Isonymy and isolation by distance in Germany

Area of Science:

• Population Genetics
• Human Geography
• Computational Linguistics

Background:

• Isonymy, the use of identical surnames, can reflect population structure and historical migration patterns.
• Understanding surname distribution aids in studying genetic relatedness and geographic isolation within populations.

Purpose of the Study:

• To analyze the isonymy structure of Germany using surname data.
• To investigate the relationship between geographic distance and surname similarity.
• To explore correlations between isonymy clusters and German linguistic regions.

Main Methods:

• Utilized a dataset of 5,150,310 private telephone users from 1996.
• Selected 106 towns across Germany based on a geographic grid system.
• Calculated Lasker's distance to quantify isonymy between localities and constructed a dendrogram using UPGMA.

Main Results:

• A significant linear correlation was found between Lasker's distance and geographic distance (r = 0.51).
• The analysis revealed two primary isonymy clusters corresponding to northern and southern Germany, aligning with major linguistic divisions.
• Subclusters were identified within these main clusters, reflecting finer linguistic and geographic variations. Eastern Germany showed higher estimated inbreeding than western Germany.

Conclusions:

• Germany exhibits a relatively homogeneous isonymy structure with clear "isolation by distance" effects, though less pronounced than in Switzerland.
• The observed surname clusters strongly correlate with historical German sublanguage distributions.
• Isonymy analysis provides insights into population structure, historical relationships, and regional differences in Germany.