There is also an accompanying commentary paper by Jobling of the paper below. I haven't read either yet, but will post more on this soon.
From Social to Genetic Structures in Central Asia
Current Biology, Vol 17, 43-48, 09 January 2007
Raphaëlle Chaix, Lluís Quintana-Murci, Tatyana Hegay, Michael F. Hammer, Zahra Mobasher, Frédéric Austerlitz, and Evelyne Heyer
Abstract: Pastoral and farmer populations, who have coexisted in Central Asia since the fourth millennium B.C. , present not only different lifestyles and means of subsistence but also various types of social organization. Pastoral populations are organized into so-called descent groups (tribes, clans, and lineages) and practice exogamous marriages (a man chooses a bride in a different lineage or clan). In Central Asia, these descent groups are patrilineal: The children are systematically affiliated with the descent groups of the father. By contrast, farmer populations are organized into families (extended or nuclear) and often establish endogamous marriages with cousins [2, 3, 4]. This study aims at better understanding the impact of these differences in lifestyle and social organization on the shaping of genetic diversity. We show that pastoral populations exhibit a substantial loss of Y chromosome diversity in comparison to farmers but that no such a difference is observed at the mitochondrial-DNA level. Our analyses indicate that the dynamics of patrilineal descent groups, which implies different male and female sociodemographic histories, is responsible for these sexually-asymmetric genetic patterns. This molecular signature of the pastoral social organization disappears over a few centuries only after conversion to an agricultural way of life.