Genealogy Can Unite Us… And Also Single Us Out

Genealogy Can Unite Us… And Also Single Us Out

Why has there been such a sudden increase in people’s interest in learning about their ancestry?

Knowledge of our ancestry has long had importance beyond just determining relationships. In Biblical times the Cohanim, or priests, ran the ancient Temple in Jerusalem; they were thought to have descended from Aaron, the brother of Moses and the first “High Priest” or Cohen Gadol. In synagogues today, Cohanim are still often given special honors and responsibilities. This traditional ancestral knowledge has now been backed up by modern scientific studies using DNA markers. These have shown that the Cohanim have a special genetic signature: the vast majority of today’s Cohen males have a Y chromosome that appears to have descended from a single male founder of this lineage that lived approximately 3,300 years ago.

DNA can also solve long-running mysteries by finding connections between people, including those that they might not aware of or forthcoming about. A striking example of the new use of DNA in forensic science at work can be seen in new developments of the case of the “Golden State Killer”, who committed a string of crimes beginning as early as 1976. This case remained cold for more than 25 years, until a 72-year-old man was recently arrested. This suspect was ultimately found in part by using DNA databases that can combined to create a family tree.

In this case, genetic information created connections between a collection of more conventionally obtained evidence. For forensic investigations, in terms of accuracy, the use of DNA to identify perpetrators has surpassed all older methods such as fingerprints and eyewitness accounts. Typically, when police can find DNA at the scene of a crime, they will first try to match it directly to existing suspects in their records. If they don’t find a match with those, they may have luck using computers to search the large collections of DNA information saved in the Combined DNA Index System (CODIS) database maintained by the FBI. CODIS currently contains DNA information from more than 13 million people convicted of crimes (or in some cases just arrested) from all over the US.

There is one major limitation, however, to the use of this search engine: the FBI’s current policy, with rare exceptions, is to only report a result when there is a perfect match to DNA in their database. However, when no perfect matches are found, many police would like to know if there were at least any partial or incomplete matches in the database. A partial match may include a relative or someone closely related to the actual perpetrator because they share some of their DNA, and this may still be of great help in the search.

In the case of the Golden State Killer, police opted instead to upload the DNA evidence to GEDmatch, an open-source personal genome platform that offers free searching and reporting; unlike the FBI database, it also reports both complete and partial matches. The GEDmatch searchDNA, apparently returned someone that was only a distantly related family member. But this result, combined with other evidence in authorities’ possession, was apparently enough to allow police to finally track down the actual killer.

As companies like GEDmatch, 23andMe or become more and more popular, we are finding new ways to interpret and use both DNA and genealogical records. And indeed, we are finding more and more unexpected connections between people. Not only are these scientific methods helping us better understand traditional Biblical groups such as Cohanim, it’s helping us confirm the idea proposed in Genesis that all humans are originally descended from the same ancestors. It also further supports the metaphor of the Tower of Babel, which is usually used to explain the origin of different languages, but also describes the migration of early human groups out from a central locality to form the different ethnic and geographic groups we recognize today.

Also beyond discussing the stuff of murder cases and paternity trials, scientists often fall back on references to Biblical characters to explain their findings. For example, one of the earliest comprehensive studies of human lineages using DNA relied on the use of genetic markers derived from mitochondria in our cells. Using mitochondrial DNA lineages, Rebecca Cann and other scientists have been able to identify a woman they described euphemistically as the “mitochondrial Eve” because she can be framed as the historical mother of all living human beings. Likewise, some of the other genetic markers most often used in current genealogical studies are derived from the Y chromosome. These Y chromosome lineages can ultimately be traced to a man similarly referred to as the Y chromosome “Adam.”

So, the stories contained in our DNA should make us stop and wonder if perhaps Biblical stories represent more than just morality plays designed to help us learn how to live together on this thing we call planet Earth. If the DNA left on a crime scene can now tell us the truth about things that happened over 40 years ago, surely too we can find new ways to use it to build on our inherited similarities for generations to come.


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