Introduction
Both heredity and hormones are considered as possible factors to explain human behavior. Hormones act in two ways to affect human behavior: directly and indirectly through their impact on genes. Thus, heredity factors and hormonal factors to explain human behavior are interlinked. What is heredity? It is merely the development in the offspring of the same characters which were present in the ova from which the parents developed. When the same characters are passed from one generation to another, the process is labeled as heredity. When new characters are determined in the ovum, not due to changes in the environment, we call them variations. When a fertilized ovum develops into a new individual, it undergoes repetitive division to form a large number of cells united into a single mass. Gradually, the parts of this mass are differentiated to form the tissues and organs of the body or soma, but some of the cells remain in their original condition and become the reproductive cells which will give rise to the next generation. The reproductive cells also undergo division and increase in number and when they separate from the new individual and unite in fertilization, they still possess all the determinants of the fertilized ovum from which they are descended. Heredity thus continues (Nyborg, 1994).
Main body
Chemical neurotransmitters and circulating hormones act to alter electrical brain activity and structure. Genes of the hereditary material are acted upon by these chemical messenger with the result heredity is continually contributing to our behavior (Nyborg, 1994). At the same time, heredity is not longer recognized as the omnipotent force. Environmental factors such as light and dark, heat and cold, the season of the year, and the experiences we have are all able to regulate the secretion of hormones of the gonads, adrenals, and thyroid gland, which have direct impact on gene expression throughout the developing and adult brain. The brain responds to these hormones by altering its circuitry and chemistry, and the brain is shaped and maintained by the interactions of the circulating hormones with its own neuro transmitters and neuropeptides. The developmental history of the brain includes its exposure to sex, thyroid and adrenal hormones, and the developmental actions of these hormones determine how the adult brain responds to the environment, including how rapidly and in what way it ages (Nyborg, 1994). Even the process of learning and memory now appear to be analyzable in terms of chemical and structural changes within the brain brought about by electrical activity and chemical messengers. Professor Nyborg holds that individual differences in complex behavior maybe shaped at least in part, by circulating hormones.
Interpretation of behavior genetic research by the general press consistently presents each gene-behavior association as an association attributable to a specific gene for that association. However, this has been found not to be true. This concept of a gene contributing to each trait of human behavior is one that is popularized by the common press writers and not by behavioral; Public misunderstanding that there is a gene for every behavioral trait is fostered by application of genetic models to behavioral phenotypes for which gene-behavior pathways can only be highly indirect as in the case of voting, volunteering for military combat, and watching TV (Rose, 1995). That genetic dispositions make some indirect contribution to individual differences in voting behavior, combat exposure, and TV viewing habits may be true; perhaps no dimension of human behavioral variation is immune to effects, however indirect, of genetic variation. But genetic analyses of such phenotypes are of uncertain meaning (Prescott et al, 1991). For example, no gene for TV watching, a behavioral phenotype nonexistent three generations ago, could plausibly exist.
According to Rose (1995), people do not uniformly react to environmental situations, nor do the situations we encounter “just happen.” They actively seek opportunities to develop and display the dispositional characteristics, so adult personality differences reflect, not fixed consequences of hereditary variance, but interactive processes of lifestyle selection. With rare exceptions (e.g. Huntington’s Disease), genes do not mandate life outcomes (Rose, 625). This finding cancels out both genetic and hormonal effects on human behavior.
Hormones are glandular secretions that often impact human behavior. For example, differences in gender behavior are explained through hormones effectively – far more effectively than through hereditary theory or genetic theory. Because of their different reproductive strategies, men and women have evolved different hormonal processes that generate different dispositions. Testosterone and other hormones that trigger the development of male physical characteristics also organize personality traits (McGinnis, 1999). Psychological studies also suggest that men and women have different predispositions from the beginning. Even before children understand that trucks are associated with boys and dolls associated with girls, girls tend to like dolls and other toys that lend themselves to nurturing and empathy, while boys reach for the Tonka Trucks (McGinnis, 1999).
Behavioral endocrinology and biological psychology claim that sex hormones play an important role in the production of sex differences in human and other animal behaviors. David Crews argues that “all somatic sexual dimorphisms, including brain, and hence behavior, result from gonadal hormone production that begins after morphological differentiation of the gonad” (1988, 332). In this view, brain and behavioral factors derive directly from sexed bodily differences. In recent times, for example, they have been held in popular scientific literature to indicate that women are better suited than men to child-rearing, and to underlie women’s incapacity for certain types of work (Roberts, 2000).
Conclusion
Thus it has been found that hormones do play a vital role in deciding human behavior either working with the brain’s cells and altering heredity on a continuous basis or by acting on the genetic factors themselves.
Bibliography
J. T Cunningham (1921). Hormones and Heredity. London Constable and Co. Ltd. 1921. Web.
McGinnis, O. John (1999). Science – sex differences and human behavior. National Review.
Nyborg, Helmuth (1994). Hormones, Sex and Society: The Science of Physiology. Greenwood Publishing Group.
Prescott CA; Johnson RC; McArdle JJ (1991). Genetic contributions to television viewing. Psychol. Sci. 2:430-31.
Roberts, Celia (2000). Biological Behavior? Hormones, Psychology and Sex. NWSA Journal. Volume: 12. Issue: 3.
Rose, J. Richard. Genes and Human Behavior. Contributors: Annual Review of Psychology. Volume: 46. 1995. Page Number: 625+.