Despite concerns by some groups about the safety and environmental impact of these new products, genetically engineered foods are cautiously building increased market presence. In plants or animals, DNA directs the production of proteins, which make up physical structure and determine physical traits, such as hair and eye color. Gene alteration is as old as genes themselves. Random changes in plant or animal DNA are nature's way of allowing life to evolve. Genetic variations may lead to a stronger plant or animal, which will survive to reproduce and pass its genes onto its offspring.
Humans participate in the process by selectively breeding for specific desirable traits.
All genes, plant or animal, are made up of the same basic units in different arrangements, so scientists can replace a gene with one from a different plant or even an animal. This speeds evolution because the change is rapid and predictable. Des Moines' Pioneer Hi-Bred produces grain products, such as corn with the Bt gene, which helps it resist the European corn borer with fewer pesticides. She says most of Pioneer's crops don't go to consumers. More than 80 percent of the corn and almost all of the soybeans are used in livestock feed.