Animal models play a crucial role in biomedical research, helping scientists understand the mechanisms of human disease, evaluate the effectiveness of new treatments, and test the safety of drugs. Animal models typically include mice, rats, rabbits, monkeys, etc., which share certain physiological and genetic similarities with humans, allowing researchers to derive important information from them.

First, animal models provide a controlled environment for research. In the lab, researchers can precisely control variables, such as diet, environmental conditions, genetic background, etc., to obtain more reliable experimental results. This property allows scientists to conduct a large number of experiments in a relatively short period of time, exploring the pathogenesis of diseases as well as potential treatments.

Second, animal models have played an important role in drug development. In the early stages of drug development, researchers use animal models to assess the drug's efficacy and toxicity. For example, by looking at the physiological response of a drug to an animal, researchers can tell if the drug is promising for translation into a clinical treatment. While animal experiments do not fully mimic human physiological responses, they provide important preliminary data that can help reduce the risk of subsequent clinical trials.

However, the use of animal models also presents certain ethical challenges. With increasing concern for animal welfare, the scientific community is exploring alternative approaches, such as cell culture techniques and computer simulations. These alternatives, while showing promise in some areas, are still difficult to fully replace animal testing, especially in complex physiological and behavioral studies. As a result, the scientific community is constantly working to implement the three principles of substitution.