A Gene Story: the Negritos’ Early Southern Migration

ResearchBlogging.orgCurrent Biology’s article, The Human Genetic History of East Asia: Weaving a Complex Tapestry, presents another interesting evidence on the peopling of East Asia using evidences from mitochondrial DNA (mtDNA) and non-recombining Y chromosomes (NRY) haplogroups.

Stoneking and Delfin’s genetic evidence presented an early southern dispersal that created refugia populations. The authors suggested that Philippine Negritos, Malaysian Semangs, Andamanese, and indigenous Australians were descendants of this early migration. They said that C-M130 is found sporadically in India and southeast Asia, and reaches its highest frequencies in eastern Indonesia and some Filipino Negrito groups. Previous investigators revealed that NRY haplogroups, C-M130 and D-M174, are indicators of an early southern migration route.

The authors claimed that the colonization of East Asia may had been a south-to-north route. They posited that there is a “strong and highly significant correlation between haplotype diversity and latitude, with higher diversity in the south and lower diversity in the north.” This pattern is a “compelling evidence for a primary south-to-north direction for the colonization of east Asia.”

The genetic evidence of the Negrito groups also suggested that there was an “early isolation and followed by a recent admixture.” Stoneking and Delfin posited that “the ancestors of the Negritos either represent an earlier migration, or they were isolated from other Asian groups early after entering Asia in the same migration as the ancestors of non-Negrito groups, to account for the distinctive mtDNA and NRY lineages in Negrito groups.” Nonetheless, the genetic similarities between Negritos and non-Negrito groups may have been due to high levels of contact in recent times.

There has been much debate on the peopling of the Philippines among anthropological circles. So, this paper is a welcome addition to the theorizing of the Philippine’s prehistoric past. What gets the most press in Philippine archaeology has been the north-to-south Neolithic dispersal, championed by Peter Bellwood. His theory argues that proto-Austronesian groups from Taiwan migrated to the Philippines, Indonesia, and went all the way to Madagascar, bringing with them their language, technology, and culture. Absent in Bellwood’s model however, which is supplied here by Stoneking and Delfin, is the understanding of the Philippine past before agriculture came about–the time of the Philippine Paleolithic.

What is quite surprising is the fact that the genetic evidence for an early southern migration fits well with H. Otley Beyer’s claim that the Philippines was first settled by Negritos then repopulated by more recent migrations. Beyer, who was the first to propose a theory of the peopling of the Philippines, has been a target board for generations of Philippine anthropologists wanting to propose an alternative model for the human colonization of the Philippine archipelago.

Stoneking, M., & Delfin, F. (2010). The Human Genetic History of East Asia: Weaving a Complex Tapestry Current Biology, 20 (4) DOI: 10.1016/j.cub.2009.11.052

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