February 23, 2006

Surnames and Y chromosomes

An interesting surname study shows that the probability of a surname match decreases as the surname frequency increases. In other words, it's quite unlikely that men with a common surname, say "Smith" will share a patrilineal ancestor, but very likely if the surname is rare.

Moreover, surname studies have forensic implications. By studying the Y chromosome it is possible to limit search to a few promising surnames. Of course, catching rapists is a worthwhile cause, but the recent success of an adopted teen to track down his biological father with Y-DNA testing shows, there are more sinister uses of this technology.

Curr Biol. 2006 Feb 21;16(4):384-388.

Genetic Signatures of Coancestry within Surnames.

King TE, Ballereau SJ, Schurer KE, Jobling MA.

Surnames are cultural markers of shared ancestry within human populations. The Y chromosome, like many surnames, is paternally inherited, so men sharing surnames might be expected to share similar Y chromosomes as a signature of coancestry. Such a relationship could be used to connect branches of family trees , to validate population genetic studies based on isonymy , and to predict surname from crime-scene samples in forensics . However, the link may be weak or absent due to multiple independent founders for many names, adoptions, name changes and nonpaternities, and mutation of Y haplotypes. Here, rather than focusing on a single name , we take a general approach by seeking evidence for a link in a sample of 150 randomly ascertained pairs of males who each share a British surname. We show that sharing a surname significantly elevates the probability of sharing a Y-chromosomal haplotype and that this probability increases as surname frequency decreases. Within our sample, we estimate that up to 24% of pairs share recent ancestry and that a large surname-based forensic database might contribute to the intelligence-led investigation of up to approximately 70 rapes and murders per year in the UK. This approach would be applicable to any society that uses patrilineal surnames of reasonable time-depth.


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