Hank Green: Here at SciShow HQ, we have a little food area for the employees, sometimes there's donuts, sometimes there's nuts, sometimes some dried mango, but the one thing that never sticks around and is gone as fast as we can buy it is the wonderful, beautiful, noble banana. Unfortunately for us, it may not be around forever.

[SciShow Intro plays]

First, the good. Bananas are healthy, packed with nutrition and energy, they fit in your hand and give nice little cues when they're perfectly ripe and are easy to peel and eat. Shocking statistic, the banana is Wal-Mart's #1 selling item, not the potato chip, not Coca-Cola, not 50 Shades of Grey, bananas! They appear to be so perfect for human consumption that Kirk Cameron attempted to use them to prove the existence of God. Of course, this banana was not created by God or really even nature.

Bananas, at least the ones you see at the store, were created by people. Don't get me wrong, there are wild banana plants, lots of them, they're native to South and Southeast Asia, and there are dozens of species and thousands of varieties. They're just not the ones we eat. Some of those species, as you might suspect, have seeds, 'cause that's what fruits are, they're fleshy bodies containing seeds, so you might wonder, why have you never eaten a banana seed? Well, you have, kinda, in cultivated bananas, the seeds have pretty much stopped existing. If you look closely, you can see tiny black specks, those are all that's left, and they're not fertile seeds. If you plant them, nothing grows. Today's bananas are sterile mutants. I'm not trying to be mean, that's just the truth.

Unless you were alive in the 1960s, hats off to all those older SciShow viewers out there, every banana you have ever eaten was pretty much genetically identical. This is a Cavendish, the virtually seedless variety that we all eat today, but it wasn't always our banana of choice. Until the 1960s, everyone was eating the same banana, it was just a different banana, the Gros Michel, a bigger, sweeter fruit with thicker skin. You might notice that banana flavored things don't really taste like bananas, well, they do. They taste like the Gros Michel. The genetic monotony of the Gros Michel crop was its undoing. A fungicide resistant pathogen called Panama Disease began infecting Gros Michel crop. By the time growers understood how vulnerable their crops were, the Gros Michel variety was all but extinct.

The entire banana industry had to be retooled for the Cavendish. Since they're seedless, the only way to reproduce them is to transplant part of the plant's stem, and for the last 50 years, we've been good with the Cavendish, 'cause it's more resistant to the Panama Disease. However, somewhat terrifyingly, a strain of Panama Disease that affects the Cavendish strain that we all know and eat has been identified. A global monoculture of genetically identical individuals is a beautiful sight to a pathogen. The fungus only has to figure out how to infect and destroy a single individual, and suddenly, there's no diversity to stop it, or even slow it down. That's led to a lot of scientists worrying about, or even predicting the outright demise of the Cavendish. This wonderful, most popular of fruits might completely cease existence.

The good news is, we now have a much better understanding of genetics, epidemics, fungi, and pathology. Scientists and growers have already taken steps to protect the Cavendish, some growers are creating genetically different bananas that might replace the Cavendish crop if it fails, while scientists are attempting to genetically engineer Cavendish plants with immunity to Panama disease. Plus, we learned a lot from the Gros Michel debacle. Infected fields are quickly being destroyed and new crops are grown from pathogen free lab grown plant stock. So, thanks to the people who work tirelessly to grow and harvest bananas and bring them to us, so that we can offer them inexpensively to our employees, and thanks to the growers and scientists working tirelessly to make sure that they don't go the way of the Gros Michel.

Thanks for watching this episode of SciShow. If you have any questions or comments or suggestions for us, you can find us on Facebook, Twitter, or in the comments below, and if you want to continue getting smarter with us here at SciShow, you can go to YouTube.com/SciShow and subscribe.

[SciShow endscreen plays]