Often it is not possible to study biological factors in behaviour in humans due to ethical considerations.  Instead, animals are often used.  They are used because they are physiologically and anatomically similar to humans, they are readily available, and they have a short lifespan which makes it possible to study a behaviour over several generations. However, there is a debate in psychology about whether it is ethical to use animals in the study of biological factors such as hormones. The question is whether the costs outweigh the benefits.

One of the great discoveries in biology was the discovery of the hormone, leptin. Leptin appears to play a role in stopping our eating.  When we eat, our leptin levels rise in line with glucose levels.  When leptin reaches a certain level, the hypothalamus signals that we are “full.”  The discovery was made by Friedman.  He used two mice.  One mouse was “normal”, but the other mouse was hyperphagic – that is, it couldn’t stop eating and was very obese.  Friedman believed that one of the two mice must have something biological that the other mouse did not.  To test this, he sewed the two mice together, joining their circulation systems.  He found that the hyperphagic mouse lost weight.  This was the beginning of the process that led to the isolation of the hormone, leptin.

This research has some serious ethical concerns.  One of the basic ethical standards is to avoid undue stress or harm. It is clear that this study caused serious physical harm to the mice.  They would have to be “humanely” euthanized at the end of the experiment.  One of the other guidelines for animal research is the three R’s: Reduce, refine, replace.  In this case, the number of animals was literally two.  So, the number was the minimum necessary. However, the question is whether the procedure could have been refined so that it would not be traumatic for the mice. The researcher should have had a vet available to oversee the process and to make sure that the mice suffered as little pain as possible.  The final “r”, replace, asks whether the researcher could have used another way to investigate this question without using the animals.  Although it may have taken longer to find certain results, this might have been done through blood analysis.

Not all animal research is as unethical as Friedman’s study. Meany carried out a study to see if stress in childhood would lead to memory impairment in old age.  Research has shown that Adverse Childhood Experiences have a negative effect on health, but these are all correlational studies.  In addition, it is difficult to monitor the health developments of an individual across the lifespan.  This is why Meany used rats.  Rats from the same litter were allocated to one of two conditions.  In one condition, they were taken away from the mother soon after birth and were groomed by researchers using brushes. The other condition was taken away from the mother but not groomed.  This led to higher levels of stress – and an increased level of glucocorticoids. When the rats were two years old, they were put into a pool of milky water where they were to find a platform to get out of the water. Meany found that the rats that had been handled by the researchers learned the location quickly, but the unhandled rats, those with high levels of glucocorticoids, took longer to find the platform. Meany argued that high levels of glucocorticoids in childhood led to the inability to manage stress throughout their life and hippocampal cell death as a result of high cortisol levels, leading to memory impairment.

Meany’s research also has the problem of harm to the animal.  He euthanized the rats in order to measure the volume of the hippocampus. At the time of the research, there was no other way to do this.  Today, modern scanning techniques would allow for the rat’s brain to be measured without having to kill it. In addition, it was important that Meany used as few rats as possible and that they are kept in conditions that would be considered as “naturalistic” as possible.

In both cases, the researcher has to carry out a cost-benefit analysis to justify the research. However, since the results cannot be known with certainty before doing the experiment, it may be that the expected benefits do not actually happen.  In the case of Friedman’s research, although leptin was discovered, it has not shown to be effective as a treatment for obesity. However, leptin has been used to explain some cases of obesity. In Meany’s research, the findings support what we see in humans and help researchers to understand the role of cortisol through experimental methods.

As already mentioned, it is important that the three Rs are used in research.  For example, with refinement – that is, keeping the rats in naturalistic conditions – researchers can eliminate the stress of confinement.  Especially in older research, there is the question of whether the animals’ stress of being in poor living conditions may have played a role in findings.  In Meaney’s research, the level of care for the animal was important so that the stress could be isolated to the lack of maternal grooming.  However, the ethical standard of reduction is problematic.  If we reduce the numbers too low, then we cannot be sure that the findings are reliable.

The third R is “replace.”  It is a question whether we can easily replace animals with computer models or in vitro testing.  In the case of Friedman’s research, it would not be possible to create a computer model to find a hormone that we are not sure exists.  Computer models have to be based on a certain amount of knowledge in order to be built. Theoretically, in Meaney’s study, he could have used in vitro testing, looking at the effect of glucocorticoids on hippocampal cells.  The problem is that animals, including humans, are systems. Meany’s research showed the interaction of environment, genetics, hormones, and memory over the lifetime of an animal, something that is not currently possible with cell cultures.  Although in vitro can show us what happens on a micro-level, it does not allow us to observe behaviour that is the result of these changes at the micro-level.

The question of whether to use animals in research is complex. We recognize the need to treat animals ethically, but such practice may put limitations on necessary research.  Both studies above have contributed to our understanding of the role of hormones in human behaviour, but it can be argued that this happened at a great cost to the animals. In considering the three R’s prior to carrying out their research, psychologists are attempting to be ethical in their practice. It is important that we continue to question this practice, with the hope of decreasing the number of animals used.