Irish Potato Famine, and Why Natural Selection Failed To Prevent It

The Irish Potato Famine, also called the great famine, was a period of mass starvation and disease in Ireland from 1845 to 1852. The great famine claimed one million lives and caused millions to flee their country. In the aftermath of the famine, Ireland’s population fell 25%, and Irish nationalism and separatism gained support. Accordingly, Ireland, for the most part, left the union, United Kingdom of Great Britain, and Ireland in 1922, following the Irish War of Independence.

Political decisions made thereafter aside, the cause of the Irish Potato Famine was a potato blight that infected potato crops throughout Europe during the 1840s, including the island of Ireland.

The Brief History of Potato in Ireland

Sir Walter Raleigh born in 1554 was an English adventurer and writer. He is known to be a favorite of Queen Elizabeth I, who even knighted him. However, Elizabeth’s successor, James I, has imprisoned him for treason in the Tower of London and eventually put Sir Raleigh to death. What makes Sir Raleigh particularly important is that it was Sir Raleigh, who introduced the potato to Ireland, smoking to Europe.

It is estimated that the Inca Indians in Peru were the first to cultivate potatoes in 8000 BC. However, it was not before 1536 that Spanish conquerors in Peru discovered the flavors of potato, and carried them to Europe. From there, Sir Walter Raleigh introduced this new crop to Ireland in 1589.

By the end of the eighteenth-century potato was already a staple food for the Irish, especially among the poor. The popularity of potatoes was thanks to the fact that it was a satisfying crop, rich in calories, minerals, vitamins, and protein. Additionally, it was easy to produce in masses and had a low spoilage rate.

The only problem with potatoes in agriculture is their susceptibility to disease, which eventually caused the Irish Potato Famine.

Like many other crops, there are two ways of reproducing potatoes. Sexually and asexually.

True Potato Seed Formation

Sexual Reproduction of Potatoes

The sexual reproduction of potatoes surprisingly resembles human reproduction. Like in humans, potato plants’ sexual reproduction requires genetic material (DNA) from two parents, in potatoes’ case, two-parent potatoes.

Potato plants produce flowers at the end of their growing season. In these flowers, every potato has male and female sex cells, called gametes. Thanks to bees, male cells of potatoes are carried to female cells of other potatoes, and gametes couples combine to produce offspring. This process is called fertilization.

The genetic information of sexually produced potatoes is different from the genetic information of their parents. Therefore, in a population of sexually produced potatoes, there will be a genetic variation. The genetic variation in a population is crucial for natural selection, and it could have prevented the Irish Potato Famine, but we will come to that later.

A depiction of asexually grown potatoes

Asexual Reproduction of Potatoes

Planted potatoes grow multiple more potatoes under the soil. Naturally, these asexually formed potatoes share the same genetic information with their mothers.

There are several reasons why in agriculture, the asexual reproduction of potatoes works miracles.

Asexual reproduction of potatoes increases its productivity.

A high-quality potato will grow high-quality potatoes with the identical DNA as their mother.

Farmers can protect potatoes against pesticides.

The Irish Famine was the result of farmers not being able to protect asexually grown potato plants against pesticides.

Asexual reproduction of unicellular organisms.

How Natural Selection Works

Natural Selection is the evolutionary mechanism in which individuals that are better suited to their environment survive and reproduce most successfully. This way over time species better adapts to their environment.

The most important assumption of natural selection is variation in the inheritable characteristics of the individuals in a population. In case there is no genetic variation among the individuals of a species they will all either thrive or die with changes in the external factors; there will be no “selection.”

For animals with long generation times, (e.g. humans) asexual reproduction would never work because by the time mutation creates enough genetic variation in the population, it is almost certainly a virus will wipe out the whole population. Accordingly, the well-being of asexually produced potatoes depends on the protection provided by the farmers.

- Why Do We Have Unique DNA?

- How genetically diverse are humans?

A potato infected with phytophthora infestans

Why Natural Selection Failed To Prevent Irish Potato Famine

The European Potato Failure was a food crisis caused by a potato blight that struck Northern Europe in the mid-1840s, which is also known as the Hungry Forties. While the crisis produced excess mortality and suffering across the affected areas in Europe, particularly affected were the Scottish Highlands and even more harshly Ireland.

The same potato blight first struck in the USA in 1843 and then in Canada in 1844. It is assumed that the potato disease traveled to Europe on trade ships and spread to England and finally to Ireland before spreading to other countries in Europe.

In September 1845 a strange disease struck the potatoes as they grew in fields across Ireland. Many potatoes were found to have gone black and rotten and their leaves had withered. The strange disease, which later became known as potato blight, destroyed between one-third and half of the potato crop in the harvest of 1845. It was not possible to eat the blighted potatoes, and the rest of 1845 was a period of hardship, although not starvation, for those who depended on it.

The cause of potato blight spreading so fast in North America, and Europe with dire consequences was that potatoes grown in this region shared either the same or too similar genetic information. As a result, many potatoes were vulnerable to the same potato disease. Had there been enough genetic variation among the potatoes grown the impact of potato blight would be limited, and potato disease would not spread fast.

Classiebawn Castle in Ireland

Was the Irish Potato Famine Inevitable?

The 1840s were decades away from Charles Darwin’s publication of Evolution Theory. Additionally, before the twentieth-century scientists had a poor understanding of reproduction, genetic inheritance, and DNA. After the disappointing 1845 potato harvest, scientists were not able to foresee if the farmers planted potatoes with the same DNA as before, their 1946 crop would be entirely wiped out too, and break Ireland.

With what scientists know in the 1840s on population genetics the potato blight was perhaps inevitable. However, this does not mean that the Irish Potato Famine was inevitable either. It is safe to say better political decisions prevent, or at least mitigate the Irish Potato Famine.

For instance, the queen of the UK £2,000 donated to Ireland, an island where millions of her subjects lived. Given the devastation of the famine, not only £2,000 was a drop in the bucket but also it also created a domino effect by creating a cap for the amount the other countries donated to Ireland since donating more than what the Queen donated would not be good diplomatic manners.

Today, the Republic of Ireland is of course a different country compared to what it was in the mid-nineteenth century. With more than $80.000 average annual income per person, it is the second only to Luxembourg among the richest countries.