Those who defend the use of animals in research contend that nonhuman animals are enough like humans to make them scientifically adequate models of humans, but different enough to make it morally acceptable to experiment on them. In addition to the ethical objections to causing suffering to other sentient species, inherent issues with animal models including differences from humans in both size and physiology, genetic differences, and variations in biological targets limit the ability of data collected from an animal model to be translated to people.
