The project aimed at examining the putative correlations between certain genetic features and linguistic markers in various regions of the world, contact situations, and on different scales (dialects vs. languages).
Intuitively, one might assume a correlation between genes and languages because both are passed on from parents to children. When populations disperse their genes and languages tend to become dissimilar. However, after divergence, groups can still be in intensive linguistic or genetic contact, thus becoming similar again. While horizontal transfer of genes is not found in humans, it is actually very common in languages. In these cases, the genetic evidence tells another story than the linguistic evidence. Also migration patterns and residence patterns of females and males vary as well as their social history. This may lead to different patterns in the paternal vs. maternal line.
On the other hand, linguistic features could be non-informative about biological relationships because of a more rapid rate of change and parallel or reverse changes.
Y-chromosomal data and mitochondrial data were used as well as structural and lexical linguistic data to examine correlations between them at a global scale, in smaller geographic areas, and within particular language families.