 The scenarios outlined by Hammer include an out of Africa migration over 100,000 years ago, the YAP+ insertion on an Asian Y-chromosome 55,000 years ago and a back migration of YAP+ from Asia to Africa 31,000 years ago by its subclade haplogroup E. This analysis was based on the fact that older African lineages, such as haplogroups A and B, were YAP negative whereas the younger lineage, haplogroup E was YAP positive.Haplogroup D, which is YAP positive, was clearly an Asian lineage, being found only in East Asia with high frequencies in the Andaman Islands, Japan and Tibet.Because the mutations that define haplogroup E were observed to be in the ancestral state in haplogroup D, and haplogroup D at 55kya, was considerably older than haplogroup E at 31kya, Hammer concluded that haplogroup E was a subclade of haplogroup D and migrated back to Africa.