It had long been thought that an influx of farmers from Western Asia, approximately 5,000 to 10,000 years ago, rapidly displaced and replaced the incumbent stone age hunters. But recent research has both backed this theory and disproved it.
     The first set of research centred on the male Y chronosome, which gets passed down from father to son with very little change. This allows scientists to trace back into geographical origins with a reasonable degree of accuracy. The Y chromosome researched was a type known as R-M269. This was chosen as it is shared by more than 100 million current European males and it was thought that this was a large enough genetic group to give a good understanding. The research had been carried out by a team from Leicester University, England. One of the markers they used was that of genetic diversity, the principle being that the older the lineage, the greater the diversity.
     The result of their research was consistent with an expansion of the population from the west, between 5,000 and 10,000 years ago. But these results have already been challenged by a team from Oxford University, who suggest that there was no geographical trend in the diversity, which would be expected if there had been such an influx from Western Asia. They further suggest that current analytical tools are not sufficient to unlock the secrets of R-M269. So where does that leave us? Well, in simple terms no further forward or, as Dr Capelli of the Oxford University team is quoted as saying "I would say that we are putting the ball back in the middle of the field".

Edited from BBC News (23 August 2011)