ABO blood group system and likely predates human migration from Africa. The O01 allele is considered to predate the O02 allele. Some evolutionary biologists theorize that there are four main lineages of the ABO gene and that mutations creating type O have occurred at least three times in humans. From oldest to youngest, these lineages comprise the following alleles: "A101/A201/O09", "B101", "O02" and "O01". The continued presence of the O alleles is hypothesized to be the result of balancing selection. Both theories contradict the previously held theory that type O blood evolved first. It is possible that food and environmental antigens (bacterial, viral, or
Jehovah's Witnesses and blood transfusions their comments into English reads: According to sociologist Richard Singelenbreg, the statement appearing in the Dutch edition of "Consolation" may have been published without knowledge of the doctrinal position published in the English July 1945 issue of "Consolation" by the Watch Tower Society's headquarters in the United States. In 1945, the application of the doctrine on blood was expanded to prohibit blood transfusions of whole blood, whether allogeneic or autologous. The prohibition did not specify any punitive measures for accepting a transfusion, but by January 1961—in what was later described as an application of "increased strictness"—it was ruled that it