 In 1949 Frank Burnet, and later in 1953 Peter Medawar, observed that the developing fetus was, in fact, similar to a transplanted "foreign" organ, because of the father's contribution to its genome.In 1960, Medawar and Burnet were awarded the Nobel Prize in part for their early contributions and discoveries related to understanding the necessity for the development of tolerance to the developing eutherian.It is now apparent that a human fetus is tolerated by its birth mother, even when it is completely unrelated.