These findings effectively neutralized the argument of an Asian origin of the YAP+ based on the character state of the M40 and M96 mutations that define haplogroup E. According to Underhill et al. 2001, the M174 data alone would support an African origin of the YAP insertion. In Altheide and Hammer 1997, the authors argue that haplogroup E arose in Asia on an ancestral YAP+ allele before migrating back to Africa. However some studies, such as Semino et al., indicate that the highest frequency and diversity of haplogroup E is in Africa, and East Africa is the most likely place of origin of the haplogroup. The models supporting an African origin or an Asian origin of the YAP+ insertion both required the extinction of the ancestral YAP chromosome to explain the current distribution of the YAP+ polymorphism. Paragroup DE* possesses neither the mutations that define haplogroup D or haplogroup E. If paragroup DE* was found in one location but not the other, it would boost one theory over the other. Haplogroup DE* has been found in Nigeria, Guinea-Bissau and also in Tibet. The phylogenetic relationship of three DE* sequences has yet to be determined, but it is known that the Guinea Bissau sequences differ from the Nigerian sequences by at least one mutation. Weale et al. state that the discovery of DE* among Nigerians pushes back the date for the most recent common ancestor (MRCA) of African YAP chromosomes. This, in his view, has the effect of reducing the time window through which a possible back migration from Asia to Africa could occur. Chandrasekhar et al. 2007, have argued for an Asian origin of the YAP+. They state: "The presence of the YAP insertion in Northeast Indian tribes and Andaman Islanders with haplogroup D suggests that some of the M168 chromosomes gave rise to the YAP insertion and M174 mutation in South Asia." They also argue that YAP+ migrated back to Africa with other Eurasian haplogroups, such as Haplogroup R1b1* (18-23kya), which has been observed with especially high frequency among the members of some peoples in northern Cameroon, and Haplogroup T (39-45 kya), which has been observed in low frequencies in Africa. Haplogroup E at 50kya is considerably older than these haplogroups and has been observed at frequencies of 80-92% in Africa.