Few concepts in science are as powerful, or as widely misunderstood as the theory of evolution. Through his assertion that, “Nothing in biology makes sense except in the light of evolution,” biologist and geneticist, Theodosius Dobzhansky, illustrates that an understanding of life’s diversity, as well as the great unity among organisms, can be facilitated when examined within the context of evolution. A recent discussion in my Introductory Psychology class raised the question – “What is the role of evolution in the fields of cognitive and behavioral science?” It provoked me to question evolution’s function in determining an individual’s learning and decision-making skills.
As the unifying theory of the life sciences, evolution by natural selection offers an unparalleled ability to integrate disparate research areas such as those in biology and psychology – an interplay that psychologist, David Myers, recognizes as critical to fully understanding this psychological phenomenon. Thus, the evolutionary perspective creates a powerful framework for understanding the complex patterns of causality in behavioral and mental phenomena. Ultimately, evolution serves to explain the development of species and how individuals can adapt favorable behavior through the biological process of social learning.
In order to understand the roots of behavioral and mental processes, evolutionary scientists turn to the works of the English naturalist, Charles Darwin. Darwin made two major points in his publication, “On the Origin of Species”. First, he argued from evidence that the species of organisms inhabiting the Earth at the present time descended from ancestral species. “Descent with modification” conveys that as the descendants of those ancestral organisms spilled into various habitats over millions of years, many underwent adaptations, which accounted for the vast diversity among organisms.
Darwin’s second point posed a mechanism that enables evolution, which he termed “natural selection.” This is the principle that among the range of inherited trait variations in a population, those “favorable” traits, contributing to survival and reproduction, will most likely be passed on to succeeding generations. Darwin supported this observable phenomenon with empirical evidence of his studies of the adaptations of Galapagos finches and marine organisms.
Individuals often acquire their beliefs and behavior from their parents, peers, and others members of their social environment. “Social learning” is thus an essential part of adaptation and a key factor in a species’ ecological success. Understanding how an individual uses information available from others is important for not only understanding that individual’s decisions, but also for comprehending patterns of change and variation among species over time.
In the study, A Bayesian Approach to the Evolution of Social Learning, investigators at UCLA sought to understand when natural selection will favor individuals who imitate others, as environments change and individuals must determine which behaviors are beneficial to survival. To build models of cultural evolution, investigators modified mathematical formulas drawn from population genetics and epidemiology to account for features of social learning. This Bayesian statistical research approach uses probability estimates to infer the unequal ability of individuals to conform to the favorable behavior of others in changing environments.
As the experiment varies the environment (independent variable) proportionately from state 1 to state 2, the adaptive problem for individuals is to infer the current state of the environment using two sources of information:
1. Other individual’s behavior from the previous generation (social cues).
2. Individually learned details about a habitat, acquired possibly through trial and error processes (environmental or nonsocial cues).
Individuals who exhibit one of two behaviors acquire either a favorable or unfavorable fitness depending on which state the environment is in. Thus, individuals who can accurately determine the current state of the environment, using the two former mentioned cues, will be able to choose the preferable behavior to emulate and survive better. This will result in a higher reproductive success for the individual.
Because the psychological mechanisms that make social learning possible are partly products of natural selection, statistical models can help us understand their design. While this type of experimental approach can help eliminate biases that may arise in other experimental designs, (such as a response based survey), it cannot rule out the possibility of chance. Also, just because there is a correlation between two variables, for example, a fluctuating environment and a decreased chance of perceiving favorable behavior, doesn’t always mean that causation is a factor.
Overall, the results largely support the theory that conformist individuals are favored by natural selection under a wide range of environmental conditions. It is reasonable to assume that during the course of evolution, individuals routinely have had access to many models for which to base their behavior, which raises the possibility that this experiment has underestimated the range of environmental conditions (confounding variables) that favor conformism. Additionally, the researchers may have underestimated the specific strategic circumstances under which non-conformity is critically adaptive – which may require a whole different investigatory lens.
Humans today descended from a long line of successful ancestors. Yet there may be individual and group differences in psychological domains that are partially a result of differential selection pressures on ancestral populations and even subsequent mutations. Daniel J. Krugar of the University of Michigan noted that, “Humans have colonized nearly every land area on the surface of the earth, and each of these diverse ecologies shaped our psychological design.” Today, humans strive to advance medicine, security, and technology, which create an environment that pressures our psychological development. Genes are not the only script for a pre-ordained destiny. Nearly everything about us as individuals is a product of complex interactions between our genetic make up and trigger aspects of the environments in which they are expressed. In the light of evolution, humans can gain a greater understanding of the behavior and mental process that distinguish them from other organisms and the basic biological structures that unify them with all species.
Campbell, A., Neil, & Reece B. Jane. (2002). Biology (6th ed.). San Francisco, CA: Cummings.
Kruger, J., Daniel. (2009). Evolutionary Psychology and the Evolution of Psychology. Evolutionary Theory and Psychology, 2-4.
Myers, G., David. (2013). Psychology (10th ed. in modules). New York, NY: Worth.
Perreault, C., Moya, C., & Boyd, R. (2012). A Bayesian approach to the evolution of social learning: Evolution And Human Behavior, 33(5), 449-459. doi:10.1016/ j.evolhumbehav. 2011.12.007