Serge Voronoff was a French surgeon of Russian extraction who gained fame for his technique of grafting monkey testicle tissue on to the testicles of men for purportedly therapeutic purposes while working in France in the 1920s and 1930s. The technique brought him a great deal of money, although he was already independently wealthy. As his work fell out of favour, he went from being highly respected to a subject of ridicule. In 1999, some speculated that the AIDS virus discovered in the 1980s entered the human population through Voronoff’s transfer of monkey parts into humans in the 1920s.