Kohanim and DNA
It's a funny world we live in. Used to be that three centuries of family tombstones engraved with ha-Kohan after the name meant something. Used to mean that one's lineage was without question. Back in the 1800's no one would even think about falsifying their lineage because it was impossible to do. Most communities were small, they knew your father, your grandfather, and some of the old timers may have even remembered your great-grandfather. Under those conditions of intense and close scrutiny it would have been impossible to fabricate anything about your family history, especially a priestly title on a headstone.
But now we live in an age of doubt and skepticism. We trust no one and in nothing. We believe only ourselves and even then we are filled with self doubts. We have a love/hate relationship with science. We enjoy all the fruits of its discoveries yet we want to blame it for everything that has gone wrong in the world. We want all the benefits but without any of the costs. It is just one more sign of a society out of control and doomed to self destruction. But that's another story for another time. Today we're talking about DNA and how everyone wants to be a geneticist because we even doubt our own parentage. Most of these private DNA testing companies are making their fortunes because people want to run parental tests to either prove or disprove their natural parental links. That in itself is a very sad comment on society because as it was written a long time ago, it's not the farmer that planted the seed, but the one that actually nutures and raises the crop that deserves to receive the rewards. If people can't appreciate that simple fact then they will always feel an emptiness in their lives.
So when I get people saying "how do you know you're Kohan," despite the fact that father to son has said so for three millennia, it is quite disheartening because it tells me that Jews no longer believe in the old ways; they no longer trust in the Torah; they no longer possess the essence or divine spark that infused our understanding of our place in this world. I for one disagreed with the use of DNA testing to determine if one accuratelly described their lineage because it meant we no longer trusted in tradition, in God, in ourselves. For Jews, that is a very sad commentary.
So what is all this science and genotyping about? As Kohanim it's the perfect tool for determining what was the common thread handed down to us by Aaron. You see, being a patrilineal descent, it meant that there would be genes incorporated into the Y chromosome which comes from the father that would be continuous from generation to generation since the mother doesn't have a Y chromosome that can dilute it out. That being the case, then those common elements on the chromosome of people that are Kohanim would be from the original ancestor. The actual science is as follows:
Y-chromosomal Aaron is the name given to the common ancestor of the patrilineal Jewish priestly caste known as Kohanim. In the Torah this ancestor is Aaron, the brother of Moses.
But here's where the danger begins because the original research showed that the majority of present-day Jewish Kohanim either share, or are only one step removed from, a pattern of values for 6 Y-STR markers. But six markers are hardly unique and subsequent work found that the 6 marker pattern was not specific just to Kohans, nor even just to Jews, but was a survival from the origins of Haplogroup J, about 30,000 years ago. So the first tests had a lot of people thinking they were Kohans that weren't and this only made an absurdity of those that knew their patrilineal descent.
So in order to fix it's first mess, scientists began using a larger number of Y-STR markers to gain
higher resolution. And what they found was that about 50% of today's Jewish Kohanim, share Y-chromosomal
haplogroup J1e (also called J-P58) and this is fairly specific to them. But the problem created is now there's another 50% that don't share the common genes. What does this mean? What it means is confusion, confrontation, and a conundrum. Because if all Kohanim descended from Aaron, then how is it that there are 50% out there that know they're Kohanim by continuous descent but they don't have the same haploid groups as the other 50%.
And to make this even more complicated, of that 50% that didn't share the J1 genes 15% of those Kohanim fall into a second distinct group, but have a different but similarly tightly related ancestry. This second group fall under haplogroup J2a (J-M410). But this means there's a further 35% of Kohanim that all belong to a significant number of smaller lineage groups.
So as anticipated, there's a large number of J1e Kohans that are screaming from the rooftops, "We're Number 1, We're Number 1." But the reality is that being in the majority may not be a good thing because the ages of the genes would suggest that J1e was a later development. The J1e and J2a Cohen haploids have been estimated for Sephardis as descending from most recent common ancestors living 3,200 ± 1,100 and 4,200 ± 1,300 years ago respectively and for Ashkenazis 2,400 ± 800 and 3,800 ± 1,200 years ago respectively. Which would suggest that the J2a which originated around 1800 BCE was more in line with the Patriarchal descent into Egypt and the J1e originated either at the time of the Exodus or at the time of the return from Babylon.
Now the fun begins because amongst Kohans, they are debating who is more Aaronic than the other. One of my distant relatives had the DNA test performed and he came back as J2a. His comment to me was that we must be more Aaronic because our distinct descent goes back further in time. But further in time would suggest that there was a unique separation in our family well before Aaron and that the family was preserving a unique heritage before the Exodus. Then there are those that are of the J1e that have pointed out this discrepancy to me and say that they are the true descendants of Aaron because they do not predate him. To which I look at the Ashkenazi (the majoirty) dating and say that you didn't become a unique lineage until after the exile in Babylon and we know from Ezra and Nehemiah, that they had difficulty in filling the rosters with sufficient Priests and Levites. Perhaps they had to expand the numbers of priests by taking from lower castes? So what this would suggest is that perhaps neither is the true line of descent from Aaron, or perhaps both are and that there's another set of genetic markers that we just haven't measured as yet. Did we really need this confusion? The answer is no, we didn't because for the past three thousand years we did just fine with father telling son, generation after generation and all was in accordance with the Torah.