A Southeast Asian Origin for Human Y Chromosomes Outside Africa

Abstract

The genomes of present-day humans outside Africa originated almost entirely from a single migration out ~50,000-70,000 years ago[1, 2], followed by mixture with Neanderthals contributing ~2% to all non-Africans [3, 4]. However, the details of this initial migration remain poorly-understood because no ancient DNA analyses are available from this key time period, and interpretation of present-day autosomal data is complicated due to subsequent population movements/reshaping [5]. One locus, however, does retain male-specific information from this early period: the Y-chromosome, where a detailed calibrated phylogeny has been constructed [6]. Three present-day Y lineages were carried by the initial migration: the rare haplogroup D, the moderately rare C, and the very common FT lineage which now dominates most non-African populations [6, 7]. We show that phylogenetic analyses of haplogroup C, D and FT sequences, including very rare deep-rooting lineages, together with phylogeographic analyses of ancient and present-day non-African Y-chromosomes, all point to East/South-east Asia as the origin 50,000-55,000 years ago of all known non-African male lineages (apart from recent migrants). This observation contrasts with the expectation of a West Eurasian origin predicted by a simple model of expansion from a source near Africa [8, 9], and can be interpreted as resulting from extensive genetic drift in the initial population or replacement of early western lineages from the east, thus informing and constraining models of the initial expansion.