In , the organic chemist Justus von Liebig published a pioneering treatise that explained how plants depend on nitrogen. Along the way, he extolled guano as an excellent source of it. Sophisticated farmers, many of them big landowners, raced to buy the stuff. Their yields doubled, even tripled. Fertility in a bag! Prosperity that could be bought in a store! Guano mania took hold. In 40 years, Peru exported about 13 million tons of it, the great majority dug under ghastly working conditions by slaves from China.
Seize the guano islands! Spurred by public fury, the U. Congress passed the Guano Islands Act in , authorizing Americans to seize any guano deposits they discovered. Over the next half-century, U.
Guano set the template for modern agriculture. Ever since von Liebig, farmers have treated the land as a medium into which they dump bags of chemical nutrients brought in from far away so they can harvest high volumes for shipment to distant markets.
To maximize crop yields, farmers plant ever-larger fields with a single crop—industrial monoculture, as it is called. Before the potato and corn , before intensive fertilization, European living standards were roughly equivalent to those in Cameroon and Bangladesh today. On average, European peasants ate less per day than hunting-and-gathering societies in Africa or the Amazon. Industrial monoculture allowed billions of people—in Europe first, and then in much of the rest of the world—to escape poverty.
The revolution begun by potatoes, corn and guano has allowed living standards to double or triple worldwide even as human numbers climbed from fewer than one billion in to some seven billion today.
It sends out tiny bags of 6 to 12 spores that are carried on the wind, usually for no more than 20 feet, occasionally for half a mile or more. When the bag lands on a susceptible plant, it breaks open, releasing what are technically known as zoospores. If the day is warm and wet enough, the zoospores germinate, sending threadlike filaments into the leaf.
The first obvious symptoms—purple-black or purple-brown spots on the leaves—are visible in about five days. By then it is often too late for the plant to survive. Scientists believe that it originated in Peru. Large-scale traffic between Peru and northern Europe began with the guano rush.
Proof will never be found, but it is widely believed that the guano ships carried P. Probably taken to Antwerp, P. The blight hopscotched to Paris by that August. Weeks later, it was destroying potatoes in the Netherlands, Germany, Denmark and England.
Governments panicked. It was reported in Ireland on September 13, Cormac O Grada, an economist and blight historian at University College, Dublin, has estimated that Irish farmers planted about 2.
In two months P. The next year was worse, as was the year after that. The attack did not wind down until A million or more Irish people died—one of the deadliest famines in history, in the percentage of population lost. A similar famine in the United States today would kill almost 40 million people.
Within a decade, two million more had fled Ireland, almost three-quarters of them to the United States. Many more would follow. Today the nation has the melancholy distinction of being the only country in Europe, and perhaps the world, to have fewer people within the same boundaries than it did more than years ago. Despite its ghastly outcome, P. Its name notwithstanding, this orange-and-black creature is not from Colorado.
Nor did it have much interest in potatoes in its original habitat, in south-central Mexico; its diet centered on buffalo bur, a weedy, spiny, knee-high potato relative.
Biologists believe that buffalo bur was confined to Mexico until Spaniards, agents of the Columbian Exchange, carried horses and cows to the Americas.
Quickly realizing the usefulness of these animals, Indians stole as many as they could, sending them north for their families to ride and eat. The humble tuber was already there. If a strong, numerous population was crucial for economic production and military might, the state needed to understand and manage the nutritional components of what people were eating.
Abundant, healthy food became central to Empire-building, Earle writes in her paper Promoting Potatoes in Eighteenth-Century Europe. Thus, she argues, the fascination with potatoes does not come from the emergence of a new crop, but from novel European ideas of the relationship between food and the state.
In this regard, the potato was unrivalled. A question of measuring arises, Earle admits. How did scholars like Smith and his contemporaries compare nutritional value? But as she argues, potatoes served this state-building purpose not only because of their nutritional value, but because they were already planted in gardens and fields across the continent.
Its fans praised its virtues. They were not wrong. A widely cited economics paper reviewed information from military records of French soldiers born after and showed that eating potatoes made people slightly taller.
According to The Quarterly Journal of Economics: for villages that were fully suitable for potato cultivation, its introduction increased average adult heights by approximately one-half inch. That same paper provides a stronger claim: that population in Europe and Asia exploded after the spread of the potato. According to the researchers, the tuber introduction accounts for close to one-quarter of the growth in Old World population and urbanisation between and The potato frenzy continued unstoppably until a blight paved the way for the Great Famine of in Ireland.
The failure of the crop, compounded by the utterly inadequate response by the British Government in London which decided against relief and bet on market forces , led to the death of a million people, the emigration of one million people to the US and the steady departure of two more million elsewhere. Such a homogenous food block made the potato susceptible to diseases, as its genetic diversity had been washed away from domestication.
To be fair, some mixing of varieties had already taken place in Europe around the s. This first admixture only provides some handy traits, but not enough genetic depth, so breeding programmes over the years have been looking at ways to improve food security for potato farmers.
In the early decades of the 20th Century, scientists began combining genes from mainstream potatoes, hoping to keep their domesticated traits, with wild potatoes, hoping to get their resistance to diseases.
Nonetheless, in Raleigh did plant potato seeds at his Irish estate in Cork before offering them as a gift to Queen Elizabeth I. The potato carried on its journey to wider European countries through the hands of sailors who brought the spud to different ports. The spud had a shaky start with farmers who labelled them as distrustful, but it soon became a staple food and crop which inevitably played a role in the 19 th century population boom.
During this time, the potato crop became diseased leaving many people to emigrate from Ireland to survive. Trade halted and with that unemployment followed suit leaving a drought of opportunities. It also highlights how human activity has contributed to the widespread geographical expansion of potato crops. The study is a good example of how valuable specimens housed in places like the Museum are key to solving not only mysteries of how plants have adapted to their environments, but also helping to solve modern-day problems such as food shortages.
This research adds to this collective endeavour. Get email updates about our news, science, exhibitions, events, products, services and fundraising activities. You must be over the age of Privacy notice. Smart cookie preferences. Change cookie preferences Accept all cookies. Skip to content. Read later. You don't have any saved articles. By Tammana Begum. How people changed potatoes People in the Andes changed potatoes over time, gradually cultivating larger tubers that were easier to eat.
Why we study potatoes This research shows how combining genetic analysis of contemporary and historical samples allows us to begin to understand the complex history of crop adaptation to new environments.
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