Given their transmission, surnames behave as alleles at a locus in the Y chromosome, and they also carry linguistic, social, and historic information. We selected a list of 50 Catalan surnames and gathered ~50 men for each of those surnames, for a total sample of 2,550. We typed 17 Y-chromosome STRs and 68 SNPs in those samples, and we addressed the following questions: 1) How are surname frequency and genetic diversity related? The frequency of a surname may be the result of polyphiletism, namely, the fact that it may have been founded multiple times (think of Smith or Jones, John's son); in that case, surname frequency and its internal genetic diversity should be positively correlated. Alternatively, certain surnames may have become more common by natural selection: surnames may be markers of social status, which, quite often, determined survival and fertility. We have found that Catalan surnames follow the first model. 2) Were the carriers of German patronymic surnames of a different genetic origin from the rest of the population? In Catalonia, as in France, a frequent source of surnames is former first names of Germanic origin (Albert, Robert, Grau, etc). We have compared some of those to patronymic surnames of Latin origin (Oriol, Pons, etc), and found that they are not different from each other. 3) Is that also the case for ethnonym surnames? Some Catalan surnames (Alemany, Danés, Anglès, Guasch) denote geographic origin (they mean German, Dane, English, and Gascon, respectively). However, the Alemany or Danès Y chromosomes are much more similar to those of the general Catalan population than to those of Germans or Danes. 4) What is the probability of identifying the surname of the anonymous donor of a biological sample, in a forensic situation? What would be the false positive rate? The answers are 60% and 17%, and we found evidence that false positives may reveal an old surname in the same biological paternal lineage that subsequently changed by false paternity, adoption or transmission of the maternal surname.

Reference article: Neus Solé-Morata, Jaume Bertranpetit, David Comas, and Francesc Calafell:  ^" Y-chromosome diversity in Catalan surname samples: insights into surname origin and frequency". European Journal of Human Genetics, doi:10.1038/ejhg.2015.14

See also the web page of the project: http://cognoms.upf.edu