Genetic and archaeological perspectives on the initial modern human colonization of southern Asia

Abstract

It has been argued recently that the initial dispersal of anatomically modern humans from Africa to southern Asia occurred before the volcanic "supereruption" of the Mount Toba volcano (Sumatra) at ∼74,000 y before present (B.P.)-possibly as early as 120,000 y B.P. We show here that this "pre-Toba" dispersal model is in serious conflict with both the most recent genetic evidence from both Africa and Asia and the archaeological evidence from South Asian sites. We present an alternative model based on a combination of genetic analyses and recent archaeological evidence from South Asia and Africa. These data support a coastally oriented dispersal of modern humans from eastern Africa to southern Asia ∼60-50 thousand years ago (ka). This was associated with distinctively African microlithic and "backed-segment" technologies analogous to the African "Howiesons Poort" and related technologies, together with a range of distinctively "modern" cultural and symbolic features (highly shaped bone tools, personal ornaments, abstract artistic motifs, microblade technology, etc.), similar to those that accompanied the replacement of "archaic" Neanderthal by anatomically modern human populations in other regions of western Eurasia at a broadly similar date.

Keywords: India; Paleolithic; archaeogenetics; mtDNA.

Fig. 1.

Comparison of the two alternative models for the initial modern human colonization of South Asia discussed in the text. The graphs show the inferred correlations between “archaic” and “modern” populations and their associations with Middle Paleolithic vs. microlithic technologies in the two models. The date indicated for the initial, pre-Toba modern human colonization in the Petraglia et al. model is a minimum number (∼74 ka), with other estimates ranging up to 120–130 ka (5). For relevant references, see main text. Graphic by Dora Kemp.

Fig. 2.

Map of sites referred to in the main text. The zone of “high marine productivity” is inferred from Google Earth satellite images of chlorophyll concentrations in coastal waters. Graphic by Dora Kemp.

Fig. 3.

Microlithic, “backed-segment” forms from Howiesons-Poort-like sites in South and East Africa (Left) and early microlithic sites in South Asia (Right). The illustrations show the close similarities in the range of “geometric” (crescentic, triangular, and trapezoidal) forms in the two regions (3, 20, 22, 41, 43, 46).

Fig. 4.

Comparisons of ornamental “bead” forms and “symbolic” design motifs from later MSA (Howiesons Poort and Still Bay) sites in South and East Africa and early microlithic sites in South Asia (3, 7, 21, 22, 37, 39, 40, 42) (oes, ostrich eggshell). Patne oes and Blombos ochre reproduced from (7).

Fig. 5.

Age ranges for mtDNA lineages in Africa and Asia. Ninety-five percent confidence ranges are shown for the coalescence times of mtDNA haplogroup L3 in Africa and founder ages for haplogroup N in Arabia/Southwest Asia and haplogroups R and M in South and East Asia, estimated using ρ and maximum likelihood (ML). For details, see Genetics and Tables S1–S5.