Jewish priesthood (Cohen or Kohen; plural: Cohanim or Kohanim), has been determined by patrilineal descent. Modern Kohanim claim descent from a biblical person, Aaron, brother of Moses, in the direct lineage from Levi, the patriarch of the Tribe of Levi, great-grandson of Abraham, according to the tradition.
For human beings, the normal number of chromosomes is 46, of which 23 are inherited from each parent. Two chromosomes, the X and Y, determine sex. Women have two X chromosomes, one inherited from each of their parents. Men have an X chromosome inherited from their mother, and a Y chromosome inherited from their father.
Males who share a common patrilineal ancestor also share a Y chromosome, diverging only with respect to accumulated mutations. Since Y-chromosomes are passed from father to son, all Kohanim men should theoretically have nearly identical Y chromosomes; this can be assessed with a genealogical DNA test. As the rate that mutations accumulate on the Y chromosome is relatively constant, scientists can estimate the elapsed time since two men had a common ancestor.
Common last names of Jewish Cohanim:
Y Chromosomes and What is YAP and YAP- (YAP Negative)
YAP stands for Y-chromosome Alu Polymorphism. This means this is some change in the Y chromosome. YAP negative means that someone is missing this mutation.
Men have a Y chromosome, which they inherit from their father and is unique to men (women have XX, men have XY).
Within the Y Chromosome, there are very clear markers or mutations that occurred at some point in the past. These mutations act as a genetic identification as to where you descended from.
These mutations get passed down, so it can tell you if you have a common male ancestor or which paternal line you came from.
So, every man passes those markers or mutations down to their male children (which scientists have segregated into haplogroups).
Scientists have built a paternal ‘tree’ that give you a hierarchy of these mutations. See this chart.
Geneticists have segregated these markers into different groups and subgroups, based on which male ancestor you’re from.
See more about YAP+.
Can YAP Status Show You That You’re a Cohen?
No. Some people make a big fuss that 99% of Cohanim are YAP Negative or missing that mutation.
The issue is, however, that most of the world is YAP negative.
For example, almost 90% of East Asians (China, Hong Kong, Macau, Taiwan, Japan, South Korea, North Korea and Mongolia, Vietnam) are YAP negative. 85% of Jews are YAP negative.
The YAP mutation occurred 65k years ago, so it doesn’t match up with history as being the original point of Cohanim.
If the common ancestor was the man without YAP (Aaron HaCohen), that person would be the father of 90% of Asians as well and most of the world, in which case it would mean that:
- 90% of Asians are Cohanim, so you are more likely to be a Cohen if you’re Asian than if you’re Jewish
- Most of the world are Cohanim
- Aaron HaCohen lived 65k years ago
Because the Cohanim are focused in the haplogroup J1 (especially JP58), which is YAP negative, this skews 99% of Cohanim to YAP negative, because they are over-represented in J1.
When Did Cohanim Begin?
If you assume that Aaron HaCohen started the Cohen line (which is a core assumption in Orthodox Judaism), then ALL of his male descendants will be in the same Haplogroup.
The original ancestor of Cohanim is very likely from the J1 lineage. Specifically, J1-P58 lineage and in particular ZS227 seems to be the Cohen paternal line.
The two most common Jewish subgroup of J1-P58 are Z18297 and ZS227. ZS227 includes the Cohanim haplotype .
Here is J1 from Wikipedia:
Men from this lineage share a common paternal ancestor, which is demonstrated and defined by the presence of the SNP mutation referred to as M267, which was announced in (Cinnioğlu 2004). This haplogroup is found today in significant frequencies in many areas in or near the Middle East, and parts of the Caucasus, Sudan and Ethiopia. It is also found in high frequencies in parts of North Africa, Southern Europe, and amongst Jewish groups, especially those with Cohen surnames. It can also be found much less commonly, but still occasionally in significant amounts, throughout Europe and as far east as Central Asia and the Indian Subcontinent. 
This chart gives you a timeline when different lineages started.
The J1-p58 subgroup originated 14,000 years ago, so it’s likely the start of Cohanim were from a subgroup. Arabs also descend from J1-P58 .
Cohen Modal Haplotype (CMH)
The original scientific research was based on the hypothesis that a majority of present-day Jewish Kohanim share a pattern of values for 6 unique markers (YSTR), which researchers named the Cohen Modal Haplotype (CMH) .
Of those who did belong to Haplogroup J, the Kohanim were more than twice as likely to have a pattern close to the CMH-6, suggesting a much more recent common ancestry for most of them compared to an average non-Cohen Jew of Haplogroup J .
This means that you need to belong in J to have the CMH .
Additional research using 12 unique markers, which is more accurate, indicated that about half of contemporary Jewish Kohanim shared Y-chromosomal J1 M267, specifically haplogroup J-P58 (also called J1c3). Other Kohanim groups share a different ancestry, including haplogroup J2a (J-M410). Both of these groups are in the “J” line .
Genetics research published in 2013 and 2016 for haplogroup J1 places the Y-chromosomal Aaron within subgroup Z18271, with an age estimate 2,638 – 3,280 years ago .
In a study published in 2009, based on genotypes at 12 markers (Y-STRs), they identified an extended CMH on the J-P58* background that predominates in both Ashkenazi and non-Ashkenazi Cohanim and is remarkably absent in non-Jews .
The estimated divergence time of this lineage based on 17 STRs is 3,190 +/- 1,090 years. These results support the hypothesis of a common origin of the CMH in the Near East well before the dispersion of the Jewish people into separate communities, and indicate that the majority of contemporary Jewish priests descend from a limited number of paternal lineages .
Critique of CMH
It’s important to note that the CMH is only found in J1 or J2.
Following the discovery of the very high prevalence of 6/6 CMH matches among Kohanim, other researchers and analysts were quick to look for it. Some groups have taken the presence of this haplotype as indicating possible Jewish ancestry, although the chromosome is not exclusive to Jews. It is widely found among other Semitic peoples of the Mideast .
Critics such as Avshalom Zoosmann-Diskin suggested that the paper’s evidence was being overstated in terms of showing Jewish descent among these distant populations .
The Cohen Modal Haplotype (CMH), while frequent among Cohens, also appeared in the general populations of haplogroups J1 and J2 with no particular link to the Cohen ancestry. These haplogroups occur widely throughout the Middle East and beyond. Thus, while many Cohens have haplotypes close to the CMH, a greater number of such haplotypes worldwide belong to people with no likely Cohen connection at all .
The authors of one study (Elkins, et al.) warned in their report that “using the current CMH definition to a infer relation of individuals or groups to the Cohen or ancient Hebrew populations would produce many false-positive results” .
Even within the Jewish Cohen population, it became clear that there were multiple different Cohen lineages, including distinctive lineages both in Haplogroup J1 and in haplogroup J2. Other groups of Jewish lineages were found in Haplogroup J2 that matched the original 6-marker CMH, but which were unrelated and not associated with Cohens. Current estimates, based on the accumulation of SNP mutations, place the defining mutations that distinguish haplogroups J1 and J2 as having occurred about 20 to 30,000 years ago .
A 2014 article analyzing earlier research attempting to trace Jewish ancestry (not just of the Lemba) states:
In conclusion, while the observed distribution of sub-clades of haplotypes at mitochondrial and Y chromosome non-recombinant genomes might be compatible with founder events in recent times at the origin of Jewish groups as Cohenite, Levite, Ashkenazite, the overall substantial polyphyletism as well as their systematic occurrence in non-Jewish groups highlights the lack of support for using them either as markers of Jewish ancestry or Biblical tales .
Finding Out I’m Not a Cohen
My last name is ‘Cohen’ and I’m supposedly as reliable as a Cohen as it gets.
But after looking at my genetics test results, I found out I’m the Haplogroup G. Specifically G-M377.
Only 2 out of 215 Cohanim belonged to our paternal line. This means that less than 1% of Cohanim belong to my line. Since Cohanim descend from the same paternal ancestor, they all need to be in the same haplogroup.
If I was a Cohen, it means that Aaron HaCohen should also be from the same G-M377 lineage. But it’s pretty much impossible because the “G” lineage is completely different than the “J” lineage.
Indeed, less than 1% of Cohanim are G-M377, whereas 3.7% of non-Cohen Jews have that. So this is pretty much impossible to be the haplogroup of Cohanim, or else almost all Cohanim aren’t really Cohanim. If that were the case, then the whole thing shouldn’t be taken seriously because you’re more likely to be a Kohen if you don’t identify as one.
Now 46% (99/215) of Cohanim are from the group J1-P58, compared to 14% of non-Cohanim (87% of Ashkenazim are in a larger umbrella of J). So J1-P58 is likely to be the start of the Cohen line (or a subgroup).
We know that many people who think they are a Cohen today, aren’t really one. For example, you never know who the true father is. Some people say that up to 10% of kids are from a different father than they think in every generation (infidelity, exile, adoption, rape, etc…) and through many generations, you’ll have people who think they are Cohanim and aren’t. At one point in time, it was lucrative to be a Cohen, so it would be something that would have an incentive to try and fake.
So it makes sense that the percentage of Cohanim won’t be 100% from any group, because it will be diluted through time. But what the study found was that people who are Cohanim were way more likely to be from the J group, particularly J-P58.
So it’s likely that Cohanim descended from that individual with those markers. This is used as evidence that Cohanim came from one 1 male.
So if there is an Aaron Hacohen, J-P58 is probably his lineage (but to be 3000-3500 year ago, it would need to be a subgroup of J1-P58 such as ZS227), and anyone who isn’t in that group got mixed up with being a Cohen somewhere in the last 3000 years.
It’s theoretically possible that any line is the true Cohen line, even those with little Cohanim today (including G). But if that is the case, then it means that any evidence about the true Cohen line is going to be nonsensical and that even if you believe you are Cohen, you’re not more likely to be a Cohen than someone else.
It’s clear that “J” is the group with the Cohanim.
If you aren’t in Haplogroup J1 (especially JP58), then you didn’t descend from the true Cohen line, no matter what your last name is or what documents you have proving your ancestry.
The great thing about genetics is it’s based on facts, not opinions.
According to Orthodoxy, however, it’s irrelevant what your genetics is because whether you’re a Cohen goes based on tradition.
- Obtain genetics testing to see which one you are
- Plug it into SelfDecode to get health reports on your genetics.
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