In this work we focus on a microsatellite-defined Y-chromosomal lineage (network 1.2) identified
by us and reported in previous studies, whose geographic distribution and antiquity appear to be
compatible with the Neolithic spread of farmers. Here, we set network 1.2 in the Y-chromosomal
phylogenetic tree, date it with respect to other lineages associated with the same movements by
other authors, examine its diversity by means of tri- and tetranucleotide loci and discuss the
implications in reconstructing the spread of this group of chromosomes in the Mediterranean area.
Our results define a tripartite phylogeny within HG 9 (Rosser et al. 2000), with the deepest branching
defined by alleles T (Haplogroup Eu10) or G (Haplogroup Eu9) at M172 (Semino et al. 2000), and a
subsequent branching within Eu9 defined by network 1.2. Population distributions of HG 9 and
network 1.2 show that their occurrence in the surveyed area is not due to the spread of people from
a single parental population but, rather, to a process punctuated by at least two phases. Our data
identify the wide area of the Balkans, Aegean and Anatolia as the possible homeland harbouring the
largest variation within network 1.2. The use of recently proposed tests based on the stepwise
mutation model suggests that its spread was associated to a population expansion, with a high rate
of male gene flow in the Turkish–Greek area.