Humans and mice don't look alike, but both species are mammals and are biologically very similar.
Almost all of the genes in mice share functions with the genes in humans. That means we develop in the same way from egg and sperm, and have the same kinds of organs (heart, brain, lungs, kidneys, etc.) as well as similar circulatory, reproductive, digestive, hormonal and nervous systems. These similarities make it possible for scientists to study the physiology of mice to glean information about how human beings grow, develop diseases and age.
This genetic similarity also means that mice and humans inherit traits in the same way. This includes physical traits such as hair color (coat color in mice) and susceptibility to diseases such as heart disease or Alzheimer’s.
Because mice live short lives compared to humans — about two years in laboratory care, but much less in the wild — it’s possible to learn a great deal about how chronic diseases progress over a lifetime, and about the processes of aging. Mice are small and relatively economical to maintain, making them the ideal laboratory animal model.
Thousands of laboratory mouse strains are now available, so scientists can therefore choose the ideal mouse model to study different diseases and disease processes. And the mouse genome is easily manipulated in order to create even more precise models of specific diseases.
Because scientists have been studying laboratory mice for more than 100 years, more is known about their biology and genetics than any animal except for humans. This sheer volume of data, maintained and provided to the worldwide scientific community by The Jackson Laboratory as the Mouse Genome Database, makes the mouse the model of choice for biomedical research.