Exploring European ancestry among the Kalash population: a mitogenomic perspective

With a population of around 4 000 individuals, the Kalash people have been living in the Hindu-Kush mountain valleys of present-day northern Pakistan for centuries. Due to their mysterious origin and fairer European complexion, the genetic history of this ethnic group has been investigated previously using different markers. To date, however, the maternal genetic architecture has not been systematically dissected based on high-resolution complete mitochondrial genomes (mitogenomes), making their maternal genetic history, especially their genetic connection with Europeans from a matrilineal perspective, unclear. To unravel this issue, we analyzed mitogenome data of 34 Kalash samples together with 6 075 individuals from across Eurasia. Our results indicated exclusive western Eurasian origin of the Kalash people, represented by eight haplogroups. Among these haplogroups, J2b1a7a and R0a5a (accounting for ~50% of the Kalash gene pool) displayed in situ differentiations in the Kalash and could be traced to the Mediterranean region. Age estimations suggested these haplogroups arose in the Kalash population ~2.26 and 3.01 thousand years ago (kya), a time frame consistent with the invasion of Alexander III of Macedon to the region. One possible explanation for the maternal genetic contribution from Europeans to the Kalash people would be the involvement of women in foreign campaigns of ancient Greek warfare, followed by a founder effect. Our study thus sheds important light on the genetic origin of the Kalash community of Pakistan.