Aristotle and Erasistratus were among the first to perform experiments on live animals. Galen, a physician in 2nd-century Rome, dissected pigs and goats and is known as the "father of vivisection." Avenzoar, an Arab physician from 12th-century Moorish Spain who also practiced dissection, introduced animal testing as an experimental method for testing surgical procedures before applying them to human patients. Animals have been used repeatedly throughout the history of biomedical research. The founders, in 1831, of Dublin Zoo were members of the medical profession, interested in studying animals both while they were alive and when they were dead. In 1880, Louis Pasteur convincingly demonstrated the germ theory of medicine by inducing anthrax in sheep. In the 1890s, Ivan Pavlov famously used dogs to describe classical conditioning. Insulin was first isolated from dogs in 1922 and revolutionized the treatment of diabetes. On November 3, 1957, a Soviet dog, Laika, became the first of many animals to orbit the earth. In the 1970s, antibiotic treatments and vaccines for leprosy were developed using armadillos, then administered to humans. Man's ability to modify the genetics of animals took a big step forward in 1974, when Rudolf Jaenisch managed to produce the first transgenic mammal, integrating the DNA of the SV40 virus into the animal genome.