Elder and Eldest are for People. The main point stressed by many usage experts is that elder and eldest are used only of persons, while older and oldest can be used of both persons and things:. At the very least, the elder painter was the young man's mentor if not his actual teacher, for he was one of the delegation of two who called on Maria Thins on Vermeer's behalf to ask her to give up her ... More @Wikipedia
Hover over any link to get a description of the article. Please note that search keywords are sometimes hidden within the full article and don't appear in the description or title.