Precisely how humans came to initially populate Asia is a matter of some contention. After migrating out of Africa, it is generally agreed upon that humans moved along the coastline, and settled along the way, eventually pushing inland. Another hypothesis posits that humans passed through the mountainous regions by following waterways. Asia is home to several great waterways, including the Mekong, Salween, and Irrawaddy, and all three could have created hospitable environments and pathways for migration. Indeed, if humans did move inland following the river systems, Myanmar probably served as the corridor. Unfortunately, testing the latter hypothesis is no easy task due to little archaeological research and a general scarcity of genetic information that could provide support for the hypothesis.

Recently, Dr. ZHANG Yaping and Dr. KONG Qingpeng of the Kunming Institute of Zoology, Chinese Academy of Sciences (KIZ, CAS) began investigating the Myanmar hypothesis by gathering genetic samples from several Burmese populations. After collecting more than 845 samples from 14 different Burmese populations, analysis of Mitochondrial DNA (mtDNA) along with 5907 previously published samples found that somewhere between 50 and 20,000 years ago, there was an enrichment in the basal lineage of the mtDNA. This enrichment suggests that Myanmar was an important of differentiation when human arrived in south-east Asia.

Further analysis of the basal lineages reveal several shared haplogroups dated to around 200 BCE, which was likely due either to population expansion or trade. Other shared haplogroups date even further back, to somewhere between 20,000 and 10,000 years ago. In sum, genetic evidence of both recent gene flow and ancient migration provides strong support for the hypothesis that humans migrated along waterways, as well as along the coast.

The research has been published online at "Scientific Reports” http://www.nature.com/srep/2015/150326/srep09473/full/srep09473.html。