Yes! We Have No Bananas

One argument made in favor of inbreeding companion pets is the observation that such practices are routinely used in agribusiness to produce both crops and livestock for human consumption.  If the professionals do it, why can’t the hobbyist?  Fellow blogger Joanna Kimball of Ruffly Speaking left one such comment regarding inbreeding on my Inbred Mistakes III post:

The reason you can go to your fridge, open it up, take out some bread and peanut butter and jelly and make yourself a sandwich – and it didn’t cost you $80 to do it – is absolutely one hundred percent because of inbreeding.

The strains of wheat, oats, peanuts, grapes, and sugarcane that make your sandwich produce gigantic healthy crops at minimum cost because they were inbred so tightly that the individual plants are basically clones of each other. Inbred plants are the reason someone in the US won’t starve if they’re on minimum wage, and the reason the world can support four billion more people than it did fifty years ago.

Ignoring the made up dollar amount and overzealous percentage given to our debt to inbreeding, Joanna is correct in pointing out that inbreeding absolutely plays a major roll in agribusiness and what we eat.  The problem is, this in no way absolves the practice of the pitfalls or makes it safe or smart for a model to breed dogs. [N.B. Joanna is no inbreeding advocate, but the food issue is one raised by those who are, so it’s worth looking at in more depth.]

Even in food, inbreeding is a model that emphasizes short term profits and developmental shortcuts over long-term health and sustainability.  This is perhaps best exemplified in the banana.

Exhibit 1: The Banana

Besides being an ironic argument against “intelligent design,” the banana is the most popular fruit in the world, dominating international trade and domestic consumption.

It is a “very delicate commodity on economic, social, environmental, and political grounds:” it’s a major staple crop for developing nations [it prevents billions from starving], it’s the major source of income and employment for most countries where it is grown [billions more subsist on the banana trade], and it was the cornerstone of American hegemony exerted through the Roosevelt Corollary [this is our back yard] to the Monroe Doctrine [so stay on your side of the Atlantic, eurotrash].

Unlike apple and orange growers, banana importers sell only a single variety of their fruit, the Cavendish. There are more than 1,000 varieties of bananas — most of them in Africa and Asia — but except for an occasional exotic, the Cavendish is the only banana we see in our markets. It is the only kind that is shipped and eaten everywhere from Beijing to Berlin, Moscow to Minneapolis.

By sticking to this single variety, the banana industry ensures that all the bananas in a shipment ripen at the same rate, creating huge economies of scale. The Cavendish is the fruit equivalent of a fast-food hamburger: efficient to produce, uniform in quality and universally affordable.

But there’s a difference between a banana and a Big Mac: The banana is a living organism. It can get sick, and since bananas all come from the same gene pool, a virulent enough malady could wipe out the world’s commercial banana crop in a matter of years.

By all measures, the banana is already a terminal patient.  It’s a highly inbred clone, it hasn’t reproduced sexually in centuries–all plants are grown from cuttings, it has no seeds from which to grow new fertile plants or make natural hybrids via pollination, no one bothered to keep a fertile healthy strain in reserve should future problems arise, and it’s so prone to environmental hazards that commercial operations bathe the plants in anti-fungals and pesticides in unprecidented levels.  Heck, it’s also the most radioactive food you’ll ever eat [so much so that scientists often measure radiation in the “banana equivalent dose”] unless you take tea with the Russian mob.

After 15,000 years of human cultivation, the banana is too perfect, lacking the genetic diversity that is key to species health. What can ail one banana can ail all. A fungus or bacterial disease that infects one plantation could march around the globe and destroy millions of bunches, leaving supermarket shelves empty.

Even when they still reproduced sexually via pollination, edible bananas were not that diverse.  Almost all common strains of edible bananas come from the same species which was, through domestication, highly inbred.

With fewer than 600 million base pairs, the banana genome is relatively small. The consortium will sequence Musa acuminata, a wild species that grows in Southeast Asia. Most cultivated banana varieties are descendants from this plant.

Bananas have been near an evolutionary standstill, say leaders of the project. The over-cultivation of a few popular strains has reduced genetic diversity in the species, making the plant vulnerable to parasitic worms, weevils, and viruses such as the banana streak virus. The virus exists in the banana genome itself and emerges to cause disease during times of stress.

Another threat to bananas is the black Sigatoka fungus, which was discovered in Honduras in the 1980s and is spreading worldwide. Certain wild varieties have genes that confer resistance to the leaf-destroying fungus, and a long-term goal of the sequencing project is to identify these genes.

The banana we know and love and eat isn’t even able to reproduce sexually at all.  To make it seedless, cultivators have made an infertile hybrid, much like we see with the Mule. Normal bananas are diploid, meaning they have two copies of each chromosome, one from each parent.  Sometimes during meiosis the cells don’t reduce to only one copy of the chromosomes and if two unreduced gametes meet it’s possible to produce a new fertile plant with twice the number of chromosomes, making a tetraploid organism.  This is one way new species are formed as the offspring are often no longer interfertile with the source organism.  Haploid (2N) bananas x tetraploid (4 N) bananas can sometimes produce a triploid organism with 3 copies of each chromosome that has compromised fertility but is otherwise very much like the parent plants.  In bananas this dysfunction means the inability to produce seeds, a desirable trait for eating.

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Although this sounds alarmist, a bananapocalypse has happened before. The song in the video above was written in response to one of several global banana shortages when the untreatable Panama fungus began taking out entire countries’ worth of banana crops one by one starting in the early 1900s.

Bananas stand in greater peril to disease and insect damage than the majority of other fruits because they are sterile, seedless mutants.  New plants are created from cuttings of existing ones, making them little more than clones of one another.  Without the natural diversity resulting from sexual reproduction, bananas continue on generation after generation with the same genetic makeup.  Their inability to mutate and adapt leaves them vulnerable to species-wide disaster, because what fells one of them will prove the undoing of every plant within that particular variety.

The singular cultivar then was the Gros Michel, the “Big Mike,” which was by all accounts larger, tastier, and more resistant to bruising than the Cavendish we eat today.  In every way a superior product, save resistance to the incurable Panama disease.

Inbred Banana: One spore from extinction

As plantation after plantation went under, the big companies simply pulled up anchor and found a new “banana republic” to invade, raze, and plant.  The growers hopped their way around the Caribbean and Latin America leaving toxic mudslides in their wake.  As old forests were torched from mountain to shore, the new plantations would be lucky to survive long enough to produce a crop before succumbing to the fungus.

Growers adopted a frenzied strategy of shifting crops to unused land, maintaining the supply of bananas to the public but at great financial and environmental expense-the tactic destroyed millions of acres of rainforest. By 1960, the major importers were nearly bankrupt, and the future of the fruit was in jeopardy. (Some of the shortages during that time entered the fabric of popular culture; the 1923 musical hit “Yes! We Have No Bananas” is said to have been written after songwriters Frank Silver and Irving Cohn were denied in an attempt to purchase their favorite fruit by a syntactically colorful, out-of-stock neighborhood grocer.) U.S. banana executives were hesitant to recognize the crisis facing the Gros Michel, according to John Soluri, a history professor at Carnegie Mellon University and author of Banana Cultures, an upcoming book on the fruit. “Many of them waited until the last minute.”

The banana companies ran from the problem, cashing in until the last minute, several times failing to have enough crop to meet demand and leaving havoc in their wake.  It was only luck [that there were still specimens of a 100 year old cultivar able to have cuttings taken after 50 years of searching] and a lowering of standards that made the Cavendish a temporary solution.

[The Banana Market] was saved at the last minute by the Cavendish, a Chinese variety that had been considered something close to junk: inferior in taste, easy to bruise (and therefore hard to ship) and too small to appeal to consumers. But it did resist the blight.

The Cavendish’s time has come to an end.  The fungus has gotten more virulent and now there are no strains immune from its effect.  Nor is it likely that the global community will stand for the same ruthless trade off of tropical forests for a temporary stay from extinction that the fruit companies employed during the last bananapocalypse.

Banana experts disagree on when the Latin American and African crops will be hit by the Panama fungus. Ploetz won’t venture a guess, but he notes that the Malaysian plantations went from full-scale commercial operations to “total wipeout” in less than five years. Currently, there is no way to effectively combat Panama disease and no Cavendish replacement in sight.
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How much time is left for the Cavendish? Some scientists say five years; some say 10. Others hold out hope that it will be much longer. Aguilar has his own particular worst-case scenario, his own nightmare. “What happens,” he says, with a very intent look, “is that Pan-ama disease comes before we have a good replacement. What happens then,” he says, nearly shuddering in the shade of a towering banana plant, “is that people change. To apples.”

Although the industry has come out and yelled “all is well,” there’s no reason to believe that the more virulent fungus will travel the globe any less swiftly than it did a century ago and there’s no reason to think that the fruit companies are any more likely to get ahead of the problem.  They’ve been working on a solution since the Gros Michel died out and have yet to find something that kills the fungus or is immune to its effects.

As it is, we’ve been living most of the last century with an inbred inferior product whose remaining days are limited, whose governing bodies are greedy and lack initiative and foresight, and whose legacy is perhaps more pain and destruction than sweetness and light.  All the while the public who buys this product has been kept blissfully in the dark.  Sounds sort of like the situation with kennel club dogs, no?

Read more in my next post, We have no CHIHUHUAS either.

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