Afghanistan's Ethnic Groups Share a Y-Chromosomal Heritage Structured by Historical Events

Abstract

Afghanistan has held a strategic position throughout history. It has been inhabited since the Paleolithic and later became a crossroad for expanding civilizations and empires. Afghanistan's location, history, and diverse ethnic groups present a unique opportunity to explore how nations and ethnic groups emerged, and how major cultural evolutions and technological developments in human history have influenced modern population structures. In this study we have analyzed, for the first time, the four major ethnic groups in present-day Afghanistan: Hazara, Pashtun, Tajik, and Uzbek, using 52 binary markers and 19 short tandem repeats on the non-recombinant segment of the Y-chromosome. A total of 204 Afghan samples were investigated along with more than 8,500 samples from surrounding populations important to Afghanistan's history through migrations and conquests, including Iranians, Greeks, Indians, Middle Easterners, East Europeans, and East Asians. Our results suggest that all current Afghans largely share a heritage derived from a common unstructured ancestral population that could have emerged during the Neolithic revolution and the formation of the first farming communities. Our results also indicate that inter-Afghan differentiation started during the Bronze Age, probably driven by the formation of the first civilizations in the region. Later migrations and invasions into the region have been assimilated differentially among the ethnic groups, increasing inter-population genetic differences, and giving the Afghans a unique genetic diversity in Central Asia.

Uniparental Markers in Italy Reveal a Sex-Biased Genetic Structure and Different Historical Strata

“…Indeed, comparisons with other European and Near-Eastern populations (Table S6) suggest a stronger affinity between NWI with Iberia and Central Europe, while SEI is more related to the Balkans and Anatolia. The emergence of population structures during the Neolithic has been recently shown in two different studies using Y-chromosome markers, in Near East [71] and in Western Europe [27]. Our results confirm these findings and emphasize the role of demographic expansions and cultural advances related to the Neolithic revolution in shaping human genetic diversity, at least for male lineages.…”

A Population Survey of the Glucose-6-Phosphate Dehydrogenase (G6PD) 563C>T (Mediterranean) Mutation in Afghanistan

“…The data do show that in individuals in Afghanistan without the Mediterranean mutation, background polymorphic markers are evenly mixed among various ethnic groups, a finding that is consistent with the late development of population structure between Afghanistan’s various ethnic groups after the Bronze age [36]. The relatively high prevalence of 563C>T reached in Pashtuns (8.4%) and the clear differences in its prevalence between different ethnic groups, also described in another large survey [32], are consistent with positive selection occurring after that period, in an analogous manner to the emergence of both the 563C>T variant in Europe and the Middle East [34] and the G6PD Mahidol variant in southeast Asia [37].…”

Afghan Hindu Kush: Where Eurasian Sub-Continent Gene Flows Converge

“…Retracing the main historical events in the gene pool of the present Afghan populations has been strongly restricted, because of sampling work in this country being inadvised, with the exceptions of recent Y chromosome studies [30]–[32]. Herein, we contribute to fill this gap by providing a detailed genetic picture of the five main ethnic groups inhabiting the mountainous region of the Hindu Kush.…”

“…Central Asia displays very high genetic diversity [32], [41], [72]. This region has been proposed to be the source of waves of migration leading into Europe, the Americas and India [36].…”

“…Despite this rich and complex history, the few genetic studies devoted to Afghanistan have been restricted to Y-chromosome and/or to the Pashtun population [30]–[32].…”