Final answer:
Chief Joseph became chief following his father due to hereditary succession, making him the hereditary ruler of the Nez Perce tribe.
Step-by-step explanation:
Chief Joseph followed his father as chief because he was the hereditary ruler. In the political structure of Plains groups, chiefs and councils were common. Although there were distinctions between war chiefs and peace chiefs, leadership positions were often passed down through hereditary succession. Chief Joseph was a leader of the Nez Perce tribe (Niimiipuu) who resisted the forcible relocation from their lands in the Wallowa River Valley of Oregon. Despite his later actions which might imply he favored peace, his initial ascent to leadership was due to the fact that he was the hereditary ruler after his father.