Can it be that deep in our ancestors’ bodies, hidden in their cells, silent historians recorded the dead secrets of our past?
Over ten years ago, longtime nephrologist and medical researcher Dr. Kalman Skorecki was davening Shacharis in his Toronto shul when a kohein was called up to the fi rst aliyah of Krias HaTorah. As he watched the kohein striding up the bimah steps, a strange idea fell into Dr. Skorecki’s mind.
I am a kohein and he is a kohein, he thought to himself. Even though my parents are from Eastern Europe and his parents are from Morocco, we have a common bond that transcends geography – we are both direct descendants of Aharon HaKohein. Could it be that this link has somehow been physically preserved? Could it be that the common bond between us is upheld not only by tradition, but is also a physical fact readily identifiable in the test tube and microscope?
On the face of it, such an idea would seem preposterous. True, a son often looks like his father, and grandsons sometimes look like their zeidies, but after many generations, what chance is there that kohanim could have any characteristic linking them to their forefather, Aharon, who lived so many generations ago?
However, as a doctor and researcher, Dr. Kalman realized that it was not only possible, but even likely, that a physical bond existed, since deep within every cell of the human body are structures that determine not only every detail of our physical and mental being, but also harbor secrets of the distant past. Anchored in these microscopic structures are many secrets of human ancestry. These mysterious constructs are our chromosomes and genes.
For centuries, savants and researchers agonized over how information is passed from parent to child. Why does a whale grow into a whale and not into a mouse? Why do children generally have two ears like their parents and not sprout an extra one or two of these useful appendages?
The Genetic Age broke on February 28, 5713/1953, when two English researchers, Francis Crick and James Watson discovered the “secret of life.” After years of effort they had figured out the shape of DNA (deoxyribonucleic acid), a structure so long that to fit into our tiny cells it wraps itself into a tiny bundle.
It took Crick another four years to figure out DNA’s brilliant code. Basically, DNA is composed of four molecules represented by the letters A, C, G, and T, each one called a nucleotide. Each of our cells contains the human genome, which consists of three billion nucleotides packed into 23 pairs of chromosomes. Just as a computer can record millions of facts simply through endless rows of ones and zeros, so these billions of nucleotides, in their endless combinations and permutations, record everything about us and transmit it to future generations, from the color of our eyes to our level of intelligence.
There are two intriguing facts about this incredible letter sequence that encodes our body structure and function from the cradle to the grave. First of all, the genome code is virtually identical for all members of the human population. Broadly speaking the whole human race is made up of identical twins regarding 99.9% of their make-up. The vast human diversity regarding skin color, height, nose size and length is determined by the puny 0.1% that makes Tom different than Dick and Harry.
Secondly, only a small percentage of the genome’s three billion nucleotides transmit useful information. The rest of the sequence, known as “junk DNA,” has no obvious effect on the body at all. Because of this lack of obvious function, junk DNA has one important practical use – scientists have discovered that specifically because of its “uselessness,” it serves as a faithful record of a person’s ancestry. Why is this?
Useful DNA needs to remain in perfect working order in order to serve as an accurate blueprint of the human body. Any blurb in the DNA sequence can wreak havoc on the human body, causing genetic flaws and terrible diseases such as Tay-Sachs.
Junk DNA is different. Since it serves no obvious purpose, its sequences often undergo changes that have no detrimental effect on the organism. These changes are then passed down through the generations and provide evidence of one’s distant ancestry. Let’s say certain links in Mr. Sam Levi’s DNA chain got mixed up five generations ago. These changes can sometimes pass on to his children and great grandchildren, branding them forever more as his descendants.
Dr. Skorecki considered it likely that Aharon HaKohein had such markers, which would have been passed down to the approximately 350,000 kohanim of our time.
The problem is that children generally have a combination of their parents’ DNA. Modern day kohanim are the progeny not only of Aharon, but of all the thousands of wives kohanim have married throughout history. Is there any DNA that retained Aharon’s stamp without the input of these endless marriages?
There was! Among the human cell’s 46 chromosomes (DNA bundles) is the Y chromosome that is possessed only by males. No woman since creation has had a Y chromosome in her genome. Every father bequeaths his sons with an exact copy of his Y chromosome, free from female influence. When Aharon had a son, this son received an exact copy of Aharon’s Y chromosome. Therefore, since kehunah passes exclusively down the male line, it stands to reason that every kohein alive in our day possesses an exact copy of Aharon’s Y chromosome.
But how to determine whether the Y chromosome of modern day Sam Cohen is the same as Aharon’s? Is there some way to differentiate between the Y chromosomes of Tom, Dick and Harry? As mentioned earlier, there is! If the junk DNA of all modern kohanim’s Y chromosome is found to possess aberrations common to all, this would prove that they all had a common male ancestor, presumably Aharon HaKohein.
At the conclusion of two studies, Dr. Skorecki’s efforts were crowned with success. After investigating a number of kohanim by painlessly scraping off some cells from the inner cheek, it was discovered that almost all of them shared six unique chromosome markers in the Y cell; 97 of 106 kohanim tested showed this common bond back to a single ancestor. These six markers are now known as the Cohen Modal Halotype (CMH).
On top of that, scientific evidence indicates this marker extends back 106 generations, or 3,300 years, the time when the Jews left Egypt. And since Avrohom Avinu was only seven generations before Aharon, this CMH marker may also be the genetic marker of the first Jew!
Ongoing research revealed that over 80% of contemporary kohanim possess the CMH marker, while the kohanim of the Tunisian island of Djerba have a 100% percent rating, leading Dr. Kalman Skorecki to conclude that:
“The oral tradition of the priesthood has a DNA or genetic counterpart. The scientific information confirms that the majority of contemporary Jewish males who identify themselves as kohanim are descended from a common male ancestor who founded a patrilineal dynasty consistent with the tradition of the Jewish priesthood.
“It’s almost equivalent to finding a remnant of the garb of the first priest’s family, as if you went to Sinai and found some remnant of Aharon’s anointment ceremony.”
Regarding kohahim who do not have these genetic markers, Rav Yaakov Kleiman, author of “DNA and Tradition,” emphasizes that for various reasons these scientific findings have no halachic significance whatsoever.
“At present there are no halachic ramifications from these discoveries,” he writes. “No one is certified nor disqualified because of their Y-Chromosome markers.”
ALL YISROEL ARE BROTHERS
Encouraged by the success of the so called “Kohein Gene,” researchers in the USA, England and Israel turned their attention to investigating the origins of world Jewry. Could it be demonstrated that Jews worldwide have a common origin in the Middle East whose traces have survived two thousand years of exile? Investigation of the Y-Chromosome and genetic signatures of 29 population groups including seven Jewish groups revealed that Jews from the Near East and Ashkenazim had almost identical genetic profiles despite Ashkenazi Jews separating from their eastern cousins about 1,200 years ago.
This led Professor Michael Hammer of the University of Arizona to comment that:
“Despite their long term residence in different countries and isolation from one another, most Jewish populations were not significantly different from one another at the genetic level. The results support the hypothesis that the paternal gene pools of Jewish communities from Europe, North Africa and the Middle East descended from a common Middle Eastern population and suggest that most Jewish communities have remained relatively isolated from neighboring non- Jewish communities during and after the Diaspora.”
But if so, you might ask, why do many Jews look like the residents of their adopted countries? Why do German Jews look like Germans and Moroccan Jews look like Moroccans?
According to the Vilna Gaon, much of the physical traits of nations are dependant on their particular geography and weather. For example, those that live in sunnier climates will be darker than those that live in colder climates. So it is possible that after living in a particular area for hundreds of years, we may have developed different physical appearances.
Another answer is that it has been estimated that in the course of the 50 generations of European Jewry, the influx of converts is about 0.5% in each generation. This is sufficient to account for the Jews’ resemblance to the non-Jews of their host countries, while allowing a distinctively Jewish genetic profile to survive.
We are all linked by an invisible thread.
(Source: Kleiman, Rabbi Yaakov. DNA & Tradition, the Genetic Link to the Ancient Hebrews. Devorah Publishing, 2007.)