Even the most ardent supporters of the use of genetic modification would admit one potentially troubling fact about the technique: It's very new. Though genetically modified organisms have become ubiquitous on farms across the world, especially in the United States, they only became available for commercial use in the '90s. Many critics of GMOs (and modern agriculture more broadly) argue that returning to the agricultural practices that sustained human life for the thousands of years before their advent would be the best course of action.