The majority of the most important advances in medical history in the twentieth century were made using animals as test subjects. It is doubtful whether many of these would have been achieved if animals were not available for use by medical researchers.

There are alternatives to animal research (these will be examined in the next article in this series), but in many cases they are simply not acceptable substitutes for a living, breathing organism. The Institute for Laboratory Animal Research of the U.S. National Academy of Sciences agrees that even the most sophisticated computer modeling is currently unable to successfully model the molecular and cellular interactions that occur in even the least complex of live organisms, particularly in an environmental context.

Medical science is in agreement, for the most part, that the use of animals in medical research is a practical necessity. Both the United States and the British governments, among many others, support the use of animals in research, provided that suffering of experimental animals is minimized.