Final answer:
The Plains Indians' staple food source was the bison. This animal was essential for nourishment and provided materials for clothing, shelter, and tools. Bison hunting practices evolved significantly after the reintroduction of the horse, leading to changes in the Plains Indians' way of life.
Step-by-step explanation:
The staple food source of the Plains Indians was the bison, which was central to their diet and way of life. Following European contact and the reintroduction of the horse to North America, many Plains Indian tribes, such as the Sioux, transformed from agriculturalists to nomadic hunter-gatherers who relied heavily on the bison. They used the bison not only for food but also for clothing, shelter, and tools, making it the backbone of their culture and sustenance.
In addition to bison, the Plains Indians hunted other game such as antelope, deer, and small animals. They also gathered edible plants like seeds, berries, nuts, acorns, and tubers, which varied by region and season. The use of horses enabled them to follow the great bison herds more efficiently, transforming their hunting practices and mobility.
The Plains Wars and other historical events such as the near extermination of the bison herds had significant impacts on the Plains peoples, leading to changes in their lifestyle and ultimately to their confinement on reservations. Despite these challenges, the bison remains a symbolic and historical figure in Plains Indian culture.