HENRY

One of the most important questions in evolutionary biology today is how closely are genes and cultures linked. A new study in the latest issue of Molecular Biology and Evolution compares genetics and a heritable cultural marker: surnames. Just like Y chomosomes, surnames are (or were) paternally inherited, and should be strong markers of father-son descent patterns.

In particular, the authors were interested in the surnames left behind after the Viking raids and subsequent settlement of England around 1200 years ago. This ~200 year influx had a major influence on English history and culture (e.g. Danelaw). This is also demonstrated by the prevalence of Scandinavian placenames in the region (such as names ending in -thorpe or -by).

To do this, the authors compiled a list of 236 surnames from multiple sources including a 1545 survey of all the households during the reign of Henry VIII court proceedings records dating from 1353, and ale-house licensing records from 1572 (Aside: the fact that these records were considered so important to be kept for hundreds of years tells you a lot about the English!).

Then, the authors sampled Y chromosome data from individuals in two regions (West Lancashire and Wirral). Using the surnames, they could then divide this sample into two. People with surnames NOT present in the historical data were placed in a group called “modern”, whilst people with surnames - such as Brown - found in the records dating back 500 years were grouped as a “medieval” sample.

Their results show a strong difference between the “modern” and “medieval” samples. The “medieval” samples had much higher genetic diversity, which suggests that the “modern” families had undergone some level of homogenisation, possibly due to immigration from populations with low genetic diversity. Unsurprisingly, the “medieval” samples also showed a higher proportion of haplotypes with a Scandinavian origin.

Open Access PDF: Excavating Past Population Structures by Surname-based Sampling: the Genetic Legacy of the Vikings in Northwest England.

The abstract:

The genetic structures of past human populations are obscured by recent migrations and expansions, and can been observed only indirectly by inference from modern samples. However, the unique link between a heritable cultural marker, the patrilineal surname, and a genetic marker, the Y chromosome, provides a means to target sets of modern individuals that might resemble populations at the time of surname establishment. As a test case, we studied samples from the Wirral peninsula and West Lancashire, in northwest England. Place names and archaeology show clear evidence of a past Viking presence, but heavy immigration and population growth since the Industrial Revolution are likely to have weakened the genetic signal of a thousand-year-old Scandinavian contribution. Samples ascertained on the basis of two generations of residence were compared with independent samples based on known ancestry in the region, plus the possession of a surname known from historical records to have been present there in medieval times. The Y-chromosomal haplotypes of these two sets of samples are significantly different, and in admixture analyses the surname-ascertained samples show markedly greater Scandinavian ancestry proportions, supporting the idea that northwest England was once heavily populated by Scandinavian settlers. The method of historical surname-based ascertainment promises to allow investigation of the influence of migration and drift over the last few centuries in changing the population structure of Britain, and will have general utility in other regions where surnames are patrilineal and suitable historical records survive.

Wang et al in PloS Genetics:

We examined genetic diversity and population structure in the American landmass using 678 autosomal microsatellite markers genotyped in 422 individuals representing 24 Native American populations sampled from North, Central, and South America. These data were analyzed jointly with similar data available in 54 other indigenous populations worldwide, including an additional five Native American groups.

The Native American populations have lower genetic diversity and greater differentiation than populations from other continental regions. We observe gradients both of decreasing genetic diversity as a function of geographic distance from the Bering Strait and of decreasing genetic similarity to Siberians—signals of the southward dispersal of human populations from the northwestern tip of the Americas.

We also observe evidence of: (1) a higher level of diversity and lower level of population structure in western South America compared to eastern South America, (2) a relative lack of differentiation between Mesoamerican and Andean populations, (3) a scenario in which coastal routes were easier for migrating peoples to traverse in comparison with inland routes, and (4) a partial agreement on a local scale between genetic similarity and the linguistic classification of populations. These findings offer new insights into the process of population dispersal and differentiation during the peopling of the Americas.

The full paper’s available at PLoS Genetics, and alternate coverage here.