Wave-of-Advance Models of the Diffusion of the Y Chromosome Haplogroup R1b1b2 in Europe

Per Sjödin,Olivier François

doi:10.1371/journal.pone.0021592

Abstract

Whether or not the spread of agriculture in Europe was accompanied by movements of people is a long-standing question in archeology and anthropology, which has been frequently addressed with the help of population genetic data. Estimates on dates of expansion and geographic origins obtained from genetic data are however sensitive to the calibration of mutation rates and to the mathematical models used to perform inference. For instance, recent data on the Y chromosome haplogroup R1b1b2 (M269) have either suggested a Neolithic origin for European paternal lineages or a more ancient Paleolithic origin depending on the calibration of Y-STR mutation rates. Here we examine the date of expansion and the geographic origin of hgR1b1b2 considering two current estimates of mutation rates in a total of fourteen realistic wave-of-advance models. We report that a range expansion dating to the Paleolithic is unlikely to explain the observed geographical distribution of microsatellite diversity, and that whether the data is informative with respect to the spread of agriculture in Europe depends on the mutation rate assumption in a critical way.

Highlights

Since the development of molecular markers, genetics has been extensively used to address the question of the diffusion of agriculture into Europe, one of the long-standing debates in archaeology and anthropology [1,2,3]
We used nine microsatellite markers from 840 European Ychromosomes typed from hgR1b1b2 (R-M269), a common haplogroup in Europe [15]
To test whether similar levels of allelic richness could be reproduced by the 14 wave-of-advance models, genetic variation was simulated at 1,000 microsatellite loci under each model (Figure 1)

Summary

Introduction

In 1971, a seminal work by Ammerman and Cavalli-Sforza used radiocarbon dates from Neolithic sites to propose a ‘‘wave-of-advance’’ model of the spread of agriculture in Europe In this ‘‘demic’’ process, local population growth and migration produce demographic expansion following a traveling wave from the southeast to the northwest of Europe [5]. Several archaeologists have hypothesized a cultural model of the development of agriculture, where cultivated plants, domesticated animals and the associated agricultural techniques were adopted with only limited human movements [3,8]. According to this ‘‘cultural’’ model, the Neolithic farmers did not migrate. The prehistory of European populations is poorly understood, and the debate between the demic and cultural diffusion models is still active today

Methods

Results

Conclusion