Identifying Genetic Traces of Historical Expansions: Phoenician Footprints in the Mediterranean

The Phoenicians were the dominant traders in the Mediterranean Sea two thousand to three thousand years ago and expanded from their homeland in the Levant to establish colonies and trading posts throughout the Mediterranean, but then they disappeared from history. We wished to identify their male genetic traces in modern populations. Therefore, we chose Phoenician-influenced sites on the basis of well-documented historical records and collected new Y-chromosomal data from 1330 men from six such sites, as well as comparative data from the literature. We then developed an analytical strategy to distinguish between lineages specifically associated with the Phoenicians and those spread by geographically similar but historically distinct events, such as the Neolithic, Greek, and Jewish expansions. This involved comparing historically documented Phoenician sites with neighboring non-Phoenician sites for the identification of weak but systematic signatures shared by the Phoenician sites that could not readily be explained by chance or by other expansions. From these comparisons, we found that haplogroup J2, in general, and six Y-STR haplotypes, in particular, exhibited a Phoenician signature that contributed > 6% to the modern Phoenician-influenced populations examined. Our methodology can be applied to any historically documented expansion in which contact and noncontact sites can be identified. The Phoenicians were the dominant traders in the Mediterranean Sea two thousand to three thousand years ago and expanded from their homeland in the Levant to establish colonies and trading posts throughout the Mediterranean, but then they disappeared from history. We wished to identify their male genetic traces in modern populations. Therefore, we chose Phoenician-influenced sites on the basis of well-documented historical records and collected new Y-chromosomal data from 1330 men from six such sites, as well as comparative data from the literature. We then developed an analytical strategy to distinguish between lineages specifically associated with the Phoenicians and those spread by geographically similar but historically distinct events, such as the Neolithic, Greek, and Jewish expansions. This involved comparing historically documented Phoenician sites with neighboring non-Phoenician sites for the identification of weak but systematic signatures shared by the Phoenician sites that could not readily be explained by chance or by other expansions. From these comparisons, we found that haplogroup J2, in general, and six Y-STR haplotypes, in particular, exhibited a Phoenician signature that contributed > 6% to the modern Phoenician-influenced populations examined. Our methodology can be applied to any historically documented expansion in which contact and noncontact sites can be identified. The Phoenicians were a distinctive and independent civilization that dominated the Mediterranean Sea during the first millennium BCE, emerging from a coastal section of the Eastern Mediterranean, including the four main Bronze Age maritime cities of Tyre, Sidon, Byblos, and Arwad and located in the modern countries of Lebanon and southern Syria. From here, their maritime expertise allowed them to establish a trading empire throughout the Mediterranean and beyond.1Stieglitz R.R. The geopolitics of the Phoenician Littoral in the Early Iron Age.Bull. Am. Schools Orient. Res. 1990; 279: 9-12Crossref Google Scholar, 2Moscati S. The World of Phoenicians. Weidenfeld and Nicolson Ltd., London1973Google Scholar, 3Markoe G. Phoenicians. British Museum Press, London2000Google Scholar, 4Aubet M.E. The Phoenicians and the West: Politics, Colonies and Trade. Cambridge University Press, Cambridge2001Google Scholar, 5Marston E. The Phoenicians. Benchmark Books, New York2002Google Scholar, 6Harden D. The Phoenicians. Penguin Books, London1971Google Scholar Their strategy included the establishment of settled colonies, foremost among which was Carthage in modern Tunisia, and many trading posts, where they stayed for shorter periods4Aubet M.E. The Phoenicians and the West: Politics, Colonies and Trade. Cambridge University Press, Cambridge2001Google Scholar (Figure 1A). Their activities were recorded by contemporary writers, including the Egyptians, the Greeks, Biblical sources, Strabo, Pliny the Elder, and Avienus, and the remains of their cities and trading goods have been documented extensively by archaeologists.6Harden D. The Phoenicians. Penguin Books, London1971Google Scholar Thus, we have a good understanding of their origins and spread from historical sources. We set out to complement this historical information by searching for Phoenician genetic traces within modern populations. We chose the nonrecombining region of the Y chromosome for this purpose, because its male specificity means that it would have been carried by the predominantly male Phoenician traders, and its high level of geographical differentiation provides the greatest chance of recognizing colonization events.7Jobling M.A. Tyler-Smith C. The human Y chromosome: an evolutionary marker comes of age.Nat. Rev. Genet. 2003; 4: 598-612Crossref PubMed Scopus (684) Google Scholar Human genetic history, however, can be viewed as a palimpsest, in which multiple events from different times but with similar geographical patterns are superimposed. Expansions from the Eastern Mediterranean could include the initial peopling by modern humans during the Paleolithic era, the subsequent Neolithic-era transition originating in the Fertile Crescent ∼8000 BCE, and later events, such as the Greek expansion or the Jewish Diaspora. All of these, and possibly additional events unrecorded in history, could result in broadly similar genetic patterns with an origin in or near the Levant and decreasing gradients toward the west. Several previous studies have identified Y-chromosomal types showing gradients originating in the Near East8Rosser Z.H. Zerjal T. Hurles M.E. Adojaan M. Alavantic D. Amorim A. Amos W. Armenteros M. Arroyo E. Barbujani G. et al.Y-chromosomal diversity in Europe is clinal and influenced primarily by geography, rather than by language.Am. J. Hum. Genet. 2000; 67: 1526-1543Abstract Full Text Full Text PDF PubMed Scopus (479) Google Scholar, 9Semino O. Magri C. Benuzzi G. Lin A.A. Al-Zahery N. Battaglia V. Maccioni L. Triantaphyllidis C. Shen P. Oefner P.J. et al.Origin, diffusion, and differentiation of Y-chromosome haplogroups E and J: inferences on the Neolithization of Europe and later migratory events in the Mediterranean area.Am. J. Hum. Genet. 2004; 74: 1023-1034Abstract Full Text Full Text PDF PubMed Scopus (310) Google Scholar, 10Semino O. Passarino G. Brega A. Fellous M. Santachiara-Benerecetti A.S. A view of the Neolithic demic diffusion in Europe through two Y chromosome-specific markers.Am. J. Hum. Genet. 1996; 59: 964-968PubMed Google Scholar, 11Semino O. Passarino G. Oefner P.J. Lin A.A. Arbuzova S. Beckman L.E. De Benedictis G. Francalacci P. Kouvatsi A. Limborska S. et al.The genetic legacy of Paleolithic Homo sapiens sapiens in extant Europeans: a Y chromosome perspective.Science. 2000; 290: 1155-1159Crossref PubMed Scopus (634) Google Scholar and have sometimes linked them to the Phoenicians,12Mitchell R.J. Earl L. Fricke B. Y-chromosome specific alleles and haplotypes in European and Asian populations: linkage disequilibrium and geographic diversity.Am. J. Phys. Anthropol. 1997; 104: 167-176Crossref PubMed Scopus (11) Google Scholar but further work is needed to distinguish between the general pattern and the specific Phoenician contribution. Therefore, we have developed a strategy for identifying a geographical genetic pattern associated with a specific historical expansion, rather than an overall geographical gradient. The key to this was the use of historically documented locations of greater or lesser contact—in our case, Phoenician locations—matched approximately for distance from the source. Such paired locations would be expected to share general genetic patterns, reflecting the sum of multiple events, but to differ specifically in their Phoenician genetic influence if genetic transfer had taken place. Other historical expansions would have involved different locations of greater and lesser contact and so would not have produced a distinct geographically detailed signal in the same populations at this fine level of resolution. To assess the significance of any pattern that we might detect, we developed a two-fold analytic approach: first, a statistical component, the investigation of whether such a pattern might have originated by chance; and second, an empirical component, the application of the same analytical strategy to additional data sets not expected to differ in their Phoenician influence, representing instead the general Neolithic spread or the independent Greek expansion. Haplotypes that would not be expected to exhibit the specific short-ranged variational features by chance and that did not correspond to other known expansions could be considered as potentially Phoenician. With the very active intervening history, we cannot reasonably expect to identify a statistically significant signature linking the Phoenician homeland to every identified colonization region. However, colonization is expected to have produced a noisy but systematic trace of signatures. This study presents a method that identifies significant geographical preponderance of such signatures in order to decipher the genetic palimpsest. In order to apply this strategy, we therefore needed to (1) choose suitable population sample sites for investigating Phoenician and other expansions, (2) generate or identify from available sources Y-chromosomal data sets from the chosen sites, (3) develop our test methodology, and, finally, (4) consider the broader significance of any signals that emerged from the chosen population sites. When choosing populations, we considered that trade-driven colonization would have mediated the genetic legacy of the Phoenician expansion. Minor colonization sites were established for the servicing of ships en route, as well as for connecting with and guarding interests in foreign trade centers. This servicing was necessary for the expansion of trade throughout the Mediterranean basin with the maritime technology of the first millennium BCE and established the regional variations that we seek to detect. Carthage emerged as the dominant Central Mediterranean colony, connecting western-metals trade to the rest of the wealthy Mediterranean trading sites. Opportunity for establishing Phoenician colonization was greatest and most lasting in minimally occupied regions. Documented major colonies and trading posts are summarized in Figure 1A. We constructed pairs of testing sites generally orthogonal to the anticipated background of the Neolithic gradient originating in the Levant, resulting in localized groups of tests. The Phoenician-influenced regions selected were, thus, the coastal Lebanese Phoenician Heartland and the broader area of the rest of the Levant (the “Phoenician Periphery”); then Cyprus and South Turkey; then Crete; then Malta and East Sicily; then South Sardinia, Ibiza, and Southern Spain; and, finally, Coastal Tunisia and cities like Tingris in Morocco (Figures 1B and 1C). For each, we identified nearby sites of lesser or no Phoenician contact. Examples of the comparisons used thus include heartland trading and trading noncontact sites. In we to Phoenician lineages from those spread by other colonization expansions many of the same and regions. We constructed a test set by choosing paired sites from the of which known Phoenician and comparing the to the Levant with that and available The colonization by and later groups regions by the Greek sites are in Figure 1A. We wished to similar to a signature of the Jewish Diaspora. however, the of the of in were than within A. of the B. Scholar The through and were with established and sometimes on multiple thus, to identify any where significant Jewish did not for at E. A of the Jewish From the of the to the New Scholar Therefore, our was not suitable for identifying lineages associated with the Jewish which been well with the use of other D. M.E. D. L. patterns of Y chromosome in Jewish and European Genet. 2004; PubMed Scopus Google with for Phoenician Neolithic and Greek S. N. E. S. N. N. N. N. W. S. Coastal Coastal in a new from Lebanon were J. N. L. R.J. J. et al.Y-chromosomal diversity in Lebanon is by historical J. Hum. Genet. Full Text Full Text PDF PubMed Scopus Google Scholar and we collected 1330 additional from and with at three of information on their geographical origin and for this were with and with as J. N. L. R.J. J. et al.Y-chromosomal diversity in Lebanon is by historical J. Hum. Genet. Full Text Full Text PDF PubMed Scopus Google Scholar We our with suitable data on from sites sites that we were to include in our included and southern of which could have Greek sites. The Y-chromosomal data were of two haplogroup data on and data on types are carried on the same chromosome and are J. M.E. T. for haplogroup from Y chromosome 4: PubMed Scopus Google Scholar they were because they have different and because data sets of the two data A set of haplogroups that most of the information was used as J. N. L. R.J. J. et al.Y-chromosomal diversity in Lebanon is by historical J. Hum. Genet. Full Text Full Text PDF PubMed Scopus Google Scholar was necessary to develop a similar for the information by the regions and of by of through a by and for of the on Scholar We identified that regional and sample the of and We of the of that were applied to the The geographical of the and the was not and the regional that could be constructed from historical were not for genetic marker For were included and in the set but not in the The were constructed and in a noncontact was constructed for general background reflecting Neolithic and the data were for significant reflecting general non-Phoenician background which the Phoenician pattern be identified. a colonization for identification of features of the subsequent and Greek colonization was The Greek test to identify features of the Greek expansion but on those distinct from the Phoenician expansion. the Phoenician colonization of Tunisia a test between the coastal regions and and populations, because it a different Neolithic B. S. Zerjal T. M. A. Tyler-Smith C. A predominantly Neolithic origin for Y-chromosomal in J. Hum. Genet. 2004; Full Text Full Text PDF PubMed Scopus Google Scholar and no intervening the colonies are expected to be than the major Phoenician but to Greek pairs for haplogroups to the Phoenician expansion are in Figure and those for haplotypes are in Figure representing were as and two were to establish these The first test was by means of the sites were as if the was than the The of out of a of expected by chance be a with so the that or would have been by chance to the test we applied test to the of or out of by chance that they were taken from contact and the two test with the the of be considered to be a the a level of the was considered a if This would be expected to be an of the For an a significant or significant level is However, testing for with of is for independent sites with the use of the in the same that the of or the of a be R.R. The and of in W. 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