Male line information: Y-group R1b

All members of Y-group R1b can trace their Y-chromosomes back to one man who is thought to have lived about 35,000 years ago. This man may have belonged to a group of hunter-gatherers, who were among the first modern humans to colonize Europe. Such groups likely took refuge in Northwestern Spain during the last Ice-Age, when most other parts of Europe were uninhabitable. When the Ice-Age waned, between 10 and 15 thousand years ago, the descendants of these groups are thought to have expanded into previously uninhabitable regions of Europe.

Today, members of Y-group R1b are primarily found in European populations, where it is the most common Y-group. In Europe, the highest concentration of Y-group R1b members is in the west, in the British Isles and the Iberian Peninsula, where it accounts for 60 to 70 percent of all males. The frequency of Y-group R1b members decreases as we move further east within Europe and becomes negligible east of Central and South Asia.

A subset of Y-chromosomes found within Y-group R1b show an interesting correlation with surnames purported to have descended from the most powerful and enduring dynasty of early medieval Ireland, the Uí Néill, literally translated as “descendants of Niall”. Gaelic genealogies were important records used to validate claims to prestige and power and linked most ruling families in the northern part of Ireland to the Uí Néill, who claimed high-kingship of Ireland from the 7th to the 11th century AD. The ultimate origin of this dynasty is attributed to the conquering sons of the eponymous and possibly mythological 5th-century warlord, Niall of the Nine Hostages.