posted
Genetic Studies is not my cup of tea. Can any genetic buffs on this site tell me their conclusions from the following studies please. Thanks in advance for your help.
1. The DNA Evidence for Israelite Ancestry: The Jewish Priests and Cohanim DNA Study
The search for Israelite/Middle Eastern DNA among contemporary Jewish populations properly begins with Dr. Karl Skorecki’s landmark genetic study of the Cohanim, the priests of the Jewish religion. The study came about based on the following story:
Dr. Skorecki, a Cohen of Eastern European descent (Ashkenazim), was attending synagogue one morning. During the service, a Cohen of Sephardic descent from North Africa was reading from the Hebrew bible. According to Jewish tradition, all Cohanim (plural of “Cohan” or “Cohen”) are direct descendants of Aaron, the brother of Moses, and serve important priestly functions within the Jewish religion. The line of the Cohanim is patrilineal, allegedly being passed from father to son without interruption from Aaron, for 3,300 years, or more than 100 generations. Dr. Skorecki wondered if this claim could actually be tested. Could he find scientific evidence to support the oral tradition of an ancient priestly lineage? Did he and the Sephardic Cohen possess a set of common genetic markers indicating they shared a common ancestor?
Dr. Skorecki, a nephrologist already involved in molecular genetic research, contacted Dr. Michael Hammer of the University of Arizona, a pioneer in Y chromosome research, and the Cohanim DNA study was born. Their findings clearly indicated that the Cohanim did indeed share a common ancestor. They discovered that a particular haplotype was found in 97 out of the 106 participants tested. This haplotype has come to be known as the “Cohen Modal Haplotype” or “CMH”. According to the study, calculations for dating the CMH yielded a time frame of 106 generations from the ancestral founder of the lineage – approximately 3,300 years ago (Thomas et al. 1998).
Not only did the genetic researchers corroborate the oral history of an ancient Jewish priestly caste, but they also confirmed the genetic link between both Sephardic and Ashkenazi populations, indicating that before the two populations separated, those who shared the CMH also shared common Israelite ancestry. Today, the CMH is considered not only the standard genetic signature of the priestly Cohanim, but also the yardstick by which all Jewish DNA is compared for determination of Israelite genetic ancestry. Thus, if a haplogroup is not shared by both Sephardim and Ashkenazim at a similar frequency, then it is generally not considered to be of Israelite origin.
Skorecki and Hammer reported that the CMH occurred within Y chromosome haplogroup J (Skorecki et al. 1997). We now know significantly more about haplogroup J than when these studies were originally published. Haplogroup J consists of an ancestral form (J*) and two subgroups – J1 and J2. Although you can have the CMH in either J1 or J2, it is the genetic signature in J1 that is considered the Jewish priestly signature.
What is not widely reported is that only 48% of Ashkenazi Cohanim and 58% of Sephardic Cohanim have the J1 Cohen Modal Haplotype (Skorecki et al. 1997). So nearly half of the Ashkenazi Cohanim results are in haplogroups other than J1. Overall, J1 constitutes 14.6% of the Ashkenazim results and 11.9% of the Sephardic results (Semino et al. 2004). Nor is Cohanim status dependent on a finding of haplogroup J1.
Additionally, many other haplogroups among the Ashkenazim, and among the Cohanim in particular, appear to be of Israelite/Middle Eastern origin. According to Behar (2003), the Cohanim possess an unusually high frequency of haplogroup J in general, reported to comprise nearly 87% of the total Cohanim results. Among the Sephardim, the frequency of 75% is also notably high (Behar 2003). Both groups have dramatically lower percentages of other haplogroups, including haplogroup E. Given the high frequency of haplogroup J among Ashkenazi Cohanim, it appears that J2 may be only slightly less common than J1, perhaps indicating multiple J lineages among the priestly Cohanim dating back to the ancient Israelite kingdom.
However, J1 is the only haplogroup that researchers consider “Semitic” in origin because it is restricted almost completely to Middle Eastern populations, with a very low frequency in Italy and Greece as well (Semino et al. 2004). The group’s origins are thought to be in the southern Levant. Its presence among contemporary Sephardic and Ashkenazi populations indicates the preservation of Israelite Semitic ancestry, despite their long settlement in Europe and North Africa. Further, the CMH is considered the putative ancestral haplotype of haplogroup J1 (Di Giacomo et al. 2004).
Researchers believe that marker 388=17 is linked with the later expansion of Arabian tribes in the southern Levant and northern Africa (Di Giacomo et al. 2004). There were two migrations of J1, the first occurring in the Neolithic period, spreading J1 to Ethiopia and Europe (Semino et al. 2004). A second wave of J1 occurred in the 7th century, spread by Arab expansion from the southern Levant into North Africa. This secondary migration is also distinguished by a mutational event at marker YCAII—YCAIIa=22 and YCAIIb=22 (Semino et al. 2004).
The Cohanim study was widely misinterpreted by the public as indicating that all Jews were in haplogroup J and had the CMH. Furthermore, many non-Jews in haplogroup J mistakenly believed that they must have some Jewish ancestry hidden in their past to explain their DNA results. As it turned out, most non-Jews were in subgroup J2 rather than J1 (Semino et al. 2004). Interestingly, Jews were later found to have as much J2 ancestry as J1.
The misinterpretation of the Cohanim results was damaging in some ways to the wider understanding of Jewish genetic ancestry. For example, one widely published media quote went like this: “This genetic research has clearly refuted the once-current libel that Ashkenazi Jews are not related to the ancient Hebrews, but are descendants of the Kuzar (sic) tribe – a pre-10th century Turko-Asian empire which reportedly converted en masse to Judaism.” Further, it was claimed that “[r]esearchers compared the DNA signature of the Ashkenazi Jews against those of Turkish-derived people, and found no correspondence” (Kleinman 1999).
However, it would soon become very clear that Jewish DNA was much more complicated than was presented by the media in their reporting of the Cohanim data. And Jewish Khazarian ancestry would come to the public’s attention yet again when another DNA study was conducted, this time on the Jewish priestly group known as the Levites.
2 The Levites: The DNA of the Jewish Khazarian Priests
The other Jewish priestly caste is known as the “Levites.” Like the Cohanim, Levites are recorded in the Hebrew Bible as direct descendants of Aaron, Israel’s first High Priest. In fact, the Cohanim are actually a special subsection of the Levites (Telushkin 1997, p. 125).
In the second study published on the Cohanim, researchers reported that despite a priori expectations, Jews who identified themselves as Levites did not share a common set of markers with the Cohanim (Thomas et al. 1998). Unfortunately, the reporting that the Levites did not share a genetic signature from a common patrilineal ancestor with the Cohanim flew in the face of Jewish tradition. This led to some rather bizarre and disparaging explanations, like the following from Rabbi Yaakov Kleiman (1999) in Jewish Action:
It is interesting to note that the tribe of Levi has a history of lack of quantity…After the Babylonian exile, the Levi’im (plural) failed to return en masse to Jerusalem, though urged by Ezra the Scribe to do so (They were therefore fined by losing their exclusive rights to maser.). Though statistically, the Levi’im should be more numerous than Cohanim, in synagogues today it is not unusual to have a minyan with a surplus of Cohanim, yet not one Levi.
In point of fact, the Levites were shown to have a common set of genetic markers – just not the CMH. These markers were not even part of the same J1 haplogroup as found in the Cohanim. The majority of Levites shared a common haplotype, indicating a shared common ancestor among them, but this haplotype occurred within haplogroup R1a and, more specifically, within subgroup R1a1. Furthermore, this haplogroup was found only in the Ashkenazi Levites; it was not shared with the Sephardic Levite population in the same fashion as the CMH. Given the fact that the Ashkenazi Levites did not share R1a with their Sephardic counterparts, it appeared that this haplogroup had entered the Jewish population sometime during the Diaspora.
In one of the first studies to closely examine the high levels of R1a among Levites, researchers found that R1al formed a “tight cluster” within the Ashkenazi Levites (Behar et al. 2003). This suggested to the researchers a very recent origin of this group from a single common ancestor (Behar et al. 2003).
In a subsequent Levite study, the modal haplotype reported for Ashkenazi R1a1, known as “H6,” was reported to occur twice as often as the second most common R1a1 haplotype among Ashkenazim, known as “H10” (Nebel et al. 2005). Out of a sample of 55 individuals, 25 had haplotype “H6” and 12 had haplotype “H10” (Nebel et al. 2005, Supplementary Material).
Behar believed that among Ashkenazi Jews, R1a1 was essentially restricted to Levites. However, we know from subsequent research that R1a1 comprises nearly 12% of Ashkenazi results, while the Levites only make up about 4-5 % of the Jewish people (Nebel et al. 2005). Thus, these results extend well beyond the Levite priestly class to approximately 5-8% of the Cohanim and Israelites (the non-priestly Jewish population) as well.
Haplogroup R1a1 is relatively rare within Middle Eastern populations, but very common among Eastern European and Scandinavian populations (Behar et al. 2003). It is found at a frequency of 7% in some Near Eastern groups (Behar et al. 2004b). However, given that Sephardic groups did not share R1a1 frequencies with the Ashkenazim, it was apparent that Jewish R1a1 was probably not of ancient Israelite origin.
Confirmation of the high frequency of Haplogroup R1a1 among Ashkenazim as compared to other Jewish and non-Jewish Middle Eastern populations was found in a genetic study on Samaritan and Israeli groups (Shen et al. 2004). Although population samples were small, consisting of twenty participants from Ashkenazi Jewish groups, all were Eastern Ashkenazim of Polish ancestry. Ashkenazi results were compared to other Jewish groups from Iraq, Libya, Morocco, Ethiopia and Yemen, as well as to non-Jewish Samaritan, Druze and Palestinian populations. Shen found that haplogroup R was found in 10-30% of all the groups, with the exception of Palestinians and Ethiopian Jews, though the majority belonged to R1b and R*. In contrast, the Ashkenazim had the highest percentage of haplogroup R (30%), with two-thirds of those results found in haplogroup R1a (Shen et al. 2004).
As for when R1a1 first entered the Jewish community, Behar (2003) estimated a mean TMRCA (time to the most recent common ancestor) of 663 years before the present using the Simple Stepwise Mutation Model and a mean time of 1,000 years before present under the Linear Length-Dependent Stepwise Mutational Model. This calculation was striking because it fit precisely within the time period that Koestler believed the mass migration and absorption of the Khazars by the larger Eastern European Jewish communities occurred.
R1a1 is found in very high frequencies not only in the area of Eastern Europe where the Khazarian kingdom is reported to have existed, but also in many Central Asian populations as well, where some of the Khazarian population may have originated (Nebel et al. 2005). Furthermore, the most common Ashkenazi haplotype, H6, is identical to the most common haplotype found among European R1a1 (YHRD 2003). Ashkenazi H10 is identical to the fifth most common European R1a1 haplotype.[1]
Behar (2003) noted that Ashkenazi R1a1 haplotypes clustered closely with those seen in Sorbian and Belarusian groups in Eastern Europe, yet the haplotypes were dissimilar enough to convince him that these groups were not the original source population for Ashkenazi R1a1. While the Ashkenazi H6 haplotype is also one of the most common haplotypes among the Sorbian and Belarusian populations, the modal haplotypes found among these two Eastern European groups do not appear among Ashkenazim (Behar, 2003). However, it is possible that genetic drift could have led to the loss of other Jewish R1a1 lineages (Behar, 2003).
Nebel (2005) emphasized that the R1a1 haplogroup must have entered the Jewish gene pool from outside sources because the ancestral haplotype (H6) is almost completely absent in Sephardic Jews, Kurdish Jews and Palestinian population samples. He suggested that R1a1 in Ashkenazim “may represent vestiges of the mysterious Khazars.” However, he also argued for a single founder event early on in the Jewish Diaspora, proposing that the TMRCA for R1a1 among Ashkenazi was approximately 62.7 generations ago, or 1567 years ago.
However, the proposal that R1a1 originated with a single founder event early in the Diaspora has become increasingly unlikely as research on Jewish DNA progresses. Since R1a1 is spread fairly evenly in haplotype distribution and frequency throughout the Ashkenazi populations from various countries (Germany, Lithuania, Czechoslovakia, Hungary, Romania, Poland, Russia and the Ukraine), then the founders must have entered the community either before it expanded and spread to Eastern Europe, or merged separately into both eastern and western Ashkenazi groups. However, Nebel (2005) is forced to assert an extremely early TMRCA due to his belief that R1a1 must have originated with a single founder or very small group of founders. In order for R1a1 to reach its high frequency (12%) among the Ashkenazim from a single founder, a very early date must be proposed for the introgression of this haplogroup. Under this scenario, R1a1 entered the Jewish community when it was extremely small and in its formative stage. Gene flow from a single R1a founder at this early stage would likely have a huge impact on the expanding Ashkenazi population.
However, it appears that the most recently revised mutational dating techniques lend support to Behar’s (2003) later date when applied to Jewish R1a1 haplotypes. If we assume that R1a1 entered the Jewish community around 1300 CE, then there would need to be enough founders to leave a 12% genetic impact on the population. Given that the Ashkenazi population at that time is estimated to be approximately 25,000 persons, it would be nearly impossible for a single founder to make such a significant genetic impact (Behar et al. 2004b). Adopting this conservative estimate of 25,000 persons, approximately two to three thousand R1a1 males probably entered the Ashkenazi community between the 12th-13th centuries.
Interestingly, there are no historical accounts of any large scale conversions or Eastern European groups entering the Jewish community at this time – except the Khazars.
Additionally, given the relatively late date of introgression and the large number of founders, these males must have already been very closely related to each other, sharing the R1a1 haplotypes that are later reflected in the Levite results. Behar (2003) noted that the lack of Levite R1a1 haplotype diversity suggested that all the founding lineages were very closely related to each other if, in fact, a large number of founding lineages contributed to the Levite R1a1 gene pool. The ancient reports on the Khazars indicate that the majority of the Jewish converts were from the Khazarian royalty and ruling classes (Koestler 1976, p.15). Although speculative, it seems likely this group would have intermarried heavily amongst itself, helping to preserve the group’s elite status. Thus, it is probable that they would have already possessed a set of closely related R1a1 haplotypes which they simply passed on to their Levite descendants.
Most importantly, the fact that these R1a1 founders were endowed with Levite status is highly revealing. Behar (2003), in fact, argues against the possibility of a large number of R1a founders because it would involve a breach of “a well-regulated rabbinically controlled barrier” and would “most likely leave some prominent trace in the historical record – which it has not.” However, he then suggests that the R1a introgression may indicate a lesser degree of stringency for the assumption of Levite status than for the assumption of Cohen status. He points to a passage in the Talmud involving a debate over whether Levite status should be accorded to a man whose father was a non-Jew and who mother was the daughter of a Levite. This suggests that assignment of Levite status other than through patrilineal descent could have been sanctioned by the rabbinical authorities.
However, the Khazars were already Jewish, having converted hundreds of years before. Although of a different ethnic make-up than the Ashkenazim of the 13th century, they were not “non-Jews.” They probably already had their own Levite caste in place who may have simply continued their priestly functions among the Ashkenazim.
Integration into the Levite priesthood would have secured for the Khazarian immigrants a place in their new community while helping them maintain a sense of elite status among a new people. Yet it is clear that the Khazars had become Jews long before they became part of the larger Ashkenazi community. Thus, it should not be surprising that six hundred years after their reported conversion, the Ashkenazim may have accorded them a special role among their Levite priesthood.
The Khazars and the Smoking Gun of Haplogroup Q
With the discovery of haplogroup Q among Ashkenazi Jews, DNA researchers may have found the “smoking gun” of Khazarian ancestry.
In one of the few DNA studies to examine haplogroup Q among Jews, researchers made the surprising declaration that only 5-8% of the Ashkenazi gene pool is comprised of Y chromosomes that originated from non-Jewish European populations (Behar et al. 2004b). But since subsequent research has confirmed that R1a1 alone comprises nearly 12% of the Ashkenazi gene pool, it now appears that Behar’s estimate is much too low. Additionally, Behar’s (2004b, Supplementary Material) own data indicate that haplogroups R1b, R1a and I comprise more than a quarter of Ashkenazi DNA results.
As for haplogroup Q, Behar (2004b) states that it is a “minor founding lineage” among the Ashkenazim, but does not discuss it any further in the study. Haplogroup Q appears in 23 out of 442 Ashkenazi results in Behar’s study, or approximately 5% of the total results (Behar et al. 2004b, Supplementary Material). Interestingly, out of 50 non-Jewish Hungarian results also appearing in this study, haplogroup Q did not appear at all (Behar et al. 2004b, Supplementary Material).
Approximately 19 out of the 23 Q results exhibited the above haplotype, with 3 additional results being a single step mutation away on DYS marker #393 (Behar et al. 2004b, Supplementary Material). In fact, so many identical haplotypes makes it difficult to accurately date Ashkenazi Q, since using a TMRCA calculation indicates these Ashkenazim, both eastern and western groups, could be related within the last hundred years. This, however, seems highly unlikely, given the separation between these populations over the last few hundred years.
By designating Q a “minor founding lineage,” Behar (2004b) places this group among “those haplogroups likely to be present in the founding Ashkenazi population.” However, given that Haplogroup Q is rarely found in Middle Eastern populations in DNA studies, the likelihood that Q can be attributed to Israelite ancestry seems remote. The presence of Haplogroup Q among all Ashkenazi groups indicates the founders of this group either mixed with a number of separate Ashkenazi populations or, more likely, entered to the Ashkenazi population in western Europe in a similar fashion to Haplogroup R1a1, before the Ashkenazi migrated in large numbers eastward in the 13th-14th centuries.
The extremely low haplotype diversity of Ashkenazi Q supports the argument of a small number of closely-related founders merging with the Ashkenazim while they still resided primarily in Western Europe, but not significantly earlier in their formation, since a longer time span would result in more haplotype diversity. It does not support the contention that Q is Israelite in origin, or that the founders merged into the Jewish population much earlier in the Diaspora. Assuming the Ashkenazi population consisted of approximately 25,000 individuals around 1200-1300 CE, then approximately 1000-1500 Q individuals became part of the Ashkenazi population at that time.
Haplogroup Q is rare in European populations as well. It occurs in low percentages in Hungary (2.6%) and much higher percentages in Siberia (Tambets et al. 2004). It can be found among populations in Norway and the Shetland Islands of Scotland where many Norwegian Vikings settled. The frequency of Haplogroup Q among Scandinavians is comparable to that found in Ashkenazim (Faux, private correspondence). It appears that Norwegians/Shetlanders and Ashkenazi Jews possess the highest percentages of haplogroup Q of any populations in Europe – a rare link between two very different populations who may share a common ancestor from Central Asia or Eastern Europe. Interestingly, Scandinavians and Shetlanders also possess high levels of haplogroup R1a1 as well, perhaps some of it originating from Central Asian sources (Faux, private correspondence).
David Faux, a researcher examining the Shetlander’s DNA and possible Central Asian links, notes the following:
The best evidence we have to date is that, although not investigated scientifically, that Q and K* arrived with R1a from the same population source in the Altai region of Russian Siberia. It is likely that what we are seeing with Q and K are very rare Scandinavian haplogroups whose origins were long ago in Asia. If this is true, then it is very unusual that there does not seem to be any Q or K along the overland pathways to Norway (e.g., in Western Russia) – but there is Q, along with R1a, in the region of Kurdistan, and among a significant percentage of Ashkenazi Jews.
Faux further hypothesized that the homeland of Norse Q lies somewhere in the populations of Siberia, such as with the Selkups (66.4% Q and 19.1% R1a) or the Kets (93.7% Q), or among the populations of the Altai mountain system extending through Mongolia, Kazakhstan and Russia (Tambets et al. 2004).
Haplogroup K* also appears among Ashkenazim, though this group is rarely discussed in the DNA literature. Behar (2004b, Supplementary Infor-mation) found 2-3% among Ashkenazi Jews. Behar identifies this group as K*-M9, though they may, in fact, be within Haplogroup K2, since they closely match the K2 haplotypes reported among Turkish groups (Cinnioglu 2004). The appearance of Haplogroup K* only among eastern Ashkenazim may be attributable to Eastern European or Khazarian admixture (Behar 2004b, Supplementary Material). Interestingly, Ashkenazi K* exhibits more haplotype diversity than haplogroup Q results, perhaps indicating a larger percentage of unrelated K* founders or genetic drift.
However, Behar (2003) reports finding a significantly higher frequency of haplogroup K* among Sephardic Levites (23%) and Sephardic Israelites (13%), perhaps the highest frequency of K* found among any European population. This may indicate that some of Ashkenazi K* is, in fact, of Israelite origin. Its absence among western Ashkenazim and very low frequency among eastern Ashkenazim suggests that the high frequency of Sephardic K* may be due to pronounced genetic drift or significantly more K* founders as part of the original Sephardic population. However, it is also possible that Sephardic K* is the result of admixture with African or Mediterranean groups. Haplogroup K* is known to reach a frequency of 10% in Cabo Verbe, an east Atlantic island population with ties to Jewish founders from Spain and Portugal (Goncalves et al. 2003).
A comparison of haplogroup Q among Altaians and Ashkenazi Jews was undertaken by Dienekes Pontikos (2004), who operates a respected website dedicated to the examination of anthropological, archaeological and genetic research. He compared the frequency of haplogroups R1a and Q among Altaian Turkic speakers and Ashkenazi Jews. For Altaians, the percentages are 46/17, or a ratio of about 2.7, while in Ashkenazim it is 12/5, or a ratio of about 2.4. Dienekes writes:
If Proto-Khazars were similar to present-day Altaians minus haplogroup C, then they would have a frequency of about 59% R1a and 22% Q. Therefore, it seems reasonable that an overall 5/22=22% of such Proto-Khazar elements into the Ashkenazi Jewish populations may be likely. But, the Khazars of Khazaria may themselves have been somewhat mixed with Western Eurasian elements, which would decrease their frequency of haplogroup Q.
Dienekes (2004) also wrote that he found the continued silence of researchers about the presence of haplogroup Q among Ashkenazim “puzzling.”
Haplogroup Q is found in high frequencies in only a few regions of the world. Native American’s possess very high percentages of Q, particularly a sub-group known as “Q3” (Zegura et al. 2004). But haplogroup Q did not originate among the Native Americans, nor did this population obtain their Q ancestry from Jewish or Scandinavian ancestors. As previously noted by Faux, its origins probably lie somewhere in northern Eurasia, in Siberia or the Altai, where Q continues to be a common Y chromosome haplogroup. It is from this group after migration to the New World that Native American Haplogroup Q3 originated.
Genetic analysis has allowed researchers to trace Native American haplogroup Q to its probable ancestral homeland – the Altai Mountains of Southwest Siberia (Zegura et al. 2004). The researchers have also pointed out that the Kets and Sekups, who currently inhabit the eastern part of Western Siberia and the Yenisey River Valley, can trace their origin homeland further south, on the slopes of the Altai mountains (Zegura et al. 2004). This region is, of course, where Faux postulated that Scandinavia’s Q and K* ancestors originated. It may also be the homeland of Khazarian Q ancestors whose descendants are found today among Ashkenazi Jewish groups.
In conclusion, it appears that some members of three very distinct populations—Scandinavian-Shetlanders, Native Americans and Ashkenazi Jews–may share common ancestors originating from the Altai regions of southern Siberia. However, the Q ancestors of the Native Americans appears to have departed from their Altai homeland much earlier than the other two groups, migrating to the New World sometime between 10,000 to 17,000 years ago, providing sufficient time for the Native Americans to develop their own unique subgroup of Q, known as Q3 (Zegura et al. 2004).
The migration of R1a and Q groups into Scandinavia is presently unknown, though Faux postulates a group from Central Asia may have moved up into Scandinavia sometime around 400 CE. Only a few hundred years later, the Khazars of southern Russia make their first appearance in the historical record. And it is to the Khazars, who undoubtedly possessed a high frequency of this haplogroup, to which the Jews most likely owe their unique Q ancestry.
Posts: 620 | From: London | Registered: Mar 2009
| IP: Logged |
UBBFriend: Email this page to someone!
Printer-friendly view of this topic