This story is bananas. But it begins with potatoes.

In the mid-1800s, Ireland depended largely on potatoes. The crop was all one species, called the Irish Lumper, grown easily by propagating new plants from old potatoes.

It was monoculture in its strictest form: the new plants were genetically identical to the old ones …

Which allowed a potato fungus to sweep across the country, devastating Ireland’s potato crop for years afterward.

A million Irish died of starvation. Two million left the country.

A hundred years later, it happened again. But this time to bananas.

The world’s banana crop was also a monoculture, grown through propagation. In the 1950s, it was all one species called Gros Michel.

When a fungus attacked, it wiped out the entire crop – in fact, it made the Gros Michel banana virtually extinct.

Growers scrambled to find a disease-resistant species, and did so in China, called the Cavendish. Now that’s our only global strain of bananas.

In Colombian plantations, a new pathogen is preying on the Cavendish. As farmers try to keep it from spreading, scientists are using modern agricultural technology to develop new resistant strains.

The moral of this bananas story? Monoculture may be efficient, and it simplifies farming. But biodiversity produces a stronger and more resilient crop.