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Intrigued by the idea that images of the corn on the ancient Zapotec
urns could constitute visions of past agriculture, she tracked
down Paul Mangelsdorf, a botanist who had retired from Harvard
University and was teaching part time at the University of North
Carolina at Chapel Hill. Mangelsdorf, she had learned, was involved
in a botanical archaeology project in Mexico. "When I walked
in and told him what I was interested in, he said, 'You're just
the student I have been looking for for years and could never find
at Harvard.' "
Mangelsdorf was interested in exploring the corn images on the
Zapotec urns as a possible archaeological treasure trove for understanding
the origins of corn. Eubanks traveled to Oaxaca to study the urns
as botanical artifacts--an effort that meant she had to learn botany,
as well. "So, very early I was getting into interdisciplinary
research between two widely divergent fields--the natural sciences
and the social sciences," she says. "And it was difficult
managing my dissertation committee, because members literally didn't
understand how to talk to each other."
Following this initial exploration, Eubanks says that her study
of the origins of corn "went dormant," although she continued
to publish and teach on archaeological and anthropological subjects.
Then she was reunited with Mangelsdorf, oddly enough, by way of
a door knocker. Earlier, as she was finishing her Ph.D., Eubanks
had come across a handsome, bronze door knocker decorated with
cast ears of corn. She bought one for herself and gave one to her
mentor.
Years later, when Mangelsdorf moved out of his house and into an
apartment in Chapel Hill, he had to leave the door knocker behind.
Missing his trademark decoration, he contacted Eubanks to ask where
he could find another. "I didn't know where to get them, so
I just took the door knocker off my door and mailed it to him," she
says. "He was pretty flabbergasted, I guess, and we reconnected.
When I visited him, I got interested in a new hypothesis he was
testing in the laboratory--that modern corn originated from a cross
between a primitive corn and a rare perennial teosinte that had
just been discovered in Mexico." Eubanks readily learned the
necessary laboratory techniques and began to explore the details
of the chromosomes of the rare plant.
She found that when she crossed the teosinte with corn, the number
and position of characteristic "knobs" on the chromosomes
of the resulting plants did not square with the theory that corn
had arisen from teosinte. "We were seeing amplification and
transposition of chromosome knobs that were definitely against
dogma and very exciting and interesting," she says.
At this point, Eubanks, who was going through a divorce and had
small children, was fruitlessly applying for tenure-track jobs
in anthropology. "It was 1984, and although I got on the short
list of all the best jobs, a woman was not hired for any of the
job openings in anthropology that year," she says. When Mangelsdorf
recommended her to corn cytogeneticist Marcus Rhodes for a postdoctoral
fellowship at Indiana University, she jumped at the chance. There,
as she studied in more detail the chromosomes of teosinte-corn
crosses, she encountered another "accident." In the experiment
station where she worked, a former student had left a collection
of gamagrass plants, Tripsacum. Eubanks began to examine the chromosomes
of this grass under her microscope. "It was very clear to
me that the architecture of the perennial teosinte chromosomes,
which was quite different from the other Zeas, was very similar
to Tripsacum."
That discovery launched Eubanks on an effort to produce hybrids
by cross-pollinating teosinte and gamagrass. To the utter surprise
and delight of Eubanks and her colleagues, the recombinant plants
not only grew and flowered but also "produced little ears,
and the little ears looked a lot like the oldest archeological
ears." Further studies showed that when she crossed the teosinte-gamagrass
recombinants with corn, the hybrids were both drought-resistant
and resistant to rootworm, a major corn pest.
Eubanks says she believes that one key to the hybrids' hardiness
is their root system, which is more extensive than that of modern
corn strains. The roots of the plants she developed reach deeper
into the soil to draw up moisture, she theorizes. In addition,
the roots of her strains possess hollow chambers called "aerenchyma" that
carry oxygen into even the most compacted soils. The aerenchyma
also render the roots distinctly unfriendly to pests. "If
you compare these roots to regular corn roots that do not have
aerenchyma and are filled with lots of wonderful tissue for the
bugs to feed on, you realize there is nothing in the roots of hybrid
plants for the larvae to eat," says Eubanks. "They just
don't get much nutrient when they feed on the roots. In fact, in
our earliest experiments when we recovered larvae and weighed them,
there were fewer, much smaller larvae coming off the recombinant
corn plants by comparison with the extensive populations of healthy
larvae that were twice as large coming off the corn control plants."
"Clearly, these plants are different," Eubanks says of
her teosinte-gamagrass-recombinant strains. "They are perennial,
so you don't have to grow them from seed. You just stick a cutting
in the ground like a begonia, and it will root. And they can tolerate
severe drought, acid soils, and even swamps. If, indeed, natural
recombinants were involved in the domestication of corn, it could
dramatically shift the paradigm of where and how corn originated." That "unshifted" paradigm
holds that only teosinte was the ancestor of modern corn and not
some oddball cross between teosinte and gamagrass.
Despite her successes, Eubanks' research continued to be called
into question, with other researchers expressing doubts that her
plants were true teosinte-Tripsacum crosses, even though she had
solid DNA fingerprinting data proving the crosses.
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