Population Dynamics among Ethnic Groups Residing in Hazarewal and Chitral-Gilgit-Baltistan:

A Dental Morphology Investigation of Biological Interactions across the Northwestern Borderlands of South Asia since the Chalcolithic Era

Abstract

The ethnic groups inhabiting the lowland and highland terrain in far northern Pakistan have recently been suggested to have served as middlemen in an interregional exchange network between Turkestan and the Indus Valley — an exchange network that may have involved populations at the northern end of the Inner Asian Mountain Corridor or populations of the Bactrian Margianan Archaeological Complex (BMAC) of southern Central Asia. Alternatively, it may be that waves of Pathan immigration during the mediaeval period into northern Pakistan introduced such extensive gene flow from the west that all trace of contacts north has been lost. Patterning of morphological trait frequencies of the permanent tooth crown are known to correlate closely with DNA patterns and are largely free of natural selection making them ideal for tracing patterns of past gene flow and genetic drift. Dental morphometric trait frequencies from living members of 11 ethnic groups of the lowlands of Hazarewal and the highlands of Chitral- Gilgit-Baltistan, along with nine archaeologically-derived samples from the Khyber Pakhtunkhwa, Indus Valley, and southern Central Asia (n= 2576 individuals), were analysed. Varying operational taxonomic units (OTUs) and data reduction techniques reveal a striking absence of evidence for interactions with populations to the north, meagre evidence of Pathan-related gene flow from the west or northwest, and little support for a genetic contribution from Chalcolithic era populations from the Indus Valley, signaling long-term local biological continuity in this region of northern Pakistan.