Animals have often been used in the history of scientific study. In the 1880s, Louis Pasteur showed the germ theory of medicine by putting anthrax in sheep. In the 1890s, Ivan Pavlov famously used dogs to describe classical conditioning. On November 3, 1957, a Russian dog, Laika, became the first animal to orbit the earth. In the 1970s, antibiotic treatments and vaccines for leprosy were made using armadillos, then given to humans. In 1974, Rudolf Jaenisch produced the first genetically changed mammal. He put DNA from a virus into the genome of mice. Genetic study grew quickly after that. In 1996, Dolly the sheep was born—the first cloned mammal.