In the history of human tragedy, the Great Famine in Ireland is a graphic and brutal reminder of the pitfalls of depending on one source of sustenance. Between 1845 and 1852, one million starved or died from disease, and another million had to emigrate, dispersing the Irish diaspora around the world. Though the disaster was economically and politically based, its very biological roots were a fungus only a cell wide, Phytophthora infestans, or potato blight. But there was more than one culprit. The root cause of the disaster was an extreme lack of diversity. The population of Ireland had become horrifyingly dependent on one type of potato, the Irish Lumper, creating a perfect atmosphere of susceptibility that transformed a crop failure into a breakdown in society.
To understand how this happened, one needs to understand the potato's unique position in Irish society first. Introduced to Ireland from the Americas in the late 16th century, the potato was a groundbreaking crop. It was highly productive, yielding more per acre than grains. It was nutritious, providing a family on a small tract of land with enough calories and vitamins to sustain them. This allowed the inhabitants to grow very rapidly on land that was, at times, poor and fragmented among heirs. For the vast majority of the poor Irish rural population, the potato was not merely a staple food; it was the food. A typical adult laborer might have consumed an astonishing twelve to fourteen pounds of potatoes daily. The entire rural Irish economic and social structure rested on this single humble tuber.
It wasn't the potato that was the issue, but the specific variety that came to dominate. Among the types of potatoes available, Irish Lumper was the sweetheart. It was a heavy-yielding, durable potato that could weather poor soil. It was perfect for the conditions confronted by poor tenants working small plots of land. Over decades, farmers all over the island planted almost this one variety by itself. They did so for sound, short-term reasons: it fed most for their households. But in doing so, they created huge, uniform, and genetically similar monocultures. All of the Lumper potato plants in Ireland were genetically identical to each other. They were all, in effect, the same plant. This was the absence of genetic diversity, the time bomb waiting to go off.
Genetic diversity is nature's insurance policy. In a field of several varieties of a crop, a disease will attack one variety but not others. There will be innate resistance in some of the plants, and they will be the ones to survive to plant the next generation. But in a monoculture, when all the plants are genetically identical, there is no such inherent protection. If one plant can be infected by a disease, that disease can infect all the plants. The entire crop is one great, homogenous target. This is precisely what occurred in Ireland. The island was a pure, homogeneous petri dish for the ideal pathogen to arrive.
The pathogen arrived in 1845, likely on a ship from North America. Phytophthora infestans is a water fungus that travels in the air in spores. It landed on the green, verdant leaves of the potato plants and began its work. The first sign was black spots on the leaves, which wilted and died shortly, putting out a putrid, characteristic stench. The blight worked down into the stem of the potatoes buried beneath the soil. The potatoes themselves would turn rotten and become a putrid, unpalatable mush. How quickly the destruction worked its way was horrifying. A healthy field one week and a black, decaying ruin the next. The fungus not only reduced the yield but also destroyed it. The partial failure brought about by the first attack in 1845 was followed by destruction in 1846. The blight ruined almost the whole potato crop across the country.
It was a sudden and ghastly blow. For those families who had stored potatoes to carry them through the winter, there was nothing. The crops that had sustained them for centuries literally rotted in the ground. People were without money, without food, and without a social safety net. They began to starve. Histories spoke of people with greenish-hued skin because they had eaten grass and nettles in a desperate bid to survive. Diseases like typhus and cholera swept through exposed populations, killing still more than hunger killed. The landscapes were post-apocalyptic. The following biological disaster was politically and economically aggravated in a holocaustic fashion.
Ireland was Britain's colony, and laissez-faire capitalism was the reigning economic policy of government non-intervention in the economy. Irish citizens were starving as Ireland continued to grow and ship phenomenal quantities of food—wheat, oats, cattle, and pigs—to England. These crops were grown on the massive absentee landlord-owned estates and were considered cash crops, not local food. The government came slowly, and relief was often ineffective and misguided. Public works projects required starving people to perform hard labor for poor food. Soup kitchens that opened helped ease the crisis, but the British government spelled it out: the Irish shouldn't get too accustomed to being given something. The famine was viewed by some as not a human rights matter, but as an unfortunate but natural realignment for an overcrowded and profligate economy. The ramifications of that one-reliance-on-a-potato kinda thing are still being felt today.
The Irish population fell precipitously and never again reached pre-famine numbers. The mass emigration, particularly to the United States and Canada, created a global Irish identity at the expense of immense suffering. The famine left a deep scar on the Irish psyche and opened a century of grievance and nationalist mobilization against Britain. The tragedy became a watermark in Irish history, a symbol of colonial languor and resilience. The Irish Potato Famine is a lesson learned that is uncomfortably relevant today.
Industrial agriculture today still relies on monocultures. Great swaths of the globe are planted with a handful of high-yielding types of wheat, corn, and rice. This exposes the world to the same kind of vulnerability that destroyed the Irish potato crop. The only variation nowadays is the scale; a serious illness in one of the world's most vital staples would have the potential to create a worldwide food crisis. The famine did, however, teach us something: the sheer necessity of diversity. Saving heirloom seeds, investing in crop breeding to fight disease, and protecting gene banks are not intellectual games; they are acts of worldwide security. The story of the Irish Lumper is a hard-learned lesson. It illustrates that putting all our eggs in one basket, or all our potatoes in one patch of land, is a risk with the worst possible outcome. The famine was a natural disaster in waiting to occur, but it was a human decision as to what crop to grow that turned a blight and turned it into a disaster, demonstrating the life-saving potential of diversity to the world in a difficult lesson.