The evolutionary approach is used to understand and explain human behaviors and mental processes such as adaptation and natural selection. It explains how aggression, mate selection, fear, depression and decision making has changed in the human. As one can see, that includes multiple areas in the field of psychology.
Survival of the Fittest and/or Adaptation
We must look at this branch of psychology from two perspectives. First there is the Darwinian perspective of survival of the fittest. That is looking long term at how the organism changed doe to adaptation to the needs of the individual and the group. That is the most well known way to look at this. However there is a second area to look at that is connected to learning, cognition and human development. That is adaptation in the present. Thirty years ago Mick Jagger said he would never sing ‘I Can’t Get No Satisfaction”. Today it is a standard in most of his concerts. What happened? Mick Jagger changed. That change is adaptation. We adapt all the time. Today parenting and direct child care is done by both parents, men cook and women are professionals in the business world. We have adapted. This is also a part of evolution. It is perhaps more studied than the greater Darwinian view because it is more finite and it does not take so long to see the changes.
Evolutionary psychology has integrated itself into many areas of psychology so for the everyday psychologist they use this theory to understand their own area in the field. In the field of cognitive psychology it has helped us understand many theories that are accepted as cognitive theory such as auditory looming bias or the signal and detection theory and many more. It informs our understanding of sensation and perception theory which is a part of neuro psychology as well as human development theory. Even personality theory is now beginning to see adaptive individual differences in personalities due to evolution. We are using Functional Magnetic Resonance Imaging (fMRI) to test hybrid social hypothesis such as social exclusion adaptations, emotions especially sexual jealousy and things like kin recognition which is social psychology. This area of psychology has facilitated our understanding of emotions, memory and sexual behavior all of which are governed by an evolving brain (Plotnik, Kouyoumdjian, (2013).
Evolutionary Theory Unite Sub-Areas of Psychology
Most recently we see evolutionary psychology breaking barriers between traditional areas in psychology. It is evolutionary psychology that has caused us to look at all the above mentioned areas within psychology, neruo psychology, developmental psychology, cognitive psychology, social psychology and yet to be mention forensic psychology) from a new more integrated perspective. Once we understand out adaptive mechanism we can better understand how these adaptations can break down making clinical psychology more relevant and treatment for disorders more specific, faster and more effective.
Evolutionary Theory Unites Disciplines
There are basic laws that govern social interaction. This is social psychology or sociology. Neurobiology and fMRI give us information about brain function that helps us understand social performance. This is beginning to be used a lot in not only sociology and social psychology but also Forensic psychology. An example of this kind of a social law is protection in evolutionary research:
Socially we know we need others for mutual defense against aggression. So we accommodate that in some way. We live close by, greet strangers in groups, pay for police protections and so on. When we take part in the group process we are more likely to survive that the non-conforming individual who goes off alone and neither receives or provides protection (Foder, 1983).
Evolutionary psychology gives us a metatheory for psychology that unites the areas in the field as well as uniting many of the social sciences. Its knowledge is more valuable for understanding and helping the human when combined with other theories than when standing alone. It is likely that each subarea of psychology is stronger and more clinically useful when understood and supported by evolutionary theory.
Fodor, J.A. (1983). Modularity of the Brain.. Cambridge. MA.MIT Press
Plotnik, R. &Kouyoumdjian,H. (2013). Introduction to Psychology, ninth ed., Belmount CA. Wadswoth Publishing.
 fMRI is a form or imaging that uses magnetic resonance to look at the function of the brain. It measures blood flow to areas of the brain. The areas with the greatest flood flow show the brightest. Other areas are not so bright according to the about of blood being used. It idea is that the areas of the brain working the hardest need the most fuel. The brain’s fuel is glucose. The more fuel it uses the brighter it is. We can then see the connections in areas of the brain and how they function together.