The Origins of the Royal Spanish Surname Castilla: Genetics and Genealogy

Abstract

In most Western European societies, surnames pass from generation to generation and in cases where surnames are shared by fathers to children, the Y chromosome passes down from fathers to male offspring in the same way as surnames do. The aim of this study was to ascertain the patrilineal relationship between individuals with the surname “Castilla” and their respective Y-chromosome haplotypes. The toponymic surname “Castilla” is part of the Spanish royal family. Genealogical studies of this surname have allowed the formulation of different hypotheses about its origin, most of which were centered in Burgos. To shed some light on the origin of the surname Castilla and to investigate the possible co-ancestry behind the living carriers of this surname, markers located in the Y chromosome-specific region were analyzed in a sample of 102 men whose paternal surname was Castilla. The study aimed to establish the minimum number of founders and the expansion time of the lineages from our sample. Two major haplogroups were identified: R1b and E1b1b-M81. The high frequency of the E1b1b-M81 haplogroup in comparison to that of the general Spanish population, its low haplotype diversity, and its young TMRCA (323+/− 255 years CE) are compatible with the historical timing of the obligation to use surnames. However, the coincidence of the most common haplogroup in the Castilla sample and the most frequent haplogroup in the Spanish general population, R1b, makes it difficult to identify founder haplotypes/haplogroups in the history of the Castilla surname.

Genetic Diversity Based on Human Y Chromosome Analysis: A Bibliometric Review Between 2014 and 2023

“…The genealogical and genetic origins of the Spanish regal surname "Castilla" were the subject of the most recent investigation studied in Spain [ 35 ]. The study group consisted of participants having the surname "Castilla" along with their corresponding Y chromosome haplotypes.…”

“…In the red cluster, the most common word is "population," which appears in the forms "Population structure" and "population/s." In this cluster, the most powerful laws are between diversity-Y chromosome (power 41) and diversity-history (potency 36) but there are also strong laws between mitochondrial DNA and diversity (35), suggesting that many studies analyze both Y chromosome and mitochondrial DNA to evaluate genetic diversity or population expansions, highlighting a common concern for understanding the evolution and genetic structure of different population groups.…”