired Seneca to write our first surviving discussion of them, in the sixth book of his
Natural Questions
.
Climate change moves at a faster pace. But in climatic terms, too, the ancient Mediterranean was very similar to the one we know today.
3
We live within the same interglacial period as the Romans, the Holocene, which began around 12,000 years ago with the retreat of the European glaciers and the northward expansion of the Sahara Desert. As the region warmed there were consequent movements of plant and animal species. Such movements are slow: in botanical terms the Mediterranean can be considered as still in postglacial recovery, and not all its native species of plants are yet well adapted to the current climate. Around 6,000 years ago the Mediterranean basin became significantly warmer, establishing today’s pattern of mild wet winters and warm dry summers. ‘Mild’ means no long freezes which kill many species of tree and plant. ‘Dry’ means the Mediterranean as a whole was, and remains, an arid environment. There was never sufficient rainfall to support either dense forests or the grasslands on which herds of ruminants such as cattle, horses, and bison depend. Some parts of the Mediterranean world are exposed to droughts severe enough to cause many crops, including wheat, to fail as often as one year in four. Droughts of that kind are not predictable, and have knock-on effects on species that depend on susceptible crops. Humans that farm are among such species. Classical civilization was built in the shadow of scarcity and risk.
4
The Roman Empire originated in the Mediterranean basin. But from the end of the last century
BC
, it had expanded into adjacent ecological zones. The climate changed most dramatically as one went north or south. This ecological gradient had economic consequences, since many of the central components of the polite culture adopted by local elite members across the empire remained Mediterranean in character. Wine was the alcoholic drink of choice, even where it was easier to produce beer: in the
early first century
AD
some Mediterranean producers grew rich producing wine for export until grape varieties were developed that could survive in the Rhineland and even southern Britain. Olives could not (and still cannot) be cultivated in regions susceptible to frost. Yet olive oil was essential not only for cooking but also as fuel for lamps and for use in Roman bathing, where it was rubbed onto the skin and then scraped off along with any dirt. Olive oil was consequently traded northwards in great quantities.
5
The southern half of the Mediterranean is notably warmer. From the late second century
BC
, great quantities of grain were being exported from modern day Tunisia, Sicily, and Egypt to cities in the northern half of the Mediterranean.
6
By the early first century
AD
olive oil production had also increased in southern Spain and various parts of North Africa.
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North of the Mediterranean basin, temperate Europe had harsher winters and much more plentiful rainfall. That made it a much better area for raising large domesticates. Rome’s European provinces would come to supply much of her cavalry. The accumulating evidence of animal bones found on Roman period sites also shows much more beef eaten north of the Alps, with sheep and goat most evident in the assemblages from sites in the more arid south and east of the empire.
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Studies of faunal material (bones), of seeds and other biofacts, and of container amphorae all also show how the most powerful and privileged members of Roman society—local aristocrats and soldiers for the main part—were able to consume more or less what they liked wherever they were. The main limit on exchange across these sharp ecological contrasts (ecotones) was the cost of transport. Even the journey to north Italy made olive oil so expensive, according to St Augustine who was born and brought up in North Africa, that it was too expensive to burn lights all night long. Traffic beyond the Mediterranean basin was blocked at several points by mountain ranges. A few cities, located at the southern terminal of north–south river valleys or mountain passes, grew rich on trade: Aquileia and Aosta in Italy, Arles and Narbonne in southern France still impress visitors with their Roman period monuments.
The climate of Holocene Europe has not been completely stable. A relatively warm period in the Middle Ages was followed by the Little Ice Age which ran from 1300 to 1800 and was at its coldest at the end of the seventeenth century. Mean temperatures were perhaps a degree or more below those today, but this was enough to make the Thames freeze over on a regular basis. Evidence is mounting for a Roman Warm Period, one that perhaps
raised the mean temperature as much as two degrees above those of today.
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The proposed peak is around 150
AD
, with temperatures dipping until they began to rise again at the start of the Medieval Warm Period, perhaps around 900
AD
. Geophysical evidence from ocean sediments and ice-cores, and tree-ring data, is supported by literary and archaeobotanical indications that some plant species existed further north or at higher altitudes during the early Roman Empire than they do today. The reality of this phenomenon remains very controversial. Unlike the early modern cold period, any change in antiquity was too slow to be noticed by ancient observers. But it may have been important. It has been pointed out that this Warm Period would coincide chronologically with the empire’s furthest northward extent and with the Roman urban maximum. Might a period of warming have increased the productivity of southern Mediterranean agriculture, and made it easier to adapt crops for northern Europe at just the right moment? And might the subsequent cooling have put pressure on Roman agriculture (weakening the empire)? Or else on the barbarian peoples living north of the empire (driving them south)? Investigating these apparent correlations is a priority for future research.
A World of Farmers
Most ancient writers took their physical environment as a given. But they were well aware of the transformative power of one human activity, and that was farming.
Agriculture was an invention of the Holocene, one made independently on at least half a dozen occasions, around the globe. Each invention was based on different combinations of crops—cultigens—that could together supply the carbohydrate needs of humans, and some of their protein. Societies that experienced a Neolithic Revolution were utterly different from those that had preceded them. Population levels rose, permanent settlements were almost always necessary, and in these growing villages and cities, new social discipline was required. As Neolithic societies achieved a new order, so too did Neolithic landscapes. Areas suitable for agriculture were cleared, restricting hunting to marginal territories. Meat eating began to decline. Populations who lived on high-carbohydrate diets, in closer than ever proximity to each other, were less healthy than their ancestors. The domestication of successive animals improved the protein supply, but
brought more diseases. Our leap down the food chain came at a heavy price, but once population levels had risen it was in effect irreversible.
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The nearest farming revolution to the Mediterranean world was also the earliest on the planet. It began around 7000
BC
in the Near East in what is sometimes called the Fertile Crescent. This broad band of territory arcs from Jordan up through Syria and down through modern Iraq to the Persian Gulf, skirting the northern desert of the Arabian Peninsula. Successive innovations had their origins in this region, and in its surrounding upland margins, especially in Anatolia. The move from gathering to cultivating wild crops was followed by the domestication of animals first for food and later for hides, wool, milk, and traction. Arable farming moved across Europe at the rate of about 25 kilometres (15 miles) a generation, reaching the Atlantic by 3000
BC
. The first farmers used tools of flint or obsidian, with handles of wood and bone, and they had no traction animals. Forests were hard to clear with stone axes, and wooden scratch ploughs (
ards
) were most effective on lighter soils. The main crops farmed were husked varieties of wheat, emmer, and einkorn, and in the most arid regions barley. Grains were supplemented in their diets by pulses and some green vegetables. Hunting and fishing made up a tiny proportion of most people’s nutrition. Agriculture spread more rapidly in the Mediterranean world than in temperate Europe for two reasons. First, communications were easier across the islands and coastal settlements of the inland sea than through the forests and mountains of Europe. Second, the aridity of the Fertile Crescent meant the ecological distance was less to the dry Mediterranean than to colder and wetter regions. These two factors together explain why population growth, cities, and states came to Mediterranean Europe before they reached the continental interior. But the Mediterranean only had a head start. Once northern populations had mastered the techniques of farming and developed ways to unlock the much greater potential of Europe’s deeper soils, more abundant, and more dependable rainfall, the Mediterranean would lose its advantage. Today southern Europe is the poorer half of the continent, the recipient of subsidies provided by richer economies of the north. That shift took place in the Middle Ages. Classical antiquity is very largely the history of the period in which the Mediterranean kept ahead of temperate Europe in this respect.
The great story of the Mediterranean Holocene is one of successive movements from east to west. New cultigens, domesticated animals, technologies, and social forms all had their origins somewhere or other east of the Mediterranean world, most around the Black Sea, in Anatolia,
Egypt, and Mesopotamia. Greek and Roman writers treated the Mediterranean as the normal centre of the world. The further one went away from it, the stranger were the peoples and plants and animals one encountered. But in reality the Romans’
orbis terrarum
was just one of several peripheries to the continental mass of Eurasia and Africa.
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The Old World, in ecological and civilizational terms, has always had a common history, within which Mediterranean and European history has always been a secondary development.