During the Last Glacial Maximum (LGM) around 20 thousand years ago, the ice sheet had extended whereas the see level had dropped. This situation had been turned over after the LGM as the climate became warmer. As a result, the eustatic movement occurred in the coastal regions of mainland and islands, and was likely to influence human dispersals in these regions.

In East Asia, the formation of current Hainan Island is the result of the eustatic movement in Beibu Bay (Gulf of Tonkin). To trace the potential genetic footprint left by this movement in current gene pool, Prof. Zhang Yaping’s group from Kunming Institute of Zoology focused on mitochondrial DNA (mtDNA) variation of Hainan islanders. The results revealed that Hainan islanders showed close genetic relationship with populations from Guangxi in mainland southern China. The recent gene flow from the mainland was likely to contribute significantly to the current gene pool of Hainan islanders. More importantly, the extensive analyses identified that mtDNA haplogroups might represent the genetic relics of the ancient population that populated Hainan Island. And the later phylogeographic analyses based on mtDNA genomes suggested the early colonization could be traced back to ~ 7 – 27 thousand years ago when Hainan Island was connected with the mainland. This conclusion also received support from archaeological evidence that some Paleolithic sites proposed in the Upper Pleistocene had been found in Hainan Island.

This work has been published online in BMC Evolutionary Biology (http://www.biomedcentral.com/1471-2148/11/46).