Bioanthropology of the Hindu Kush Borderlands

A Dental Morphology Investigation

Abstract

This paper seeks to test conflicting hypotheses concerning possible migrations into or out of the Indus Valley associated, by some researchers, with the dispersal of Indo-Aryan languages. The Aryan Invasion Theory (AIT) calls for a substantial invasion of central Asian populations into the Indus Valley during the 2nd millennium B.C. This invasion is held to have led to the establishment of classical Vedic culture and its subsequent spread throughout the subcontinent by Brahminic missionaries. The Out-of-India Model (OIM) calls for the development of Indo-European languages within the Indian subcontinent, with subsequent dispersal throughout Central Asia and beyond through population movement after the 5th millennium B.C. The Early Intrusion Model (EIM) calls for two immigration events into western South Asia. The first, and most influential, entry occurred during the 5th millennium B.C. and likely signals a substantial immigration of proto-Elamo Dravidian- speaking populations. The second entry occurred during the last two millennia B.C. and may have involved a gradual introduction of central Asian genes and perhaps lndo Aryan languages into a large resident South Asian population.
Fifty-seven non-metric variations of the permanent dentition were assessed from over 1400 living and prehistoric individuals from the Indus Valley, peninsular India, and Central Asia. Frequencies of 25 traits could be compared across all 16 samples. Eight traits were eliminated from consideration, because of few observations in living samples or insufficient heterogeneity across samples. Phenetic distances between samples based on the remaining 17 tooth-trait combinations were calculated with C.A.B. Smith's mean measure of divergence statistic and patterns of affinities were assessed with neighbor-joining cluster analysis and principal coordinates analysis. The results provide no support for either the Aryan Invasion theory or the Out-of-India model. There is no significant break in Indus Valley biological continuity during the 2nd millennium B.C. (contra AIT), nor is there any evidence of significant emigration out of the Indus Valley into Central Asia after the 5th millennium B.C. (contra OIM). Rather, the results reveal a significant discontinuity event in Indus Valley biological affinities between the 7th to 5th millennia B.C., followed by a milder discontinuity event during the last two millennia B.C. As such, the results of this study offer greatest support for the Early Intrusion model.