The History of the World in 100 Plants

ONE

STRANGLER FIG

To sit in the shade and look upon verdure is the most perfect refreshment.

Jane Austen, Mansfield Park

It begins with a tree. Perhaps every story does. Let us ascend, branch by branch, our own family tree, climbing up through our ancestors, great above great above great. If we climb high enough – which means descending through time deep enough, counting in millions of years instead of centuries – we reach ancestors who spent most of their time in trees. They were smart, they had hands with opposable thumbs, which were great for grasping branches, and they had excellent three-dimensional vision, all the better to judge distances between branches. They lived in Africa and were admirably adapted for life in the trees. So far, so stable. Then the climate changed. That too will be a repeating theme in these pages.

When the climate changes, everything else changes, as we are in the process of rediscovering today. The world became a good deal cooler. The forests died back and the land became open grassland dotted with islands of trees. If you wanted to get from tree to tree, you needed to travel on foot. Humans began to walk upright, at first in order to reach the next tree more efficiently. And they found, in the course of advancing generations, that their grasping hands were suitable for using and making tools, their vision was as useful on the ground as it was in the trees, and their keen intelligence made them adaptable and resourceful. They became hunters and gatherers and the savannahs of Africa were their home.

But trees were still central to their existence, and not just as a source of food. Try walking on the savannah, as I have done many times. The environment provides food and water to those who know what they’re doing, but hunting and gathering in the heat of the day is a fool’s game. And whatever else our ancestors were, they were not fools. Their daily round involved a lay-up of at least four hours: out of the killing sun that overheats, exhausts and dehydrates. Every adult’s mental map was based around shade trees. Trees that throw a deep, wide shade, with dense layers of branches overhead, have a great value to those who walk. When I escort visitors on walks in Zambia, we start at six. After three hours, the decision to rest up in the shade is greeted with rapture: to rest, to eat and drink, to talk, to think things over. It is an experience of unexpected depth and meaning for all who take part. It brings us back to our roots.

Sweet cool: ostriches and elands beneath a spreading strangler fig at De Hoop Nature Reserve, South Africa.

Of all the shade trees on the savannah, the strangler fig bears the crown. To walk beneath its shade is like entering a cathedral on a hot day’s sightseeing: instant physical and spiritual refreshment, and a consequent sense of gratitude, even reverence.

The shade is impossibly wide; a mature strangler fig throws out branches in a radius of 65 feet (20 metres) from the trunk. You could rest dozens under these branches: families and wider social groups could come together and share the shade without imposing on each other. Here you could while away the hours: dozing, eating, drinking, singing, socialising, flirting, in time talking and planning. Human civilisation began in the shade of tree, and a strangler fig for preference.

There are various species of strangler fig in the savannahs of Eastern and Southern Africa, but they all have the same lifestyle. They evolved as forest trees: and forest life is about the competition for light. The conventional approach is for a seed to start on the ground; once germinated, roots grow into the earth and a green shoot grows upwards towards the light, seeking to outcompete all those around. The figs invented a way to beat the system.

There are about 850 species in the genus Ficus, including the familiar Ficus carica, the one that we eat. Figs have been cultivated for about 10,000 years; there is a case for claiming that they are the oldest cultivated plant. Pliny the Elder, the great observer and recorder of Roman times, noted that ‘figs are restorative and the best food that can be taken by those who are brought low by long sickness’. As everyone who has eaten a fig knows, when you eat figs you eat a lot of seeds as well. Birds – in Africa especially green pigeons – eat fruit and later deposit the seeds with a generous dollop of fertiliser. The bad news for most fruiting plants is that often the birds dump the seeds in the tree they are perching in. But that is exactly what the fig wants. From the high branches a new shoot had only a relatively short distance to go to reach the light. As it sprouts a shoot, it also grows roots capable of taking moisture from the air.

So far so good. Many tropical plants have adopted this strategy, with aerial roots that never reach the ground. Such plants take nothing from the tree apart from its load-bearing ability: in tropical rainforests you can see trees festooned with plants, known collectively as epiphytes; in the moist air it’s easy for the aerial roots to gather the water the plant needs. But the fig has greater ambition than these. Its roots keep growing downwards, and when everything goes well for the plant, the roots reach the ground. Once there the fig can start to spread itself. Soon it no longer needs the host for support; that makes it a hemiepiphyte.

The host tree is now held fast within a web of roots. At this mid-term stage, it’s like looking at a single tree with two different kinds of leaves, two different sorts of flower and two different kinds of fruit. At this stage, association with a fig can even help the host, adding welcome support in times of storm. But eventually, if things work out, the fig will overwhelm the host, which will often die as a result. The trunk that gave the baby fig tree such tremendous support will rot away and the fig will be left standing free, supported by a lattice of roots. It will be hollow on the inside, and easy to climb. No point in cutting it down: waste of a good shade tree, waste of a good fruit tree, and besides, the timber from all those straggling roots is pretty useless.

In season, the fig trees fed as well as sheltered the bands of human ancestors who sought out their shade. The trunk is also home to insects, bats, lizards and other reptiles, rodents, amphibians and birds. Fig trees often fruit at times when other trees all around do not, becoming an essential source of food for many species. This makes figs a keystone species in their environment: that is to say, a species that helps to maintain the environment it lives in.

It’s not surprising that many traditional tales are told about as well as around the fig tree. A fig is crucial to the origin myth of the Kikuyu of Kenya; it is also a place that holds the spirits of dead ancestors. An infusion made from its bark is said to be helpful in pregnancy and makes for an easy birth; fig trees can also be used to make a poultice for wounds. The fruit is almost notoriously effective as a laxative in African as well as many other cultures. There is a charming tradition among the Nyanja people in response to the tight bond between the fig tree and its host: an infusion of fig bark can be used to reinforce the bond between man and woman, as a drink or even as a shared bath. There is an African proverb, relating to the fig and the small parasitic wasps that exploit the fruit: even if the fig tree is the most beautiful, it may have worms in its fruit – a useful principle for us all.

A fig tree also played a part in another story of origins. The fig species found in Southeast Asia fascinated the explorer-naturalist Alfred Russel Wallace, who called them ‘the most extraordinary tree in the forest’. His study of the fig’s struggle for existence helped him to an understanding of the mechanism by which life operates. He communicated his thoughts to Charles Darwin: and what Wallace had come up with was exactly the theory Darwin had been working on for the past quarter-century. Darwin, who had been postponing publication for years, knowing that he was sitting on a keg of dynamite, was at last spurred into action. Their joint theory was presented – to complete indifference – to the Linnean Society in London in 1858, but a year later, Darwin published On the Origin of Species as a solo project. That’s when all hell broke out and Wallace, who had offered the only gentlemanly response to the issue of priority in the history of science, was reduced to a footnote. But without Wallace and his fig tree, Darwin might have sat on his theory for ever.

I have on many occasions sat beneath the shade of a fig, sipping tea, talking, not talking, just looking out upon the savannah beyond, grateful for the rest, planning what to do next, or as often as not just sitting. To sit beneath a fig tree is to make a journey back to the dawning of our species. Humanity was born in the shade of the strangler fig.

TWO

WHEAT

Give us this day our daily bread.

The Lord’s Prayer

The world has been conquered by grasses from the genus Triticum. Fly over the agricultural countryside of the developed world, or just drive through Nebraska, and it becomes clear that humans are managing the planet for wheat. The crushed seeds of these grasses have nourished humans for centuries, for longer than we have cultivated them. For most of the world, they are not just an important food; they are food itself. Bread of course, but also pasta, noodles, semolina, bulgur, couscous, biscuits, muesli, pancakes, pizza, cakes and breakfast cereals.

Seeds have always been part of the human diet. Chewing on sunflower seeds in their hulls unites us with our ancestors – and makes it clear that a fair amount of energy is required for a comparatively small reward. Better to hull the seeds in a mass: a more economical use of time and energy.

We modern humans differ from our ancestors by the musculature of our heads. We no longer have enormous jaws with powerful muscles; we no longer have a sagittal crest, to which still more powerful muscles could be attached. All this power was for processing food before digestion. Our more recent ancestors discovered more effective ways of getting nutrition: processing food before putting it in their mouths. They hulled, softened and moistened seeds, they tenderised plants by heating them and they tenderised the muscles of mammals and birds, breaking down the connective tissue that holds them together, again using heat. Starch residue 30,000 years old has been found on rocks by ancient human settlements: starch that came from seeds: seeds that have been crushed to make them easier to eat. At some stage the resulting stuff was cooked. You could make porridge with water; with a little less water, you could make a dough and heat that. It was perhaps humanity’s first prayer, and the first prayer to be answered: give us this day our daily bread.

The greatest change in the history of humanity – the change from which all other changes followed – came around 12,000 years ago. Humans invented agriculture, became farmers, settled in a fixed place and established fixed communities. They gained security and a greater life expectancy in exchange for a lifetime of toil. Agriculture was invented more or less simultaneously in several places across the world, but so far as Europe and the cultures of West Asia are concerned, it all began in the Fertile Crescent.

Winter defeated: The Harvesters, 1565, by Pieter Breugel the Elder (c. 1525-30 to 1569).

This is the land associated with the Nile, the Tigris and the Euphrates; on the map it looks more like a boomerang than a crescent. It was here, in these helpful circumstances – good climate, fertile riverine soil and easy access to water – that people stopped looking for food and started producing it. They domesticated animals and they domesticated plants. The most important plants were grasses of the Triticum genus. (A genus – a group of relatives – is one step up from species and one step down from family.) That is to say, wheat.

At some stage people started to use the pounded seeds to make leavened bread. The date for this invention is open to speculation, but you can recreate it in your own kitchen, as I often do myself. If you leave a porridge of water and pounded wheat – flour – it will gather wild yeast spores from the atmosphere and start to ferment. You can expedite this process with yoghurt, which brings in lactobacilli. Let this mixture develop, mix it vigorously with more flour, and you have a dough. Leave this dough a good few hours to rise and then cook it – and you have a loaf of sourdough bread, as ancient a cooked food as there is on the planet. Keep some of your fermenting mixture back, keep feeding it with flour and you always have the basis of bread to hand.

Wheat provides us with carbohydrates in the form of starch, which we use for energy, and a moderate amount of protein in the form of gluten, which we use for building tissue. (Modern strains of wheat are richer in gluten than their predecessors, and this causes problems for some people.) Gluten binds the dough, and is activated by kneading: the yeast releases carbon dioxide, which is held in the dough by the sticky gluten. You can feel the change in texture as you knead: the dough becomes bouncy. Gluten-free bread needs a binding agent like egg white to create pockets for the carbon dioxide. Bread also provides fibre. Flours with whole wheat (which includes the germ and bran from the seeds) have a good deal of fibre. Humans can’t digest the fibre, but it adds bulk to stools and makes the human processing of food more comfortable.

Bread is central to the human cultures that use it: that is to say, more or less everywhere apart from the rice-centred areas of Asia. It lies at the heart of Christian ritual. The service of the Eucharist take the form of a symbolic meal of bread and wine. The bread represents – and to a Catholic actually is – the body of Christ, to be consumed in thankfulness.

The Roman satirist Juvenal poured scorn on people and politicians who look no further than gratification of appetite and cheap entertainment: bread and circuses, a phrase as relevant now as it was then. Pliny the Elder said: ‘There were no bakers in Rome before [174 BC] and the war with King Perseus. The citizens used to make their own bread and this was the special task of the women, as it is even now in most nations.’ The establishment of professional bakers was a step forward, for bread-making is a time-consuming business.

Agriculture was never a soft option. It was (and is) bitterly hard work, in the preparation of the soil, in the weeding of the fields, in defending it from pest species, in the gathering of the crop and subsequently in the processing of the seeds into flour and the manufacture of bread. Agriculture has always been vulnerable to the uncertainties of weather. Domesticating plants is a double-edged business, for there is always a payback. By planting a field of wheat, the owner has all the seed he wants. But he has also created vulnerability: for there is little resilience in a monoculture. As agriculture developed, it has increasingly moved away from diversity. Diseases, fungi and insects will all take advantage, easily moving from plant to plant, without unviable or unpalatable species to interrupt their progress. Traditional agriculture always flirts with disaster: to be warded off by prayers, hard work and anything else you can come up with.

Soil can be improved by the addition of fertilisers, initially the dung of domestic animals. Productivity could be increased by rotating crops: alternating wheat with legumes. Legumes include beans and lentils, also clover and alfalfa that can be grown as fodder crops: they fix nitrogen in the soil, and that benefits the cereals that you plant the following year. Crop rotation was invented at least 6,000 years ago. It also pays to rest the land occasionally: the book of Leviticus in the Bible instructs the Israelites: ‘When you come to the land which I will give you, then shall the land keep a Sabbath unto the lord.’

The pace of agriculture hotted up in the eighteenth century, with the invention of a series of mechanical devices that made agriculture less labour-intensive, and therefore capable of feeding more people. The seed drill was actually invented centuries earlier, both by the Ancient Babylonians and the Chinese, but it wasn’t in widespread use in Europe until much later. Before the seed drill was invented, seed was broadcast: a word that now has another use altogether. The haphazard nature of this business is caught in the biblical parable of the sower; the seeds lost to the farmer from a bad landing are compared to souls lost to the Lord from a bad life. But a seed drill planted seeds a uniform distance apart at a uniform depth, creating the regimented fields that we know today. The inventor of the horse-drawn seed drill was the eighteenth-century genius Jethro Tull.

Wheat’s conquest of the world continued with the increasing industrialisation of farming and baking, and also with the increasing Westernisation of the world. Bread infiltrated all cultures, even the rice-growers. (A favourite snack in India is the toast sandwich.) The process was made easier by the invention of the combine harvester: a machine that combines the three great tasks of reaping, threshing and winnowing: that is to say, cutting down the corn, removing the seeds and then removing the seed husks. The first combine harvester was in use in the United States in 1835 and was pulled by a horse.

These days diesel-powered combine harvesters work in formation across endless prairies of wheat, blowing the husked seeds into trailers that travel the fields alongside them behind their tractors. The crops are protected from insects and other invertebrates, from fungi and from other problems by chemical means. The soils are treated with synthetically produced nitrates. Competing plants – weeds – are killed by pre-emptive use of herbicides.

The advances in agriculture have allowed the world to feed a great many more people; many more people now survive and breed in their turn. The world’s human population continues to rise, and more and more food is required. Genetically modified strains are considered by some to be the answer, while opponents cite the law of unintended consequences, which have created ecological problems across the world.

Bread remains central not just to life but to the way we think about life. Marie-Antoinette is famous for a single remark, uttered, according to legend, when she was told that the poor people had no bread: ‘Qu’ils mangent de la brioche,’ traditionally translated as ‘Let them eat cake.’ In fact, brioche is not cake; it’s a bread made with a dough enriched with egg and butter: a luxury rather than a necessity. In 1917 the Bolsheviks promised the Russian peasants ‘peace, land and bread’. What more could anyone want?

Bread is the staff of life, a cliché that dates back to the seventeenth century. In my hippy youth we referred to money as bread. Money is also dough: Bobby Locke, the South African golfer who won four major tournaments in the 1940s and 1950, famously said: ‘You drive for show but you putt for dough,’ meaning that mastery of the less glamorous part of the game is what makes you a champion.

Wheat is everywhere. World trade in wheat is greater than all other crops combined. In 2021 the world produced 772 million tonnes of wheat: and that’s increasing. Wheat is the leading source of vegetable protein in most diets (wheat is about 13 per cent protein). Unsurprisingly, more land is employed for wheat production than any other crop. The planet earth has been modified and managed more or less from top to bottom for the convenience of a species of grass that grows wild in West Asia.

THREE

ROSE

Send two dozen roses to Room 424 and put ‘Emily, I love you’ on the back of the bill

Groucho Marx in A Night in Casablanca

Eye of the beholder: Marie-Antoinette with a Rose, 1783, by Elisabeth Louise Vigee-Lebrun (1755-1842).

Should you find yourself in a church with your spirits flagging, you can turn to the Bible and read the most beautiful erotic poems ever written: ‘I am the rose of Sharon and the lily of the valleys…’ The Song of Solomon, sometimes called the Song of Songs, is about 3,000 years old – and when seeking to express perfect beauty (the narrator is female), the poet turns to a rose. Poets and lovers have been turning to roses to express love and desire throughout the three millennia that followed, and no doubt for thousands of years before that.

What is the evolutionary explanation for beauty? What is its survival function? Nuptial gifts are offered in courtship throughout the animal kingdom – spiders silk-wrap food items, penguins offer pebbles, marsh harriers pass gifts of food in flight. Did one of our female ancestors adorn herself with a rose? Did a male ancestor offer her a rose, to express both his admiration for her beauty and his own desire?

My luve is like a red, red rose

That’s newly sprung in June…

That’s Robert Burns and one of the greatest out-and-out love songs of them all. What does he mean by his love? Is he referring to the woman he loves and comparing her beauty to that of a rose? Is he talking about his own passion, now in full flower? Does the redness of the rose express the physical nature of his desire? Like any poetry that’s any good, these simple verses have a dozen or more meanings: but no matter which way you pluck them, it’s clear that roses and love are inseparable.

Wild roses grow in Europe, Asia, North America and Northwest Africa. I came across a wild rose garden in a valley bottom in Armenia: a stream flowed through it, leaving pleasant uncluttered banks, and it was clear that a bottle of champagne and a beautiful girl would make it paradise:

While the Rose blows along the River Brink,

With old Khayyam the Ruby Vintage drink…

Lines from The Rubaiyat of Omar Khayyam, in the much-loved Victorian translation by Edward FitzGerald. There are about 300 species of rose, but there are untold thousands of cultivars; 30,000 has been suggested. Species in the genus Rosa hybridise enthusiastically, giving immense scope to the gardener in search of a beauty still more perfect. Most wild species are white or pink, though there are some yellow and red. Most have five petals, so the changes wrought by cultivation have been immense: a cultivated Juliet rose is no more like a hedgerow Rosa canina or dog rose than a Yorkshire terrier is like a wolf.

Rose plants are woody and bushy. They produce fruit, normally known as hips, which contain the seeds. (Note that fruit are not necessarily edible: a fruit is the ripened ovary of a flowering plant containing the seed or seeds.) The flowers of wild roses are pollinated by insects; the seeds are dispersed by birds, who eat the fruit and spread the seeds in their droppings. Many domesticated varieties don’t produce hips; many are too tightly petalled to be pollinated. Like many domesticated plants, most roses are incapable of propagating without human assistance. This is mostly done by taking cuttings: what is technically termed vegetative reproduction. The technique is familiar to all gardeners: a piece taken from a mature plant will, in helpful circumstances, put out roots and establish itself as a new plant, genetically identical to the parent plant: in effect, a clone.

When did people start cultivating roses? There is evidence dating back 2,500 years, but the idea of keeping plants for their beauty rather than their nutritional value is likely to go back much further: ever since the human elite had leisure, wealth and people to command. Perhaps humans have grown plants for their beauty for as long as they have cultivated wheat: and certainly what works for wheat works for less functional plants – weeding and manuring makes them bigger and better.

Roses were also cultivated for their scent. This can take the form of oil or attar of roses, which is obtained by steam-distilling crushed petals, and of rosewater, which is made by simmering petals in water. These covered up bodily odours in times when hygiene was less easily attained. Rosewater is used today in cosmetics and medicine; modern foods made with rosewater include baklava, halva, gulab jamun and Turkish delight.

Roses are so well-known and so greatly loved that they have grown rich in symbolic meaning. The rose was the flower of Aphrodite, the Greek goddess of love; in one story, wounded by the thorns, she stains white roses red. She anoints the body of the fallen Trojan hero Hector in oil of roses. She is painted surrounded by roses by Dante Gabriel Rossetti in his Venus Verticordia.

Roses were associated with the excesses of the Roman Empire: emperors bathing in rosewater, banqueting halls covered in rose petals, peasants forced to grow roses for imperial delight instead of crops to feed themselves. It is said that Cleopatra seduced Antony in a bedchamber paved with rose petals.

Despite – perhaps even because of – this licentious history, the rose also became a symbol of purity, associated with the Virgin Mary. The rosary, the Catholic aid to prayer, especially prayers to the Virgin, commemorates this equation. Its beads are linked in five series of decades, recapitulating the number of petals on a rose. The rosary can be used for contemplations of the sacred mysteries of Maria (note the five letters): the five joys of Mary are the Annunciation, the Nativity, the Resurrection, the Ascension and the Assumption. Dürer painted The Feast of the Rosary in 1506, in which Mary is distributing roses to surrounding worshippers. This association of Mary and the rose continues in church architecture with stained-glass windows in the shape of a rose, most famously the great rose window of Chartres Cathedral. There are sacred verses to continue this association: a hymn of 1420 begins:

There is no rose of such virtue

As is the rose that bare Jesu.

Geometrical gardens in the Islamic traditions centre on roses; two of the most important Sufi works are The Rose Garden, by Sa’di, and The Rose Garden of Secrets, by Mahmud Shabistari. Roses are found with our most elevated thoughts and with our most elemental.

Naturally the rose has been co-opted for badges and emblems again and again. It is the flower of St George, patron saint of England; it is the state flower in five of the United States; in 1986 President Ronald Reagan made the rose the floral emblem of the United States. In England in the fifteenth century the civil war called the Wars of the Roses was fought off and on for more than thirty years: on one side the House of Lancaster, whose badge was a red rose, and on the other, the House of York, with a white rose. The conflict was resolved in 1485 at the Battle of Bosworth Field; the victorious Henry Tudor of Lancaster, now King Henry VII of England, married Elizabeth of York, uniting the two houses. This was commemorated by the Tudor Rose: a red rose with a white rose in the middle, both of course with five petals.

The red rose is associated with socialism, especially after the 1848 French Revolution. A rose can mean what you choose it to mean: but that meaning is always coloured by the rose’s association with beauty and moral virtue. But like all symbols, roses remain ambiguous. In The Songs of Experience William Blake portrayed a rose in distress damaged by harmful forces. Perhaps it’s the best of all rose poems.

O Rose thou art sick.

The invisible worm,

That flies in the night

In the howling storm:

Has found out thy bed

Of crimson joy:

And his dark secret love

Does thy life destroy.

The cultivated rose was championed by Empress Joséphine of France, wife of Napoleon. She wished to turn her garden at the Château de Malmaison into ‘the most beautiful and curious garden in Europe’, and roses were at the heart of her vision. The rose is not only a flower that pleases humans on a deep level: it is also remarkably receptive to all, a kind of ingenious manipulation. The range of the forms of modern roses is dizzying, and the ideas of beauty are frequently bizarre. The family garden of my childhood had a variety of rose called Blue Moon, with flowers a rather sick-making mauve. Disliked by the entire family, it bloomed defiantly year after year and was still hard at it when my parents moved twenty-five years later.

Two imprisoned knights listen to Emilia singing in the rose garden: an illustration to Giovanni Boccaccio’s Le Teseida, published in 1468.

Roses remain the world’s favourite cut flower: picked as buds and then refrigerated, to be flown all over the world. The need for roses, for their beauty and as tokens of affection, routinely conquers our concern for the ecological cost. They have been painted with careful accuracy by Pierre-Joseph Redouté (who did the job for the Empress Joséphine) and Henri Fantin-Latour, and with impressionist energy by Monet, Cézanne and Renoir.

On St Valentine’s Day, roses are given to beloveds everywhere. Our need for roses to state our love has never waned. Umberto Eco, author of The Name of the Rose, said: ‘the rose is a symbolic figure so rich in meanings that by now it has hardly any meaning left.’ Roses are inescapable: as inescapable as beauty, perhaps. Should we ever escape the cares of work and family, we are told ‘to smell the roses’. And we do.

FOUR

PEA

A + 2Aa + a gives the series for the progeny of plants hybrid in a pair of differing traits.

Gregor Mendel

We seldom reflect, as we look approvingly at the cheerful green of the peas rolling on the plate between the fish and the chips or adding richness to the bowl of mutter paneer, that it was peas that revealed the mechanism by which life operates. And it’s rum to think that Louis XIV, the roi soleil himself, was entranced when presented with the impossible luxury of a fresh green pea.

Charles Darwin showed us the way life operates in On the Origin of Species, published in 1859. He explained why; someone else had to explain how. Darwin showed that the forces of natural selection ensure that the life forms most suited to the place and time they live in will do better than the rest: live longer and make more of their own kind – and if they bear offspring with the same advantages, these will also prosper, and perhaps in turn pass on still more favourable traits to their own offspring. The most suitable – the most fit for the purpose – do best: survival of the fittest, selected naturally by the forces of the environment. Darwin’s book set the world on a roar because it implied, though never stated, that humans must be part of the same system: that we must share a common ancestor with monkeys.

It was the logical inference from decades of intense study of living things, but there was (and is) continuing hostility to Darwin’s conclusions. Among the myriad objections was the question: ‘OK – bright idea. But how does it actually work?’ This question occupied those who supported as well as those who rejected the idea of natural selection. Darwin worked on a notion he called pangenesis, which was brilliant but wrong.

So how does it work? The answer lay in the pea. It lay in the mind of a monk who was studying and performing experiments in St Thomas’s Abbey in Brno, a vowel-deprived town in what is now the Czech Republic. He was pretty sure of his answer before Darwin asked the question: his essential work on peas lasted between 1856 and 1863. His name was Gregor Mendel and Darwin never once heard of him. His work on peas and the factors that govern inheritance was published in 1866 – and hardly anybody noticed.

How life works: Gregor Mendel, monk and pioneer of genetics, studying peas.

Mendel was born in 1822. He was educated in science, and was a brilliant mathematician, but as the son of a poor farmer he lacked the money to devote himself to education. So he became a friar, a choice that allowed him to live without the ‘perpetual anxiety about means of livelihood’, as he said. It also gave him the opportunity to do science. His baptismal name was Johannes; he took the name Gregor when he joined the Augustinian order.

He set out to study inheritance. Initially he worked with mice, but his abbot objected to the idea of a monk devoting his time to mouse sex. Mendel switched to plants, assuming rightly that the principles that govern inheritance are the same for plants and animals. He worked with a garden of 5 acres (2 hectares), studied about 28,000 plants, almost all of them peas – and he cracked it. Everyone has always accepted inheritance; it’s the founding principle of the aristocracy as well as Darwinism. Mendel told us how it works.

He worked on seven different traits in different varieties of pea plants: height, pod shape and colour, seed shape and colour, flower position and colour. He noted what took place with meticulous care and made a series of calculations of classic precision and beauty. (So much so that it has been suggested that his results, with so little experimental error, are too good to be true. All the same his conclusions have been re-proved many times.)

Inheritance is not a simple matter of blending. If you cross a tall plant with a short plant, you won’t get a bunch of medium plants. You get some tall ones and some short ones: in fact, three talls to one short, if tallness is the dominant ‘factor’, as Mendel called it. Put one of these resulting shorts to another short and you will get some short ones – and some tall ones as well, if the factor for tallness is recessive. In other words, Mendel discovered genetic inheritance. What he called factors we now term genes (or alleles, meaning groups of genes). He proposed three laws of inheritance: the law of dominance, the law of segregation and the law of independent assortment. They stand to this day.

The world throws up astonishing coincidences that startle even the most rational. In the same two-month period of 1900, sixteen years after Mendel’s death, three different researchers in three different countries rediscovered Mendel’s work and replicated his experiments. Not only that – they acknowledged his priority. Their conclusions reinforced those of Darwin, and in the 1930s and 1940s the work of the two men was viewed together as ‘the modern synthesis’ – or, in a term demeaning to Mendel, Neo-Darwinism. Darwin was helped to his understanding by breeding pigeons; Mendel worked on the equally homely pea.

Peas were grown in Egypt in the Nile Delta 7,000 years ago, but they weren’t consumed as sweet green spheres that give to the teeth. They were eaten as mature seeds, which need a fair amount of soaking and cooking to make palatable. But they are good food, high in protein and fibre. People for whom meat was a luxury could keep going with peas. What’s more, peas keep well, even in a hot climate. Dried peas, kept dry in a sealed container safe from insects, will keep until long after the next year’s crop of peas has been harvested. Peas were a significant plant in the Middle Ages; we might even owe the survival of our ancestors and therefore our own existence to peas.

Pease pudding hot! Pease pudding cold!

Pease pudding in the pot, nine days old.

Some like it hot, some like it cold,

Some like it in the pot, nine days old.

The old rhyme, its origins long lost, tells us about a food that was never a treat, but the best possible standby – and it also gave the title to Some Like it Hot, the great film of 1959, starring Marilyn Monroe. Peas filled bellies and provided fuel for tomorrow: they kept hunger and even famine at bay. They were and are extremely useful crops, as part of the rotation with wheat (see Chapter 2). The roots of pea plants fix nitrogen in the soil: once the pods are harvested the remaining plants die and return nitrogen to the soil, making it suitable for wheat-growing again.

But peas had a vogue as a luxury item, for they can be harvested before the seeds are ripe. These immature seeds are sweet, brightly coloured and easy to consume. The drawback is that they don’t keep very long: in warm weather (more likely than not when peas are harvested) they last only a few days – so fresh young peas could only be food for the rich man’s table. Louis XIV had a passion for them. He grew many delicate vegetables in the gardens at the palace of Versailles, in the 9-hectare plot known as the Potager du roi, the king’s kitchen garden. His brilliant court gardener Jean-Baptiste de la Quintinie was able to raise fruit and vegetables early in the season by using glass (at vast expense). The king loved the place and often went out there with his gardener. It was a homely idea, but they didn’t grow peasant food: artichokes, asparagus, beans in their pods (what we call French beans) – and peas. Peas were associated with prestige: there was competition among the nobility to serve the first peas of the year. People are said to have died from a surfeit of peas.

Fresh peas reached a wider public with the invention of canning: you put the food in a sealed container and then heat it, killing the microorganisms within. The process was invented in 1809 by Nicolas Appert of France; demand for canned food was accelerated by the First World War and the need to feed soldiers at the Front.

The advance of frozen food technology, along with home freezers, made young green peas still more widely available, and what’s more, they taste better than the canned variety. The technique was invented by Clarence Birdseye of America. He noticed that when fishing off the coast of Labrador in winter, a fish taken from the water froze as soon as it was pulled from the sea – and it was palatable, even tasty, months later if kept frozen.

If you freeze things slowly, it doesn’t work nearly so well. Ice crystals form and rupture the cell membranes, and when the food is thawed the water runs out and takes the taste of the food with it. Birdseye established the technique of rapid freezing in 1824. You can buy Birdseye peas in the supermarket today and live like a king.

FIVE

WILLOW

And twelve yellow willows shall fellow the shallows…

Robin Williamson, The Incredible String Band

We associate willows with a certain grace and a pronounced fondness for water. They are most recognisable in the form of the weeping willow, much planted by lakes in parks. Cricket bats are made from willow, and the more pompous commentators refer to the bat as ‘the willow’. Willows were useful to our ancestors for catching fish and making baskets. But willows can also ease fevers, aches and pains. Humans learned to synthesise the substance found in the sap of willow trees