It was pure luck that led to the actual discovery of vitamin C. Axel Holst and Theodor Frolich had been studying beriberi (another deficiency disease) in pigeons, and when they decided to switch to a mammal model, they serendipitously chose guinea pigs, the one animal besides human beings and monkeys that requires vitamin C in its diet. Fed a diet of pure grain, the animals showed no signs of beriberi, but quickly sickened and died of something that closely resembled human scurvy.