In 1849, Arnold Berthold, a German scientist, conducted the first formal experiment pertaining to hormones. He noticed that chickens that were castrated during development grew up to be passive (lacking fighting and mating behaviors) compared to normal roosters. Arnold Berthold decided to implant testes into the abdomens of castrated chickens. The chickens with implanted testes grew up to behave like normal roosters. Thus, Berthold concluded that the testes much secret some sort of substance since they were not connected to nerves. He said, "The testes act upon the blood, and the blood acts upon the whole organism" (Berthold, 1849).
In 1889, a Harvard professor (Brown), decided to inject himself with substance containing extracts from guinea pig and dog testicles; he called this concoction a "rejuvenating elixir " (Brown, 1889). Brown published in The Lancet that his energy, vigor, and overall health were restored, but the effects did not last long; Brown attributed this to placebo effect. Because of these findings, Brown was mocked by his colleagues, forcing him to give up on his research. .
In 1927 Fred C. Koch, a professor at the University of Chicago, realized the potential behind Brown work. Koch realized he had tons of potential right in his own back yard; the Chicago stockyard. Koch recruited his students to help him extract isolates from over 40 pounds of bull testes. Koch, along with help from his army of students, was able to extract a modest 20mg of substance from the bull testes. Instead of repeating the mistake of Brown and injecting the substance into a human subject, Koch decided to inject the substance into castrated chickens, pigs, and rats. Koch and his students noticed that the castrated subjects injected with the substance began to display signs of aggression and sexual behavior. .
Thanks to the vision of Brown and the aptitude of Koch, The Organon group was able to isolate, testosterone in May of 1935.
