Invasive Aliens. Dan Eatherley

own tastes were more refined.

      The occupying power set about expanding the cuisine, introducing at least 50 new species of plant foods, most originating in the Mediterranean Basin. These included fruits such as peach, pear, fig, mulberry, sour cherry, plum, damson, date and pomegranate, along with almond, pine nut, sweet chestnut and walnut. Romans brought vegetables too, from cultivated leek and lettuce, to cucumber, rape and possibly turnip, along with new varieties of cabbage, carrot, parsnip and asparagus which already grew wild in Britain. Black pepper, coriander, dill, parsley, anise and black cumin added to a bonanza of outlandish flavours. Oil-rich seeds of sesame, hemp and black mustard were also among the arrivals.

      Many introductions had supposed medicinal functions too. For the Roman historian, Cato the Elder, the cabbage surpassed all vegetables in that respect. Writing in about 160 BCE, he noted that it ‘promotes digestion marvellously and is an excellent laxative’. Moreover, he insisted, there was nothing better than a warm splash of urine collected from a habitual cabbage-eater to treat headaches, poor eyesight, diseased private parts and sickly newborns. Another plant introduced to Britain for its therapeutic properties was Alexanders – the ‘parsley of Alexandria’ – a chunky lime-green relative of celery, which grew to 150 centimetres in height and was prized as aromatic vegetable and versatile tonic alike. The Romans may have been on to something here: recent chemical analysis of Alexanders reveals high concentrations of the anticancer compound isofuranodiene.

      How many of these species were grown in Britain during the occupation rather than imported as ready-to-eat crops is unclear. The sweet chestnut, for instance, a staple of many a legionary’s mess-tin, is absent from the medieval pollen record, suggesting it was grown here only much later. A period of hotter summers across northern Europe, including Britain, during the early years of Roman occupation may have favoured the growth of warmth-loving figs, mulberries, grapes, olives, pine nuts and lentils, albeit on a modest scale, perhaps in garden pots. By the time the Romans left, several introductions, including walnut, carrot and cherry, are known to have fully established themselves.

      The origins of certain plants can be traced to Britain’s first formal gardens, laid out during the Roman period. The best-known example is Fishbourne Palace in West Sussex, built in about 75 CE, whose outdoor space boasted tree-shaded colonnades and ornamental water features, along with geometric beds, fertilised with manure and bordered by a decorative hedging box. Fishbourne is now believed to have been the residence of a loyal Brit: Tiberius Claudius Cogidubnus, chieftain of the Regni tribe; if true, it was a handsome reward indeed for his allegiance to the occupying power.

      A minority of Roman plant introductions are today regarded as invasive. One of them is probably ground-elder. This iron-rich perennial was cultivated both as culinary herb and for treating arthritis (another name for it is ‘gout weed’), but once its spaghetti-like rhizomes got a foothold, ground-elder was near unstoppable. (Rhizomes are specialised subterranean stem sections capable of putting out both roots and new shoots.) To this day, up to £1 million is spent every year eradicating it from gardens. Some experts say ground-elder is native, but because the weed is usually found close to human habitation its presence here is generally blamed on the Romans.

      As we’ve seen, sheep, cattle, pigs and goats were established in Britain prior to 43 CE, but the chicken – today the world’s commonest and most widespread livestock species – was still a rarity in this country, judging from its absence in the archaeological record. This may have been an artefact of the poor preservation of their brittle bones and difficulties in identification. The earliest remains appear in Early Iron Age burial sites (around 800 BCE), in Hertfordshire and Hampshire, and their very scarcity may have perhaps been reason enough to entomb these exotic birds from the Orient with the lately departed. But when, where and why were people first drawn to the red junglefowl, the chicken’s probable wild predecessor? No one knows for sure, but domestication seems to have occurred somewhere in south or southeast Asia around 4,000 years ago, with tame fowl brought to the Mediterranean by the eighth century BCE, reaching central Europe a hundred years later.

      Chickens and their eggs have always been eaten, but for much of human history they’ve been as prized for their pugilistic prowess as for their gastronomic qualities. Cockerels, it turned out, need scant encouragement to set at each other with beak, claw and, in the older birds, wickedly sharp leg spurs. The skirmishes have excited the bloodlust of onlookers for generations. Cockfighting spread west across India and the Middle East, the sport in turn captivating the Persians, Greeks and the Romans. Chickens held a religious significance too, the males symbolising the sun god in the Roman cult of Mithras. Caged fowl would be taken on military campaigns and their eating habitats studied for purposes of divination; if your sacred chicken, when offered food, guzzled it down, all augured well for the impending battle. Fowl-keeping in Britain grew in popularity up to and throughout the Roman invasion, albeit the preserve of a privileged few. Here, as elsewhere, chickens were multifunctional, a source of food, entertainment and devotion. Their bones are associated with Roman temples, such as one at Uley in Gloucestershire dedicated to Mercury, and they regularly turn up in Romano-British graves.

      Various other animals were imported for nutrition, status and religious reasons, with the remains of pheasant, peafowl, guinea fowl and donkey all found occurring in Roman sites. Elephants were the most impressive creatures brought to Britain; the Emperor Claudius used them to intimidate his new subjects soon after his victory – their stink had the added benefit of panicking enemy horses – although the tuskers’ visit seems to have been fleeting. Archaeologists are intrigued by the discovery at Fishbourne and on the Isle of Thanet, Kent, of numerous bones of fallow deer, a variety hailing from the Anatolia region of modern-day Turkey. Analyses of the deer teeth at both sites indicate well-established, breeding populations, a finding that hints at the existence of what might turn out to be Britain’s earliest deer parks.

      As with so many non-natives, the story of fallow deer is far from straightforward since they vanished with the Romans around 400 CE. It was long assumed that the species only returned to Britain with the Normans, but recent radiocarbon dating work suggests they were around just before the Battle of Hastings. Either a few of the Roman deer hung on in the wild, or more likely, small-scale reintroductions, perhaps as novelty items, continued to occur over the course of succeeding centuries.

      Sometimes creatures were kept for company alone. That seems to be true both for natives, such as ravens and crows, which were popular pets among the soldiers in Iron Age and Roman Britain, and for the more exotic. Examples of the latter included the Barbary macaque, a monkey whose bones have been recovered from Roman sites at Wroxeter, Dunstable and Catterick.

      The Romans weren’t averse to the odd invertebrate too, notably snails, new species of which were introduced as a delicacy. The pot lid, or Burgundy snail remains the most popular of several edible types that now support a multi-million-pound global escargot market. These days snails are largely absent from menus this side of the Channel, where they are regarded as vermin. Indeed, the 5,000 tonnes of molluscicide applied every year to keep them at bay could fill two Olympic swimming pools.

      Most creepy-crawlies arriving and spreading during Roman times came unnoticed as hitch-hikers, such as grain weevils. The earliest British remains of these and other insect pests of food stores show up at sites in London and York dating to within the first decades of the Roman occupation, suggesting that infested grain was imported from Europe soon after the invasion. Invertebrate parasites of livestock and people flourished as new forts, towns and cities sprang up, and human population density grew. The Romans were known for their close attention to personal hygiene, with flushable latrines and heated bathwater. Yet, these measures failed to arrest the proliferation of tapeworm, liver flukes, roundworm and whipworm, along with swarms of fleas, lice and the odd bed bug. The widespread prominence of fish tapeworm, a gut parasite attaining nine metres in length, is something of a puzzle since the species is rarely evidenced in earlier, Bronze and Iron Age sites. Here, the Roman weakness for a peculiar condiment called garum may have been the cause. This fermented sauce, a blend of raw freshwater fish and herbs, left to rot in the sun, was traded across the empire and could have helped spread fish tapeworms.

      From the late fourth century, the Roman Empire began to wither. Soldiers stationed in Britain were recalled to fight insurgencies on other fronts and