Final answer:
The modern crop derived from selectively breeding teosinte is maize (corn), which was genetically modified thousands of years ago by indigenous people in what is now Mexico. They selected for traits that improved the crop's yield and ease of use, resulting in significant morphological changes and the creation of a staple food source.
Step-by-step explanation:
The modern crop that is a result of selectively breeding the wild grass called teosinte is maize (corn). Thousands of years ago, indigenous people of what is now Mexico began the process of transforming teosinte – a plant with a substantially different morphology to maize – into the staple crop we recognize today. Selective breeding focused on enhancing desirable traits such as larger ears and seeds that were not encased in rigid structures which allowed easier access to edible parts, leading to the evolution of modern corn.The transformation of teosinte into maize represents one of the earliest and most significant examples of genetic modification by humans. Over generations, early farmers selected plants with favorable characteristics, like more fruits and easier to open structures, leading to the domesticated corn variety that is now a major agricultural crop globally. This genetic relationship, though once obscured by morphological differences, has been clarified through the study of developmental genes that show how fewer than ten gene changes can result in significant alterations in plant structure.Considering the historical significance of corn and its deep-rooted genetic ties to teosinte, it opens up discussions about the nature of traditional agricultural practices and what it means to have a genetically modified organism (GMO), especially in the case of crops that have been altered by humans thousands of years prior to modern genetic engineering techniques.