Tracking down the ancestors -- fun but a little pointless

WS Gilbert pokes fun at ancestral one-upmanship in The Mikado, with the absurd Pooh Bah boasting how he could trace his ancestry “back to a protoplasmal, primordial atomic globule”. How ultimately meaningless it is to brag about one’s ancestors becomes even more apparent, moreover, when one realises that, according to modern-day research, everyone is practically guaranteed to discover illustrious forebears if they go back far enough.

In his book Human History: Genes, Race and Our Common Origins (2002), Steve Olsen made the remarkable claim that the most recent common genealogical ancestor of everyone living on Earth today must have lived no more than between two and three thousand years ago. In the generations before that, moreover, more and more people with surviving descendants are common ancestors of today’s world population. By the time one goes back a further two to three thousand years prior to the appearance of the most recent common genealogical ancestor, one can conclude that everyone living today has exactly the same set of ancestors who lived 5 000 to 6 000 years ago. What is more, every one of us alive today who leaves four or five grandchildren (making it unlikely that our genealogical lineage will become extinct within a few generations), is virtually guaranteed to be an ancestor of everyone who will be living on Earth two to three millennia down the line.

Olsen was by no means the first to advance such, on the face of it, radical ideas. Others working in the field, such as Yale University statistician Joseph Chang (author of an influential 1999 paper titled “Recent common ancestors of all present-day individuals”) had already done so. Olsen and Chang, together with Douglas Rohde, subsequently laid out these theories more formally in a September 30 2004 article in Nature.

Because the number of one’s ancestors increases exponentially rather than linearly, compiling a comprehensive family tree is a formidably complex task, even when the necessary available data has been amassed. Two parents, four grandparents, eight great-grandparents, sixteen great-great-grandparents — the numbers rapidly become unmanageable. Theoretically, each person going back a thousand years or so has more than a trillion direct ancestors, a figure far exceeding the total number of human beings who have ever lived. This anomaly is resolved by factors like the interconnectedness of networks of descent, shared ancestry and the like. The mathematics of it all is exceedingly complex and I have not even attempted to understand it.

According to Chang’s model, virtually anyone with a European ancestor descends from English royalty. Similarly, everyone of European ancestry must descend from Muhammad. Wrote Olsen: “Confucius, Nefertiti and just about any other ancient historical figure who was even moderately prolific must today be counted among everyone’s ancestors.”

Confucius?! Given China’s virtually self-contained isolation for most of its history, I cannot begin to see how even Europeans can be descended from him, let alone, for example, even more far-flung populations like the Australian Aborigines.

Notwithstanding what the mathematical models are saying, in fact, I have to question how literally the conclusions drawn from them are to be taken. There are many communities throughout the world that have, for geographical reasons, been largely cut off from the main population centres until comparatively recently, leaving (I would think) insufficient time for the necessary admixture to occur. What about communities like the Jews who (naturally excluding those who adopted other religions so that they and their descendants lost all connection to Jewish peoplehood) overwhelmingly married amongst themselves, with — until recently — very few conversions to Judaism taking place?

Notwithstanding these question marks, in broad terms one can certainly accept that the human family is indeed far more interconnected than is generally realised, and that this interconnectedness steadily increases the further one goes back. As a result, we may well all have kings, as well as commoners, in our respective ancestries.

In an article he wrote for the Atlantic Monthly in May 2002, Olsen queried whether all this “took some of the thrill” out of genealogical research and quoted the reply of Dublin-based computer scientist Mark Humphreys: “You can ask whether everyone in the Western world is descended from Charlemagne, and the answer is yes, we’re all descended from Charlemagne. But can you prove it? That’s the game of genealogy.”

At the end of the day, “game” probably sums it up. Tracing one’s roots may be a personally compelling journey, but uncovering descent from yesteryear’s nobility, even royalty, is hardly something to brag about. In The Gondoliers, WS Gilbert again puts it rather well: “If everybody’s somebody, then no-one’s anybody.”