According to the X-Chromosome SNP analyses, the authors reported a high genetic homogeneity between berbers and Arabs in NW Africa, so they suggested that the [[Arabisation]] of this area was a cultural phenomenon, which did not imply a replacement of the ancestry population. Our results give support the hypothesis of an early settlement of northwest Africa. The original berber population seem to have received a low genetic influx from the surrounding areas. Different hypothesis have been suggested to explain the genetic differentiation of the Moroccan population. An initial genetic drift could have caused differences in allele frequency distribution that have not been re-established due to a certain level of geographic isolation. The Strait of Gibraltar has been described by several authors as an important genetic barrier. Even a certain level of genetic exchange probably occurred between NW Africa and the South of the Iberian Peninsula, sharp frequency changes have been described in this area. Also the Sahara desert has been suggested as responsible of the genetic isolation of NW African populations from Sub-Saharan populations. There is no consensus about the impact of the Neolithic demic diffusion in the Mediterranean area. According to our results, a low impact of the Neolithic expansions and/or later migration events on NW African populations would have occurred.