Russian biologist who pioneered research into the immune system and human aging. He won the the Nobel prize in Medicine in 1908 for his revolutionary work on phagocytosis.
Passionate about natural sciences, he tested and taught Charles Darwin's evolutionary theories.
He is often credited with coining the term gerontology, which describes the study of aging and longevity.
His first wife, Ludmilla Feodorovitch, succumbed to tuberculosis; he met his second wife, Olga, two years later.
Louis Pasteur and he worked in the same field, but they had their disagreements.