Historians tell us that the reason for studying the past is to prevent us from repeating the mistakes of our ancestors. The rest of us know that its true purpose is to allow us to smile smugly at the follies of forebears. Proof of this, if proof were needed is the potato, which more than any other crop has attracted the attentions of historians. So what have we learnt from the potato induced disasters of the past?
Potatoes were first domesticated about 7000 years ago in the Peruvian high Andes around Lake Titicaca. In this region wild species of potato can still be found. They include highly variable sexually promiscuous species and less variable inbreeding species. Occasionally tubers are still harvested from the wild, but they are extremely bitter and rendered virtually inedible by toxic compounds called alkaloids. These same chemicals are also responsible for the poisonous nature of the potatoes relative the deadly nightshade. The first step in the domestication process must therefore have been the selection of less bitter, less toxic varieties. This was achieved with some success, but it is frequently said that if the potato were to be invented to day, it would be banded because of the toxic residues it contains. The next stage of domestication involved a doubling of the number of chromosomes. Potato scientists cannot agree if this occurred automatically or following the hybridisation of two different species. But this matters little to the story.
Many historians and comedians have spun wondrous and apocryphal yarns about the introduction of the potato into Europe. Sir Frances Drake is said to have discovered them in the Caribbean whist return from evacuating a failed British settlement in Virginia. Considering them too good for Queen Elizabeth, on his return Drake passed his potatoes to Sir Walter Raleigh who had them planted on his estate in southern Ireland. By 1590 they were ready to harvest, unfortunately Sir Walter tried to eat the toxic potato fruit. Disgusted by the experience Sir Walter ordered the plants distorted, and only then when his gardener took a spade to the plants were the potato tubers finally found. Of the details included in this version of the story, only the date is anything like accurate.
The Spanish were the first to introduce the potato into Europe in around 1570. Twenty or so years later they were independently introduced into Britain, both introductions were from the South American Andes. In spite of the fact that the British frequently referred to the crop as the potato of Virginia, it was not known in North America or the West Indies until being introduced via Europe in 1621. Another inaccuracy in the tale of Drake and Raleigh is the production potato tubers at all. The first plants brought into Europe, being from the Andes were not adapted to the long summer days of the temperate North. Andean potatoes are stimulated to form tubers by the short days of more tropical clines. It was to take almost 200 years of selection before the new arrival became adapted to European long summer days. This factor and a reluctance to eat a plant, which so closely resembled the poisonous nightshades, combined to prevent the widespread planting of the crop in Britain until about 1800.
Partly because it thrives in mild wet conditions and also because their English landlords kept much of the best land capable of growing cereals for themselves, the Irish took to potato cultivation in a big way in the early eighteenth century. The crop was grown in long strips of ground about two metres wide, along which manure, seaweed or rotted turf had been heaped, on top of this earth taken from between the strips was piled. The potatoes were planted with a dibber or placed on top of the manure layer during construction. Either way ensured that they were above ground level and so protected from water logging. The method was so effective that with a few other basic supplies a strip of land just 700 metres was all that was required to support a family. The beauty of the system was that because it kept the potatoes frost-free it also worked as a store. Once planted it required no further attention until the day came to lift them for consumption. For this reason, the Irish strip method of growing potatoes became known as ‘lazy beds’. The success of the crop enabled the population of the Ireland to increase dramatically, with estimates claiming a 900 percent rise from one million to nine million in the hundred years from 1740.
However, history records in a series of grim statistics that potato cultivation in Ireland was to end in disaster and in the process change the world. Although the Irish potato famine is associated with the years 1845 and 1846, the previous one hundred years had seen a procession of nearly thirty different famines. Each one was caused by the destruction of the potato harvest due to a fungal, bacterial or viral diseases. Probably as many as half a million or one third of the population died around 1740. During the blight years of 1845 and 46 one million people died and a further million and a half emigrate. This set a trend, which resulted in more than five million leaving the country before the first decade of the twentieth century. Potato cultivation played a similar role in the Highland clearances of Scotland and the mass emigrations or ethnic cleansing that followed.
With hindsight, historians and agriculturists have both retrospectively been able to predict the catastrophe. Such heavy reliance upon a single crop with only low levels of genetic diversity in a mild damp climate is a recipe for disaster. The structure of the potato’s lush dense foliage seems to invite attach from fungal diseases. As an agricultural system it could have been designed to propagate pathogens.
So have we learnt the lessons of the potato? Global production of the crop is steadily increasing, and is still based on a very narrow genetic base. It is the only non-cereal in the top eight crops, which dominate world food supply. On top of which can be added the uncertainties of climate change. Predictions vary but generally forecasts include increases in both temperature and precipitation i.e. the climate looks like becoming more favourable for plant diseases. It would strike you as perhaps a good time to be storing away food reserves just in case one of the eight major staple food crops was to suffer attach from a new ‘blight’. Just the reverse has occurred, set-aside policies and the pressures of free trade have seen the depletion of the Food Mountains of the 1980’s.
On the positive side plant breeders now better appreciate the value of genetic resources, and great efforts are made to collect and conserve the genes of all the world’s major crops. For both historical and political reasons the Centro Internacional de la Papa (the international potato centre and world potato gene-bank) is located in Peru. For years the research centre has been regarded as a legitimate target by terrorists. So next time you eat a plate of chips, spare a little thought to the group of international potato scientists, who live their lives behind two sets of barbed wire and armed security guards to ensure that it is not chips for the future of the potato.