Human beings owe a great deal to animals. From the earliest periods of history of mankind, animals have been used by humans for food, clothing, tool making, and for several other purposes. Primitive artists painted animal figures onto stone surfaces; animal figures became parts of religions and tribal identities. Over time, some animals were domesticated, serving as regular sources of meat and milk; additionally, animals were used in farmwork and for transport. Dogs were used to defend property and were trained for rescue missions. Cats were used as pets as early as the ancient Egyptian Kingdom. Interesting additional missions have been given to animals such as searching for illicit drugs, explosives, and mushrooms. Some areas where we are still strictly dependent on animals include the drug industry (e.g., insulin isolated from swine pancreas), but there are also areas subject to intense debate (e.g., fur farming, fox hunting, and the cosmetics industry).

We are very much dependent on animals in medical research and in clinical surgery training. Neurological diseases comprise a major health problem all over the world and their importance continues to grow as the population ages and as neurology moves from being largely a diagnostic field to one with more therapeutic approaches. Neurological diseases already absorb approximately one-fourth of health budgets in industrialized countries. It is urgent to develop novel effective therapies for neurological diseases: the aging of the population will increase the number of neurological patients whereas the labor force available in the health sector appears to be decreasing.