Final answer:
Most domesticated grains have a tougher axis and more brittle husk due to selective cultivation by early farmers, who favored these traits for ease of harvest and processing. This domestication was part of a larger shift to agriculture, which significantly altered human lifestyles and economies. Innovation in grain breeding, such as by Norman Borlaug, has further advanced the efficiency and yield of domesticated crops like wheat.
Step-by-step explanation:
Most domesticated grains like wheat and barley have a tougher axis and more brittle husk than wild grains due to the process of domestication. Early farmers selected plants that had desirable traits, which included a strong axis for easier harvest and a brittle husk for more efficient threshing and processing. Over generations of selective cultivation, these traits became more pronounced in domesticated grains compared to their wild counterparts. This domestication process was part of the rise of agriculture, which transformed human societies by turning people into active cultivators of crops like wheat and barley, rather than just foragers.
Domesticated grains thrived in disturbed habitats created by human activity, which likely facilitated their domestication. Additionally, the success of wheat due to human intervention—such as removing rocks and pests from fields—highlights the symbiosis between humans and certain crops, raising the question of whether wheat domesticated humans as much as they domesticated wheat. American grain production, heavily subsidized and mechanized, has influenced global agricultural economy and policies, as seen with wheat being a significant export and subject in international trade discussions.
Norman Borlaug's development of hybrid wheat that resisted stem rust and did not grow too tall when fertilized revolutionized wheat farming in Mexico, increasing yields significantly. This is an example of how human innovation has continued to refine and improve domesticated grain species. Lastly, the importance of grasses as a major source of food for humans is highlighted by the continued evolution and cultivation of grass seeds, including domesticated grains.