Science Talk

Can Science Save the Banana?

The banana is the world's most important fruit. But it's under threat from a disease spreading around the world. We'll hear from Dan Koeppel, author of the book "Banana: The Fate of the Fruit That Changed the World." And we'll visit a Guatemala banana plantation with guide Julio Cordova. Plus, we'll test your knowledge of some recent science in the news. Web sites mentioned on this episode include

The banana is the world's most important fruit. But it's under threat from a disease spreading around the world. We'll hear from Dan Koeppel, author of the book Banana: The Fate of the Fruit That Changed the World. And we'll visit a Guatemala banana plantation with guide Julio Cordova. Plus, we'll test your knowledge of some recent science in the news. Web sites mentioned on this episode include

Podcast Transcript:
Steve: Welcome to Science Talk, the weekly podcast of Scientific American for the seven days starting April 23rd, 2008. I'm Steve Mirsky. This week on the podcast, we're going bananas. We'll talk to Dan Koeppel author of the book Banana: The Fate of the Fruit that changed the World and I'll play you some audio from my recent visit to a Banana plantation in Guatemala. First up, Dan Koeppel; he is a contributing editor at National Geographic Adventure and has written for Outside, Popular Mechanics, Popular Science, Audubon, and The New York Times Magazine. He was in Amherst, Massachusetts, for his speaking engagement when we talked.

Steve: Hi Dan. Great to talk to you today.

Koeppel: Hi Steve. Thanks for having me.

Steve: It's my pleasure. You say in your book that you've became a bit of a banana obsessive, so why don't you tell us some of the things that have obsessed you.

Koeppel: Well, the thing which obsessed me the most I think is the contrast between the, sort of, complexity of the banana—s, has the 7000 years of banana history—as it's become the world's most important and cultivated fruit; and the, sort of, simplicity of our relationship with the banana, as a piece of popular culture: the Banana that we have jingles about and that we collect as stickers on and then we slice into our corn flakes. There's a real, sort of, contrast between what the banana is scientifically and politically and this, sort of, humble fruit that we slice into our corn flakes everyday.

Steve: For one thing, according to your book, the banana is actually a berry?

Koeppel: Yeah, that's right. You know, there is [are], sort of, some banana knots [myths]. The banana tree is not a tree; the banana is actually an herb. The banana tree, it's actually a stem. There is no bark. The Banana is a fruit, but it is actually a giant berry; like as I said, it's the world's largest herb. So there is a lot of, sort of, things about the banana that we assumed to be true that are not true; and that's one of the things that gets—you know, almost anyone who learns about bananas begins to, sort of, fall into this web of fascination. You know, one of the things I thought really interesting is that the banana we eat, the Cavendish banana is just one of over 1,000 different banana species, but unless you travel to those other banana species, it is unlikely that you will ever taste another one.

Steve: Seriously, most Americans are probably [only] ever had one, and it's always been the Cavendish, if they are young enough.

Koeppel: Yeah, that's right. I mean except for a couple of red bananas that you might find in a Whole Foods market, that yellow Cavendish is the only banana out of that 1000 [the thousand] kinds that is hardy enough to travel the great distances that bananas must in order to make it to our supermarket, so that's pretty much it. Now the Cavendish is actually not the first banana that Americans have had. That first banana was a type called the Gros Michel, but that one went extinct functionally about 50 years ago. So that Banana was the Banana that our grandparents ate, but that's not our banana. And so that's another thing that is fascinating is the Banana that our grandparents ate has disappeared and most people don't know that either.

Steve: So if your grandparents are old enough and they said, you know, the bananas that I ate when I was a kid, they just tasted better than these bananas, they're actually right.

Koeppel: That's right. It's not just, sort of, just some nostalgic memory about things being better back in the old days. In fact that Gros Michel banana was a bigger banana, a tastier banana. I like to tell people—and I've actually managed to taste the Gros Michel, since I wrote the book, because they're, sort of, held in captivity—I like to tell people that it's the difference between Häagen-Dazs ice cream and cheap supermarket ice cream. The Gros Michel is a richer-tasting, creamier-tasting Banana. Our Cavendish banana is an inferior banana in every way except one. The Cavendish banana was resistant to the disease that ultimately wiped out the Gros Michel Banana and that's why it became our banana, our only banana.

Steve: Tell us about that disease and about how it's kind of resurfacing today.

Koeppel: Sure. That disease is a fungus and it is called Panama disease, which is named after the country where it first began. The Gros Michel was introduced, it was the first Banana introduced to Americans a little over 100 years ago and almost immediately these banana plantations began to succumb to this mysterious disease and this began a cycle. As soon as the Banana plantations succumbed, banana companies began to plant new plantations; they began a cycle of plantation building, abandonment, and replanting all across Central America. It was a race, hopscotch race against these diseases. Finally around 1950, they ran out of room. The banana companies were almost bankrupt and at the very last minute, they adopted this Cavendish banana, which they had resisted. They felt it was an inferior banana, such a bad banana that they really resisted. They didn't want to use it and they, sort of, were forced into it. And for 50 years, more or less, they've, sort of, lively ran along, and didn't do much to preserve this banana—they thought it was immune to Panama disease. But about 10 years ago they planted some Cavendish bananas in Asia and lo behold the new strain of Panama disease emerged and it started afflicting the Cavendish. And from those small plantations in Malaysia, where that first new strain of Panama disease emerged, that Panama disease has now spread even faster than the old one did. It is now in India, in Pakistan, in China. It has spread all the way through the Pacific to Australia and it is coming to our hemisphere. It has not hit yet, but I have said often and it is absolutely true that it is coming. No banana scientists, no plant pathologist denies that. The question is when. And it is probably five or 10 years away. And as of now there is no cure, and when it comes it will go fast and it will go very devastatingly, will probably wipe out the entire banana crop, unless something is done about it, unless some kind of cure is found or unless we diversify our banana crop before that.

Steve: One of the big dangers with any kind of monoculture agriculture is if one of them is going to get it, they're all going to get it because they are clones of each other.

Koeppel: Right. And that's what makes the banana so wonderful: In a way that banana was the first fast food, you know? Every single banana is exactly the same as every other one. They are totally reliable, they ripen at the same rate; they taste the same. This is what made the banana so practical. I mean, if you think about it, bananas are cheaper than apples, yet they come from thousands of miles away; and the reason for that is that bananas have these tremendous economies of scale because they are all the same and they require the same shipping methods. They don't require six different kinds of techniques, the way the six different apples we eat do. So a banana is just the, sort of, perfect thing for cheapness. And, you know, but because each banana is identical, each banana is susceptible to the same disease. This Cavendish banana in Pakistan is susceptible to the same disease as this Cavendish banana in Guatemala. And so once the disease hits, it spreads very quickly, and that's what's happening with Panama disease right now.

Steve: Now there are some scientists who are working to try to figure out what the next banana is going to be or to stop the Cavendish from going extinct; and the world capital of banana research is in a very unexpected place, tell us about that.

Koeppel: Right! The world capital of banana research is unexpected on the surface. It is Belgium of all places, and that is where most of the work on genetic engineering of bananas is being done: in a laboratory at the Catholic University of Leuven, Belgium, which is right outside of Brussels. And the reason for that actually is because the most important bananas in the world and the bananas that are subsistence bananas where people actually rely on them for their primary source of nutrition is in Africa. And Belgium had a great colonial interest in Africa to [through] much of the 19th century, and that colonial interest has transferred in the 20th century to a scientific interest, and so Belgians are the great banana experts of the world.

Steve: It's a fascinating artifact of colonial history. Other artifacts of colonial history, they are not even artifacts, they're still going on. Talk a little bit about the relationship between the banana and Central American politics. I mean, it's not even a relationship, the banana has been the Central American politics for [a] lot of the century.

Koeppel: Right and you know, banana companies, in order to keep bananas cheap, had to really control the cost of labor and land. By control, I mean, control. You know, they had to have no cost for labor and land. They have to have slave labor and free land and they had to take over countries and that meant brutal tactics. They had to use the U.S. military and massacres and all sorts of terrible things. Over 20 times, there were interventions whenever there were attempts to unify banana workers or have fair prices for land and these countries that were taken over by banana companies, that's where the term "banana republic" come[s] from. Interestingly, from a scientific perspective, all these needs for takeovers spring from Panama disease. Because as these banana lands go fallow, you can't grow new bananas in them once they're stricken by disease. The banana companies have a desperate need for new lands to grow their bananas and so the more the disease spreads, the more they need land; and this is why they have to take over countries and become ever more brutal because there is this geometric progression of fallow land and this desperate need to maintain their profit margins, all spreading from this advancing malady, Panama disease.

Steve: And we're talking about what Guatemala, Honduras what else?

Koeppel: Almost every nation in Central America and then spreading down to Columbia, Ecuador, and even into some of the Caribbean nations, Cuba and early on into Jamaica; you know, almost anywhere that you will see, if you go into your super market, you will see a sticker with the country of origin on it, on that banana, it was a banana republic at one point. And in some cases it still can be: [In] Ecuador, one of the perennial candidates for president is the head of the biggest banana company that is not Chiquita or Dole.

Steve: The Banana that I ate about half an hour ago had an Ecuador sticker on it.

Koeppel: Right, probably Bonita Banana or ...

Steve: It was indeed, yeah.

Koeppel: Yeah.

Steve: So, what do you think after all your research? What would you guess would be the future of the banana?

Koeppel: Well, I think there have to be two things done. Number one, genetic engineering is really important. The banana is a very slow-to-grow fruit. I mean, in order to develop a new fruit, there have to be a lot of cycles, first in the lab and then in the field. So genetic engineering is really important because you [have] got to jump-start those needed qualities. If you don't use genetic engineering, you have to have many generations of hybridization, conventional hybridization, so we need advanced techniques to jump-start that and get test bananas out in the field to look for resistance to the Panama disease. Number two, diversity: We have to start adapting other bananas, and that means adopting new technologies to ship and transport bananas. That will mean increased banana prices. People are gonna have to be willing to accept [more expensive] bananas. Right now, bananas live in this, sort of, price range of 49 cents to 69 cents a pound, with organics costing more. I think banana prices will go up, and that's, sort of, a major shift in the way people think about bananas. And banana companies are gonna need to think about a new technology—each different variety of banana is going to require different technologies to control and regulate ripening, to keep them fresh and intact while shipping. One of those interesting things that people will have to face is, probably one of the candidates that is best for replacement of the Cavendish is this banana called the red banana that you can find in, mostly in Whole Foods market. Is America ready for a red banana? And you think about the Chiquita Banana girl—she is not red, she is yellow. Are we ready to change the color of our banana? I don't know if we are or not. Chiquita certainly doesn't think so and that's one of the reasons they have been hesitant to even introduce that to anything but specialty markets.

Steve: Well, we've [got] green apples and red apples, maybe we'll get used to red bananas too.

Koeppel: Yeah, I think we might have to.

Steve: Dan Koeppel, the book is Banana: The Fate of the Fruit that Changed the World. Thanks very much.

Koeppel: Thank you for having me, I appreciate it.

Steve: Dan Koeppel's last book was, To See Every Bird on Earth. His Web site and blog is

(song plays)

Steve: I was in Guatemala on January 31st, a stop on a science cruise sponsored by Scientific American and InSight Cruises and I visited a banana plantation with a few of the other passengers. Our guide was Julio Cordova. You can see some of the photos of what we're going to be talking about on the Web page for this podcast. I want you to be ready, because Cordova refers to "killing the mother"—he is talking about the banana tree and the banana tree is always killed after its bananas are harvested because that allows its clone which is already growing from the same roots to then produce the next batch of bananas. The crunching noises as you [will] all hear are us stepping on banana tree detritus.

Cordova: Good afternoon once again. My name is Julio Cordova and I have a little talk about the banana, about the harvesting process. We are located right now, in one, obviously in one banana field. This field belongs to Del Monte, okay? We're not going to stay here so long because I understand it's very hot, okay. Common questions: For example, I want to tell you that banana plant[s] produce only once in their life; only [one] banana bunch in their life, okay? After they produce the bunch, happens this: (sound of cutting a banana tree) They kill the mother, okay? Before they used a machete and they cut the mother, they need to be sure that the children, the child who is standing right next to her is six months older. The time that takes the banana bunch to grow, it is 90 days. Ninety days are three months, right? Okay. So when he is six months, he is ready to produce one bunch, in the next three months, 90 days exactly. Sometimes, we get a few fungus in Guatemala. The common fungus in Guatemala, it's called Sigatoka. We have two kinds of Sigatoka in the country—the yellow Sigatoka and the black Sigatoka. Why is every single plant tied with this white poles to one to another, remember that we're located in the Caribbean coast of Guatemala, and sometimes the wind here gets harder, so they need the plant to grow straight. Every single banana that you eat at home, it has been measured here one by one, needs to have the right size and the right weight. Over there, weevil repeller, you see him, at the top—why? They use one weevil repeller per week, so the workers who are seeing how is the fruit; they know the age of the fruit, okay? They use 12 different colors, one per week. So 12 weeks are exactly three months, when the bunch is ready it is going to weigh over 100 pounds. There are three workers looking for the bunch that it is ready. So there is one man who puts a ladder right here, he climbs, he cuts, and there is another man right here waiting with a foamy on his shoulder waiting when it falls down. Then there is another man over there—you see the wire over there, they have a hook, they put a hook in here and they transport the whole entire bunch to the packing station. We are going to see right now that the bananas are still green, why? Remember this bunch for example, let's say that Julio is going to cut this bunch today, remember after Julio cut[s] the bunch, automatically, Julio is going to kill the mother automatically. That's the result why we can see all these here: They use it for organic matter, okay, looks exactly like my room.


Cordova: Na! Just kidding!

Voice: Julio, what happens to the baby, if there is a baby, now they kill that too and another one grows?

Cordova: Another one grows.

Voice: Okay.

Cordova: Yeah, that's one of the benefits of having banana plants. They keep growing and growing and growing and they never have to be replanted. For example this one looks like it's kind of new. In some other, oh! Here we go, I want to show you something. (leaf rustling sounds)Here for example, let's say that this is the mother alright, this is the son, and let's say that for example we've already coming ...

Voice: The daughter?

Cordova: No, the grandchildren.

Voice: Oh! The grandchild!

Cordova: The grandchild, it's coming. How do we know the age of this son? We count the leaves, (1 .... 2 .... 3 .... 4 .... 5.... 6 .... 7 .... 8 ....). This baby or her son it's two months, one leaf per week... Yeah, exactly, if the black Sigatoka attacks the field they have to burn the whole entire field.

Voice: Oh, my God!

Cordova: Yeah, they have to burn; they have to destroy the whole entire field. This field, it's almost new kind of because when the Hurricane Mitch came to—Isabel—destroyed the whole entire field from Del Monte. Okay, thanks goodness, we didn't have another, we haven't had another hurricane since 1998.

Voice: How many bananas are there on a bunch?

Cordova: Good question. We can see here that somebody cut (1 ... 2 .... 3 .... 4 .... 5 ....) clusters. Why? Because the mother doesn't have enough food to feed too many members. Okay, that's the reason. Why do we see always one banana at the bottom in every single bunch? Why? This bunch has blood, of course we don't call [them] blood, we call them savia and the savia comes and goes around and this it works like a stop, you know, stop the savia and help it come and go. Many people ask me, Julio why these bananas are green? Why? The reason, it's because let's say, for example, I cut this bunch today, today is Thursday. This bunch is going to be in the dismissing process, the selecting process, the packing process today. Today at the night it's going to be in the pier, it's going to be traveling, Friday, Saturday, and Sunday. Monday it's going to be in the United States pier port—I don't know, at Tampa or whatever. Tuesday, it's going to be in the warehouse, Wednesday in the supermarket and in one week, exactly one week, it's going to be on your table, that's the reason.

Voice: Okay let's move, let's move on.

(sounds of rustling leaves)


Steve: Now it is time to play TOTALL....... Y BOGUS. Here are four science stories; only three are true. See if you know which story is TOTALL....... Y BOGUS.

Story number 1: Prozac has been shown to correct so-called lazy eye in animals.

Story number 2: A study finds that people between 18 and 24 are the happiest age group in America.

Story number 3: The defense department has created a new medical institution and one goal is to find a way to regenerate limbs.

And story number 4: Researchers have induced lightning in thunderclouds with laser beams.

Time is up.

Story number 1 is true. Prozac helped correct the rat version of lazy eye. The drug may return adult neurons to a more juvenile state where they can develop anew and properly this time. The study appeared in the journal Science. The researchers hope to test Prozac in people with a developmental eye disorder.

Story number 4 is true. Scientists in New Mexico pointed powerful pulse lasers at thunderclouds and made lightning. The research appeared in the journal Optics Express. Such artificial lightning is useful in studies of airplane and power line sensitivity to the discharges. For more check out the April 22nd episode of the daily SciAm podcast, 60-Second Science.

And story number 3 is true. The defense department announced on April 17th that it was creating the Armed Forces Institute of Regenerative Medicine. The institute will focus on burn repair, wound healing, craniofacial reconstruction, but also limb transplantation and even regeneration.

All of which means that story number 2, about 18 to 24 year olds being the happiest group in America, is TOTALL....... Y BOGUS, because it is the oldest among us who are in fact the happiest. That's according to a study in the April issue of American Sociological Review. Older people tend to be more content than the young strivers out there and the midlife people feel hassled probably by their 18 to 24 year old kids and their happy parents.


Well that's it for this edition of the weekly SciAm podcast. You can write to us at and check out for the latest science news, all of our podcasts and full articles from Scientific American magazine. For Science Talk, the weekly podcast of Scientific American, I'm Steve Mirsky. Thanks for clicking on us.

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Banana “tree” with next generation in front.
Credit: Steve Mirsky

Lone banana at bottom of bunches acts as plug to keep internal fluids circulating.
Credit: Steve Mirsky

Grandchild stem forming at base of mature “tree.”
Credit: Steve Mirsky

Bananas about to be cut from stem and packed.
Credit: Steve Mirsky

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