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-R. Jeremy Kalmanofsky
Jews, Genes and Genetics: A Look at Family, Haplotypes and Peoplehood
In the United States today, the freest and richest nation on the planet, a country characterized by opportunity and mobility, the reality is that most Jews are Jews, if at all, by choice. For some, that choice is relatively easy, a coincidence of birth, culture and acceptance. For others, the situation is more complicated, involving perhaps disaffection with the faith or circumstances into which one was born and raised or, conversely, an attraction to a set of beliefs or patterns of behavior newly encountered.
Regardless of one’s position, in the open and fluid society that is America, most adults are not forced to be Jewish, i.e., to engage in conduct commonly understood to be specifically Jewish, such as attending shul, keeping kosher, studying sacred texts or simply identifying as a Jew. Nor are they forced to believe in a particular collection of ideas or ideals, including whether God exists, or, if they think that God does, what attributes or aspects that God may or may not have. Certainly strong social pressures can operate on an individual to motivate him or her to behave or believe one way or another, but most individuals still retain the ability to choose whether to be Jewish.
There is, however, one matter that is not open to choice, much less dispute or revision, and that is one’s genetic structure. And here, as elsewhere, advances in science in the relatively recent past have allowed us to investigate, to probe, to attempt to provide science based perspectives, if not answers, to the most basic questions: “Who am I?” and “Where did I come from?”.
Much as astrophysicists and cosmologists can look at electromagnetic radiation in various forms such as invisible cosmic microwaves or visible light that reaches Earth each day and use that information to look back in spacetime to the origins of the known universe, geneticists study the mechanisms of inheritance. They can look deep into the cellular structure of organisms and derive information which allows them to understand the historical ancestors of the organisms they are studying, both individually and in relation to similar organisms.
The astrophysicist and cosmologist can assert that we are made of stardust, and that is true. But it is also true that that stardust has been fashioned by biochemical mechanisms that we do not fully understand. And the geneticist knows that with respect to the human species, our evolution has been both affected and effected by a process of genetic shuffling.
The mechanisms which are the focus of genetic study are found in the cellular structure of organisms. The body of every living organism on Earth is made up of one or more cells. Humans have about 50 trillion cells in their bodies, some for brain and blood, others for skin and bone, and still others for the myriad functions that cells perform. Inside each of these cells is an enclosed portion called the nucleus.
The nucleus of a cell houses genes which consist of molecules of deoxyribonucleic acid, or DNA, a molecule characterized by two long, intertwined and interconnected helical shaped strands of sugar and phosphate units. (See From So Simple A Beginning (Macmillan 1993) at 61.) DNA is associated with the transmission of genetic information from parent to child. This information is contained in a sort of code which can be understood as consisting of four nucleotide bases, generally known by the letters A, T, C and G. In the DNA, the letters are arranged in various combinations of three letters to form the words of the genetic code. Each of the 64 possible triplets relates to a specific amino acid, the building block of a protein. Each protein, in turn, plays a specific role in the cell of the host organism. The double stranded DNA molecule is, then, a chain of information, call it a roadmap, which governs the development of the organism. (Id. at 61-62.) The totality of the genetic information of an organism is known as its genome. The genome for the human species is about three billion base pairs of DNA. (See Goldstein, Jacob’s Legacy: A Genetic View of Jewish History (Yale University Press 2008) at 128.)
In humans, as in other organisms, the DNA is divided into packages called chromosomes. There are forty-six (46) such segments, combined into twenty three (23) pairs of chromosomes in a human’s body. (Id. at 127.) In the process of human pro-creation, each mate contributes half of its chromosomes which combine to form the genetic structure of a new individual. With two exceptions, the bits and pieces of each parent are shuffled, i.e., essentially sliced and diced and recombined.
One of the exceptions to the process of recombination relates to the male sex chromosome, known as the Y chromosome. With respect to sex chromosomes, while women have two X chromosomes, men have one Y chromosome in addition to one X chromosome. Therefore, each sperm will contain either an X or a Y chromosome. Because human males have them, and females do not, if the successful sperm carries a Y chromosome, the resulting embryo will be male. Consequently, the Y chromosome is transmitted from father to son, but never from father to daughter. Moreover, the Y chromosome “carries few genes [and] possesses little variation . . . .” (Id. at 25.) While “small changes in chromosomal DNA do occur,” a son receives an “essentially unchanged” Y chromosome from his father. (Id.; see also Entine, Abraham’s Children: Race , Identity and the DNA of the Chosen People (Grand Central Publishing 2007) at 55.)
In theory, one could study genetic information in the Y chromosome of one human male and see whether there were any similarities to another human male such that the two males might be related. In theory, with sufficient data, one could see whether male members of a particular social, ethnic, national or other group were related. By virtue of their history, both mythic and real, Jews should be ideally suited to such a study. Until the 1980s, however, the scientific tools to undertake such a study had not yet been developed. (See Id. at 54-55.)
The story of the first Jewish Y chromosome studies is fascinating on several levels, and provides a wonderful great example of how scientific discoveries are often the result of circumstance and serendipity. In 1994-95, within a very brief period of time, not one, but two men independently came up with the same idea of testing the Y chromosomes of a limited subset of Jews. They arrived at the same place from different paths and with different perspectives, but they joined together and embarked on a remarkable journey.
In late 1994, in England, Neil Bradman, a successful middle-aged businessman was in the midst of leaving his publishing and real estate ventures, and returning to his youthful love, science. His son Robert was then pursuing a graduate degree in genetics, and looking for a research project to be undertaken in Israel where his girlfriend lived. Bradman is a Levite by tradition, i.e., a theoretical descendant of the Biblical Levi, third son of the patriarch Ya’akov (Jacob). He recalls that he and his son quickly arrived at the concept of “‘testing the story of the Jewish priests.’” (See Id. at 76-77.)
In January, 1995, clinical nephrologist and university professor Karl Skorecki was attending Shabbat morning service in Toronto, Canada. Like Bradman, Skorecki was in his mid-fifties and also planning a major change in his life. In Skorecki’s case, the plan was to move to Israel. (See Id. at 65-69.)
At this particular service, the rabbi was looking for a Kohen to read from the Torah. A Kohen, according to Jewish tradition, is a descendant of the priests who served in the Temples in Jerusalem. The Biblical narrative sets the inception of the Jewish priesthood to a date several months after the Exodus from Mitzrayim (Egypt), or, by some accounts, just over 3300 years ago, when Moshe (Moses) presided over the investiture of Aharon (Aaron) as the first Kohen Gadol, or high priest, and his sons as Kohanim (plural for priests). (See Ex. 29:9.) Once established, the priests were assigned specific unique duties and granted special privileges. (See, e.g., Lev. 6:16, 29, 22:10-16; Num. 6:22-26, 27:21; Deut. 21:5, 31:9-13, 33:10.) The appointment was to be everlasting, extending throughout all the generations. (See Ex. 40:15; Num. 18:19, 25:13.)
The rabbi’s search was answered by a Moroccan Sephardic Jew. Skorecki, of Polish descent, and the sole child of Holocaust survivors, considered himself to be a Kohen as well. As he looked at the Jew of North African ancestry, whose physical traits were so different than his, he wondered whether they were really descended, as the Bible and subsequent tradition would have it, from the same person, including possibly the first high priest, Aharon. If they were, and more broadly, if all Kohanim were as well, Skorecki hypothesized, they should share common genetic markers, which are changes or mutations in a gene. Testing this idea would be “‘a great summer project for a medical student,’” he thought. (See Entine, above, at 69-70.)
Bradman and Skorecki independently reached out to Batsheva Bonne-Tamir, a professor of genetics at Tel Aviv University, to inquire about the possibility of locating distinguishing markers in the genes of Jewish men. Bonne-Tamir encouraged both men to contact Professor Michael Hammer, a genetic anthropologist and an expert on the Y chromosome, at the University of Arizona in Tucson. Ultimately, the Bradman-Skorecki-Hammer team was formed and a study plan adopted. The purpose of the exercise was not to prove the historical truth of the biblical account of the priesthood, but rather to see whether there was any genetic basis for the Kohen narrative of common ancestry extending back to Aharon. (See Id. at 85.)
Later in 1995, between Rosh Hashanah and Yom Kippur, Bradman’s son Robert collected almost 200 vials containing the saliva of Jewish males, split evenly between those of Ashkenazi (Central and Eastern European) descent and Sephardi (Iberian) descent. About one-third of these men also claimed to be Kohanim. (See Id. at 78.) When the data was analyzed, the researchers discovered an amazing fact: regardless of the national origin of each of the participants, regardless of their designation as Ashkenazi or Sephardi, they almost all (98.5%) had a relatively unique mutation, called a haplotype, one shared with only 3-5% of the world Jewish population. (See Id. at 79; see also Goldstein, above, at 27.) This result suggested at least two important things: First, there was a high correlation between the cultural and genetic records and, second, the original possessor of the haplotype pre-dated the millennia old separation of Jews into Ashkenazim and Sephardim. (See Entine, above, at 79.)
The researchers were reasonably, but not always, cautious when disclosing their results. Their circumspection apparently did not matter. Some in the press exuberantly declared that science had traced the Jewish priestly line back three thousand years to Aharon, the first high priest. (See Entine, above, at 81.)
The research team apparently understood better than others the limits of their initial study, and the need for more sampling and further analysis. Enter David Goldstein, an American transplant to England. Goldstein was a geneticist who had done research on microsatellite markers, variations that exist in more than one form, and used a process of linkage analysis to identify genes susceptible to disease. (See Entine, above, at 86; Goldstein, above, at 128.)
To further their research, the expanded team collected samples of 306 Jewish men who self-identified as Kohanim, Levites or Israelites. (See Goldstein, above, at 30.) What they found was 109 different types of Y chromosomes, which is a substantial variety of such chromosomes. But there was a significant difference between the kind of Y chromosomes found in the Israelite and non-Israelite populations. Only 12% of the Israelite group shared a common type of Y chromosome, but over half of the Kohanim had the same type of Y chromosome. (See Id. at 31.) Moreover, the substantial prevalence of that particular Y chromosome was found in Kohanim of both Ashkenazi (45%) and Sephardi (56%) origin. (Id.) The scientists named that frequently appearing chromosomal type the Cohen Modal Haplotype (“CMH”).
Accounting for chromosome types with small mutations in very short base pairs, they then found other types “clearly related” to the CMH. (Id.) Together, these accounted for almost two-thirds of the chromosomes studied in the Kohanim. Again, the prevalence of a shared haplotype within the modal cluster was similar in the Ashkenazim (69%) and the Sephardim (61%). By clear contrast, only 14% of Jews identified as Israelites have chromosomes within the modal cluster. (Id. at 31-32.) These findings were undoubtedly not the result of random behavior. (See Entine, above, at 87.)
The second research team therefore not only confirmed, but extended, the findings of the first team. It identified the CMH, and refuted the notion that there was much outside interference with the line of male ancestry. What the results did not prove, though, was how old that line is, and, specifically, whether it traced back continuously to the time of the Biblical priesthood.
How far back could this line be traced? Hammer had thought the first study showed lineage extending fifty (50) generations in the past, itself a stunning result. (See Entine, above, at 79.) Goldstein’s novel approach of dating by mutations, held the promise of more precision. And he developed a computer model that considered the time necessary to develop the differences in the observed chromosomes from the Cohen Modal Haplotype.
As Neil Bradman in Israel provided Goldstein with raw data telephonically, Goldstein could see where the data was leading. The results of the second study were eclipsing those of the first. According to Goldstein, he then inputted the numbers into his computer for refinement. After entering the information for the microsatellites, the computer model indicated that founder of the Kohanim line lived about 3,000 years ago, give or take a few hundred years. (See Goldstein, above, at 37-38.) At thirty years per generation, that would cover one hundred (100) generations. And, even at the lower end of the range, the start date for the Kohanim line would have preceded the date of the destruction of the First Temple in 586 B.C. E. by at least a century. (See also Entine, above at 89.)
Goldstein concedes that the “range of possible dates was and is very board” and that “the origin of the line cannot be assigned with precision to the time of Aaron, Solomon, or any other named individual . . . .” (See Goldstein, above, at 38.) Still, Goldstein cannot resist the suggestion that if the Biblical Exodus occurred at all, and if it can be dated to the late thirteenth century B.C.E., then the start date for the CMH haplotype would be “well within the interval we predict for the origin of the (K)ohanim.” (Id. at 39.) His more modest and “best guess” is that the priestly line was founded prior to “the time of the Romans and perhaps before the Babylonian conquest in the sixth century B.C.E.” (Id. at 39; see also Entine, above, at 90.).
What does all this mean? Well, paradoxically, quite a bit and not all that much, both respect to the Kohanim and Jews generally.
The science is more than intriguing. For the first time, we have data which seem to be consistent with extensive oral and written traditions and appear to show extraordinary, perhaps unique, continuity of lineage over two to three millennia in time and across national boundaries, despite countless wars, persecutions, famines, diseases, and other scourges and challenges, not the least of which is random happenstance. Even if one is not religious, the breadth and depth of this lineage, and its implied fidelity to family and tradition is astonishing, and gives new resonance to the ancient reference in the Jewish prayer books to L’dor vador (To all generations).
At the same time, CMH is not limited to Jews. It has been found, albeit in lesser concentrations, in numerous non-Jewish populations from Iraq to Italy, including Palestinian Arabs. (See Entine, above, at 91.)
What are the practical consequences of what we have learned? The Reform, Reconstructionist and Humanist approaches to Judaism are already disinclined to recognize distinctions between classes of Jews. They are unlikely to reinstate favored status for Kohanim based on this genetic information. Over the last seventy years, the Conservative movement has modified its views on several previously understood priestly privileges. (See “Priests and Levites in the Bible and in Jewish Life,” in Etz Hayim (Jewish Publication Society 2001) at 1444-46.) Though persuasive, the lack of certainty attendant to genetic testing today does not seem sufficient to cause a reversion to prior practice. Because the Orthodox community’s commitment to traditional rituals was not dependent on genetics in the first place, the Kohanim studies should not have much affect at all, unless there were a move to formalize recognition under Jewish law, which seems doubtful. Similarly, Israel’s Law of Return for Jews is unlikely to be amended to provide for genetic “proofs.”
The Center for Kohanim in Israel promotes study of the Biblical role and history of Kohanim and L’viyyim (the Levites). While it was formed over a decade before the studies on the Kohanim yield the results discussed above, the Center features these results, seeing the findings as supportive of the statements in the Torah to the effect that not only will the Aaronide priesthood be everlasting, but the Torah is “truth.” It encourages all Kohanim and Levites to register with it, and looks forward to a day when the Israelite Temple is rebuilt and “Kohanim [are] at their service, Levites on the Temple platform Israelites at their places.” (See http://www.cohen-levi.org/the_tribe/kohanim_forever.htm.)
Aside from the massive political problems associated with the rebuilding of the Temple, science, however, has not yet proven that the Exodus events as told in the Bible actually occurred at any time, much less at the time suggested by the text. Indeed, the narrative of migration and conquest is a matter in considerable dispute. (See Post, February 29, 2012.) Similarly, the historicity of Aharon and his immediate descendants has not been proven by either of the Kohanim studies discussed above.
Further, the story of an unbroken line of priests is internally contradicted by the Torah text itself as well as other Biblical and historic writings. For example, Deuteronomy refers to L’viyyim generally as well descendants of Aharon as being eligible for the priesthood. (See Deut. 17:18, 10:8-9, 33:8-10.) And the Maccabean revolt in the second century B.C.E., celebrated in the Hanukkah holiday, was not simply against Antiochus IV, but also the Jewish priests who may or may not have been in the Aaronide line but who, in any event, supported his efforts to Hellenize Judaism. Matityahu’s son Shimon (Simon) may have assumed Aharon’s role as Kohen Gadol, the high priest, but justified or not, his doing so was a stark departure from the theme of direct lineage. Finally, it is not at all clear that Aaronide lineage was restored during the Roman occupation of Palestine.
In short, as resonant as are the results of the Kohanim studies, they do not appear likely to make much of a difference, except perhaps to the psyche of some self-identified Kohanim.
What of the 95-97% of Jews who are not, or do not believe themselves to be, Kohanim? There are a number of broader lessons here. First, science is not static. The Kohanim studies were ground breaking, but also limited in scope due to subject matter, sampling size and the sophistication, or lack of it, of the researchers’ tool kit. Moreover, while patrilineality was key to Jewish identification in biblical times, it no longer is today, as a general matter, and has not been for fifteen to twenty centuries. Tracing Jewishness along the maternal path obviously requires investigating something other than the Y chromosome studied for the Kohanim. It means focusing on mitochondrial DNA, or mtDNA, which, while present in both males and females, is transmitted between generations only from mother to daughter. (See Goldstein, above, at 80.)
The Kohanim studies, and more advanced technology, did spur a spate of investigations into Jewish population genetics. Collectively, these studies did several things that the Kohanim studies did not do. They looked at a wider variety of Jewish populations, a wider variety of presumably non-Jewish populations for comparisons and control, greater numbers of participants and, by no means least, one more very important gender. Information concerning some of these more recent projects may be accessed at http://www.khazaria.com/genetics/abstracts-jews.html (Jewish Genetics: Abstracts and Summaries).
For instance, studies led by Naama Kopelman and Harry Ostrer confirm that Jews in different Diaspora groups share a common Middle Eastern deep ancestry, and “show a high level of genetic similarity to each other . . . .” (Abstract, at 7.) While each of the Jewish groups studied demonstrated its own distinctive genetic traits (id. at 6), there remained a “‘genetic coherence,’” a “‘high level of genetic relatedness’” among the groups. (Id. at 4-6.) Steven Bray’s study, however, while agreeing that Ashkenazi Jews share a common Middle Eastern origin with other Jewish populations, also suggests that there is more genetic diversity in the Ashkenazi population than previous thought. His results “show subtly more similarity to Europeans than Middle Easterners” and “aligning closest to Southern European populations . . . .” (Id. at 2.) Nevertheless, the ability of geneticists to specify when and how populations intermixed remains limited.
Geneticists have identified eighteen principal Y-chromosome haplogroups. A haplogroup is a population which shares the same collection of markers. Each of these major lineages bears an alphabetical designation from A through R. Ashkenazi Jews generally, but not always, fall into either the E or J haplogroup. (See Entine, above, at 88, 359-62.) (The twin ironies here cannot go unnoticed. Eighteen is the numerical equivalent of the Hebrew word for life. Higher Biblical criticism posits that the Hebrew Bible is an amalgam of four principle collections of writings, designated E, J, D and P, with E referring to an author who preferred to refer to God as Elohim and J referring to an author who favored YHVH.) The CMH haplotype is a subset within the J haplogroup.
The J1(M267) haplogroup, to which this Blogmaster belongs, emerged some 100,000 years ago in the southern Fertile Crescent, possibly where Iraq is located today. Over time, and through major immigrations, members of the group moved to Europe, Ethiopia, and later to North Africa and the Iberian Peninsula. All of this is also consistent with the Biblical story that places the patriarch Avraham (Abraham) initially in present day Iraq (whether northern or southern is in dispute, see Etz Hayim, above, at 62 n.28) and then traveling to Canaan and Mitzrayim. It in no way proves the existence of Avraham or that he engaged in the conduct described in the Bible, but it is consistent with the notion of a Middle Eastern origin for the Jewish People. More than half of J1(M267) in one database are Ashkenazi Jews, genetically connected to historic Jewish origins in the Middle East.
Long before genetic anthropology was a field of study, Mordecai Kaplan tried to resolve the question of the nature of Judaism by positing that Judaism was the evolving, religious civilization of the Jewish People. But that definition, while comprehensive, is still somewhat circular. Who or what are the Jewish People? Clearly they are other than merely co-religionists, because there are sharp disagreements among religious Jews about the most basic of religious principles and there are many non-religious Jews. Equally clearly, all Jews are not members of the same race, as that term is conventionally understood. Jews come in all colors and exhibit a wide variety of physical traits.
Nor, based on the information collected to date, can one reasonably argue that all Jews belong to a distinct genetic group. No haplotype is either necessary or sufficient for Jewish identity, whether viewed internally or externally. Similarly, genetics is not a conclusive basis for confirming or denying anyone’s Jewishness. Consequently, those who look to genetics, either to promote Jews or a Jewish cause or to reject Jews or a Jewish cause, are doing so without a firm scientific basis.
Despite the recent studies, and the sensationalized headlines that accompanied them, Jews remain something of an enigma, a people bound by a variety of common threads to each other, related by one or more of faith and culture, language and literature, desire and circumstance, and custom and experience. Today’s Jews are heirs not just to tales, texts and traditions that began thousands of years ago, but in some cases literal descendants of individuals who helped shape the collective history. Some consider themselves chosen, and others have made a choice to be part of the Jewish People, sharing not only history but destiny. The result is a multi-racial, transnational, sometimes fractious extended family. And, though an exceedingly small segment of the greater human family, an exceptionally interesting one at that.
To address this puzzle, in another insightful, if awkwardly phrased, thought, Mordecai Kaplan called this cluster of Jewish markers Peoplehood – a notion of inclusiveness and interconnectedness, of community consciousness and transcendence. Vague and complex, to be sure, Peoplehood allows for belonging in a way in which an unfeeling bio-chemical analysis of genes can never do.
Those interested in tracing their ancestral genetic line have many options. Among them are https://www.23andme.com/ and http://familytreedna.com/. Consider carefully the scope, terms, conditions and costs of any of these programs before participating. Test to satisfy curiosity, belong if you so choose.