Investigating sex-biased migration during the Neolithic transition in Europe, using an explicit spatial simulation framework

Abstract

Cultural practices can deeply influence genetic diversity patterns. The Neolithic transitions that took place at different times and locations around the world led to major cultural and demographic changes that influenced and therefore left their marks on human genetic diversity patterns. Several studies on the European Neolithic transition suggest that mitochondrial DNA (mtDNA) and Y-chromosome data can exhibit different patterns, which could be owing to different demographic histories for females and males. Archaeological and anthropological data suggest that the transition from hunter-gatherers (HGs) to farmers' societies is probably associated with changes in social organization, particularly in post-marital residence (PMR) rules (i.e. patrilocality, matrilocality or bilocality). The movements of humans and genes associated with these rules can be seen as sex-biased short-range migrations. We developed a new individual-based simulation approach to explore the genetic consequences of 45 different scenarios, where we varied the patterns of PMR and admixture between HGs and farmers. We recorded mtDNA and Y-chromosome data and analysed their diversity patterns within and between populations, through time and space. We also collected published mtDNA and Y-chromosome data from European and Near-Eastern populations in order to identify the scenarios that would best explain them. We show that: (i) different PMR systems can lead to different patterns of genetic diversity and differentiation, (ii) asymmetries between mtDNA and Y-chromosome can be owing to different behaviours between males and females, but also to different mutations rates, and (iii) patrilocality in farmers explains the present patterns of genetic diversity better than matrilocality or bilocality. Moreover, we found that (iv) the genetic diversity of farmers change depending on the HGs PMR rules even though they are assumed to disappear more than 5000 years ago in our simulations.

Community differentiation and kinship among Europe’s first farmers

“…The pattern among the sexes is quite consistent with marriage within a patrilocal kinship system, which is also consistent with independent archaeological (11,43), genetic (6,18,19,48), anthropological (16,(44)(45)(46), and even new linguistic (49) evidence concerning Neolithic Europe. These results have implications for genetic modeling of Neolithic expansion, for which sex-biased mobility patterns and status differences are increasingly seen as crucial (17)(18)(19)40).…”

“…These results have implications for genetic modeling of Neolithic expansion, for which sex-biased mobility patterns and status differences are increasingly seen as crucial (17)(18)(19)40). Generally speaking, "male inheritance of land means that males tend to live where they were born, while females marry and move elsewhere" (40).…”

“…Because genetic modeling approaches also begin to incorporate sex-biased mobility differences (18,19), there is increasing need for explicit evidence concerning these phenomena more directly.…”

Spatial and Temporal Simulation of Human Evolution. Methods, Frameworks and Applications

“…These simulators can be classified as individual-based or deme-based population modeling (see Table 2 ). In theory, individual-based simulations can be more realistic than deme-based simulators but in practice, a similar performance was observed from both approaches [e.g., 74, 87]. …”

Interview with Laura Fortunato, Winner of the 2011 Gabriel W. Lasker Prize

“…Through analysis of strontium isotopic data, Bentley et al (2012) find evidence of community differentiation and virilocality among the first farmers of early Neolithic central Europe, possibly associated with differential land use. The inference of virilocality is also supported through the analysis of genetic data (Rasteiro et al 2012). This pattern is compatible with the interpretation I propose.…”