This article originally posted at http://hnn.us/blogs/entries/12334.html
Palestinian Genes Show Arab, Jewish, European and Black-African Ancestry
David Storobin, Esq. - 6/9/2005
A study by the University of Chicago found that Arab populations, including Palestinians, Jordanians, Syrians, Iraqis, and Bedouin, have at least some sub-Saharan African genes. Non-Arabs from the region, including Turks, Kurds, Armenians, Azeris, Georgians, and Jews did not have any African roots.  A possible explanation is the proximity of the Arabian peninsula to the Black African nations. This conclusion is favored by the fact that Yemenite Arabs have 35% Black African genes in their mtDNA (which passes through the mother), while others have less. Yemen, of course, is very close geographically to several Black African nations. Other Arabs, especially those far away from the Arabian peninsula, have as little as 10% African blood in their mtDNA. As such, it is possible that the African gene was merely diluted by the introduction of non-Arab (and non-African) genes to the pool when Arabs began to conquer other Middle East people after the rise of Islam. The "real" Arabs -- those who have Arab ancestors stretching beyond the last 1,400 years - are actually 35% Black in their mtDNA. These Arabs are from the Arabian peninsula.
Other populations that are now called 'Arabs' became Arabized through intermarriage and adoption of the Arabic language and culture. These people are partially Arab and partially descendants of the nations that lived in their region prior to the rise of the Muslim faith. Just as their "Arab gene" was diluted by mixing with local genes, so too the 35% of the mtDNA that is Black African was diluted and reduced to around 10%.
The reduction of the Black genes from 35% to around 10% also suggests that the large majority (around 70%) of genes belonging to the Arabs outside the Arabian peninsula come from the local nations. The claim is supported by the historical fact that the original Arab population was relatively small and could not have populated a region stretching from Iraq to Morocco with such density, no matter the birthrate (and, in any event, where did the original populations go?). Both historically and genetically, it is almost definite that the Arab population intermarried with locals, including Palestinians, upon their conquest.
Palestinians, however, differ from other Arabs in some ways. As the web site for Harper's Magazine reported, one study showed that Jews and Palestinians have common ancestry that is so recent that it is highly likely that at least some of the Palestinian blood actually descends from Jews.  Another study by New York University confirmed a remarkable similarity between Jewish and Palestinian genes. "Jews and Arabs are all really children of Abraham," said Dr. Harry Ostrer, director of the Human Genetics Program at New York University School of Medicine, who worked on the study. "And all have preserved their Middle Eastern genetic roots over 4,000 years. 
According to several other studies, Palestinians and Jews are genetically closer to each other than either is to the Arabs of Arabia or to Europeans . A study of congenital deafness identified an allele limited to Palestinian and Jews of Ashkenazi origin (those who lived in Europe in recent centuries), suggesting a common origin. Furthermore, Y-chromosome polymorphism is very similar among Palestinians and Sephardic Jews. . While current studies show a lot of similarities and genetic closeness may be used to confirm claims of both sides to Israel/Palesitne, but right now, results are incomplete and are subject to much interpretation.  The above statements are based on the currently available information, but may be questioned by future studies.
There is a significant Christian population among Palestinian Arabs, leading some to claim that at least part of the Palestinian population (the Christians) descended from the original followers of Christ, who were, of course, Jews (they were Jews ethnically, even if they didn't follow Judaism). Despite extensive research, I have not been able to find any scientific studies supporting this claim.
Furthermore, the fact that there is joint heritage of 2,000-3,000 years ago does not mean that new genes were not introduced into the Palestinian genetic pool. For one, genes from the Arabian peninsula were introduced after the spread of Islam. As part of the Arabian genes, African genes were introduced, as described above.
Several studies have shown that Palestinians have a larger than usual (among Arabs) European blood. This may be explained by the Crusades and the establishment of a Crusader Kingdom in medieval times. It is highly likely that at least some percentage of the Palestinian population mixed with Europeans, either through intermarriage or rape of Arab women by Europeans, as well as European women by Arabs. Additionally, cities with significant Palestinian populations, including Bethlehem, Nazareth and Jerusalem, are sites of many Christian holy landmarks, which draw a large number of European tourists. This, too, may have played a role in the disproportionate amount of European genes found among Palestinians.
In more recent times, among Palestinian Muslims, there is a significant number of people who are recent immigrants from other Arab states. Official records of the Ottoman Empire (colonial power until WWI) and Britain (colonial power from the 1920's to 1948) show that there was very significant Islamic immigration into holy land. In some years, there were more Muslim new-comers than Jewish.