The other day my great-uncle Alfred gave me a handful of the year's green beans, dried and ready for planting next summer. "Give them something high up to grow on," he told me. "They'll grow seven feet tall."

Alfred knows. He's planted this variety in his garden for seven years now, every year saving a bit of his harvest for the next year's seed. And for good reason: This variety is resistant to a common garden pest known as the black aphid. As green beans go, this is a true garden-variety green bean. Its flat pod is delicate and tender, its fresh taste sublime in a salad. The pulpy beans in the produce aisle of your supermarket -- more roadworthy than table-ready -- are a distant relative at best.

Alfred's green beans have a history that goes back 60 years. That's when his neighbors settled in the Seattle, Wash., neighborhood where he still lives. They were Greek immigrants, and a satchel of seeds was tucked in the luggage they carried. These beans had come from the old country, a place where vegetables are precious, almost like gems -- never just commodities to be bought and sold.

Like his Greek neighbors, Uncle Alfred saves seed every year. As a kid on the farm, this is how Alfred learned to prepare for the coming year: You save the best of the crop. It's natural, like breathing. In Guatemala, Mayan subsistence farmers hang next year's seed, the most perfect ears of yellow, white and blue corn, from the beams of their adobe homes.

On the Great Plains, farmers fill 10,000 bushel-silos with saved seed. And in a quiet Seattle neighborhood, Uncle Alfred keeps a 60-year-old neighborhood tradition alive by saving a few strings of beans for next year's garden.

Every seed contains a genetic signature -- Alfred's green beans included -- that does not belong to anyone. This signature is as public as the air we breathe. Yet recently, U.S. companies such as Monsanto have won permission to patent the genetic signatures contained within their genetically engineered seeds. In this way, business is now selling what has never before been up for sale. It's changing the way we grow our food.

Private ownership comes at a price that the well-oiled public relations machine of the biotech industry neglects to tell us. What's at risk is the millennia-old practice of saving seed. That's because when farmers plant genetically-engineered crops such as corn and soybeans, they are no longer allowed to put aside the best of their crop for next year.

Put another way, if Uncle Alfred's green beans were an engineered variety, he'd be breaking the law by saving them.

The patented plants we're talking about boast some unusual characteristics that border on science fiction. The leaves of the new Monsanto corn contain a bacteria that wards off insect pests. It's considered a plant that packs its own pesticide. What's worrisome about these genetically engineered varieties of corn is that their sci-fi abilities can spread to other plants. This means that this so-called "terminator technology" could end up in a neighbor's crop, and in the era of globalization, your neighbor doesn't necessarily live next door. Genetically engineered corn has appeared in the crops of subsistence farmers in Oaxaca, Mexico, though nobody knows how it got there.

The new technology has tipped the cart of the world's farmers. "All of the traditional varieties could be lost," says seed collector Kent Whealy. "Genetic contamination means that Monsanto could control all the seed a farmer could save."

He ought to know. For more than 20 years, he has run the Iowa-based Seed Savers Exchange, a nonprofit group with a collection of more than 20,000 varieties of heirloom seeds. By collecting these varieties, Seed Savers hopes to preserve seeds that could otherwise go extinct as manipulated varieties spread.

Whealy says there is something consumers can do. We can follow the lead of the European Union and ask decision-makers in Washington, D.C., to require the labeling of all foods containing engineered ingredients. We can also press food companies to stop including genetically engineered ingredients in their products.

It's time to act: Our supermarket shelves are already full of genetically engineered ingredients while the jury is still out on what's safe to eat. Labeling genetically engineered foods is a step towards educating consumers about what they're feeding their families, and how corporate agriculture is changing the way we grow our food.

Dustin Solberg is a contributor to Writers on the Range, a service of High Country News in Paonia, Colorado (hcn.org). He is a Westerner temporarily living in Decatur, Georgia.