User:Reallyskeptic

Critic on the "Genetic studies" section in the "Jews" entry
Let's review several examples.

The Cohen Modal Haplotype (CMH) original study was supposed to prove the genetic coherence of a a Jewish sub-population that avoided mixed marriages for many generations and thus support the notion of a common origin of present day Jews. However, a later study made by the same researchers on larger samples casted grave doubts on the historical relevance of CMH.

The last study of this research group found several Cohen lineages, not one. Moreover, their datings are based on controversial generation length (according to studies it should be at least 30 years not 25 for males) and mutation rate. With a more realistic mutation rate (0.0024 instead of 0.00069 as found in a recent Y STRs study based on fathers and sons) the Cohen lineages were founded long after the time indicated by the Bible.

This is not very surprising, a lot of archeological research is incompatible with the Bible so there is no reason to expect genetics will be different.

An even more striking example is Helmut Muhsam's old demonstration that Jews are probably not an ancient people in the process of assimilation into the gentile societies they live in, but the complete opposite.

Muhsam used the blood types data of Arthur Mourant and his co-workers to test the popular hypothesis of Jewish common origin. Such an hypothesis automatically requires that the frequency of Jewish blood types, starting at a set of common (but unknown) values will diverge over time towards the values of the gentile populations each Jewish community lives in.

To his chagrin Muhsam found the blood type frequencies are not diverging but very clearly converging.

Yet another example is...

These examples illustrate that Jewish genetics research doesn't really "prove" that the origin of present day Jews is from ancient Israel. In fact the opposite may be indicated.

Is there an alternative to the Jewish common origin hypothesis?

Considerable historical and anecdotic evidence indicates that intermarriage occurred not only between Jews and non-Jews in the communities in which they lived but also between different Jewish communities, even those quite far apart, both geographically and traditionally: Brides from Poland were married to Iraqi bridegrooms; Rabbis from Germany took up positions in Spain and their progeny were later expelled to North Africa; Rabbis from Morocco were hired to serve in Russia; Travelers from Europe spent long periods among Eastern communities, etc (see, e.g., ).

Thus, a model of a trellis may explain the genetic variability among Jewish communities better than that of the branching tree rooted in the ancestors who lived as a compact community in the land of Israel two millennia ago.

If this trellis model holds, it may be claimed that much of the genetic relations between Jewish communities are essentially secondary consequences of their common cultural connections: Having common religion and tradition caused the maintenance of a constant trickle of gene-exchange between communities; this explains the shared genetic composition of Jewish communities, some of these introduced alleles may have spread to reasonable frequencies.

Such a trellis model of the distribution of gene frequencies among Jewish communities does not exclude that at least some of the common alleles stem from the populations that inhabited the Near East in ancient times.

Testing a trellis model will eliminate an important theoretical reservation to Jewish genetics research, the fact that no alternative hypotheses to the common ancestors assumption were examined. The analyses were performed explicitly to uphold the traditional preconception that the Jewish communities differ from the non-Jews among whom they lived and have common frequencies of genetic markers because they are direct descendants of the ancient Biblical nation of Israel. On this assumption computer programs were applied to construct pedigree trees that identify the genetic composition of the ancestors at the root of this tree and the time the lived.

Summary
Can we safely conclude that most current day Jews are descended from immigrants or exiles from an ancient Jewish state that had existed in the Middle East? Certainly not! There is not sufficient data and what we have seems to point in the opposite direction.

Old stuff
<!-- There are many reservations, mainly methodological, from the above mentioned genetic studies and the conclusions derived from them. These reservations were raised by various researchers of population genetics, demography and statistics who have challenged the assumptions at the base of the studies:


 * 1) The studies lack good comparisons (?) and have other flaws, like the definition of what constitutes a Jewish population (for instance, North African Jews are by no mean a population but a term describing a few distinct and quite different Jewish populations).
 * 2) The question whether current day Jews are the descendants of ancient Jews should be asked separately for each Jewish population.
 * 3) The Y chromosome and the mtDNA are not good markers to examine the origin of populations, because they are single uniparental markers that do not represent the whole history of the population, and because their smaller effective population size makes them much more vulnerable to severe genetic drift caused by demographic bottlenecks, which actually makes them quite useless as a tool to study the origins of the Ashkenazi populations. The right markers to use are the autosomal markers and there is no mention there of these.
 * 4) The Cohen Modal Haplotype (CMH) study is supposed to prove the genetic coherence of a a Jewish sub-population which didn't practice mixed marriages and thus support the notion of a common origin of current day Jews. However, further study made on larger samples by the same researchers casts grave doubts on the historical relevance of CMH. The last study [Hammer et. al. (2009), Human Genetics 126:707-717] ^[1] found several Cohen lineages and includes datings based on a controversial mutation rate and generation length (according to studies it should be for males at least 30 years not 25). With a more realistic mutation rate (0.0024 instead of 0.00069, as found in a recent Y STRs study based on fathers and sons) the Cohen lineages probably started long after the Biblical specified time.
 * 5) An important theoretical reservation is that no alternative hypotheses to the common ancestors assumption were examined. The analyses were performed explicitly to uphold the traditional preconception that the Jewish communities differ from the non-Jews among whom they lived and have common frequencies of genetic markers because they are direct descendants of the ancient Biblical nation of Israel. On this assumption computer programs were applied to construct pedigree trees that identify the genetic composition of the ancestors at the root of this tree and the time the lived.
 * Considerable historical and anecdotic evidence indicates that intermarriage occurred not only between Jews and non-Jews in the communities in which they lived but also between different Jewish communities, even those quite far apart, both geographically and traditionally: Brides from Poland were married to Iraqi bridegrooms; Rabbis from Germany took up positions in Spain and their progeny were later expelled to North Africa; Rabbits from Morocco were hired to serve in Russia; Travelers from Europe spent long periods among Eastern communities, etc [see, e.g., Sand, S. (2008). When and How the Jewish People was Invented? (in Hebrew). Tel Aviv: Resling].
 * Thus, a model of a trellis [Templeton, A. R. (1998). Human races: A genetic and evolutionary perspective. American Anthropologist, 100, 632-650] may explain the genetic variability among Jewish communities better than that of the branching tree rooted in the ancestors who lived as a compact community in the land of Israel two millennia ago.
 * If this trellis model holds, it may be claimed that much of the genetic relations between Jewish communities are essentially secondary consequences of their common cultural connections: Having common religion and tradition caused the maintenance of a constant trickle of gene-exchange between communities; this explains the shared genetic composition of Jewish communities, some of these introduced alleles may have spread to reasonable frequencies.
 * Such a trellis model of the distribution of gene frequencies among Jewish communities does not exclude that at least some of the common alleles stem from the populations that inhabited the Near East in ancient times [Falk, R. (2006). Zionism and the Biology of the Jews (in Hebrew). Tel-Aviv: Resling].

In view of these reservations, the conclusion that most current day Jews are descended from Jewish immigrants or exiles from a Jewish state that had existed in the Middle East seems hasty and unwarranted.

According to critical genetics researchers who base their opinion on all the available data (only some of it has been published), at least most if not all Jewish populations are not the descendants of the ancient Jews, who inhabited the Land of Israel 2,000 years ago, but rather the descendants of proselytes. It's estimated that even for the Jewish populations whose origins are still obscure, the likelihood of them being descendants of the ancient Jews is not high and lower than the likelihood that the Palestinians are descendants of the ancient Jews.

1. ^ [1] Hammer et. al. (2009), Extended Y chromosome haplotypes resolve multiple and unique lineages of the Jewish priesthood, Human Genetics 126:707-717 -->