A 2006 study by Seldin et al. used over five thousand autosomal SNPs to demonstrate European genetic substructure. The results showed "a consistent and reproducible distinction between 'northern' and 'southern' European population groups". Most northern, central, and eastern Europeans (Finns, Swedes, English, Irish, Germans, and Ukrainians) showed >90% in the "northern" population group, while most individual participants with southern European ancestry (Italians, Greeks, Portuguese, Spaniards) showed >85% in the "southern" group. Both Ashkenazi Jews as well as Sephardic Jews showed >85% membership in the "southern" group. Referring to the Jews clustering with southern Europeans, the authors state the results were "consistent with a later Mediterranean origin of these ethnic groups".

In a 2006 study, how many autosomal SNPs were used?