The first ahnentafel, published by Michaël Eytzinger in Thesaurus principum hac aetate in Europa viventium Cologne: 1590, pp. 146–147, in which Eytzinger first illustrates his new functional theory of numeration of ancestors; this schema showing Henry III of France as n° 1, de cujus, with his ancestors in five generations. The remainder of the volume shows 34 additional schemas for rulers and princes of Europe using his new method.Seize quartierscoat of arms display document (1786)
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.
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;[1] 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;[2] 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.[3]
"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.
Inductive reckoning
To find out what someone's number would be without compiling a list, one must first trace how they relate back to the subject or person of interest, meaning that one determines for example that some ancestor is the subject's father's mother's mother's father's father. Once one has done that, one can use two methods.
First method
Use the definition that a father's number will be twice that individual's number, or a mother's will be twice plus one, and just multiply and add 1 accordingly. For instance, someone can find out what number Sophia of Hanover would be on an ahnentafel of Peter Phillips (son of Princess Anne and grandson of Elizabeth II). Sophia is Phillips's mother's mother's father's father's father's mother's father's father's father's father's father's mother. So, we multiply and add:
Write down the digit "1", which represents the subject, then from left to right write "0" for each father and "1" for each mother in the relation, ending with the ancestor of interest. The result will be the binary representation of the ancestor's ahnentafel number. Then convert the binary number to decimal form. Using the Sophia example:
We can also work in reverse to find what the relation is from the number.
Reverse first method
One starts out by seeing if the number is odd or even.
If it is odd, the last part of the relation is "mother", so subtract 1 and divide by 2.
If it is even, the last part is "father", and one divides by 2.
Repeat steps 2–3, and build back from the last word.
Once one gets to 1, one is done.
On an ahnentafel of Prince William, John Wark is number 116. We follow the steps:
116/2 = 58
58/2 = 29
29 − 1 = 28 and 28/2 = 14
14/2 = 7
7 − 1 = 6 and 6/2 = 3
3 − 1 = 2 and 2/2 = 1
father
father
mother
father
mother
mother
We reverse that, and we get that #116, John Wark, is Prince William's mother's mother's father's mother's father's father.
Reverse second method
1. Convert the ahnentafel number from decimal to binary, then replace the leftmost "1" with the subject's name and replace each following "0" and "1" with "father" and "mother" respectively.
The generation number can be calculated as the logarithm to base 2 of the ahnentafel number, and rounding down to a full integer by truncating decimal digits.
For example, the number 38 is between 25=32 and 26=64, so log2(38) is between 5 and 6. This means that ancestor no.38 belongs to generation five, and was a great-great-great-grandparent of the reference person who is no.1 (generation zero).
Example
The example, shown below, is an ahnentafel of the Prince of Wales, listing all of his ancestors up to his fourth great-grandparents.
122. William Smith Marr (27 November 1810 – 13 February 1898)
123. Helen Bean (1814/5 – 20 July 1852)
31. Ruth Littlejohn (4 December 1879 – 24 August 1964)
62. David Littlejohn (3 April 1841 – 11 May 1924)
124. William Littlejohn (12 August 1803 – 8 July 1888)
125. Janet Bentley (26 January 1811 – 1 October 1848)
63. Jane Crombie (died 19 September 1917)
126. James Crombie (13 January 1810 – 31 January 1878)
127. Katharine Forbes (1 December 1812 – 10 April 1893)
Multiple numbers for the same person
An ancestor may have two or more numbers due to pedigree collapse. For example, in the above Ahnentafel for Prince William, Queen Victoria is both no.79 and no.81. She is no.79 because she was the great-great-grandmother of William's grandfather Prince Philip, and she is also no.81 because she was the great-great-grandmother of William's grandmother Queen Elizabeth II. The relationships are easier to follow using the ancestry tree with ahnentafel numbering.
European nobility took pride in displaying their descent. In the German language, the term Ahnentafel may refer to a list of coats of arms and names of one's ancestors, even when it does not follow the numbered tabular representation given above. In this case, the German "Tafel" is taken literally to be a physical "display board" instead of an abstract scheme.
In Nazi Germany, the Law for the Restoration of the Professional Civil Service required a person to prove non-Jewish ancestry with an Ariernachweis (Aryan certificate). The certificate could take the form of entries in the permanent Ahnenpass (that was sorted according to the ahnentafel numbering system) or as entries in a singular Arierschein (Aryan attestation) that was titled "Ahnentafel".
^Eytzinger, Michael, Thesaurus principum hac aetate in Europa viventium, quo progenitores eorum... simul ac fratres et sonores inde ab origine reconduntur... usque ad annum..., Cologne: G. Kempensem, 1590 (1591). Note: In commentaries, his surname may appear in variant forms, including: Aitsingeri, Aitsingero, Aitsingerum, Eyzingern.
^Kekulé von Stradonitz, Stephan, Ahnentafel-atlas. Ahnentafeln zu 32 Ahnen der Regenten Europas und ihrer Gemahlinnen, Berlin: J. A. Stargardt, 1898–1904. This volume contains 79 charts of the sovereigns of Europe and their wives.
