In chalky, barren lands bordered
by the sea, along
the rocky Chilean coast,
at times
only your radiance
reaches the empty
table of the miner.
Your light, your cornmeal, your hope pervades America’s solitudes …
Pablo Neruda, ‘Ode to Maize’
Maize, along with wheat and rice, is one of the most important crops in the world – a crucial source of food, fuel and fibres. And it’s grown in an astonishing variety of different places. When you choose plants for your garden – whatever those plants are – you might look for species or varieties that are naturally suited to the habitat. The garden may have clay or crumbly, humic soil; it might be cold and damp or hot and dry. Some plants will tend to do better than others in it. Even within a garden, some plants will do better in darker, cooler spots, while others will flourish against a south-facing wall.
But maize, it seems, is not so difficult to please. It appears to be extraordinarily cosmopolitan. It’s the most geographically ubiquitous grain. In the Americas, it grows in fields in the south of Chile, forty degrees south of the equator – all the way up to fifty degrees north, in Canada. It thrives in the Andes, 3,400 metres above sea level – all the way down to the lowlands and coasts of the Caribbean. The key to maize’s global success surely lies in its prodigious diversity – in looks, habits and genes. But as a global crop, its history is incredibly difficult to disentangle. Although its worldwide expansion happened in just the last five hundred years, written sources are very vague, for instance, about the introduction of maize to Africa and Asia. DNA provides additional clues, but global trade and exchange have ensured that the genetic history of maize is a very tangled web. The globalisation of maize is intertwined with human history, following that ebb and flow – with voyages of discovery, trade routes stretching around the world, and the expansion and collapse of empires. But there’s one thread that is easy to pick out from this mesh: a distinct moment in time that would ensure the globalised future of maize.
During the thirteenth century CE, Mongol emperor Genghis Khan and his successors carved out a huge territory for their Empire – stretching across Asia from the Pacific Ocean in the east to the Mediterranean Sea in the west. Nearly a century of aggressive expansion was followed by several decades of relative political stability: the Pax Mongolica, or ‘Mongol Peace’. During this time, trade routes between east and west were actively protected, and business flourished. Then it all began to fall apart. In 1259, Genghis’s grandson, Mongke, had died without a successor – and the great empire had already begun to fragment into separate khanates or kingdoms. Still, relative peace had prevailed and the Silk Road remained open for business. But by the end of the thirteenth century, the khanates of the Mongol Empire were only very loosely allied. In the early fourteenth century, wars between these separate states divided them, and one by one, they fell, to other rising powers across Asia. At the same time, the hideous spectre of the Black Death hitch-hiked along the routes that had once conveyed spices, silks and porcelain, and both Asia and Europe were plunged into turmoil.
And yet Europe still yearned for the spices of the east. These flavours of the Orient were highly sought-after precisely because they were exotic. Sandalwood, nutmeg, ginger, cinnamon and cloves were the flavours of power, the scents of status. The overland connection to the East was not only dangerous, it involved chains of middlemen, all wanting a mark-up. And so European merchants and explorers had been searching for some time for a viable sea route to the Orient – to India, the Spice Islands, Cathay and Cipangu (which we know as Japan). Africa was unhelpfully in the way. In 1488, the Portuguese explorer Bartolomeu Dias battled on, round the Cape of Storms – later renamed the ‘Cape of Good Hope’ – and the prospect of a south-east sea route seemed possible at last. But Italian explorer Christopher Columbus had another idea. A Florentine astronomer called Paolo Toscanelli had suggested that sailing west from Europe could be a quicker route to the Far East. Earlier that century, others had made attempts – they’d got as far as the Azores, only to be beaten back by westerly winds.
Columbus had worked as a sugar merchant, sailing out west from Europe to Porto Santo, in the eastern Atlantic, near Madeira. From the contacts he made on his voyages, he learnt that, while westerly winds predominated in the north, when you moved further south in the Atlantic, the winds mostly blew from the east. It was a risky thing to try – explorers usually preferred to sail into the wind, knowing they would be assured a safe return trip. But Columbus had a thirst for discovery – and social advancement. He didn’t just want to find new territory, he wanted to claim it for himself: to be the governor of any islands he discovered, and to pass that position on to his heirs. Eventually, he secured financial backing from King Ferdinand and Queen Isabella of Spain, and the voyage was on.
In the third century BCE, the Greek mathematician and geographer Eratosthenes had reckoned the circumference of the globe to be 252,000 stadia. That’s about 44,000 kilometres. The actual circumference is just over 40,000 kilometres – Eratosthenes was only 10 per cent out. But later geographers thought the Ancient Greeks might have profoundly overestimated the size of the earth. Toscanelli was one of them. And in 1492, a cartographer in Nuremberg – who had corresponded with Toscanelli – produced a small globe of the known world: an ‘erdapfel’, or earth-apple. It’s the oldest known globe in the world, and historian Felipe Fernandez-Armesto has called it ‘the most surprising object’ of 1492. And on it, the Americas are conspicuously absent. The implication is: if you set sail from Europe, heading west, you’ll eventually reach Asia.
Setting off in 1492, Columbus chose to sail west from the Canary Islands, just off the coast of Morocco, with three ships. Not only was the wind filling their sails here, they were embarking on what they believed, from record of previous explorations, to be just about the right latitude to hit the famous port of Guangzhou in China. And so, heading into the unknown, the tiny fleet – the Niña, the Pinta and the Santa Maria – weighed anchors on 6 September. After a month – no landfall, and Columbus’s fellow commanders were becoming impatient. The sailors were looking a little mutinous. The three ships changed course, to the south-west. In the early hours of Friday 12 October, a lookout on the Niña spied land. It was probably the island we now know as San Salvador, in the Bahamas.
Just imagine those Iberian explorers and sailors arriving on this island. This, to them, was the Indies: an island off the east coast of Asia. After so long at sea, they’d reached this idyllic place – the darkness of the deep sea changed to the clearest turquoise as they approached the palm-fringed beach. The island was lush and forested, full of promise. And although history is full of strings of happenstance and contingency, it feels as though it turns on this point, when Columbus sets foot on that beach – as his boots sink into the sand.
He met the islanders. They seemed not to be desperately suspicious of his motives, and instead were amicable and hospitable. How different history might have been had Columbus not met with such a friendly reception. To Columbus, the natives were humans, not monsters; they were naked and natural; they were morally pure, perhaps – but also easy to conquer. But this was not the Eastern civilisation he was expecting to encounter. There were none of the riches of the Orient here. There were crops, though. On 16 October 1492, Columbus wrote in his ship’s log: ‘It is a very green island, and very fertile and I don’t doubt that all year round they plant and harvest panizo.’
When some of his companions came back from exploring nearby Cuba, on 6 November, Columbus recorded that they’d found a distinct type of cereal growing there: ‘… another grain, similar to panizo, that they call mahiz, and it tastes good when boiled and roasted.’
It’s likely that these two cereals – on San Salvador and on Cuba – were in fact the same plant: maize. Plant scientists think that Columbus probably saw maize in flower on San Salvador, and thought it looked similar to panizo – sorghum or millet, something he was familiar with back home. So the ‘panizo’ he described was in fact the same thing as the ‘panizo-like’ grain that the Cubans called mahiz – maize.
And so, with those mahiz grains in his pocket, Columbus went on to explore other islands. The islanders, who travelled around by canoe, knew the local geography very well – and shared this knowledge with Columbus. But where was Japan? Where was China? He had high hopes of finding Asian civilisation on Cuba – but it wasn’t there. There were no spices and silks. The inhabitants were quite poor – these were not the trading partners he was looking for.
He sailed on to the island of Hispaniola, now divided between the Dominican Republic and Haiti. There, he found both civilisation – at least a civilisation capable of producing stone-built architecture – and, perhaps more importantly, gold. Leaving a garrison on Hispaniola, he gathered up his trophies – including gold, of course, but also chilli, tobacco, pineapples and maize – and headed home. Battered by storms on the return journey, Columbus was forced to land in Lisbon – where he was interrogated by Bartolomeu Dias, before being released to sail on to Huelva. Although many doubted his story, he insisted to his patrons, Ferdinand and Isabella, that he’d fulfilled his contract: he’d found the eastern edge of Asia. In fact, he didn’t know where he’d been – but he knew how to get back there.
He returned the following year, but the friendly reception he’d enjoyed in 1492 had turned sour. The garrison on Hispaniola had been massacred. Rumours of cannibalism proved to be true. And the climate was feverishly hot and humid. The indigenous people of the New World were not going to acquiesce to foreign sovereignty as easily as Columbus had imagined.
Columbus is, of course, a person who has inspired admiration and vilification in almost equal measures. He forged a connection which would see the empires of Europe rising to become global superpowers, while the Eden of the Americas was plundered and its civilisations destroyed. Setting foot on that beach, he sealed the fate of tens of millions of Native Americans and ten million Africans. The impact of that moment would ripple out through history. Until this point, Europe had been something of a backwater – but the establishment of colonies in the New World would change all that. The rise of the West had begun.
And the impact would be felt not just throughout human societies, around the world, but by the species that had become our allies – on both sides of the Atlantic. This contact between Europe and the Americas would quickly turn into a sustained connection between the Old and New Worlds. These supercontinents had been largely separate since the break-up of Pangaea, which began around 150 million years ago. During the Great Ice Age, the Pleistocene, the world went through repeated glaciations. And during the glacial periods, sea levels would fall to such an extent that the north-east tip of Asia would be joined to the north-west corner of North America, via a tract of land known as Beringia – or the ‘Bering land bridge’. This bridge would allow some interchange of plants and animals between Asia and North America. It was the route by which humans first colonised the Americas, around 17,000 years ago. And yet the ancient, underlying theme of divergence and difference between the flora and fauna of the Old and New Worlds persisted – until the human-mediated transfer of plants and animals which started with Columbus bringing back his pineapples, chilli and tobacco in 1492. Plants and animals which had been contained and separate from each other made that leap across the pond, to find themselves facing new landscapes, new challenges and new opportunities on the opposite side. Cattle and coffee, sheep and sugar cane, chickens and chickpeas, wheat and rye travelled from the Old World to the New. Turkeys and tomatoes, pumpkins and potatoes, Muscovy duck and maize made the reverse journey.
The Columbian Exchange has been described by some as the most significant ecological event on the planet since the dinosaurs were wiped out. It was the beginning of globalisation: the world became not just interconnected but interdependent. But it had a wretched inception.
The fortunes of Europe (and, in due course, Asia and Africa) were transformed by the domesticated species brought back from the New World. Novel crops boosted agriculture and populations began to recover from war, famine and plague. But that was in the Old World. In the Americas, a scene of devastation ensued. Just as plants and animals had followed separate evolutionary trajectories on either side of the Atlantic, the pace and direction of technological change had been different in the Old World compared with the New. The Europeans possessed advanced technology: their military and maritime kit was vastly superior to that of the Native Americans. The immediate consequences of contact, with heart-stopping, dreadful inevitability, were tragic. Disease organisms were also part of that Columbian Exchange: the Europeans brought back syphilis from the Americas, while introducing smallpox there – with disastrous consequences. The indigenous population of the Americas plummeted after conquest. It was decimated: by the middle of the seventeenth century, 90 per cent of the indigenous population had been wiped out.
It’s easy to focus on the power imbalance that existed between the Old and New Worlds in the fifteenth and sixteenth centuries. Human societies had developed in different ways in the Americas and in Europe, but it wasn’t as though the Native Americans were entirely without technology – far from it. When it came to their exploitation of natural resources, they were clearly experts. It’s wrong to see the pre-Columbian Americas as, on the one hand, a natural Garden of Eden, and on the other, an innovation vacuum in need of European inspiration to realise its potential. Native American societies had a rich and diverse history of innovation, and the Americas contained completely independent centres of domestication. Many of the pre-Columbian societies of the Americas were large, urbanised – and already dependent on agriculture.
The Spanish explorers didn’t pluck wild plants, out of relative obscurity, recognise their utility for the first time, and transform them into something which would greatly benefit humanity. What the Europeans found on the other side of the Atlantic were organisms which had already changed away from wildness, over thousands of years – which had already entered into a tightly bound, successful alliance with humans. What Columbus discovered was not only a new land, previously unknown to Europeans, but a wealth of useful, tamed animals and plants – ready-made domesticates.
Among those prizes was that cereal he’d spotted and written about, just four days after landing on San Salvador – the cereal that was not only a staple food but a sacred food for the Aztecs and Incas, whose civilisations would soon be swallowed up by the Spanish Empire: maize.
Columbus returned home from his first voyage to the Bahamas with samples of seeds, bringing back even more on his subsequent trips. News of the arrival of maize spread quickly – reaching the Pope and his cardinals by 1493. Written on 13 November, a letter from an Italian historian attached to the Spanish court, Pedro Martir de Angleria, to an Italian cardinal, Ascanio Sforza, described the new grain:
The ear is longer than a hand, pointed in shape and as thick as an arm. The grains are beautifully laid out, and are a similar size and shape to chickpeas. They are white when unripe, becoming black when ripe; after milling, they are whiter than snow. This type of grain is called maize.
A follow-up letter from Martir in April 1494 apparently accompanied a sample for the cardinal. And in 1517, maize appeared in a fresco painted on a wall in Rome. But although this tropical plant seems to have settled in well in Spain, it didn’t take well to more temperate climates. Cold winters stunted its growth, and long hours of daylight in summer would have discouraged the plant from setting seed. So it seemed that, in central and northern Europe, maize was highly unlikely ever to become a dependable crop and a staple food, as it was in the Caribbean. And yet it started to pop up in increasing numbers of records – and not just from southern Europe. In 1542, the German herbalist Leonhart Fuchs wrote that it was ‘now growing in all gardens’. By 1570, it was growing in the Italian Alps. It seems extraordinary that this tropical plant had evolved so quickly, adapting to the significant challenges of a temperate climate.
Careful reading of the great sixteenth- and seventeenth-century European herbals suggests that something else was happening. The writers of these botanical records tended to follow a fairly strict format: they’d list the names of a plant; then they’d describe the plant – its leaves, flowers and roots as well as its uses; its medicinal properties were laid out; and its geographic origin. The entries were accompanied by illustrations printed from woodcuts. Maize first appears in these herbals in the 1530s. But for some thirty years after that, its New World origin isn’t mentioned. While the Spanish explorers were writing about this cereal that they’d brought back with them, many people seemed to think that maize had arrived in Europe from Asia. The first reference to maize in the herbals appears in the work of the German herbalist Jerome Bock in 1539. He referred to maize as welschen korn – ‘strange grain’, something new in Germany – and he thought it had come from India. The Medieval herbalists were so entranced with the classical world, it was almost as though they couldn’t escape its stranglehold. Confronted with novel plants, they looked to the Ancient Greeks – especially Pliny and his contemporary, Dioscorides – for help. Surely they’d described everything: they must have the answer. The geographic confusion and conflation that accompanied the discovery of the New World certainly didn’t help the matter. The Spanish explorer and inspector of mines, Oviedo, had written a History of the Indies. Even having visited the Americas, and seen maize growing there, he thought that it had probably been described by Pliny. He says of Pliny’s ‘millet of India’ – ‘I think it is the same as what we call “mahiz” in our Indies.’
Fuchs called maize Frumentum Turcicum – Turkish corn. He wrote:
This grain, like many others, is one of those varieties which have been brought in to us from another place. Moreover, it came into Germany from Greece and Asia, whence it is called ‘Turkish corn,’ for today the huge mass of Turkey occupies the whole of Asia.
Maize wasn’t the only species whose origin was obscured by this tendency to regard and label anything new and exotic as ‘Turkish’. In some cases it’s stuck with us all the way to the present day. We still call the American bird Meleagris gallopavo a ‘turkey’.
In 1570, the penny dropped. The Italian herbalist Matthiolus had read Oviedo, and saw through that confusion between India and the Indies. He was brave enough to suggest that everybody else was wrong – and that maize really had come, across the Atlantic Ocean, from the West Indies. After this, it seems to have been fairly generally accepted that maize was a New World plant – or that at least one variety of it came from the Americas. Some herbalists differentiated between two distinct types of maize. One had yellow and purple kernels, an ear with eight to ten rows, and slender leaves, which was labelled Frumentum Turcicum. Another type is described as having some black and brown kernels, and broader leaves, called Frumentum Indicum. The implication was that Indicum had come from the West Indies, while Turcicum or Asiaticum came from Asia.
The differences between these two, apparently quite distinct, types of maize suggest an interesting possibility. The first type, Frumentum Turcicum, sounds much more like the type of maize now known as a ‘Northern Flint’. This variant has very hard kernels, and it doesn’t hail from the Caribbean at all. It comes from New England and the Great Plains of North America. Rather than being evidence of fast adaptation in maize brought over from the Caribbean, and spreading from Spain into the rest of Europe, the careful descriptions of Frumentum Turcicum in those sixteenth-century herbals suggests that there had already been a separate introduction of maize into Europe – this time, from North America.
Another clue appears in the English herbal of John Gerard, first published in 1597. Gerard writes that he has grown maize in his own garden, and that it’s called ‘Turkie corne’ or ‘Turkie wheat’. He adds some details about its provenance, and thinks – like many of his contemporaries – that one type came from the ‘Turkes Dominions’ of Asia. But of the New World sources of this grain, he writes that it comes ‘out of America and the Ilands adioyning … and Virginia and Norembega, when they use to sowe or set it, and to make bread of it’. The mention of both Virginia and Norembega flag up a potential North American source of maize.
Virginia is still familiar to us, as a modern state of the US. It’s said to have been named by Sir Walter Raleigh – possibly after his virgin Queen, possibly after an indigenous leader – in 1584, the year in which Raleigh sent his first colonisation and research mission to North America. But Norembega is an odd-sounding name; it starts to appear on sixteenth-century maps, in roughly the area of modern New England. The name also became attached variously to a legendary and fantastically wealthy city – an ‘El Dorado’ of the north; to a river in Maine; and to a putative Viking settlement – founded by Leif Eriksson, of course. In the nineteenth century, Boston’s elite found this last incarnation particularly alluring. They liked the idea that the Vikings had settled New England, and had effectively founded their nation. Eriksson was somehow the acceptable – even the heroic – face of European colonisation. And while Columbus was Catholic, Eriksson was – if not Protestant – then at least Nordic.
There’s that possible Viking settlement at L’Anse aux Meadows on Newfoundland – and this island may well have been the Vinland described in the sagas – but this didn’t develop into a European colonisation of the eastern seaboard of North America. There’s no evidence that the Viking presence in North America extended to New England, and on Newfoundland any early Viking settlements seem to have been very short-lived – and thoroughly extinct by the time the sixteenth-century European explorers arrived.
It seems likely, then, that the ‘Norembega’ that Gerard is vaguely referring to is not a Viking settlement or a mythical city, but simply the area which would later become known as New England. But the English presence there would only become firmly established in the early seventeenth century, decades after the publication of Gerard’s Herbal.
In 1606, James I issued a charter to the London and Plymouth Virginia Companies – effectively sponsoring them to form new trading connections and aggressively lay claim to land in North America. In 1607, the English explorer and ex-pirate John Smith, working for the Virginia Company of London, founded James Fort – which would become the first permanent British settlement in North America: Jamestown. John Smith was injured in a battle with Native Americans – being famously (and possibly apocryphally) saved by the chief’s daughter, Pocahontas – and returned to England. But he headed back over to North America in 1614, exploring and mapping the area which he would name ‘New England’. The Mayflower settlers arrived soon after, in 1620, leaving from Plymouth in England, and founding New Plymouth in Massachusetts. This is also recognised as a seminal moment in the history of colonisation, and for some marks the true beginning of the permanent settlement of New England.
So, by the time English settlers had put down these permanent roots in North America, what appears to have been North American – not Mexican – maize had been growing in English gardens for more than two decades. Had someone brought this domesticate over even before the Virginia Companies were granted their Royal Charter? Raleigh’s research mission to Virginia in 1584 is clearly too late. But the European presence in North America does go back a little earlier than that. Further north, the English colony in Newfoundland was officially recognised in 1610 – but it had been claimed for the English crown in 1583, by Raleigh’s half-brother and fellow adventurer, Humphrey Gilbert.
That’s surely still too late for the spread of maize through the gardens of England – just fourteen years before Gerard first published his Herbal. But Gilbert wasn’t the first European person to set foot on Newfoundland since the Vikings. The European discovery of the island predated Gilbert’s voyage by eighty-six years.
Hanging in Bristol’s Museum and Art Gallery is a huge painting which has entranced me since I was a small child. It was painted by an artist called Ernest Board, who studied art in Bristol and seemed to enjoy historical subjects and large formats. The painting shows a grey-haired man, standing on a quayside, in splendid Medieval get-up, wearing a doublet of red and gold brocade, scarlet leggings and wonderfully long, pointed leather boots. He’s gesturing to the ship moored to a post at the quay, while at the same time shaking the hand of an older man in a long, dark robe, who’s wearing a mayoral chain of office. Half-hidden between these two is a younger man, with auburn hair, in a red doublet. Behind the mayor in his dark robe – and closer to us – is a bishop, dressed in an embroidered chasuble, his red-gloved hand grasping his golden crook. He’s flanked by two small, white-robed acolytes, one carrying a Bible, and the other a candle.
There’s a gaggle of other people in the background, all craning to get a better look. In the foreground, a pile of weapons and helmets lies on the cobbles, and a man in a crenellated white hood is picking up an armful of halberds or bills, presumably to load on to the ship. All that we can really see of the ship itself is its prow, but its billowing foresail forms the backdrop for the scene on the quay. Half-hoisted, the sail is painted with a castle and a mast in front – the coat of arms of Bristol. In the distance, we glimpse the Medieval skyline of the city. And, to the right, a tower stands on the horizon. It looks a lot like the Wills Memorial Building, which towers over the city today – but that was only built in 1925. It must be the spireless tower of St Mary Redcliffe. The painting is entitled The Departure of John and Sebastian Cabot on their First Voyage of Discovery, 1497. The grey-haired man at the centre of the painting must be John. Standing behind him, in the red doublet, is his son, Sebastian.
Five years after Columbus set sail for the Indies, in a south-westerly direction, under the sponsorship of Ferdinand and Isabella of Spain, John Cabot left England to sail north-west. He was an Italian by birth, and became a citizen of Venice – so we should really call him Giovanni Caboto, or, for a Venetian twist, Zuan Chabotto. A maritime trader, Cabot (as I’ll persist in calling him) worked out of Venice and Valencia, and then turned up in London. He was planning a northerly exploratory voyage across the Atlantic – and this was diplomatically extremely sensitive. A papal bull, or decree, of 1493 had already granted Spain and Portugal exclusive permission to explore the non-European world. Cabot really needed royal support for what would undoubtedly be seen as an incursion into Spanish and Portuguese territory. The Spanish ambassador wrote to Ferdinand and Isabella to explicitly warn them that ‘uno como Colon’ – one like Columbus – was in London. But Cabot got the support he needed. Presumably Henry VII didn’t see why the Spanish and Portuguese should have it all stitched up, and in 1496 he granted Cabot a licence for exploration. The licence accorded Cabot the right to hold, in the king’s name, any land he took possession of, and to have a monopoly over any trade routes he forged. But Cabot still needed financial backing for the voyage. It seems he may have obtained some funds from Italian bankers in London, but also from wealthy Bristol merchants, willing to gamble on this venture. One merchant in particular, who was also a customs officer, has led to the formation of an alluring myth. His name was Richard ap Meryk, also known as Richard Ameryk.
It’s generally accepted that the ‘Americas’ are named after the Italian scholar and explorer Amerigo Vespucci, who voyaged to South America between 1499 and 1502, and realised that those ‘West Indies’ weren’t part of Asia at all – but an entirely new land mass. But what about this Richard Ameryk? His surname has sparked a suggestion that the Americas were in fact named after him. It’s a popular explanation, in Bristol at least, but even Ameryk’s connection with Cabot is more than a little tenuous. While some have suggested that Ameryk was the principal backer of Cabot’s expeditions – and even the owner of the ship in which Cabot set sail, the Matthew – there’s unfortunately no documentary support for any of these speculations.
Still, the Bristol connection itself is secure. Cabot’s charter stipulated that he should sail from this maritime city, which already had some history of Atlantic exploration. A couple of expeditions in the early 1480s had aimed at finding new fishing grounds. But there were also stories of a mythological island called ‘Hy-Brasil’ that might have stimulated some adventures – and there were even rumours that Bristol sailors had found it. Perhaps some Bristolian really had already discovered North America – even before Columbus made his trip – but we’ll probably never know the truth of it.
Cabot set off in 1496, but short supplies and inclement weather forced him back. Undeterred, he got ready to have another go at it in 1497. He left Bristol on 2 May, and reached the other side of the Atlantic on 24 June. Various historians have suggested Nova Scotia, Labrador and Maine as the site of that landfall, but Cape Bonavista, on the east coast of Newfoundland, is thought by many to be the most likely landing place – and it was to there that a replica of Cabot’s ship, the Matthew, sailed from Bristol in 1997. Some five hundred years earlier, Cabot had been pretty sure that he’d been to the east coast of Asia. Back in England, Bristolians thought he’d probably found the mythical Isle of Brasil.
Cabot returned to the New World for further exploration, but his wanderings are imprecisely recorded. A historian who made some exciting but extraordinary claims about Cabot’s adventures, Alwyn Ruddock, died before publishing her research on the subject – and ordered her research notes to be destroyed as soon as possible after her death, which can hardly fail to raise suspicions. But Ruddock asserted that, in 1498, Cabot explored the entire east coast of North America, claiming it for England, and made an incursion into the Spanish territory in the Caribbean.
Amongst the documents that do survive, relating to Cabot’s voyages, there’s a disappointing dearth of information about the plants and animals he encountered. In stark contrast to the descriptions of Columbus’s voyage, no one seems to mention anything that Cabot brought back with him from the New World. After the first voyage, Henry VII gave Cabot a whole ten pounds for his trouble, but commercially the voyages had been a failure. Diplomatically, this venture was a bit of an embarrassment too. While Cabot had been away, Arthur, Prince of Wales, had become betrothed to Catherine of Aragon – daughter of Ferdinand and Isabella. The marriage was intended to cement an Anglo-Spanish alliance. Better, then, not to tread on Spanish toes, and to sweep that less-than-entirely-successful voyage of exploration under the carpet. The royal marriage went ahead in 1501; Arthur died six months later. But there was still hope for the kingdom, in the form of Arthur’s brother. Eight years on, Catherine married that brother – becoming the first wife of Henry VIII.
Still, there was a whole New World out there, and English explorers and pioneers – including John Smith and Henry Gilbert – continued to investigate and lay claim to the northern continent. The names of seventeenth- and eighteenth-century sailors and explorers would become stamped on the map of North America, from Henry Hudson to George Vancouver.
But it was the earlier pioneers who must have introduced the North American varieties of maize to northern Europe – in plenty of time for them to be recorded in Gerard’s Herbal. John Cabot’s son, Sebastian, pictured in that Ernest Board painting, reported that some Native American tribes lived off meat and fish, while others grew maize, squashes and beans. It’s impossible to imagine that – in the decades that followed John Cabot’s slightly hushed-up discovery of North America – none of these sixteenth-century English explorers brought the northern variant of maize back with them.
And maybe Cabot himself had brought a few grains with him; he would have needed supplies for the return journey, after all. So – imagine Cabot coming home, sailing up the Severn, then the Avon, back into port in August 1497, with not only a head full of new geographical knowledge, but his pockets full of maize kernels. This is a fiction, a figment – as fanciful and romantic as the Board painting – but I love to think that Cabot returned to Bristol and grew sweetcorn in his garden.
When history of the more traditional variety, laid out in ink on parchment, vellum and paper, runs out, we can turn to the genetic archive – the precious rolled-up scrolls contained in the nuclei of the cells of the organisms themselves. The nuclear narrative; the chromosome chronicles.
Back in 2003, a group of French plant geneticists published the results of their research into maize genetics. By looking at patterns of difference and similarity among 219 separate samples of maize, from the Americas and Europe, they had hoped to uncover some of that forgotten history. They used a technique which involved cutting up DNA with enzymes, then comparing the lengths of the fragments that had been produced – between different samples. It’s essentially the same technique that was developed for forensic purposes, which became known as ‘DNA fingerprinting’. It’s fairly crude, compared with modern DNA sequencing, but it does reveal patterns of similarities and differences between genomes – and, using it, the French geneticists gained some very clear insights into the saga of maize domestication and globalisation.
They found that maize was wonderfully diverse – much more than had been previously thought. The American populations – especially those from Central America – contained much more variation than the European ones. Maize was clearly, originally and entirely, an American plant – there was no hint of any Asian heritage. Within the Americas, Northern Flint maize, from the higher latitudes of North America, appeared genetically very similar to Chilean varieties. Both these types have long, cylindrical ears and long husk leaves, and hard-as-flint kernels. And genetic similarities between populations of maize on either side of the Atlantic preserved memories of voyages of discovery. Closely related, genetically similar samples of maize would appear as tight clusters in the analysis. The geneticists found that six southern Spanish populations clustered with Caribbean populations – the two were clearly closely related. Presumably the southern Spanish maize varieties were the descendants of the first maize brought back from the New World. But this Spanish maize, quite obviously, had not spread into the rest of Europe. Even Italian maize was different to the Caribbean varieties – it was closest to South American types, from Argentina and Peru. And North European maize was genetically closest to the American Northern Flints. The hints in the herbals – of a separate introduction from North America – were borne out in the DNA of maize growing in northern Europe today. The sixteenth-century German botanist Fuchs was so sure of the Asian, or Turkish, origin of this grain. But his herbal of 1542, the first to contain an illustration of maize, depicted a plant with long ears – with eight to ten rows of kernels – and long husk leaves. It looks like a Northern Flint.
Historians have suggested that maize from North America was brought over to Europe in the seventeenth century, but the combination of evidence from genes and the great European herbals pushes the introduction right back into the first half of the sixteenth century – if not slightly earlier. And this isn’t at all far-fetched. Archaeological and genetic studies have shown that, by this time, Iroquoian populations were growing maize – as a staple food – across a great sweep of eastern North America – precisely the territory which was being thoroughly explored by English and French pioneers in the sixteenth century.
It’s odd that there’s such a hole in the historical literature when it comes to maize in the north. But it was such a novel thing, and it seems that words failed the European adventurers. Two explorers, commissioned by King Francois I of France, Giovanni Verrazano and Jacques Cartier, may have referred to maize in rather oblique terms that have been missed in the past. These two were both exploring, and writing about their discoveries, in the 1520s and 1530s. Verrazano writes about an excellent and delectable ‘legume’ that he tastes when meeting Native Americans living near Chesapeake Bay. Later French texts describe maize as a legume. Cartier, exploring what would become Quebec, describes ceremonial feasts involving ‘gros mil’ – a term for sorghum, which has surely been appropriated here for maize.
It seems clear that there were ample opportunities for an early introduction of North American varieties of maize into northern Europe – from the end of the fifteenth century into the first half of the sixteenth. More recent genetic analyses strongly suggest that there were indeed multiple introductions of Northern Flints into Europe. Cabot and son, Verrazano and Cartier, are just a few of the pioneers who could have brought Northern Flints back with them. As well as coming back with official voyages of discovery, maize probably hitch-hiked with unofficial Atlantic fishing expeditions. And in contrast to the tropical Caribbean maize, the North American varieties were already adapted to temperate climates – they would have thrived immediately in central and northern Europe.
The genetic story of maize plays out in a similar way in eastern Asia. Maize in tropical latitudes, from Indonesia to China, is closest to Mexican maize. But this time, history supplies the details – the Portuguese introduced maize into south-east Asia as early as 1496, and another wave of maize arrived with the Spanish colonisation of the Philippines in the sixteenth century. The genetic map of maize in Africa is complicated, with early introductions of South American maize to the west coast by Portuguese colonisers in the sixteenth century. This history echoes in the African names for maize – mielie or mealies – which derive from the Portuguese word for maize, milho. Later, from the nineteenth century onwards, varieties from the southern half of North America, known as ‘Southern Dents’, were introduced to eastern and southern Africa. Up in the north-west corner of Africa, there’s evidence of Caribbean ancestry – just as in southern Spain. That Caribbean genetic signal is also scattered across western Asia, from Nepal to Afghanistan. Linguistic and historical clues support the role of Turkish, Arab and other Muslim traders in the spread of maize from the Middle East, by sea and by land – from the Red Sea and the Persian Gulf out into the Arabian Sea and eastwards to the Bay of Bengal; along the Silk Road and through the Himalayas.
But it’s the DNA of maize from the middling latitudes of its new homes around the world that’s most fascinating. In the north of Spain and the south of France, European maize is equally related to North American and Caribbean types. It looks like hybridisation created the perfect in-betweener – as early as the seventeenth century. Strains of maize which had diverged away from each other, adapting to different environments, in the Americas, were brought back together in the foothills of the Pyrenees.
The dissemination of maize across the world was astonishingly fast. Genetic analysis and molecular dating suggests that maize was domesticated around 9,000 years ago in the Americas. It stayed in this region for 8,500 years, going global in just the last 500 years. But in fact its spread was even faster than this implies – the documentary evidence shows that maize had spread right across Eurasia, from Spain to China, in just six decades after Columbus first brought it over from the Caribbean. In some ways, this spread and adoption seems quite extraordinary – these were regions of the world where agriculture had been practised for millennia, and there were already well-established fields of wheat and rice to provide populations with staple foods. The historical records show that farmers didn’t immediately swap their traditional crops for this new grain. Instead, maize was often grown on marginal land, by impoverished farmers trying to eke out a living in relatively barren areas. It was considered a food of the poor – and yet, once it had a foothold in the Old World, the global future of maize was assured. Its sheer variety, and ability to grow in such a wide range of environments, meant that – as soon as it crossed the Atlantic – it was poised to spread throughout the world.
Back in the Americas, genetic studies have been crucial, not only in estimating the timing of maize domestication, but in tracking down the identity of the wild progenitor, establishing how many times maize was domesticated, and where this happened. Maize is a subspecies – Zea mays mays – and there are three other subspecies within the same species – all of which are wild, and known more colloquially as teosinte: a name that comes from the Aztec language of Guatemala. The Aztecs venerated maize, in the forms of the goddess Chicomecoatl and the god Cinteotl.
The three teosintes – Zea mays huehuetenangensis, mexicana and parviglumis – grow wild in Guatemala and Mexico. Although the teosintes look quite distinct from their domesticated cousin, maize hybridises freely with all of them. If we imagine evolution as a branching tree, it seems likely that one of these cousins will be closer to maize than the others, and may even represent the surviving wild descendants of the original population that was also domesticated.
Analysis of enzymes in maize and the teosintes had suggested that one of the wild subspecies was indeed more similar to maize than the others. And in 2002, this was confirmed by a large genetic study. Having tested 264 samples in total – of maize and the three teosintes – the geneticists found that Mexican annual teosinte Zea mays parviglumis was closest to the domesticate.
As the study contained so much data on American maize populations – 193 of the 264 samples were from maize – it was also possible to construct a phylogeny, a family tree, for this domesticate. All the maize lineages – from the temperate-adapted Northern Flints to the tropical types in Colombia, Venezuela and the Caribbean – tracked back and coalesced, converging on a single stem. So maize was domesticated just once. Or at least, if it was domesticated several times, only one, branching lineage has survived to the present. The stem of the phylogenetic tree was rooted in Mexico. But pinning down the place where the domestication first started was tricky. The most primitive form of domesticated maize on that phylogenetic tree grows in the highlands of Mexico. But the closest wild relative is a lowland plant: it’s the Zea mays parviglumis of the Balsas River Basin of central Mexico, or Balsas teosinte.
By the time this genetic information emerged, the earliest evidence of maize in the archaeological record – in the form of whole cobs – came from the Mexican highlands, dating to 6,200 years ago. So it seemed that, either Balsas teosinte had been carried up into the mountains to be planted, or it was first domesticated down in the valleys, spreading to higher altitudes later.
Over thousands of years, climate and environments have changed quite a bit, and species will have shifted accordingly. But, given the new genetic data and the identification of the closest wild relative to maize, archaeologists believed it was still worth having a good look down in the Balsas Valley. And so they began to scour the area for traces of ancient cultivation and domestication. What they needed was something which would clearly distinguish the wild from the domestic.
When it starts growing, teosinte can be difficult to distinguish from its domesticated cousin, making it a vexatious weed in maize fields. But when it matures, it looks quite different. Each teosinte plant is bush-like, with branching stalks – whereas maize grows with a single, tall stalk. Teosinte ears are small and simple, with a staggered row of about a dozen kernels attached to a central rachis. Maize cobs are huge in comparison, crammed with hundreds of kernels. Teosinte kernels are small, and each contained in a hard case; maize kernels are large and naked. And just like wild wheat, wild teosinte ears shatter at maturity, whereas maize kernels stay firmly attached to a non-shattering rachis. Geneticists have been able to pinpoint just a handful of genes which have undergone mutations to produce the differences in branching, kernel size, fruitcases and seed shattering between teosinte and maize.
This is all very well, but down in the tropical lowlands, preservation of plant remains is pathetic at best – the archaeologists had no hope of finding whole plants, whole cobs, or even intact kernels. Instead, they turned their attention to much smaller components of plants – phytoliths and starch granules. Phytoliths are silica-rich and very resistant to degradation, meaning that they stick around, even in tropical places, for an incredibly long time. Both the phytoliths and starch granules of teosinte are – very usefully – characteristically distinct compared with those of maize.
The first evidence of these microscopic traces of early maize were discovered in lake sediments in the Balsas River Valley. The archaeologists followed up by excavating four prehistoric rock shelters in the region – and one of them, the Xihuatoxtla Shelter, yielded precious, early evidence of maize. Stone tools from the cave – in a layer dating to 8,700 years ago – contained diagnostic maize starch granules tucked into cracks and crevices. Maize phytoliths were also found on the stone tools, as well as being scattered throughout samples of sediment from inside the rock shelter.
The phytoliths provided further clues as to how the ancient Mexicans were using maize. It’s been suggested in the past that maize may have been cultivated, first and foremost, for its stalks. The hard fruitcases of ripe teosinte kernels would have made them unpalatable, whereas the sugary pith of the stalk could have been eaten or even used to make a fermented drink – a sort of teosinte rum. Phytoliths are different in the stalk and cobs of maize, and the archaeologists working on the samples from Xihuatoxtla found plenty of cob phytoliths but none from stalks. It seems that it was the grain that the early cultivators were most interested in – at least at this site. And the kernels appeared to have already undergone a genetic change associated with domestication, shedding their hard fruitcases – as no phytoliths from such cases were found. Other sites in Panama, dating to around 6,000 to 7,000 years ago (4000 to 5000 BCE), have presented a similar picture – of the use of cobs, not stalks. It’s still possible that hunter-gatherers may have used the sugary stalks of teosinte more than its grains, and switched to a focus on grains later, when the plant had already begun to develop domesticated features. But perhaps the difficulty of processing teosinte kernels has been overplayed. They can be made edible by soaking and grinding, and some Mexican farmers still use teosinte seeds to feed their livestock.
This discovery of early maize, in the seasonal tropical forest of the Mexican lowlands, is important. It significantly predates – by two and a half millennia – the previous evidence which was used to argue for an origin of domestication of this crop in the highlands. It also makes a lot more sense – Balsas teosinte, the closest relative of maize, grows naturally in the lowlands, not up in the mountains.
Yet, after all this sleuthing, there’s still a big, juicy question that remains. After 1493, this home-grown American crop rapidly spread all over the world, into myriad environments, getting a toehold even in some of the world’s most inhospitable landscapes. The global success of maize depended on its large portfolio of variation – but how had it developed all that astonishing variety, coming from a single origin in the lowlands of south-western Mexico?
In his book The Variation of Animals and Plants Under Domestication, published nine years after his Origin of Species, in 1868, Darwin wrote about the American origin, antiquity and wonderful variety of maize:
Zea mays … is undoubtedly of American origin, and was grown by the aborigines throughout the continent from New England to Chili. Its cultivation must have been extremely ancient … I found on the coast of Peru heads of maize, together with eighteen species of recent sea-shell, embedded in a beach which had been upraised at least 85 feet above the level of the sea. In accordance with this ancient cultivation, numerous American varieties have arisen …
Darwin didn’t know about that close relationship between annual Mexican teosinte, particularly that in the Balsas Valley, and maize. ‘The aboriginal form [of maize],’ he wrote, ‘has not as yet been discovered in the wild state.’ But then he gives an account of a young Native American man who told the French botanist Auguste de Saint-Hilaire about a curiously maize-like plant – but with husked seeds – that ‘grew wild in the humid forests of his native land’.
Darwin was impressed and intrigued by the ‘extraordinary and conspicuous manner’ in which maize varied. He believed that the dissimilarities between varieties had arisen as the crop spread into northern latitudes, developing an ‘inherited acclimatisation’ to different environments. He writes about the experiments of the botanist Johann Metzger, who tried growing various American varieties of maize in Germany – with remarkable results.
Metzger grew some plants from seeds obtained from a tropical region in America. And this is how Darwin described the outcome:
During the first year the plants were twelve feet high, and a few seeds were perfected; the lower seeds in the ear kept true to their proper form, but the upper seeds became slightly changed. In the second generation the plants were from nine to ten feet in height, and ripened their seed better; the depression on the outer side of the seed had almost disappeared, and the original beautiful white colour had become duskier. Some of the seeds had even become yellow, and in their now rounded form they approached common European maize. In the third generation nearly all resemblance to the original and very distinct American parent-form was lost. In the sixth generation this maize perfectly resembled a European variety.
This is such an astonishingly quick transformation. It seems much too quick to be down to a genetic change in the plants. It sounds more like physiological adaptation, or – if you can bear even more technical jargon – phenotypic plasticity. This concept relates to the latent potential – which is still governed by genes – for organisms to adjust, during a lifetime, to particular environments. Adult organisms usually have a limited ability to adapt physiologically or anatomically in this way. But organisms nurtured from birth, or grown from seed, in a different environment to their parents can end up looking quite dissimilar, and functioning differently too.
Darwin’s writing is brilliant in so many ways. He builds arguments beautifully, and he illustrates big ideas with carefully described, often personally experienced, details – like those ancient maize cobs which he found in the raised beach in Peru, 85 feet above sea level. Sometimes he’s laying out his argument, and providing evidence to support a particular theory. But at other times, you can almost feel the whirring of his mental cogs. He’s endlessly inquisitive and excited by new pieces of information that reach him. With Metzger’s tropical American maize grown in Germany, Darwin’s much less surprised by changes to the stem, and the time it took for seeds to ripen, than he is by the transformation of the seeds themselves. He writes: ‘It is a much more surprising fact that the seeds should have undergone so rapid and great a change.’ But then he almost argues with himself, introducing the dialectic into his own monologue: ‘As … flowers, with their product the seed, are formed by the metamorphosis of the stem and leaves, any modification in these latter organs would be apt to extend, through correlation, to the organs of fructification.’
In other words, flowers – and their seeds – develop out of the tissues of stem and leaves. So if stem and leaves are being modified by climate, perhaps it’s not so surprising after all that seeds change so much as well. In this passage, Darwin gets very close to understanding something that we can now appreciate from a genetic perspective. Separate parts of an organism are not always controlled by separate genes – far from it. The relationship between DNA, on the one hand, and the form and function of a whole organism, on the other, is much more complicated than that. A change in a particular gene can have widespread effects throughout the body of an organism – whether that’s a human, a dog, or a maize plant.
With his discussion about the astonishing changes observed in tropical maize after just a few generations of growing in that less favourable climate in Germany, Darwin is also getting very close to that, much more recently articulated, idea of phenotypic plasticity. What we now know is that this doesn’t require a change in the DNA itself – what might be called a ‘true’ evolutionary change. It just requires a modification to the way the organism reads, or expresses, its DNA. Even without genetic mutations, phenotypic plasticity can be a source of extraordinary novelty. And yet so much research into the transformation of wild species into domesticated ones focuses purely on genetic mutations, sometimes forgetting just how much the phenotype can vary, without a change to the underlying DNA code. Metzger’s tropical maize, transplanted into a temperate climate, is a fantastic example of just how malleable the phenotype can be. And one recent study uncovered an even more surprising degree of plasticity than Metzger had demonstrated with his American maize.
Dolores Piperno is an archaeobotanist at the Smithsonian Museum in Washington DC. She led the investigation that found maize phytoliths in the Xihuatoxtla Shelter in the Balsas Valley. But as well as looking for ancient traces of long-dead plants, her research also involves doing experiments with their living counterparts. She led a team from the Smithsonian Tropical Research Institute in Panama, which – between 2009 and 2012 – set about examining just how important a factor phenotypic plasticity might have been in the variation produced in maize, as it became domesticated. They took the wild ancestor of maize, Zea mays parviglumis, and grew it in glasshouses under two sets of climatic conditions. One climate replicated that of the end of the Ice Age, between 16,000 to 11,000 years ago. The other was a control chamber, replicating the modern climate. As the plants in each chamber grew, the results were astonishing.
In the modern control chamber, all the plants looked just like wild teosinte – with lots of branches, sprouting both tassels and female ears. The kernels of the ears ripened in a staggered fashion, rather than all at once. The late-Ice Age chamber was somewhat different. Most of the plants looked like teosinte, but some – about one in five – looked very much like maize. These plants developed a single stem, rather than lots of branches. Attached directly to the main stem were female flowers which developed into ears of corn where all the kernels ripened at the same time.
It’s always been a bit of a mystery as to why teosinte seemed like an attractive candidate for cultivation to those early farmers. But if some teosinte plants – back at the end of the Ice Age – looked more like maize does today – with ears close to the stem and easy to harvest, and seeds ripening all at once – then perhaps it’s not so strange after all.
Something even more intriguing happened when the researchers took seeds from just the maize-like plants grown under glacial conditions, and grew them in a climate matching that after the Ice Age, just into the Holocene, 10,000 years ago. Half of the plants from those seeds still looked like maize rather than teosinte. This means that early cultivators could have very quickly ended up with plants which mostly had that desirable, maize-like phenotype. We know that genetic changes also took place as maize became domesticated, but it seems that phenotypic plasticity is an important part of the story. The impressive plasticity of maize may represent an adaptation to variability – it suggests that its ancestors were exposed to fluctuating conditions and were more successful if they could adjust quickly to novel growing environments. We can no longer overlook this phenomenon – phenotypic plasticity – if we really want to understand how plants (and animals) became domesticated – and the important role that environment and ecology play today.
And so, changing its form in response to climate and to selection by its human cultivators, maize began to spread from its homeland in the tropical forests of Mexico – up into the highlands, and into more northerly and more southerly latitudes – as the craze for agriculture took hold. The gradual spread of maize through the Americas allowed it to adapt to different environments – crucially becoming, not only a lowland plant, but a highland one; not only a tropical plant, but a temperate one.
Phenotypic plasticity and new genetic mutations are two important sources of novelty, helping to produce the ‘extraordinary and conspicuous’ diversity of maize. But there was something else that seems to have contributed to its amazing ability to adapt to new environments – a little help from its wild relatives. As early maize spread from the lowlands to the highlands of Mexico, it hybridised with the mountainous subspecies of teosinte, Zea mays mexicana. Genetic studies have shown that up to around 20 per cent of the genome of highland maize comes from mexicana. Just like domesticated barley, picking up its drought resistance from wild strains growing in the Syrian Desert, maize was making the most of local, genetic ‘knowledge’ as it spread – by hybridising with its wild relatives.
Maize appears to have migrated from Mexico via separate highland and lowland routes, into Guatemala, and on, further south. It had reached northern South America by 7,500 years ago. By 4,700 years ago, maize was growing in lowland Brazil, and by 4,000 years ago, it was in the Andes. From northern South America, maize spread northwards to Trinidad and Tobago, and the other islands of the Caribbean. The spread of maize to North America was much slower – beginning in the south-west corner just over 2,000 years ago, but then spreading right up to the north-east, into what is now Canada, in perhaps just a few centuries. And as maize spread, it kept changing.
By the time of European contact with the Americas, a huge range of varieties of maize had developed, growing everywhere from Mexico to north-east America, from the coasts of the Caribbean and the valleys of Brazil, up into the heights of the Andes. In all its different forms, it was already a highly adapted and highly variable domesticate – primed and ready to spread rapidly across the globe – as soon as Columbus planted his foot on that beach.