Friday, June 8, 2018

Review: Unwrapping America’s genetic heritage

Review of: DNA USA: A Genetic Portrait of America
Author: Bryan Sykes
Publisher: Liveright Publishing Corporation
Source: Dallas Public Library
Grade: B

As the United States moves toward a society in which those who identify as white are fast losing their majority statues and with a biracial American grafted onto the British royal family, Bryan Sykes’ DNA USA: A Genetic Portrait of America seems increasingly relevant.

But the Oxford geneticist who pioneered the use of human DNA to explore the history of the British Isles doesn’t aim to map America’s ancestral heritage. “The sheer size of the country and the magnitude of the population rules out any kind of systematic survey,” he writes. “I had to be selective or be overwhelmed.”
To that end, Sykes offers an anecdotal, often surprising glimpse at our multiple continents of origin and the often-surprising results of sampling the genetic traces they left on America’s people.
Sykes provides brief overviews of the several ways of tracing genetic heritage – mitochondrial DNA inherited only through a person’s maternal line, Y-chromosome DNA inherited only by males through their paternal ancestors, and autosomic DNA combined and recombined from both parents, as well as how these results match – or sometimes don’t – genealogical records. 
Beginning with a look at the roots of America’s first people, and their understandably wary attitude toward the claims of outsiders, Sykes moves on to the genetic contributions of Europe and Africa. Unlike Native Americans, those who identify with European or African ancestors are generally eager to find their roots outside America. Compared to those who have inhabited the our continent for tens of millennia, perhaps even from the beginning of time, we know ourselves to be newcomers to the Americas, whether our ancestors arrived here centuries ago or the day before yesterday. Non-indigenous Americans look across the sea as well as at the ground under our feet for a sense of permanence and belonging.
And we’re sometimes surprised, even shocked, to learn where that search for belonging leads us.
There’s the not-infrequent situation of men who “look black and certainly feel black” confronted with evidence that their Y chromosome shows evidence of European ancestry, as is the case for approximately one-third of African-American males. As well as the case of the man who insisted he was of wholly European ancestry, only to find that the mitochondrial DNA inherited from his mother’s family had its origins in Africa. (In that last case, Sykes wonders why he wanted to have his DNA analyzed by a company named African Ancestors in the first place.)
Perhaps more surprising was the finding that the Y-chromosome associated with the Jewish families often surnamed Cohen in fact dates to the approximate time of their Biblical ancestor, Aaron, brother of the prophet Moses.
Sykes adds the caution that, drawn from the pool of Y-chromosomes circulating in the Middle East several thousand years ago, possession of the supposedly “Jewish” chromosome does not prove that the bearer actually is Jewish, much less a descendent of Aaron. However, its existence among American Hispanics who have family traditions that their ancestors were “conversos”—medieval Spanish Jews forcibly converted to Christianity—has led some to explore Judaism, and even re-convert to what they believe to be the faith of their fathers.
On the other hand, using Y-chromosome lineage to unmake the founder of the huge clan of Scottish McDonalds as a Viking interloper instead of a Celt has been largely taken in stride by the clan’s historians. If he kept them safe from other Vikings, he’s Scottish enough for them.
Not all DNA evidence is surprising. A number of New Englanders who volunteered their DNA for Sykes’ perusal were more blue-blooded than the Englishman, whose genes bear surprising traces of both African and Asian ancestry. (Literally “blue-blooded,” according to a method of designating individual gene origins as blue for European, green for African and orange for Asiatic, in the fascinating “chromosome portraits” included in DNA USA.) 
Although Sykes conceals the identify of most of his volunteer donors under pseudonyms, the 2012 publication date of DNA USA means it doesn’t reflect the most recent privacy concerns about the use of human genetics. (Sykes is also the founder and chairman of ancestry tracer Oxford Ancestors.) The methods used to identify DNA origins by continental origin are based on genetic material provided by limited numbers of samples, with the Asian component which Sykes uses as a stand-in for Native American, comes only from volunteer donors in China and Japan.
Perhaps less a scientific document than memoir and travelogue (Sykes makes me long to replicate his transcontinental train journey across the United States) the mix of individual anecdotes, scientific information and sources for further reading make DNA USA a fascinating account of people grappling with their distant origins. 

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