Mapping Post-Glacial expansions: The Peopling of Southwest Asia

Abstract

Archaeological, palaeontological and geological evidence shows that post-glacial warming released human populations from their various climate-bound refugia. Yet specific connections between these refugia and the timing and routes of post-glacial migrations that ultimately established modern patterns of genetic variation remain elusive. Here, we use Y-chromosome markers combined with autosomal data to reconstruct population expansions from regional refugia in Southwest Asia. Populations from three regions in particular possess distinctive autosomal genetic signatures indicative of likely refugia: one, in the north, centered around the eastern coast of the Black Sea, the second, with a more Levantine focus, and the third in the southern Arabian Peninsula. Modern populations from these three regions carry the widest diversity and may indeed represent the most likely descendants of the populations responsible for the Neolithic cultures of Southwest Asia. We reveal the distinct and datable expansion routes of populations from these three refugia throughout Southwest Asia and into Europe and North Africa and discuss the possible correlations of these migrations to various cultural and climatic events evident in the archaeological record of the past 15,000 years.

Figure 1

MDS analyses of R_ST distances based on STR haplogroup variances (a) across all haplogroups, for (b) J*(xJ2), and (c) J2.

Figure 2

BATWING population split time estimates for Middle Eastern populations marking expansion histories for haplogroups (a) J1, (b) J2 and (c) E1b1b1.

Figure 3

Genome-wide analysis of populations from Southwest Asia using 188,974 autosomal SNPs. (a) Map showing populations analyzed (Base map constructed from Map data: Google, Digital Globe, https://earth.google.com); (b) Population. structure inferred by ADMIXTURE. Each horizontal line represents ancestry probabilities of an individual in 2 constructed ancestral populations.

Figure 4. PCA showing Genome-wide analysis of populations from Southwest Asia using 188,974 autosomal SNPs.

Eigenvalues were 3.76 × 10⁵ for PC1 (not plotted, reported for scale), 2.16 × 10⁵ for PC2, and 1.62 × 10⁵ for PC3.

Figure 5

(A) Reconstructed air temperatures from the GISP 2 Ice core in Greenland (blue solid line); Isotope values from Soreq cave, Israel (orange dotted line). (B) Chronology of cultural entities in the Levant. (C) Archaeological evidence of human activities in the Upper Paleolithic; human occupation signs 29–15.2 ka, wood charcoal, nuts 15.9–11.2 ka, ▲centers of obsidian trade 16–14 ka. (D) Evidence of human activities in the Neolithic; plant domestication 12.5–9.6 ka, human occupation signs 11.9–5 ka, animal domestication, charred plants, agriculture and charcoal 10.2–7.3 ka. (Base map constructed from Map data: Google, Digital Globe, https://earth.google.com).