Niall of the Nine Zeroes
Today's New York Times reports on the genealogical research at Trinity College Dublin which hypothesizes the actual existence of an Irish King, Niall of the Nine Hostages, who was previously seen as mythical. The NYT report is in the Metro section, playing on the implication that a significant number of New Yorkers would also be descended from Niall.
This is interesting research, but it's useful to be clear that it has two parts: a scientific part finding that a large number of Irish people have a common paternal ancestor, with especially high clusters of such people in Derry and Mayo -- and then speculation that to have such a common ancestor from so far back (5th century) would require that the ancestor have been a powerful person with a reputation for having been able to look around the room and say, like Karim Bey in From Russia With Love -- "He too is my son." Niall fits the bill.
But we feel that the media tend to overemphasize the significance of these common ancestral findings, much as these occasional reports that appear about King George VII being related to Queen Elizabeth, Che Guevara to Jack Lynch (yes, we're that old) and so on. Look at it this way. This P O'Neill has two parents, 4 grandparents, 8 greatgrandparents. Or, if we go n generations back, 2n ancestors. Go back 1500 years, which is the time horizon for this research, and assume a new generation every 30 years. That's 50 generations back, meaning 250 = 1,125,899,906,842,620 ancestors.
So pick any Irish person, go back 1500 years and try to fit that pretty large number into the actual population of Ireland at the time -- think there's some chance of overlap between any two of us? [As it happens, the calculation is not quite as tight for P O'Neill, due to a family tree detour in Ipswich, but we're saving that detail for our truthy memoir]. It's good fun and good science, but we don't want Ireland's new royalty getting anxious about a resurgence of claims from an old one.