IN SEARCH OF DARWIN'S POTATO
by Robert Rhoades
During his 1839 exploration and voyage aboard the H.M.S. Beagle,
young Charles Darwin was fascinated by an amazing South American plant
that was so adaptable it seemed to defy the very laws of nature. In
his log, the great naturalist wrote:
- It is remarkable that the same plant should be found on the
sterile mountains of Central Chile, where a drop of rain does not
fall for more than six months, and within the damp forests of the
The remarkable plant Darwin observed was the potato, a gift of South
American Indians to the rest of the world.
Today the potato is the world's fourth most important food crop and by far
its most important vegetable. Cultures that may have very little else in common
share the cultivation of potatoes. Varieties of spuds are grown by people in
130 countries around the world -- more than any other crop except maize --
and their production in developing countries is increasing faster than that
of any other food crop.
Potatoes didn't mean much to me in 1979 when I became the first resident anthropologist
at the International Potato Center (CIP), headquartered in Lima, Peru. A potato
was still just a potato and nothing was more boring than a sack full of them.
At the time I couldn't have realized that the search for facts about Darwin's
remarkable vegetable would take me across four continents, through dense coastal
jungles and into remote mountain villages. That 15-year journey continues today,
and the mission remains deceptively simple: To document the dispersal of potatoes
throughout the globe and how they have come to impact diverse environments
I learned that however you slice it, few foods have a more legendary past,
natural diversity, fascination to science or a greater potential to feed our
The potato's popularity flourishes because of precisely the same characteristic
that Darwin scribbled in his notes during his 1839 Beagle expedition: Its adaptability
allows it to prosper in more than a dozen distinct climates, from equatorial
mountains slopes that soar 13,000 feet above sea level, to the ocean's edge
in tropical Sri Lanka.
Yet more than a century and a half after Darwin wrote of its impressive adaptability,
scientists and laypersons alike still share the misconception that potatoes
are a cool-climate crop suited only to northern latitudes. The potato's diversity
continues to elude us. Most Americans -- despite our voracious appetites for
potatoes fried, mashed, baked or boiled -- actually are acquainted with only
a handful of the thousands of varieties that thrive in fields and gardens around
the world. We know surprisingly little about potatoes grown beyond our borders
-- or even if we are growing the varieties best adapted to a given climate
Considering the global need for well-adapted, nutritious food crops, underestimating
the power of the potato could be a fatal mistake. That's why scientists and
farmers are working together to preserve the potato's genetic diversity, to
explore its incredible tolerance of climatic differences and to determine which
strains grow best in what regions.
With this in mind, I led a small cluster of researchers to track this quarry
and map the myriad varieties that thrive from Maine to Manila. The knowledge
gained from that effort is important to the future of the crop's cultivation.
One result is the new and better matches between potato varieties and climates.
Another is the rapid introduction, cultivation and migration of potatoes in
developing countries, where inexpensive, wholesome foodstuffs are imperative.
Low-Budget, High-Quality Research
The major research thrust of the International Potato Center is to
collect, preserve and develop the many varieties of the potato, Peru's
national treasure. The fruits of that labor are distributed worldwide,
especially to developing nations that can make quick use of the crop.
However, I soon realized the CIP potato breeding program was flawed. Germ plasm
-- seeds, tubers and other parts that give rise to new plants -- was being
shipped around the world in more or less a shotgun approach rather than according
to concrete information on climatic zones or producers' needs. To fulfill its
mandate, CIP needed a lot more information on potatoes -- their agro-ecological
zones, diseases, pests, markets and types of producers.
Ideally, that information would be logged on a global, computer-aided reference
work that research scientists, agricultural policy makers and farmers could
use to make better-informed decisions.
They soon will have one. The World Geography of the Potato, scheduled
to be published in 1995, includes data on everything from the history of its
introduction in a particular country to how spuds fit into a nation's cuisine.
In short, the book, which also will be available via a computerized, relational
data file, contains almost anything you'd ever want to know about a potato
plus things you'd never even think to ask.
But our potato geography research didn't start with such big aspirations.
In fact, it was pretty "small potatoes" as research projects
go. The project began as a small-scale, low-budget effort, quite literally
with a single
file drawer and a collection of notebooks.
Like most non-profit groups, the center was under the gun from donors and others
to justify its allocations on research programs, so the project initially received
no funding. I started slowly and simply, even though my long-term goal -- to
develop maps of potato production throughout the world -- was ambitious.
The first step was to collect data on the precise conditions under which potatoes
were being grown. Specifically, I needed to know when and where potatoes were
planted and harvested, how they were cultivated, the kinds and severity of
pests and diseases at each location, and post-harvest storage and distribution
Together with my Peruvian assistant, who was permitted to work part-time on
the project, we established the International Potato Reference Files. With
these files, we began to determine where potatoes were being farmed around
the globe and correlate potato cultivation with climate. Later these files
would form the basis of potato cultivation maps.
Despite the official-sounding name, the files were hardly auspicious. Folders
were labeled with names of developing countries known to grow a significant
amount of potatoes -- from Albania to Zimbabwe. These folders then were placed
in the bottom drawer of the only filing cabinet in my office. Our approach
was also low-key because biological scientists and CIP research managers alike
typically regard reference file activity as "just another social scientist
accumulating tons of information with no practical use."
The best way to tackle the problem was to adapt research methods used by anthropologist
George Peter Murdock. In the 1940s Murdock classified and compared the world's
human societies by systematically organizing available information on 330 groups
of people into 700 subject categories -- technology, social patterns, economics,
language, food production, etc. By the early '60s, he was using a computer
to make cross-cultural comparisons and develop original maps for a variety
of crops, including the banana, date palm and sweet potato.
Like Murdock I decided to glean and assimilate information from what is called "gray" literature
-- unpublished or obscurely published materials, literature of sciences outside
the field of agriculture, and knowledge that exists in the heads of scientists
and extension agents who deal with potatoes but who are rarely asked to compile
In our spare time, my assistant and I combed thousands of documents furnished
by Lima libraries. We set up files on 95 developing countries, which grew to
include 130 countries. I also interviewed potato scientists and other visitors
to CIP and added their information to our expanding files.
As I reviewed official government maps of potato production from various countries
and compared them with the gray literature, I realized I could learn much more
than just national statistics on total crop production or average yields. In
just one year our research was paying off: We had gathered a tremendous amount
of information on potato production in developing countries that could be used
internationally to make decisions about crop production.
By this time we had accumulated so much information that we had to augment
our filing system with loose-leaf notebooks. Organized by continent and country,
the notebooks contained categories on the history and trends of potato production;
production zones and climate; production practices such as growing seasons,
seed sources and varieties, and pests and diseases; and post-production information
on storage and processing, distribution, and preparation and consumption.
A Picture of Potato Production
To get a precise understanding of the geography of each agro-ecological
zone and the crops it would support, we translated information from
our bulging reference files to zonal maps. Such maps are instrumental
in calculating which varieties are most likely to flourish in a given
region, based on climate, crop diseases, day length, soil temperatures
and other factors. And they help CIP maximize its world-wide distribution
of germ plasm.
We plotted our data by latitude and longitude on detailed maps that included
provinces, cities and towns, rivers, mountains and other geographical features.
We included information from the hand-drawn, and often crude, maps sketched
for us by potato workers familiar with specific potato zone locations.
Then we double checked areas our maps predicted would be fertile possibilities
for potato cultivation with an "eyeball" modeling approach. Our best
guesses took into account many variables, including elevation, irrigation and
latitude. Additionally, we sought opinions about those best guesses from scientists
who were familiar with the countries in question. We even sent rough maps to
farmers, scientists and extension agents in many countries and asked them to
assess and correct our zonation. We also used descriptive data, such as provincial
census information, to help define and refine the potential potato zones on
By 1987 we were using computers to generate digitized maps of 121 developing
countries -- a further progression of the mapping process. Our maps confirmed
that most climates in developing nations are potentially suitable for potato
The maps, which included latitude and longitude, ecological and climatic zones,
topography, etc., helped us determine precise agro-ecological zones of potato
production and plot sites for trial germ plasm distribution. We could predict
the effects of climate, precipitation, temperature regimes, altitude and disease
patterns on crop production at the continental or international level.
But all this file and map research did more than merely confirm the potato's
amazing adaptability. It helped define it.
For example, we learned that, in developing countries, the potato is produced
in at least 10 distinctly different climates, making it perhaps the most adaptive
of the major food crops. Lowland tropical zones account for nearly half of
the production in these countries. As long as night temperatures fall below
68°F -- a prerequisite for potato plants to produce edible tubers -- potatoes
will grow in such hot, dry climates even when average daily mean temperatures
climb to 86°F.
They can be grown in hot, humid tropical rain forests at mid-elevations of
2,500 to 3,300 feet. Even though it's difficult to grow them in climates with
short dry seasons like those typical of tropical rain forests, CIP has grown
them successfully at Yurimaguas, Peru, which falls into this category.
Additionally, potatoes are easily cultivated in the highlands and temperate
zones, especially northern China and Turkey. New pockets of potato production
are emerging in several warm lowland climates, such as West Africa and the
Caribbean. Although climates of some areas are modified by elevation, farmers
in most areas are using techniques, such as selection of appropriate seasons,
to enhance potato cultivation.
Our research is helping potatoes gain a foothold in many countries where they
are helping feed large populations. The rapid expansion of potato cultivation
in Asia, for example, is the result both of better adapted potato varieties
and of the ability to capitalize on cultivation compatibility between potatoes
and other important crops, especially rice and wheat. Potatoes are easily rotated
with both these crops, since all three grow under similar ecological and climatic
conditions. The Asian potato-cereal food system stretches from the Punjab of
India throughout Southeast Asia into China. The potato now covers more land
and feeds more people in this area than in any other potato production zone
in developing countries.
Researchers and farmers continue to implement production systems and introduce
varieties that flourish in subtropical areas such as the Indo-Gangetic plain,
which has quickly become one of the world's leading potato-producing zones.
Tools of the Trade
Like the humble potato itself, the reference file method will continue to be
an important weapon against hunger. It is easily used to map the cultivation
and spread of any crop or livestock research program, and therefore, ideally
suited to target appropriate technologies to the farmers' and consumers' needs.
In fact, CIP has started a similar reference file on the sweet potato, and
several institutions in the Philippines have started a root crops reference
file. Although the process of gathering and organizing information for a reference
file is slow, the files are easy to update. And they provide a structure to
organize information in a permanent relational database and capitalize on available
information and research.
This research method also can shed light on many other anthropological questions,
such as technological changes, adoption patterns and many more. For example,
the World Geographic Project recently used it to generate precise information
on the migration of the potato around the world from its Andean homeland.
More importantly, the information becomes grist for our technology mills. Despite
an ever-increasing dependency on technology to divine optimal crop strategies,
satellite imagery, remote sensing devices and other sophisticated data systems
just don't work without the data that reference files can provide. Our files
not only were important in developing zonal maps but also they formed the foundation
for the recently completed Geographic Information System for the potato.
Without a doubt though, the most important aspect of this research is its impact
on future farming. By documenting the potato's remarkable versatility, we can
help developing nations set priorities and make agricultural policies that
will help put food on tables now and for generations to come.
And once The World Geography of the Potato is published, anyone will be able
to find out when potatoes first arrived in China or how they are prepared in
Singapore. Though the tome may not be nominated for Book of the Month, it's
not a bad biography for the world's most misunderstood vegetable.
Robert E. Rhoades is head of the anthropology and linguistics department.
In addition to numerous research papers for academic journals, he
has written widely on science topics for the popular press, including
National Geographic. In 1991, he received the Science-in-Society
from the National Association of Science Writers.
Debunking Potato Mythology
by Robert E. Rhoades
At one time or another, it seems, the potato has been blamed
for just about everything -- wars, lust, TB and obesity, to name a
For example, when first introduced into Europe, the potato was cursed
as the food of witches and officially banned. Beliefs developed that
syphilis and rickets, and had aphrodisiac qualities. It's even been said the
word spud is derived from the "Society for the Prevention of an Unwholesome
Diet," a 19th-century activist group dedicated to keeping potatoes out
The potato's popularity may have been hampered, in part, because of its family
tree. A member of the deadly nightshade family, it has many plant cousins that
Resistance to eating potatoes was so strong in some parts of Europe that rulers
who wished to overcome anti-potato sentiments literally had to force potatoes
down their subjects' throats. In 1651, Frederick Will of Prussia issued an
edict threatening to cut off the nose and ears of anyone who refused to plant
potatoes. This didn't work, so his successor, Frederick the Great, allegedly
held an open-air banquet and served potatoes to prove they weren't poisonous.
Although most myths disappeared long ago, one still persists that is potentially
damaging: The potato is a cool climate crop unsuited for cultivation in many
Actually, just the opposite is true. This myth, which may seem innocuous, has
hampered the spread of the potato as a basic food crop for the world's undernourished,
especially in developing nations.
In fact, potatoes are well suited for a variety of climates and countries.
In northern regions potatoes take a minimum of 150 days to attain a maximum
yield, but in tropical areas farmers may begin to harvest in one-third the
time -- a mere 50 days after planting. And farmers in the tropics also may
obtain yields that rival their northern neighbors -- 50 to 60 tons per acre
-- in less than 90 days.
And there's no myth in the potato's supreme value as the world's most important
vegetable crop. Once maligned by the masses, the potato, now grown from Alaska
to the Azores, has invaded the cuisine of more than 130 countries and become
a mainstay in the world's diet.