The authors of the book "The History and Geography of Human Genes"1, published in 1994, and the abridged version in 19962, took on the monumental task of analyzing the vast number of research articles written about genetic properties of different human populations. The senior author, Prof. L.L. Cavalli-Sforza, Professor of Genetics at Stanford University, is considered one of the preeminent human population geneticists in the world, a field that he has been working in for over forty years. After eight years of collecting this massive information, the authors spent several more years doing the genetic and statistical analyses using sophisticated computer methods. The objective was nothing less than to define the genetic variations in the entire human population of the world and, from that information, to trace the origin and migration of modern humans to their present locations on the planet (hence the "History and Geography" in the title). As the American Journal of Human Genetics stated, "This book represents a landmark in biology. There is nothing of its kind... where the evolutionary history of a single species possessing a cosmopolitan distribution is distilled from genetic, morphological, and cultural data. It represents an essential historical source for all human biologists ... " And as the New York Times said, "Perhaps more than anyone else in his field, Dr. Cavalli-Sforza ... has been able to make sense of the whisperings of human ancestors that are recorded in the genes of present-day people."
For their study, the authors chose to use data from only those populations that had been in the same geographic area for at least 500 years. They considered them as the native indigenous people of an area ("aboriginal") that could be used to trace human population origins, relationships and migrations. From analysis of the genes in these populations, it became possible to determine not only the genetic makeup of a people and the genetic relationships of different groups to each other, but also to measure the "genetic distance" between them. The analyses showed that there were sufficient data to provide statistically significant information on the genetic characteristics of 491 different human populations. Assyrians were one of them3-6. In this article, we will focus on the knowledge that has been gained about Assyrians and the genetic relationships between Assyrians and their neighbors, with the hope that it will lead to better understanding between the people of the Middle East.
Members of a specific human population, for example an ethnic group, identify with each other by a shared language and also by cultural, religious, social, geographic, and other features which are held in common. They distinguish themselves from other groups by the same criteria. What are "hidden" from external view are genetically determined attributes of the type that are only brought into the light by scientific methods such as those described in this book, and they reveal a very important component of a group - its genetic character. This can provide both a genetic definition of a group and also its relationships to other groups that would not be apparent otherwise. The use of language along with genetics to define groups is very useful, but linguistic change can occur much faster than genetic change and "languages are sometimes replaced by others of totally different origin in a very short time", as will be pointed out later in this article. As the authors state, "Only genes almost always have the degree of permanence necessary for discussing" the changes in populations that took place in the history of our species.
I have attempted the difficult task of presenting this information for the general reader in a concise way without compromising accuracy. Technical terms placed in parentheses are informative but not essential to understanding the basic ideas. But one technical element is crucial to the understanding of this information and I must briefly discuss it here. The chemical substance that makes up genes is DNA. A specific gene controlling the formation of a specific product may undergo a chemical alteration in its DNA ("mutation"). The product that it forms will then also be altered. We now have two forms of the same gene ("alleles") in the population and different individuals can get different forms of the gene. In the case of the familiar A, B, AB, and O blood types, whether an individual has the A form of the gene, the B form, or neither, determines the blood type. A human population can be genetically characterized by determining the distribution of the various forms of genes within that population ("gene frequency") - for example, what percentage of the population has the A, B, or O gene. When this is done for enough people and for enough different genes a "genetic profile" emerges for that population. Genes control the synthesis of proteins. In the "classical" studies that form the greater part of the material in the Cavalli-Sforza et al. book, the structure of the protein is analyzed as a genetic marker - the specific structure of the protein reflects the specific structure of the gene that codes for it. The proteins commonly analyzed as genetic markers are those that determine various types of blood groups, enzymes, blood serum proteins, hemoglobin, antibodies and cellular markers of the immune system (HLA system). In addition, direct analysis of DNA has recently become increasingly common and, of course, adds to the information pool about the genetic makeup of a people. In his very recent book2a, Cavalli-Sforza says: "Results with DNA have complemented but never contradicted the protein data." An example of DNA analysis will be seen later as part of the discussion of Jewish genetics.
Analysis of the Assyrians shows that they have a distinct genetic profile that distinguishes their population from any other population. It is important to understand that this applies to the population as a whole, not to any one individual. Each individual can have a variety of genetic features, but it is when all the data for the individuals are assembled together that the population can become distinctive. The authors state that "The Assyrians are a fairly homogeneous group of people, believed to originate from the land of old Assyria in northern Iraq," and "they are Christians and are possibly bona fide descendants of their namesakes." The main research paper on Assyrians is that of Akbari et al. (3), who state "that the Assyrians are a group of Christians with a long history in the Middle East. From historical and archeological evidence, it is thought that their ancestors formed part of the Mesopotamian civilization." Akbari et al. examined some 500 members of Christian communities in Iran (Armenians and Assyrians from six localities) from whom specimens were obtained and examined for a number of blood group, red cell enzyme and serum protein systems. In the case of Assyrians, the researchers studied 18 different gene sites with a total of 47 different forms of those genes (alleles) in Assyrians in two regions of Iran - Urmia and Tehran. The particular gene frequencies of those 47 genes in the population formed the basis, along with the other two studies (4, 5), for establishing the distinctive genetic character of the Assyrians. A major finding of the study is that Assyrians, especially those in Urmia (their home area in Iran), are genetically homogeneous to a high degree. That is, an individual Assyrian’s genetic makeup is relatively close to that of the Assyrian population as a whole. "The results indicate the relatively closed nature of the [Assyrian] community as a whole," and "due to their religious and cultural traditions, there has been little intermixture with other populations." The small size of the population is also a factor. The genetic data are compatible with historical data that religion played a major role in maintaining the Assyrian population’s separate identity during the Christian era.
For most of that period Assyrians existed as a Christian minority in non-Christian majority populations, and adherence to their religion, abundantly documented in the historical record, would have provided a "genetic barrier" to gene flow from external groups. In analyzing other groups in similar situations, Cavalli-Sforza et al. arrived at this opinion: "The important conclusion is that the genetic origin of groups that have been surrounded for a long time by populations of different genetic type can be recognized as different only if they have maintained a fairly rigid endogamy [ marriage within the group] for most or all the period in which they have been in contact with other groups," although genes contributed by external groups ("gene flow") can be tolerated for many centuries or even millennia by a population, provided they are not on a large scale. Later in this article we will see an analogous situation with Jews, where a religious difference allowed them to maintain their genetic characteristics as a minority over many centuries while living among non-Jewish majority populations. In any case, the data provide unequivocal evidence that Assyrians as a people are distinguishable from all other population groups in their genetic characteristics and are not a part of any other population.
The second important contribution that emerges from the book is seen when genetic relationships are made between the 18 populations of Western Asia for which enough data were available to allow meaningful interpretation. The results are summarized in the "tree" shown in the figure. The horizontal scale at the bottom quantitates the genetic distance between groups. The individual populations are listed in the general order of their relationships. The three Arab populations at the lowest part of the "tree" (Saudi, Yemeni, Bedouin) are close to each other genetically but are so far separated from the others as to constitute what the authors call a separate "minor cluster." The remaining 15 groups constitute the "major cluster."
Our primary purpose here is to define the relationships of Assyrians to their closest neighbors in the Middle East, so we will focus on seven groups that appear at the top of the "tree." Of these, Iranian and Iraqi are defined by the country of origin, after exclusion of Kurds. Jordanian, Lebanese and Turkish also mean the country of origin. Assyrians and Kurds refer to specific groups of people. All those studied were indigenous people of the area whose roots in their geographic locations go back to at least 1500 A.D. Relationship pairings are shown: Turkish and Iranian, and Assyrian and Jordanian are "loose" pairings; Druse and Lebanese form a closer pair; and Iraqi and Kurdish people form an extremely close pairing. The closest genetic relationships of the Assyrians are with the native populations of Jordan and Iraq. In point of fact, however, all of the seven populations of interest are quite close to each other. There are no wide separations between any of them. This despite the fact that they contain members of three major language families: Indo-European (Iranian, Kurdish), Turkic (Turkish) and Semitic (Iraqi, Jordanian, Lebanese - Arabic; Assyrian - Aramaic). As the authors state, "In spite of the complex history of the Middle East and the great number of internal group migrations revealed by history, as well as the mosaic of cultures and languages, the region is relatively homogeneous" [genetically]. The least heterogeneous zone of Asia "is observed in the Near East, where the highest population densities have existed the longest, especially in the central part (Mesopotamia). Ten thousand years of agriculture, ancient urban developments, and internal migrations are probably responsible for this homogeneity." Thus, in that part of the world with the most ancient civilizations, an underlying genetic homogeneity has been "masked" by great cultural, religious and linguistic heterogeneity.
The latter point is also made in studies of Jews. Based on earlier studies using classical genetic methods7 , Cavalli-Sforza et al. came to the conclusion "that Jews have maintained considerable genetic similarity among themselves and with people from the Middle East, with whom they have common origins." Evidence for the latter concept was very convincingly made and extended by an international team of scientists in a very recent research article8 ,widely reported in the press, in which the genetics of different Middle Eastern populations were studied using a completely different method than the classical methods that form the great majority of papers in the Cavalli-Sforza et al book. The research involved direct DNA analysis of the Y chromosome, which is found only in males and is passed down from father to son. Seven different Jewish groups from communities in Europe, North Africa and the Middle East were compared to various non-Jewish populations from those areas. The results showed, first of all, that "Despite their long-term residence in different countries and isolation from one another, most Jewish populations were not significantly different from one another at the genetic level." Furthermore, the genetic characteristics of Jews were shown to be distinctly different from (non-Jewish) Europeans, suggesting that very little admixture occurred between Jews and Europeans, even after about 80 generations of Jews in Europe. There was a similar distinct difference between Jews and North Africans. In striking contrast, there was an "extremely close affinity of Jewish and non-Jewish Middle Eastern populations [Palestinians, Syrians, Lebanese, Druze, Saudi Arabians] observed here ...[that] supports the hypothesis of a common Middle Eastern origin" of these populations dating back about 4,000 years. The differences between the populations were not statistically significant, demonstrating once again the close genetic relationship of Middle Eastern populations to each other. In fact, the Palestinians and Syrians were so close to the Jews in genetic characteristics that they "mapped within the central cluster of Jewish populations." As one of the Israeli scientists on the team said, "Eventually people will realize that they are not that different." Peace through Genetics?
Let us examine the situation in two areas of the Middle East where a radical change in the population and language occurred rapidly without being accompanied by a significant genetic change, and try to explain it. The land that now forms the nation of Turkey (Anatolia) was once a part of Byzantium. Greek (Christian) was the major influence there. The Turkic-speaking people arrived there from Central Asia in the 11th century A.D., spread successfully throughout the land and Turkish eventually became the dominant language as a Turkish nation was established. Turks are, as the authors state, "the only major group in the region that speak a language originated at a great geographic distance (probably in the Altaic region)." The pre-existing people in Anatolia, however, did not physically disappear. The genetic studies show that the majority became part of the new Turkish population. The genetic constitution of the Turks today is much closer to their nearest geographic neighbors, although none is a Turkic-language population, than to the Turkic-speaking populations of Central Asia. The authors interpret this to mean that "the Turkish language was imposed on a predominantly Indo-European-speaking population (Greek being the official language of the Byzantine empire), and genetically there is very little difference between Turkey and the neighboring countries. The number of Turkish invaders was probably rather small and was genetically diluted by the large number of aborigines." And [ in Turkey] "language replacement has occurred essentially without, or with very little, gene replacement."
In view of the authors’ theory explaining the genetic characteristics of the population in Turkey, it seems reasonable to consider the possibility that a similar type of event may have occurred in the Arab world of Mesopotamia and its adjacent regions - Iraq, Jordan, Lebanon (and presumably also Syria and Palestine) - to explain the genetic characteristics of those populations. In the 7th century A.D., after the conversion to Islam, the Arabs of the Arabian peninsula conquered large areas, including Mesopotamia and adjacent regions. Arabic became the major language of the region and an Arab nation was established there under Islam. But again, the pre-existing indigenous population, mainly Christian (including Assyrians), did not physically disappear, and the majority must have become part of the Arab population. Looking at the figure, one sees a very large genetic separation between the Arabs of the South - Saudis, Yemenites - and those in the region of Mesopotamia - Jordanian, Iraqi. The latter two groups are much closer genetically to the four non-Arab people of the region that we are interested in (Turk, Iranian, Kurd, Assyrian) than to the Arabs of the Arabian peninsula. As in the case of the Turks in Anatolia, these findings provide a clue that a relatively small number of Arabs from the Arabian peninsula may have carried out the conquest of a region with a much larger population, which included a number of cities, and that although the dominant language, religion and culture changed, the genes of the previous population may not have been significantly diluted and were transmitted to the present population of that region.
Finally, as seen in the figure, the two Indo-European language populations, the Iranians and the Kurds, are genetically closer to the Turks and the Semitic language group of Iraqi, Jordanian, Lebanese, Assyrian, than they are to their nearest Indo-European language speaking neighbors - Armenian, Pathan, Hazara Tajiki. In fact, the figure shows that the latter are part of a separate subcluster from the one in which the Iranians and Kurds are located.
The results of these scientific studies lead to the startling realization that Turks, Iranians, Kurds, Iraqis, Jordanians, Lebanese are more closely related genetically to Assyrians than they are to other members of their own respective language families in Asia. These seven groups (and Jews) are genetically close. The great language, cultural and religious differences are not reflected in the most fundamental aspect of their biology - their genes, which are the most accurate indicators of their shared origins and ancestry. If this were widely known, would the Assyrians seem so "different" to the others? Would changes in attitude begin to take place, especially among the intellectual and academic communities and the younger generations?
We stand with hope at the dawn of a new millennium. For mankind in general, the future holds exciting scientific prospects for understanding our past and present genetic nature. The tiniest amounts of DNA recovered from people who died thousands of years ago can now be exactly reproduced billions of times, providing abundant material for analyzing the genetic nature of ancient ancestors ("genetic archeology"). The "whisperings of our ancestors" can now be heard by us with our DNA amplifiers. Molecular genetics is poised to take understanding of the human race to heights undreamed of just a few years ago. Within the year there will occur one of the most momentous events in human history - the complete definition of the entire human genetic code (genome) of about 100,000 genes ("human genome project"). We will be able to see the complete DNA blueprint for creating a human being, God’s handwritten letter to us9. Future research will show how little difference there is between us in our DNA, giving us an unparalleled opportunity to understand how much of our humanity we hold in common.
Also standing at the dawn of the new millennium are the Assyrians - on the brink of extinction. For over 1900 years since they accepted Christianity and established the Church of the East, the Assyrians in the Middle East have survived for the most part as a religious and language minority. While this preserved their identity and kept them from disappearing, it came at a terrible price. The history of the Assyrians reads like one long unbroken story of massacre, persecution and indescribable horror, culminating in the 20th century with genocide and diaspora, followed by even more persecution and massacre. Was it just a coincidence that the first fratricide occurred in the Middle East, when Cain murdered his brother Abel? Will we ever be free of the curse of Cain? Will the younger generations of the Middle East release their souls from the dark forces of the past? Will the knowledge that Assyrians are their "blood relatives" begin to change the perception of Middle Eastern people about Assyrians? Will it be too late for the Assyrians?
References and Footnotes
- Cavalli-Sforza, L.L., Menozzi, P. and Piazza, A. The History and Geography of Human Genes. 1994. Princeton University Press. Unabridged Edition.
- As above, Abridged Paperback Edition. 1996. Contains the text of the Unabridged Edition, but not the hundreds of pages of genetic maps; has an index, and references to literature that were cited in the text. Only the unabridged version has the references for research articles that were used to arrive at each population group’s genetic analysis, listed by name for each population; also, the tables of gene frequencies.
- Cavalli-Sforza, L.L. Genes, Peoples, and Languages. 2000. North Point Press (division of Farrar, Straus and Giroux), New York. The book is a summation of the author’s work written for the general reader.
- Akbari, M.T. et al. Genetic Differentiation among Iranian Christian Communities. Am. J. Hum. Genetics, 38: 84-98. 1986. [Armenians and Assyrians].
- Papiha, S.S. et al. Isoelectric focusing of vitamin D binding protein (Gc): Genetic diversity in the population of Iran. Jpn. J. Hum. Genet., 30: 69-73. 1985.
- Amin-Zaki, L. et al. Glucose-6-phosphate dehydrogenase deficiency among ethnic groups in Iraq. Bull. WHO, 47:1-5. 1972. (References 3,4 and 5 were used to establish the Assyrian genetics in the Cavalli-Sforza et al. book).
- Ikin, E.W. et al. The blood groups and haemoglobins of the Assyrians of Iraq. Man, 65:110-111. 1965.
- Carmelli, D. and Cavalli-Sforza, L.L. The genetic origin of the Jews: A multi-variate approach. Hum. Biol., 51:41-61. 1979.
- Hammer, M.F. et al. [12 authors]. Jewish and Middle Eastern non-Jewish populations share a common pool of Y-chromosome biallelic haplotypes. Proceedings National Academy Sciences USA. The article appeared online on the website of the journal (www.pnas.org) on May 9, 2000, in advance of print publication. At the next issue of the journal, May 23, the article was still only online. Presumably, it will be in print in the following issue - June 6.
- The entire DNA code is written in an "alphabet" of four "letters," A, T, G, C, which stand for the four bases found in DNA - adenine, thymine, guanine, cytosine. The bases are lined up in a precise sequence to create a specific gene, say one that has 1,000 bases. Alteration of even one of the bases is a mutation.