Most animals used in research are small and can be handled relatively easily. In studying genetics, it is useful to be able to study more than one generation in a short time. Therefore, animals that have a short gestation period and reproductive cycle are useful because successive generations can be obtained relatively quickly. Some animals (e.g. mice) have similar sorts of brain areas and chromosomal function to humans which is useful for comparative purposes. Using animals in research can have practical benefits for the animals as well as for humans. For example, by knowing more about some animal species, zoos are able to care for them better. There are practical reasons why it is useful to use animals when studying the effects of drugs. The drug may need to be administered daily over days or weeks, which – ethical considerations aside – is more practical using animals. Some studies require examination of brain tissue after drug treatment, or need drugs to be administered to specific sites of the brain. These are procedures that can be carried out more practically on animals. Studying the process of ageing using humans is not practicable because the study might have to run over 80 years. On average, rats live for 2 years and monkeys live from 15 to 20 years. The shorter lifespans mean that results are found more quickly, which is again a practical reason for using animals. Laboratory experiments that need participants of a certain size, age, or genetic structure and which might need, for example, to restrict participants to a certain diet or to control their environment in some way are more practically carried out using animals. Evidence that findings from animal studies can be applied to humans comes from such studies as using cats and bulls and stimulating the limbic system, which affects their levels of aggression. It has been shown that in humans as well the limbic system relates to aggression. This supports the idea of using animals for practical reasons rather than humans. Animals are not the same as humans, so there can be problems in generalising results of studies on animals to humans. Even if an animal has a similar brain structure to humans it will not be identical. In order to study some diseases (e.g. Parkinson’s) they have to be artificially reproduced in animals, which is not the same as a person developing the disease. Therefore, what is studied might not be valid. There is doubt about the credibility of animal studies. For example, what is being studied is often not the same as the situation for humans, e.g. drug-induced symptoms of Parkinson’s disease or replication of control over a stressful situation for monkeys. Mice have similar chromosomal functioning to humans, which makes the findings from gene studies useful. However, when considering the whole organism, it does not seem credible to conclude that mice function the same way as humans. Some people say that the comparison between animals and humans is not credible. For example, simply because they have shorter reproductive cycles, live fewer years and have different brain structures, it is not credible to apply findings from such studies to humans. There is evidence that findings from animal studies cannot be applied to humans. The drug thalidomide was found to be safe when tested on rabbits but when pregnant women used it; many babies were affected by the drug. The main ethical reason for using animals is that procedures can be carried out on animals that for ethical reasons cannot be carried out on humans. For example: lesions, which involve damaging brain structure The main ethical reason for using animals is that procedures can be carried out on animals that for ethical reasons cannot be carried out on humans. For example: ablation, which involves removing part of the brain The American Psychological Association (APA) states that psychologists should only undertake research with animals for a clear scientific reason. The knowledge that comes from the research should increase understanding of behaviour, increase understanding of the species being studied or ‘provide results that benefit the health or welfare of humans or other animals’. Otherwise the research should not be carried out. The British Psychological Society (BPS) takes a similar view. Drugs have been developed that would not have been developed without the use of animals, e.g. drugs to treat mental illnesses, such as antipsychotic drugs. It is argued by some that humans should improve their own quality of life by whatever means. This is called ‘pro-speciesism’ More is learned about the animal species in question and the knowledge is used to improve their care. In laboratory experiments, animals are likely to be confined more than is normal; they are either in an unfamiliar environment of bred for the purpose, either of which is unethical. Surgical procedures are used, which is likely to cause the animals pain (or at least discomfort), which again is not very ethical. In some studies, animals die because of the procedures. The guidelines help to make the studies ethical to an extent, e.g. specifying the use of the minimum number of animals. However, those that are used are still caused pain and discomfort. Animal species are not sufficiently different from humans for them to be treated as ‘objects’ and not as participants’. However, in general animals are not treated as conscious beings in the way that humans are. Some researchers have put forward arguments that using animals is not as unethical as might be thought. For example, Grey (1987) argued that: When rats were deprived of food it did not cause them distress. They were usually fed after the experiment, which was once a day, which was enough. Even if they were not fed then, their body weight was maintained at 85% of what it would be if they fed normally, and that this is a healthy weight. When rats were given electric shocks, the size of the shock was what would cause a tickling sensation in humans. By looking at the detail in this way Grey helped to show that depriving rats of food and giving them electric shocks might not be as unethical as thought previously. It is suggested that some species (e.g. insects) do not feel pain, although this is still being researched.