Treetops are a concept in the genealogy software, Reunion 9 for Mac. The term refers to the earliest known ancestor of a given person. They are useful for locating and quickly navigating to brick walls and ancestors on which to focus research. It is also a handy way to move to likely targets for a descendant report or chart. This screencast video from the MacGenealogist Archives, Treetops in Macintosh Genealogy Software Reunion 9 for Mac , demonstrates the use of the treetops feature.