Haplogroup DE is a human Y-chromosome DNA haplogroup. It is defined by the single nucleotide polymorphism (SNP) mutations, or UEPs, M1(YAP), M145(P205), M203, P144, P153, P165, P167, P183. DE is unique because it is distributed in several geographically distinct clusters. An immediate subclade, haplogroup D (also known as D-CTS3946), is mainly found in East Asia, parts of Central Asia, and the Andaman Islands, but also sporadically in West Africa and West Asia. The other immediate subclade, haplogroup E, is common in Africa, and to a lesser extent the Middle East and southern Europe. The most well-known unique event polymorphism (UEP) that defines DE is the Y-chromosome Alu Polymorphism "YAP". The mutation was caused when a strand of DNA, known as Alu, inserted a copy of itself into the Y chromosome. Hence, all Y chromosomes belonging to DE, D, E and their subclades are YAP-positive (YAP+). All Y chromosomes that belong to other haplogroups and subclades are YAP-negative (YAP-). The age of haplogroup DE, previously estimated at between 65,000 and 71,000 years, was later estimated at around 68,555 years and most recently at around 76,500 years old. Origins Discovery The YAP insertion was discovered by scientists led by Michael Hammer of the University of Arizona. Between 1997 and 1998 Hammer published three articles relating to the origins of haplogroup DE. These articles state that YAP insertion originated in Asia. As recently as 2007, some studies such as Chandrasekar et al. 2007, cite the publications by Hammer when arguing for an Asian origin of the YAP insertion. 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