The famous Greek doctor Galen (AD129-200) studied animals. William Harvey used animals 400 years ago to discover how blood circulated in the body. The 'modern' era of animal research started about 150 years ago with the rise of physiology as a science. But it was very different then - there were no anaesthetics or effective pain killers, so the animals suffered a great deal, as did patients. Imagine having your leg amputated (which was not uncommon - infections could be very serious before antibiotics) without anaesthetic.

Laws around the world vary. Usually they depend on either a local system (which may be voluntary) or on national controls administered by the government. The UK is the only country in the world to have both systems running at the same time. The strict controls under the Animals (Scientific Procedures) Act 1986 were added to in April 1999 with the introduction of the Local Ethical Review Process for animal research. There are also international regulations such as the European Directive 86/609.

Researchers have good ethical, scientific and legal reasons to treat laboratory animals well and use them in minimum numbers. All animals must be properly housed, fed and cared for. Pain and distress must be minimised and the UK controls state that there must be a vet on call at all times. These controls also make sure that any animal suffering severe pain which cannot be alleviated is put down immediately.

It has proved very difficult to develop non-animal methods to replace the use of animals in research and testing. Most progress has been made in the replacement of animals in safety testing. Once non-animal methods have been developed and validated, and are accepted by the regulatory authorities world wide, then they must be used in preference to the animal tests. Animal experiments are just one method in biological and medical research - research can also be done using cells, tissues, people, and high tech equipment. Some people regard these methods as alternatives, but they are really complementary methods that are used alongside animal research to answer different sorts of questions. Animal research and testing accounts for a small propoortion of all biomedical research and testing.

Almost every major medical advance has depended on the use of animals at some stage in its research, development or testing. Examples include antibiotics, anaesthetics, insulin for diabetes, organ transplants, hip replacements, etc.

Obviously there are differences between animals and people. But under the skin, the biology of humans and other animals, particularly mammals, is remarkably similar. We have the same organs, controlled by the same nerves and hormones, as many other species. Where there are differences, researchers know about them, and such differences can actually help scientific understanding of a particular problem. Many animals suffer quite naturally from the same diseases as humans, and can be used to study those diseases. In other cases, researchers can use an 'animal model' of a disease which is close to the human condition.

We would be very unlikely to achieve many significant advances in scientific understanding or the prevention and treatment of diseases without animal research. We also need to use animals in safety testing to protect people, animals and the environment.

Animals are used when there is a need to find out what happens in the whole living body, which is far more complex than the sum of its parts. It is very difficult, and in most cases simply not yet possible, to develop non-animal methods to replace the use of living animals.

Most people carrying out the research are doctors, scientists, vets or trained animal carers, working in universities, hospitals, research institutes and pharmaceutical companies. Everyone who uses animals in research must have the necessary skills and training, and the research must be carried out in licensed premises.