By Sara Amundson and Kitty Block
Over 90% of drugs that appear successful in animal tests go on to fail in human clinical trials. This is a staggering statistic underscoring that animals are biologically different from humans, and so animal-based research can be deeply unreliable, which, in turn, hinders medical progress and slows down the advancement of our scientific knowledge. Even more closely related species like mice and rats can react very differently when exposed to the same substances.