Scientists look for ways to reduce the numbers of animals needed to obtain valid results, refine experimental techniques, and replace animals with other research methods.
Medical research is an evolving process in which questions are examined in different ways to find answers. Scientists use non-animal methods such as cell and tissue cultures and computer modeling whenever possible. When they believe that animals should be used, they are required by law in many cases to show that animals are necessary to the research. In recent years, technology has permitted the development of many new approaches. However, each has both advantages and limitations.
Cell and tissue cultures are used to study individual cells, genes, and molecules. These help us understand how biological processes operate. Information gained from such research can sometimes be used to create mathematical and computer models that predict how a molecule may interact with its environment. Such models often provide important clues to solving medical mysteries, but the story doesn’t end there.
Sometimes studies of simple living creatures such as bacteria, yeast, roundworms, or fruit flies can provide insight into dynamic biological processes. Studies with these creatures have provided a wealth of knowledge about how specific genes work. This can be very useful information since many similar genes are also present in humans and other mammals. Also, the most basic workings of the brain and nervous system have been studied extensively in squid and other mollusks.
But the body’s organs and systems interact in sophisticated ways. These biological and chemical processes cannot be understood fully by looking at simple organisms or isolated molecules or cells. Cause and effect relationships discovered within cells or between molecules may operate quite differently when the same process is studied in an intact organism. That is why it is important to study whole animals including humans as well as isolated molecules and cells.
Human beings and other mammals are complex organisms, and our health problems cannot be studied fully in animals that do not have the same organs. So scientists usually must look to other mammals to study human diseases. Scientists select an animal model based upon what is already known about the physiological similarities between that species and humans. With many diseases, there is also a progression of studies that starts by asking simple questions using mice and rats and culminates by asking more complex ones using species with greater similarities to humans, such as cats, dogs, pigs, sheep, or nonhuman primates. Because of the many and varied interactions among the human body’s organs and systems, not only diseases, but also new drugs, vaccines, and surgical techniques must be studied in whole animals to assure their safety and effectiveness.