What can biology tell us about behaviour?

Citation

Wells, D. (2000), "What can biology tell us about behaviour?", Nutrition & Food Science, Vol. 30 No. 5. https://doi.org/10.1108/nfs.2000.01730eaf.002

What can biology tell us about behaviour?

What can biology tell us about behaviour?

Psychologists are interested in biology not for its own sake but for what it can tell them about behaviour, mental processes and social interactions. This article will look at some reasons for our behaviour and aim to explain why, for example, some people are depressed or aggressive, others pining for the company of friends while other people are isolationist. Biology helps us to understand why some mental processes have a physical basis although the subject is necessarily selective. The article will also look at some aspects of biology to see how they explain some aspects of behaviour.

Behaviour is largely determined by the nervous system and the type of behaviour an animal displays is determined by the nervous system it possesses. The human nervous system is very complex consisting of between 10 and 12 billion nerve cells or neurons. A chemical called a neurotransmitter is released by one neuron and is received at the receptor site on another neuron. This transfer takes place at a synapse and can either excite or inhibit the second neuron. The complex system or interaction between the nervous system and the external environment affects the causes of behaviour of an individual. It is called the causal level of analysis.

The functional level describes how evolution over millions of years has caused an animal to adapt to its specialised environment. Behaving in certain ways ensures an animal's success in living in a certain environment. Whereas we cannot fly as birds can, human beings are able to manipulate small objects which is due to the way our fingers have developed during evolution. Evolution over many thousands of years has led to the development of the large human brain. This has transformed lives in the Western world from simple hunter-gatherers to the technological age in which we now live. We now have enormous expertise in technology, science and engineering. To a large extent this is due to culture, academic excellence and social learning.

The kind of behaviour of which an animal is capable also depends on the type of body it possesses. We tend to judge other people by their physical appearance which is a biological characteristic. We also believe that we ourselves are judged in this way. The biological trait of physical appearance affects our own self-image and reactions towards other people. Our embodiment determines to a large extent our experience as individuals. Black people should be treated no differently from white people. Sex should not be an issue in employment prospects and promotion. Disabled people should be given the help they need to lead a satisfying and fulfilling life.

I shall consider first of all the causal effects of biology. For example, the effect of excessive or inadequate amounts of neurotransmitters can influence behaviour. For example, abnormal levels of the neurotransmitter serotonin are associated with impulsiveness and aggressiveness. Too little serotonin can cause anxiety. An impulsive individual may make wrong decisions which affect the quality of his or her life. Aggression can reduce social interaction while anxiety predisposes the individual to morbid thoughts and worries which may affect his or her life detrimentally.

Parkinson's disease is caused by atrophy of dopamine releasing neurons and schizophrenia may be caused by overactivity of dopamine in the hypothalamus. Abnormally high levels of dopamine and dopamine receptors are found in the brains of deceased schizophrenics (Snyder, 1980). These two diseases are of considerable interest to social psychologists.

The nervous system also causes the secretion of hormones into the blood stream which have effects on tissues separate and distinct from the nervous system. For example, the thyrotrophic hormone, thyroxin, secreted by the thyroid gland in the neck controls metabolic rate. Too much thyroxin causes hyperactivity and anxiety while too little causes lethargy and depression. Majur et al. (1992) found that the winners of chess matches had higher levels of testosterone in their blood than the losers. High levels of this hormone suggests that the winners were more competitive than the losers (Toates, 1995). There is also some evidence that high levels of the hormone cortisol can lead to depression.

Traumatic events such as bereavement and divorce, which are influences from the external world, have an effect on the autonomic nervous system, which causes increased levels of cortisol in the blood stream. For many depressed people life's normal opportunities and the pleasure of interacting with other people are diminished and this is of considerable significance to social psychologists. Dealing with depression is one of the conditions they frequently encounter and is very difficult for the individual to come to terms with.

Adrenaline is another hormone which in our evolutionary history prepared the body for either fight or flight. The hormone enables food source of energy to be made more generally available and the heart pumps more quickly bringing the energy source and the oxygen to the muscles. The body is prepared to deal with the stress. Unfortunately, many of the stresses we encounter in this modern age do not require the individual to prepare for fight or flight. Much modern day stress is due to factors such as antagonism with associates, late arrivals of important messages and traffic hold ups. These are all factors from the outside world over which we have little or no control.

The food sources of energy, instead of being used for physical activity, can clog up the arteries especially those of the heart. Adrenaline also causes an increase in blood pressure. These two factors predispose an individual to coronary heart disease which is of considerable importance as it may lead to disability and eventually death. Disability leads to a decreased value of life while death causes distress to the relatives who are left behind.

Coronary heart disease also appears to be more common among individuals described by Meyer Friedman and Ray Rosenman as Type A personalities. Type A personalities are prone to hostility and anger in times of stress. This leads to excessive amounts of adrenaline and cortisol being released into the blood stream. On the other hand Type B personalities have a much more relaxed attitude to adversity. They are much less likely to become stressed and so appear to be at less risk from coronary heart attacks. The use of this information in social psychology is to try to provide Type A personalities with a more laissez-faire, tolerant attitude towards their fellow human beings.

Middle-class parents often put undue pressure on their children to succeed at school. So from a young age children are growing up with a propensity for a Type A personality. A more relaxed attitude from the parents, encouraging a child's aptitude but not putting on too much pressure for that child to excel in everything he or she is engaged in, would probably lead to more Type B adults. Though it is a daunting task living as we do in a competitive age with the problem of job insecurity.

Over the last 50 years the age of menarche has gradually fallen. Today, adolescents are subjected to a considerable amount of overtly sexual material and entertainment. The gonadatrophic hormones have become active sooner leading to earlier sexual development. Today, the UK has a great problem with teenage pregnancies (Department of Health). With its associated problems of interrupted education and lack of vocational training young people become virtually unemployable. The single parent may become isolated and cut off from the normal experiences of life to which another adolescent is entitled. Low income may lead to lost opportunities, resentment of the child and poor parenting.

Schachter and Singer (1962) investigated the effects of adrenaline on subjective feeling when the external environment was manipulated. The participants were told they were taking part in an experiment to test the effects of a drug called suproxin on vision. In fact some of the participants were injected with adrenaline instead of the so-called suproxin. Other participants, acting as controls, were injected with inert saline solution in case simply having an injection affected the resulting emotional state. Some participants were told of the likely side effects of the injection, others were told nothing about the effects while still more were told of effects unrelated to that of adrenaline. Stooges were involved in the experiment. To one group they acted in a happy way, to the other group an angry way.

At the end of the experiment participants were asked how they felt. Those injected with adrenaline and subjected to the happy stooge felt the emotion of happiness while those subjected to the angry stooge felt anger. These emotions were in contrast to the participants injected with the saline solution. Mood changes were particularly noticeable in the groups who had not been informed or misinformed as to the effects of the adrenaline injection. Participants who were informed of the true effects were more likely to attribute these to the injection rather than the behaviour introduced by the stooge.

Schachter and Singer (1962) concluded from this experiment that the hormone in association with the social context were responsible for the emotional states of the participants at the end of the experiment. The emotion induced were a combination of the hormone (the biological or peripheral effect) and the social context (the cognitive effect). However subsequent researchers have found difficulty replicating these results, For example, Reizenzein (1983) concluded that the peripheral action such as raised heart rate as a necessary condition for emotion was not confirmed. Subsequent research has indicated that peripheral action may play some part in determining emotional state.

Another aspect of psychology which is of interest is addiction to drugs and alcohol. There is some evidence to show that the brains of addicted persons show some malfunction. For example, certain regions of the brain are more susceptible to the effects of alcohol (Cox and Klinger, 1988). But again social context has a part to play. Being with other drug addicts may cause a powerful craving for the drug. Being in contact with others who are injecting drugs may induce a small "high" in the individual. Susceptibility to alcohol may be genetic in origin and studies of addicted behaviour in families suggests this. Here the functional aspect of biology comes into play. Causal effects may also be implicated as drinking in a social interaction may play a part.

Cox and Klinger (1988) suggest that alcoholics have to decide whether the beneficial effects they may perceive in drinking outweigh the effects of not drinking.

Addiction is a serious social problem. Cox and Klinger suggest that the way to overcome the addiction is for the alcoholic to find an alternative source of emotional satisfaction. This is of great use in social psychology but the problem is to find an appropriate source of emotional satisfaction.

A study of biology has been able to show that many of these qualities have their bases in this subject. The nervous system is responsible for behaviour and is also concerned with the secretion of hormones which have such a strong influence on attitudes and behaviour, Social psychology is also concerned with the interaction between individuals, their roles and statuses. Again biology has a part to play in determining whether the individual is aggressive or trusting, happy or depressed. Biology enables us to understand some aspects of mental life and emotion. It helps to explain how the performance of our bodies makes us the kind of person we are.

Dilys WellsEditor