 In a 2007 study, Peter Underhill and Toomas Kivisild stated that there will always be uncertainty regarding the precise origins of DNA sequence variants such as YAP because of a lack of knowledge concerning prehistoric demographics and population movements.However Underhill and Kivisild contend that with all the available information, the African origin of the YAP+ polymorphism is more parsimonious and more plausible than the Asian origin hypothesis.In a press release concerning a study by Karafet et al.