For scientists, the main thing is to research what they are researching and they choose the most relevant animal. Rat is small and they can fit more in one box to observate. They think founding a cure for humans is the main thing and they kill tons of rats and mouses because of it. Yes, I also think finding a cure is important, but they should find another way of researching, killing these tiny animals shouldn't be legal. They are alive too. Killing lives for saving lives? I don't think so.