The Japan Times
June 18, 2001
Newsday

Last kernel of doubt is removed about 'ancestry' of corn

NEW YORK - A very long and bitter scientific feud over one of the world's most important food crops, ordinary corn, has finally been resolved, scientists report.

Now they know, approximately, where corn came from.

Although most people don't fret much over where and how corn originated, among archaeologists and plant experts the history of maize has been an important, longstanding and contentious mystery. But recent discoveries based on gene-reading technology have finally ended this often rancorous conflict.

The verdict: Corn's direct ancestor is a weedy type of grass called teosinte. It can still be found growing wild in remote areas of Mexico, and its genes are clearly ancestral to corn's.

The argument bubbled and boiled for more than half a century, with one camp arguing in teosinte's favor, bucking a tide of criticism and ridicule stirred up by a Harvard-based team of researchers.

These opponents at Harvard, whose word had become gospel through the 1940s, '50s, '60s and '70s, argued that corn's ancestor had to be something other than teosinte.

They had found old samples of primitive corncobs and pollen in remote Mexican caves, and concluded they were very early versions of domesticated corn, maybe 7,000 or more years old.

This popular scenario held that an important early ancestor of modern corn must have been a very primitive corn plant, probably one that had disappeared into extinction, never to be found. In other words, corn was corn, not an offspring of teosinte.

For agriculture, the outcome of this argument is important. Today's corn breeders, for example, need to study corn's ancient ancestors in search of additional genes that might improve hardiness, drought resistance and disease resistance. Such genes, if they exist, most likely hide in corn's ancient progenitors.

Recently, the art of genetic testing — DNA fingerprinting — has shown rather clearly that teosinte is the ancient forebear of modern corn. So scientists think it's probable that people living in southern Mexico and Central America began harvesting grains from wild teosinte about 10,000 years ago.

Then, after learning to plant and nurture teosinte, early farmers kept on selecting better and better mutants. With each harvest, they chose the next crop's seeds from plants that were the most productive, easiest to thresh and hardiest.

That's how teosinte, along with squash, beans and sunflower seeds, eventually became a mainstay in the diet. Americans call it corn, but most people elsewhere allude to it as maize.

These ancient crops corn, beans, squash and sunflowers - played a central role in the foundation of agriculture in the Western Hemisphere, parallel to the emergence of agriculture using different crops, such as wheat, in the Middle East.