Medical progress depends on animal models - doesn't it?

Animal models are widely recognized as being essential to the progress of medical science. In countering the critics' arguments of the use of animals in medicine, one statement has acquired almost talismanic importance: ‘Virtually every medical achievement of the last century has depended directly or indirectly on research with animals.’ In this essay, the origins and justification of this oft-repeated statement are examined. Despite its endorsement by leading academic bodies, it is far from clear that the statement has been, or even could be, formally validated.