Can Your Personality Go The Way of the Dinosaurs?

Personality is arguably one of humankind’s most complex and fascinating features. Unfortunately for academia, centuries of philosophical musings and psychological studies have shown that personality is also one of the hardest aspects of human nature to conceptualize, exacerbated by the fact that it is also difficult to give it a definition that everyone can agree upon. Putting disagreements aside for the purpose of the discussion at hand, in this essay term “personality” will be defined as an individual’s sense of self, and from this how that individual then interacts with his or her cultural environment. Knowing that every one of 6.5 billion human beings on the planet is in possession of this incredibly intricate feature, a question that may follow is “From where, exactly, does personality arise?” While some argue that personality is a result of genes inherited from an individual’s parents, others claim that it arises simply from the way one is raised. This age-old “nature versus nurture” argument has plagued behavioral scientists and parents throughout the ages. However, perhaps some clarity can be gained on this issue by taking a step back and looking at the even broader picture, that is, what is the mechanism that gave rise to personality in the first place? If personality is taken to be a function of the brain it can then be said that, at least from the perspective of a neurobiologist, personality is a biological aspect displayed by an organ of the body. This said, one may ask, “By what mechanism do all other biological processes arise?” Thanks to Darwin and other contributing scientists, we know the answer to this question is, of course, evolution by natural selection. Thus it must be that human personality, just like any other part or function of the human body, was formed and shaped and is continually formed and shaped by the process of natural selection.

To argue this point, the fundamentals of the process of evolution seen universally in nature must first be addressed, in order to draw parallels from these processes to the process of “personality evolution.” The theory of evolution states that an organism inherits genetic material from parent individuals, and that this genetic material is variable due to random sexual recombination. The organism is born into an environment with limited resources, in which it must compete to survive. Depending on the character of the inherited traits, an individual may then be more or less able to adapt to the specific pressures of its environment. The greater degree to which the organism can adapt, survive, and most importantly, mate and reproduce, the more likely it is that the organism’s genes will be passed on to the next generation. Traits which are not suited to the environment into which the organism is born will be unfavorable to that organism, decreasing its likelihood of survival, and thus decreasing the likelihood of passing on its genes. By this mechanism, over time populations of organisms become better suited to their environment and fill all available niches (1). Consequently, evolution operates on the basis of two levels: the organism’s genetic makeup, and selective pressures of the environment. In other words, evolution correlates to a model in which both “nature” and “nurture” play a role. Taking this into account, in order to make the claim that personality is governed by natural selection, it must be first determined that personality is also under the control of both “nature” and “nurture,” that is to say, personality is both inherited and adaptive.

For some time, it was thought that most of an individual’s personality was learned as opposed to inherited. This was based mostly on empirical observation, though at this point many studies have been done to support the hypothesis of cultural influences on personality. For example, one study in Kenya followed the progress of a baboon population that was, as most baboon troops are, controlled by aggressive males. At some point the aggressive males broke into a dumpster and ate rotten meat, poisoning themselves to death. By default, the troop was then governed by the few, less aggressive, males left in the group. Surprisingly, the population converted into a very peaceful community, and remained this way for generations after the deaths of the original docile males. This suggested that the “personality” of the culture, or the bulk of individuals’ personalities, was learned by the offspring and passed on to future generations (8). Human cultures as well have an enormous impact on personality types. One study on the topic of business strategy asserted that there are predicable patterns of behavior that vary from one country to another which have been used successfully in negotiations (4). Related to this, research has also been done on the subject of personality disorders such as bulimia and anorexia, from which strong connections have been drawn between cultural influences such as the media, and the occurrence of many behavioral disorders (2, 5).

Recent studies have also been confirming the notion that much of an individual’s personality also arises from inherited material (3). Many of these studies involve monozygotic, or identical, twins separated at an early age. These individuals provide an opportunity to contrast “nature” with “nurture” as the twins are genetically identical but culturally dissimilar. The studies show that these types of twins are remarkably alike in personality, even when raised in quite different environments. (7).

Given that personality seems to find roots in both genetic and learned components, the relationship between personality and natural selection can be presented. The scenario in which “personality evolution” takes place may be slightly different than the classic concept, but the model is the same. Like other physical traits which are affected by natural selection, personality has a genetic basis that is passed from parents to offspring. The genes code for a shuffled mix of traits from both parents, which gives rise to variation in personalities of the children. Within their environment, which is their culture or society, offspring must compete to succeed. Success may be defined in many ways, but as far as evolution is concerned the most relevant definition of success is producing children of their own. While in most cases someone with personality traits which are generally seen as “unfavorable” will not starve to death as a result of their rudeness or get eaten by a predator because he or she is too chatty, traits such as aggression or severe shyness certainly might reduce that individual’s chances of finding a date, (let alone reproducing). If these individuals are not able to integrate into their culture, they are less likely to find a mate, reproduce, and pass on their personality traits to their children. Conversely, it might seem that individuals who are able to assert themselves and fit in well with social standards would be more likely to find a mate. In this way, societal pressures can be seen as selective pressures which cause shifts in the ratios of the types of personalities seen in society, just as selective pressures in nature change the physical content of a population over time.

A question that might arise form from this discussion is where “personality evolution” will eventually lead the human race. As globalization gradually homogenizes the world and many localized cultures disappear, will personalities also flatten out into one societal model, like in the novel “1984” by George Orwell, or Lois Lowry’s “the Giver?” Will we see the “extinction” of personalities? The answer is, “probably not.” Obviously, a great variety of qualities is still present in the human population, even after millennia of social adn cultural changes. So why have these personality traits persisted if those individuals who have disadvantageous or out-of-date qualities should be less likely to reproduce? Doesn’t natural selection eliminate qualities that are considered unfavorable within the environment? An important idea to point out here is that if one is to define personality as a product of evolution, it must be placed in a whole world governed by evolution, just like in nature. Though favorable traits are preserved by natural selection, it must be understood that in the world there exist millions of niches that allow for, and even cater to, variety and diversification. That is to say, just as the natural environment has a wealth of niches to be filled, the social environment possesses many different niches as well. For example, someone who is belligerent may consequently be a very effective debater, and thus still succeed in some niche of their society. Even if all other biomes were eliminated, a plot of arctic tundra would still possess many distinct species for whom the term of “favorable traits” has very different meanings. Correspondingly, even if the whole world eventually assimilates into one giant uniform culture, there will still be specialization within that culture that encourages variety in peoples' wants, roles, and actions.  Over time, natural selection functions to reduce the number of radical personality types that do not fit into any niches of society, resulting the the overarching cultural "norms" in the world today.

This model shows that despite the complexity and seemingly “ethereal” nature of personality, the genetic and social processes giving rise to variation in human nature operate under the very same mechanism of natural selection that has resulted in the myriad of species populating the planet, and emphasizes the universal prevalence and self-perpetuating nature of evolution.

References:

1) Darwin, Charles, and Alfred Russel Wallace. Evolution by Natural Selection. London: Cambridge, 1958.

2) DeGroat, Bernie. Media Influence Eating Disorders. University of Michigan Record: October 22, 1997

<http://www.umich.edu/~urecord/9798/Oct22_97/media.htm>

3) Goleman, Daniel. Major Personality Study Finds that Traits Are Mostly Inherited. New York Times, December 2, 1986

<http://query.nytimes.com/gst/fullpage.html?res=9A0DE1DC1E30F931A35751C1A960948260&sec=health&spon=&pagewanted=2>

4) PDI Cross Cultural Personality Data Reveals Core Personality Trait Differences Between Business Leaders in Different Parts of the Globe. PRNewswire, February 20, 2007

http://www.prnewswire.co.uk/cgi/news/release?id=191195

5) Roth, Deborah A., Winnie Eng, and Richard Heimburg. Cognitive Behavioral Therapy. Encyclopedia of Psychotherapy: Elsevier Science, 2002. <http://scholar.library.csi.cuny.edu/~eng/Encyclopedia_Psychotherapy_CBT_Chapte_2002.pdf>

6) Strong, Eric. The Evolution of Altruism. ENS Productions, 2001.

<http://endeavor.med.nyu.edu/~strone01/altruism.html>

7) Thomas J. Bouchard et al. Sources of Human Psychological Differences: The Minnesota Study of Twins Reared Apart. American Association for the Advancement of Science: October 12, 1990.

<http://sfx.exlibrisgroup.com:9003/brynm?sid=google&auinit=TJ&aulast=Bouchard+Jr&atitle=Sources+of+human+psychological+differences:+the+Minnesota+Study+of+Twins+Reared+Apart&id=pmid:2218526>

8) Link to a blog posting with a quote from the Wall St. Journal. (I couldn’t access the article itself.)

http://www.elise.com/weblog/archives/000459violent_behavior_learned_or_genetic.php