By extending extra effort to do the right thing, humans can reach more optimal outcomes. Instead of saying “We can’t do that” why not provide options about what you can do?
According to http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3902221/
“The average rate of successful translation from animal models to clinical cancer trials is less than 8%. Animal models are limited in their ability to mimic the extremely complex process of human carcinogenesis, physiology and progression. Therefore the safety and efficacy identified in animal studies is generally not translated to human trials.”