Monday, October 1, 2012


The wild potato is a masterpiece of evolution.  Botanists have discovered 169 species of them, widely dispersed across the Americas, but primarily located in the Andes.  Wild spuds have been able to adapt to every type of ecosystem except for lowland tropical rainforest.  Their foliage is bitter with toxic glycoalkaloid compounds that promptly spoil the appetite of hungry leaf munchers (or kill them).
Beneath the ground, small tubers grow on the roots, in a wide variety of colors and shapes.  The toxic tubers store energy and moisture as insurance against unfavorable conditions.  As they mature, the plants flower, and then produce tomato-like fruits containing up to 200 seeds.  Because the seeds are the result of sexual reproduction, each one is genetically unique.  Some will be resistant to frost, and/or drought, and/or blight.  Wherever they happen to grow, plants having the most suitable genes for local conditions will be the most likely to thrive and reproduce.  Diverse genes are essential for long-term survival.
Wild spuds are not the slightest bit interested in sprawling agribusiness monocultures, cancerous civilizations, population explosions, fungicide industries, topsoil destruction, or morbid obesity.  They simply find ways to blend into their ecosystem, live well, and not rock the boat, like all proper and dignified organisms do.
After consuming several tons of domesticated spuds over many decades, John Reader was inspired to write Potato, a highly readable book that described the amazing success of the humble spud, and the astonishing unintended consequences.  It adds one more chapter to the ongoing comedy of backfiring human cleverness.
Nobody has come up with a compelling explanation for why humans domesticated toxic little tubers, but we did.  Some of the myriad mutants resulting from wild potato sex must have produced tubers with low toxicity that tickled the imagination of somewhat-clever minds. 
Domesticated tubers are much larger than wild ones, and much better tasting.  When the plants stop growing, and the foliage withers, the tubers are no longer poisonous.  An acre of spuds can produce as much food as eight acres of wheat — in much less time.  Spuds are now our fourth most common food, following wheat, corn, and rice.
They are remarkably nutritious.  You can eat nothing but spuds for several months and remain healthy.  If you add a glass of milk to every meal, you will be completely nourished — this was the Irish peasant’s diet 200 years ago.  The average adult male ate 10 pounds of spuds daily, and 20 when working hard.  Seriously!
Potatoes can thrive where grains don’t, and they can be stored for months.  Long ago, the people of the Andes learned how to make chuño — freeze-dried potatoes, which can be stored for years, while losing no nutritional value.  Sweet potatoes are not related to potatoes, and they spoil far more quickly.
Prior to the arrival of potatoes, European peasants were typically malnourished and short-lived.  But spud-gobbling bumpkins were healthy and vigorous, despite their extreme poverty.  Potato-fed kids were more likely to survive into adulthood and reproduce.  Infants could be weaned earlier by switching them to a mix of mashed potatoes and buttermilk, allowing mom to get pregnant again sooner, and have more children.  When potatoes arrived in Ireland around 1600, the population was no more than 1.5 million.  By 1845, it was 8.5 million, of which 90 percent were hardcore spud addicts.  This explosive growth could not continue, of course.
I shall now introduce the arch villain in this story: Phytophthora infestans, a fungus commonly referred to as “late blight.”  It probably originated in the highlands of central Mexico, and then migrated to other regions.  Today it can be found almost everywhere, and wet weather is its call to action.  Blight spores can ride the winds to new locations.  Nothing gives it greater pleasure than discovering a big field of moist mature potato plants.
In 1845, spores from the US took a steam ship cruise to Ireland, where everyone was eagerly expecting a bumper crop of lumpers.  To their horror, entire fields turned black overnight.  Blight raced across Europe, destroying two million square kilometers in four months.  It struck again in 1846 and 1848.  Ireland was hit hardest, and their wretched British overlords could not be bothered to provide much assistance.  A million Irish died, and a million emigrated.
I shall now introduce the hapless victim in this story: Solanum tuberosum, the family of domesticated taters.  In the process of being transformed from wild toxic tubers to an incredibly productive super food, domestic spuds lost most of their sex drive (via male sterility).  Few produce any fruits or seeds.  So, commercial American potatoes are not grown from “true seeds.”  Instead, farmers plant “seed tubers,” which are hunks of tubers from the last harvest.
True seeds are rugged survivalists, because they are genetically diverse.  But domesticated potatoes are helpless sitting ducks, because they are genetically identical clones.  If one is susceptible to blight, they all are.  Reader says, “In fact, most modern cultivars are biological ‘monsters’ that could not survive in the wild.”  They can’t live without human caretakers (like domesticated dogs, cattle, sheep, and maize).
Scientists have two control options.  The cheapest solution is to breed new varieties that are blight resistant, but this is a time-consuming process, and there are only a limited number of gene tricks that work.  The success of any new variety can only be temporary, because the blight fungus is constantly mutating.  Blight will inevitably create offspring that can overcome the resistant spud’s defenses, and each new blight spore can produce 100,000 spores in four days.  The scientists will have to start all over again.
The other solution is more expensive and toxic: fungicides.  In wet seasons, a field might be sprayed 12 times (or 30 times in super-moist New Guinea).  Like plant breeding, the effectiveness of fungicides is temporary, because the fungus will inevitably develop resistance to them.  When one poison stops working, you switch to another, use more, or try combos.
There can be no permanent solution to blight.  Scientists will run out of clever tricks long before Mother Nature quits producing countless new fungus mutants every minute.  Rising energy costs will continue to drive up the price of fungicides, making them unaffordable for a growing number of poor farmers.
Wild spuds still thrive in the high Andes, preserving the wild gene pool that’s essential to the work of plant breeders.  Blight has never been a problem in this region — until recently.  Climate change has been making the weather warmer and wetter in the homeland of spuds.  Some crops of native potatoes have been heavily damaged.
The venerable historian William H. McNeill once penned an essay titled “How the Potato Changed the World's History.”  Europe’s population skyrocketed between 1750 and 1900, thanks in part to the spud.  Millions of surplus country folks were forced to move to cities, work in factories, earn peanuts, and live on taters.  Thus, spuds played a significant role in the mass emigration of Europeans, the growth of colonial empires, and the rise of Russia and Germany as industrial powers.
Reader lamented that “millions [of] lives were spent as fuel for the Industrial Revolution,” but in its wake, “a new and better world emerged.”  Really?  I have a feeling that it would have been wiser to leave the spuds as we found them — wild, free, and happy.
This book has many, many more spud tales to tell.  Throw some French fries in the microwave and find a comfy chair.
Reader, John, Potato — A History of the Propitious Esculent, Yale University Press, New Haven, 2009.

No comments: