Albrecht Kossel and Sven Gustaf Hedin were pioneering scientists in the field of biochemistry and protein research. Both discovered this amino acid in 1896, simultaneously but independently. Kossel and Hedin began their research by analyzing proteins from various sources of animal tissue, including muscle, blood, and organs. They used various techniques to extract and purify the proteins, such as precipitation and chromatography. After several attempts, they were able to extract histidine from the mixture and identify it.