Different animal models have their own advantages in biomedical research. Simple organisms such as yeast, fruit flies and C. elegans, a millimeter-long nematode, are especially useful in understanding mechanisms of aging because they normally live just a few weeks. Transparent zebrafish are widely used in kidney research.
Life on Earth evolved from single-celled organisms, and humans, mice and other mammals share many genes with even the simplest living creatures thanks to a principle known as evolutionary conservation. This makes it possible to study a biological process in fruit flies, for example, and then test the findings in mice for a better approximation of how it might work in humans.
Mice are the best, most widely used animal model for understanding human biology, and for finding drug targets for human disease. So why don’t all drugs developed using mice turn out to be successful treatments? One reason is the way new drugs are tested.