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Early life and education

Koch was born in Clausthal, Germany, on 11 December 1843, to Hermann Koch (1814–1877) and Mathilde Julie Henriette (née Biewend; 1818–1871). His father was a mining engineer. He was the third of thirteen siblings. He excelled academically from an early age. Before entering school in 1848, he had taught himself how to read and write. He completed secondary education in 1862, having excelled in science and math.

At the age of 19, in 1862, Koch entered the University of Göttingen to study natural science. He took up mathematics, physics and botany. He was appointed assistant in the university's Pathological Museum. After three semesters, he decided to change his area of study to medicine, as he aspired to be a physician. During his fifth semester at the medical school, Jacob Henle, an anatomist who had published a theory of contagion in 1840, asked him to participate in his research project on uterine nerve structure. This research won him a research prize from the university and enabled him to briefly study under Rudolf Virchow, who was at the time considered "Germany's most renowned physician". In his sixth semester, Koch began to research at the Physiological Institute, where he studied the secretion of succinic acid, which is a signalling molecule that is also involved in the metabolism of the mitochondria. This would eventually form the basis of his dissertation. In January 1866, he graduated from the medical school, earning honours of the highest distinction, maxima cum laude.