Pinker Doesn’t Care About Your Ancestry

Every once in a while, Harvard Psychology Professor Steven Pinker contributes his two cents in the pages of The New Republic. While most of these articles remain locked behind TNR‘s unfortunate subscription barrier, a recent article on geneology is open to the public with free registration.

Pinker is reacting to the burgeoning popularity of genotyping services that promise to reveal our ancestry and distant relatives. For example, this one promises to tell you if you are related to Marie Antoinette. The gist of his article: So What?

First Pinker exposes a common fallacy about ancestry that assumes we all have 4 grandparents, 8 great-grandparents, 16 great-great-grandparents and so on. If every position on our family tree was occupied by a unique individual, then this exponential function would predict that the earth’s population would have to be ~1,200,000,000,000,000,000,000,000 in the year 0 A.D. History teaches us that this was not the case, so we must conclude that incest was not the exception but the rule. Pinker refers to this conclusion as “pedigree collapse”:

The same arithmetic that makes an individual’s pedigree collapse onto itself also makes everyone’s pedigree collapse into everyone else’s. We are all related–not just in the obvious sense that we are all descended from the same population of the first humans, but also because everyone’s ancestors mated with everyone else’s at many points since that dawn of humanity. There aren’t enough ancestors to go around for everyone to have a family tree of his or her own. So it is a mathematical necessity, not a surprise, that genealogy will turn up strange bedfellows. George W. Bush is a distant cousin of his electoral opponents Al Gore and John Kerry (as well as of Richard Nixon, Ernest Hemingway, Queen Elizabeth, and, through her, every European monarch). Gore, for his part, is a descendant of Charlemagne, and Kerry is a descendant of Mary, Queen of Scots–and presumably also (thanks to his recently-discovered-to-be-Jewish paternal grandfather) of rabbis, cantors, and medieval moneylenders.

While the perception of kinship can have a major impact on how we relate to other people, Pinker wants to paint this preferential treatment as irrational–and in some cases–harmful. Often strong family ties weaken the strength of social institutions such as regional government. Pinker mentions this effect in reference to failed nation-building efforts in Iraq, where familial pedigrees remain relatively distinct thanks to the culturally-acceptable practice of marrying one’s cousins:

About half of all marriages are consanguineous (including that of Saddam Hussein, who filled many government positions with his relatives from Tikrit). The connection between Iraqis’ strong family ties and their tribalism, corruption, and lack of commitment to an overarching nation had long been noted by those familiar with the country. In 1931, King Faisal described his subjects as “devoid of any patriotic idea … connected by no common tie, giving ear to evil; prone to anarchy, and perpetually ready to rise against any government whatsoever.”

The implicit solution? Pass around a bottle of wine, turn up the Marvin Gaye and hope for some Sunni on Shiite love.

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