Just 12 plant species and five types of animal make up 75% of the world's food. At least 30,000 of the 350,000 known plant species on our planet are edible, according to the United Nations' Food and Agriculture Organization.
It is a woefully limited diet in the midst of such variety. Only 170 species of plant are cultivated for food on any significant scale. And around 60% of all the calories and proteins we obtain from plants come from just three grass crops – rice, maize and wheat.
There are huge risks in relying on so few plant species to feed the world. When a disease starts spreading in a particular crop variety, for example, it can surge worldwide. Often there is little genetic diversity within major crop species, leaving them even more vulnerable to disease. Climate change is also threatening our ability to grow these staple crops in many locations as they are not well suited to grow in the challenging conditions brought by greater droughts, flooding and rising temperatures.
There are some important lessons from history on the dangers of what happens if we rely on too few plant varieties for food. The devastating famine that hit Ireland in the late 1840s and 1850s, for example, resulted from the reliance on a single kind of potato by Irish farmers. When a fungal blight began destroying their crops, it wiped out a major food source for the country and over a million people died in the ensuing famine. But rather than learning from these mistakes, efforts taken in the mid-20th Century to feed the planet's rapidly swelling population have led to an over-reliance on just a few high-yield staple crops. The "Green Revolution" of the 1950s and 1960s saw agricultural scientists create varieties of wheat and corn, for example, that produced dramatically more yield per acre of land. While this has allowed farmers to continue feeding our rapidly growing population, it has also led to the spread of a mono-culture approach to agriculture.
The consequences of such mono-culture farming can be seen in a crisis that has struck one of the world's most familiar and popular fruits – bananas. There are over 1,000 varieties of banana, but 95% of the global trade in what is the fourth most important crop in the world has for decades relied on just a single variety, called the Cavendish. For the past three decades, however, a fungus known as Tropical Race 4 (TR4) - or Panama Disease – has decimated Cavendish bananas in over 100 countries, destroying crops in Latin America, Asia, Australia, the Middle East and Africa.