Commentary from Dieneke's Anthropology Blog on another new paper [Hervella et al. 2012]
on Haplogroup U Mesolithic/Epipaleolithic
hunter-gatherers in Northern Spain:
50% of the hunter-gatherers belonged to haplogroup U subclades, hence confirming for this region as well [as was found in mesolithic Scandinavia] that this lineage was over-represented in pre-farming populations ...
The mtDNA U haplogroup associated with many of the areas pinpointed in my autosomal STR results appears to be associated with scattered groups of Mesolithic/Epipaleolithic hunter-gatherers.