Ancestor Table

“An ahnentafel (German for ‘ancestor table’; German: [ˈʔaːnənˌtaːfəl]) or ahnenreihe (‘ancestor series’; German: [ˈʔaːnənˌʁaɪə]) is a genealogical numbering system for listing a person’s direct ancestors in a fixed sequence of ascent. The subject (or proband) of the ahnentafel is listed as No. 1, the subject’s father as No. 2 and the mother as No. 3, the paternal grandparents as No. 4 and No. 5 and the maternal grandparents as No. 6 and No. 7, and so on, back through the generations. Apart from No. 1, who can be male or female, all even-numbered persons are male, and all odd-numbered persons are female. In this schema, the number of any person’s father is double the person’s number, and a person’s mother is double the person’s number plus one. Using this definition of numeration, one can derive some basic information about individuals who are listed without additional research.

This construct displays a person’s genealogy compactly, without the need for a diagram such as a family tree. It is particularly useful in situations where one may be restricted to presenting a genealogy in plain text, for example, in emails or newsgroup articles. In effect, an ahnentafel is a method for storing a binary tree in an array by listing the nodes (individuals) in level-order (in generation order).

The ahnentafel system of numeration is also known as the Eytzinger Method, for Michaël Eytzinger, the Austrian-born historian who first published the principles of the system in 1590; the [[Sosa]] Method, named for Jerónimo (Jerome) de Sosa, the Spanish genealogist who popularized the numbering system in his work Noticia de la gran casa de los marqueses de Villafranca in 1676; and the Sosa–Stradonitz Method, for Stephan Kekulé von Stradonitz, the genealogist and son of chemist Friedrich August Kekulé, who published his interpretation of Sosa’s method in his Ahnentafel-atlas in 1898.

‘Ahnentafel’ is a loan word from the German language, and its German equivalents are Ahnenreihe and Ahnenliste. An ahnentafel list is sometimes called a ‘Kekulé’ after Stephan Kekulé von Stradonitz. A variant of is known in French as Seize Quartiers.”