Many biological studies that attempt to expand our understanding of personality trace their origin to the structure and aetiology of the “nature” versus “nurture” debate. Francis Galton, a 13th Century Frenchman, first coined the words “nature” and “nurture” in 1874 to argue his case about the domineering influence of both genetics and environmental factors on personality (McDevitt et al., 2010).
While pre-existing paradigms have for a long time focused entirely on environmental or learned aetiology of personality, evidence from biological studies demonstrates that genetic characteristics indeed have a considerable role to play in the formation of personality (Ferguson, 2010). It is against this background that the present paper will aim to describe the influence of biological studies on our understanding of personality.
In his study on ‘genetic contribution of antisocial behaviour’, Ferguson (2010) postulates that the decisive cause of behaviour may more likely be the evolutionary process, which inarguably initiates some genes to be preferred due to particular environmental demands, or which initiates the capacity to learn behaviour to become an adaptive characteristic.
This implies that an individual who is abused as a child may end up developing aggressive behaviour in adulthood due to either the environment in which he was raised or genetic factors or a combination of the two. In consequence, this study demonstrates that some specific genes or environmental influences that shape behaviour may be deemed proximal or immediate causes of observed behaviour (Ferguson, 2010).
Other biological studies have revealed some genes innate to an individual direct them to engage in antisocial behaviour. Such behaviour, according to McDevitt et al (2010), may include antisocial personality disorder (APD), aggression, inhibition, psychopathy, anger, aggression, violence, lying and stealing, among others.
In one particular study cited by Ferguson (2010) on minors with attention deficit hyperactivity disorder, it was found that “…children with the valine/methionine variant in the catechol O-methyltransferase (COMT) gene showed greater antisocial behaviour than those without this variant” (p. 161).
The study concluded that the COMT gene variant may have adversely affected the healthy development of the prefrontal cortex, thus lessening the children’s control over violent desires. Studies have also linked the serotonin transporter promoter gene (5-HTT) and the MAOA gene to aggressive impulses.
These and other studies positively reveal that our genetic makeup has the capacity to influence personality. It should, however, be noted that specific genes do not individually influence personality; rather, they likely corroborate with each other in ways that still remain poorly comprehended to influence personality and behaviour (Ferguson, 2010).
Away from issues of genetics and evolution, some biological studies have demonstrated that the nervous system plays a major role in the creation of introverted personality. Carducci (2009) argues that “…introverts seem to show greater nervous system sensitivity and reactivity to lower levels of noise than do extroverts” (p. 322).
Another study reported by Ferguson (2010) reveals that distorted nervous functioning has the capacity to not only trigger severe behavioural and psychological disorders, including mood and personality changes, but they can also interfere with the intricate workings of the brain, resulting in mental disability. This implies that some biological processes such as the sensitivity of the nervous system indeed contribute to the socially inhibited behaviour characteristically related to the personality of introverts.
However, it should be noted that contributions made by such biological factors towards the formation and development of personality are not intended to displace environmental, psychological or cognitive factors; on the contrary, all the mentioned types of processes compliment and supplement each other to provide a broad comprehension of personality (Carducci, 2009).
Biological studies have also broadened our understanding on how neurotransmitters and receptors influence the formation and development of personality. The nervous system, according to current estimates, has approximately 100 neurotransmitters in diverse parts of the body, not mentioning that the neurotransmitters have numerous types of receptors, each with diverse properties (Kalat, 2007).
It therefore follows that if each type of synapse has its own particular function in shaping or influencing behaviour, then individuals exhibiting less than the ordinary quantity of some transmitter or receptor due to their own genetic configuration or other underlying reasons will definitely exhibit some altered behavioural tendencies. Indeed, Kalat (2007) postulates that “…theoretically, variations in synapses should have something to do with variations in personality” (p. 67).
The author cites a study interested in variations in dopamine receptors, which revealed that individuals with one form of the D2 receptor were more likely than others to nurture pleasure-seeking personality, including severe alcoholism, drug abuse, overindulgence in eating and consistent gambling. This and other related studies inarguably demonstrate how our neurological makeup and composition affects personality.
Moving on, it is indeed true that biological studies have brought into the fore the knowledge that our anatomy directly or indirectly influence our personality. Of critical importance in most anatomy and personality studies is the function of the brain in influencing behaviour (Carducci, 2009).
Various studies as conceived by the author have positively identified the areas of human brain that are most vigorous during diverse mental tasks and disturbing reactions, not mentioning that other studies have identified regions of the brain that stimulates observed personality traits such as generosity and honesty. According to Funder (2007), “…the ascending reticular activating system (ARAS), part of the brain stem, was hypothesized by Hans Eysenck to be the basis of extraversion and introversion” (p. 253).
Another part of the brain known as the amygdale plays a critical function in generating emotional responses based on its rational computation on whether the surrounding environment seems to provide an impending threat or reward, while the frontal lobes forms the basis of exceptional human capabilities such as language development, comprehension of the self and foresight (Funder, 2007)
This implies that the personality of an individual is likely to be altered in the event that these critical areas of the brain are physically or organically damaged.
Lastly, biological studies have afforded us the opportunity to know how chemical imbalances within the body may affect behaviour. Some chemical imbalances, which are genetically predisposed, may indeed impair an individual’s capacity to make rational decisions or relate with others in a mature and responsible way (Heredity versus Environment para. 8). Such individuals may end up becoming introverts or, worse still, murderers and sociopaths.
Reference List
Carducci, B.J. (2009). The psychology of personality: Viewpoints, research, and applications. Hoboken, NJ: Wiley-Blackwell.
Ferguson, C.J. (2010). Genetic contributions to antisocial behaviour: A meta-analytic review from an evolutionary perspective. Journal of Social Psychology, 150(2), 160-180. Web.
Funder, D.C. (2007). The personality puzzle, 4th Ed. New York, NY: W.W. Norton & Company
Kalat, J.W. (2007). Biological psychology. Stamford, CT: Cengage Learning.
McDevitt, T.M., Jobes, R.D., Cochran, K.F., & Shehan, E.P. (2010). Is it nature or nurture? Beliefs about child development held by college students in psychology courses. College Student Journal, 44(2), 533-550. Web.