The idea that human pharmaceuticals should be tested on animals before humans. The only real purpose animals serve is cost (you have to pay people to test your stuff and have insurance in case something goes wrong) and to ensure it’s not obviously lethal or has permanent side effects before going to human tests, and even then you can’t 100% prove it won’t be harmful to humans with just an animal test. Dfferent species have wildly different physiologies and biochemistries so an animal test means very little in the context of effects on humans. It’s really frustrating to see news outlets take a mouse test result and immediately assume it will work the same way in humans, not to mention the ethical implications. We’re already developing alternatives to animal testing and I’m really hoping it goes obsolete within our lifetime.