Is resorting to animal models for human-health issues based on rational principles?
There is remarkably simple yet clear proof that no animal species can substitute as a reliable biological model for another species. A species is defined in terms of its reproductive isolation, meaning that members from different species cannot interbreed. This is because a given species has its own unique genetic make-up (from number, organisation and structure of chromosomes, through to regulation and control of gene expression). Modern biology has clearly demonstrated that the genetic make-up of an individual determines the precise biological activities of its cells, tissues, and organs. Hence, individuals from different species have different genetic make-ups and therefore display different biological activities, even if some may appear similar in the short term. The statement that members of a given species can substitute as reliable biological models for other species is therefore invalid. In particular, the assumption that results obtained in some mammalian species are valid for
