Taking as base the mitochondria-DNA, they have known where the migrations of the European populations were. It seems that the man entered the continent from the Middle East, expanded and in the Ice Age (at the end of the Paleolithic) he met in the Iberian Peninsula, pushed by the cold, about fifteen thousand years ago.
To reach this conclusion, it has been considered a variant or group of haplotaris of the mitochondria-DNA: It is group H. Each man or woman has a mitochondrial DNA of a haplotalde, being H the most abundant in Europe. Well, after the study of group H of 649 people from all over Europe, they have known its evolution and, due to its geographical situation, have related it to migrations of human groups.
To know the migrations of yesteryear it is used mainly the mitochondriondria-DNA, since when passing from mother to children it serves to follow the line of generations. This mitochondrial DNA is changing, but experts know the number of changes that occur over a period of time.