 A population geneticist by training, Barbujani has been working on several aspects of human genetic variation.In collaboration with Robert R. Sokal, he pioneered the statistical comparison of patterns of genetic and linguistic variation, showing that language differences may contribute to reproductive isolation, and hence promote genetic divergence between populations.His analyses of geographic patterns of genetic variation in Europe support Luca Cavalli-Sforza's Neolithic demic diffusion model, or the idea that farming spread in the Neolithic mainly because farmers did, and not by cultural transmission.