“The defining aspect of a Scottish clan is the Clan Chief. In the system of ancient Gaelic tanistry, these chiefs were elected by family heads in full assembly. In the 21st century, however, becoming chief has become a much more complex process.”
Quoted from “Becoming Chief: The State of Scottish Chiefship in the 21st Century”, the blog post by the Council of Scottish Clans & Associations traces the history and evolution of the role of the Clan Chief. Clan MacAulay Chief Joan is one of the chiefs featured in the article.