Nature vs. Nurture Debate Human

NATURE vs. NURTURE DEBATE

Human beings and other so-called "higher" forms of biological life are products of their environments in many respects. Exposure to certain environmental factors and being reared under certain circumstances can influence the direction of many types of behavior. At the same time, the field of genetics demonstrates conclusively that inheritance also determines much of the development of everything from fundamental aspects of personality to the most superficial habits, likes, and dislikes.

Twin studies have proven particularly useful in examining the respective roles of nature and nurture in that identical twins separated at birth and reared separately under the influence of entirely different external environments. The fact that identical twins, by definition, share the same genetic predispositions makes each of them, in scientific experimental terms, a control for the other. In that respect, the most fascinating observations arise in situations where identical twins are separated at birth and raised separately, only to exhibit identical behaviors in the realm of things not usually considered to have genetic components at all (Henslin, p.59).

On the other hand, various examples of some of the most extreme forms of deviant social behavior in humans have been linked very directly to specific types of formative experiences and deprivations, particularly in the case of certain criminal behavior of the type catalogued by criminal profilers (Macionis, p.192). Few doubt that elements of both nature and nurture contribute to behavioral development, but the interplay and respective roles played by each still fascinates psychological researchers and lay observers alike.

Nature:

One need look no further than at parents and their biological children to recognize the profound influence of genetics between successive generations: tall parents tend to have tall children, intelligent parents tend to have intelligent children, and the rules of genetic inheritance is so precise that it allows us to predict with accuracy the results of combining specific genetic contributors of genes known to be associated with traits that are dominant or recessive with respect to various physical traits such as eye color and color blindness (Gerrig & Zimbardo, p.112).

Behavioral traits are also dramatically influenced by genetic inheritance, although they often take much longer to reveal themselves, in addition to being more susceptible to subjective observation: whereas an individual's eye color is readily apparent on simple observation, more complex aspects of behavior are often more difficult to quantify definitively. Nevertheless, that genetic inheritance contributes to behavior, irrespective of external influences is uncontroverted.

Nurture:

The influence of external environmental factors on behavior is well documented both in human beings as well as in other organisms. Infant primates raised by secure, confident, dominant mothers tend to exhibit calm, secure interactions with their peers and to assume high status positions within their primate communities. Likewise, infant primates raised by insecure, fearful, and tense mothers tend to exhibit tense, insecure interactions with their peers and to adopt subservient positions within their communities that approximate their mothers' relative status within the hierarchical group social structure (Macionis, p.117).

Interplay Between Nature and Nurture:

This would seem to indicate simply that socially secure and dominant primates tend to pass along those social traits to their offspring, exactly the same way they pass along physical traits. However, the issue becomes much more complicated by virtue of classic experiments whereby primate infants born to extremely shy, tense, and insecure mothers were switched with infants of outgoing, calm, secure mothers, and vice-versa

Macionis, p.117).

In those experiments, researchers discovered, much to their surprise, that primate infants of tense, insecure mothers actually developed the same calm, secure behavioral traits of their adoptive mothers instead of the traits of their biological mothers and that primate infants of calm, secure mothers developed their adoptive mothers' personality traits.

Such observations strongly suggested that environmental factors are equally important in psychological aspects of primate personality development to strictly biological or genetic factors. More recent variations of these types of experiments have determined that some types of genetic traits and predispositions to certain diseases are dependent on both genetic predisposition and external environmental factors working in combination.

For just one example, clinical depression in humans has been linked to early traumatic experiences; it has also been linked to specific genetic markers. Researchers have been able to plot the respective likelihood of developing the disease among individuals with either contributing factor in comparison to individuals with both contributing factors, demonstrating that the combination of biological and environmental influences is a much stronger predictor of depression than either factor on its own (Gerrig

Zimbardo, p.498).

The Significance of Extreme (Deviant) Human Behavior and Identical Twin Studies:

Some of the most dramatic evidence of the significance of external environment and experience on personality development comes in the form of the common experiences that criminologists and criminal psychological profilers have identified as playing a role in the evolution of profoundly deviant human behavior. That evidence is relevant by virtue of its extreme departure from 'normal" human behavior as well as the fact that the individuals involved typically share very specific childhood experiences but no apparent biological similarities.

Serial killers undoubtedly exhibit some of the most extreme forms of deviant social behavior, yet they share no known biological similarities that would predispose them to their pathological crimes. However, psychologists have identified very specific types of physical abuse and parental neglect in childhood, in addition to remarkably similar childhood experiences that consistently correspond to the eventual development of this particular form of criminally violent social deviance (Innes, p.7). With no identifiable biological factors to explain their extreme behavior, the implication is that it is exclusively a function of early childhood environmental experience.

By far, some of the most interesting evidence of the opposite end of the nature vs. nurture spectrum is represented by the phenomenon of identical human twins separated at birth. In principle, this provides the opportunity to examine specific traits that are strictly due to inherent biological factors. Whereas identical twins raised together share environmental influences as well their genes, identical twins reared apart share only their genes. Therefore, any behavioral similarities between them must be attributable exclusively to their genetic similarity rather than to any combination of biology and environment.