Final answer:
Buffalo chips were used as a fuel source for fires on the plains due to the scarcity of wood, aiding in cooking, warmth, tool creation, and promoting social unity.
Step-by-step explanation:
People used buffalo chips for fire because in the vast plains regions, where trees were often scarce, dried buffalo dung or 'buffalo chips' were available in abundance and made an excellent source of fuel. Controlled fires had many uses, such as staying warm in cold climates, scaring off predators, and cooking meat to make it more digestible, which was essential for the growth of the human brain and social development. Moreover, fire enabled early humans to craft tools and gather around campfires for social functions, leading to stronger community bonds and possibly even artistic expression.