As an undergraduate student in psychology at the University of Connecticut years ago, I found the major interesting yet somewhat disjointed. In one class you’d learn some interesting but kind of random facts about human behavior – in a different class, you’d learn about how such-and-such perspective is not supported at all by data – while the class with the professor down the hall an hour later would seem to refute this point. Until I took the course titled, simply, Animal Behavior, taught by Benjamin Sachs (an expert on rat mating behavior, among other things), I couldn’t really see this field as very coherent. Dr. Sachs’ course changed this quickly and dramatically for me.

You see, Dr. Sachs immediately introduced the concept of evolution at the start of class. He showed how evolutionary principles helped shed light on species across the animal kingdom, and across behavioral domains, varying wildly from demonstrations of social status in chickens to mating calls of the coqui frogs in the Carribean and way more.

As I advanced in my career, some really cool people all around the world started to apply evolutionary principles to humans, starting with the basic idea that species-typical behavioral patterns (in humans, as in all animals) likely served the function of allowing human ancestors to effectively reproduce. Among these pioneers were David Buss, Gordon Gallup, Dave Schmitt, and David Sloan Wilson. I started to read their work about such phenomena as the following:

  • Males across the globe (relative to females) focus on markers of fertility in rating attractiveness of females (Buss et al., 1990)
  • Complex social behaviors such as kissing serve important mate-assessment functions (Hughes, Harrison, & Gallup, 2007)
  • Patterns of human promiscuity vary across human populations as a function of prevailing sex ratios (Schmitt, 2005)
  • Human religions across the globe have universal elements that seem shaped to inhibit selfish behavior and facilitate prosocial behavior within groups (Wilson, 2002)

At this point, I could see the future of my own scholarly path. Human social behavior can be understood in terms of evolutionary principles – the awesome things I learned in my undergraduate course at UConn in 1990 could help shed extraordinary light on what it means to be human. Got it.

Once I made this connection, my understanding of human psychology became strongly elucidated; human behavioral and psychological patterns are ultimately the result of evolutionary forces, and understanding evolutionary principles can ultimately shed extraordinary light on our understanding of who we are. From this perspective, now that psychologists and other behavioral scientists have a toolkit filled with evolutionary principles, we are no longer in the dark in our attempts to understand human nature. We’ve got the map and the light is turned on. And I think this is awesome.

Evolutionary Psychology 101 is my attempt to describe this growing field – in terms of

a)    the basic ideas that underlie evolutionary psychology

b)    the mountain of research that has been amassed by evolutionary psychologists in the past few decades on all kinds of behavioral domains

c)    the applications of evolutionary psychology to important human social problems, such as education and health

d)    thoughts on the future of this field in the rocky and often-unpredictable world of academia

I hope this book brings about the kind of insight and excitement for this approach to psychology that has helped guide my work over the years. And, along the way, I hope it’s fun to read – enjoy!


Buss, D. M. et al. (1990). International preferences in selecting mates: A study of 37 societies. Journal of Cross Cultural Psychology, 21, 5-47.

Geher, G. (2013). Evolutionary Psychology 101. New York: Springer. 

Hughes, S. M., Harrison, M. A. & Gallup, G. G. (2007). Sex differences in romantic kissing among college students: An evolutionary perspective. Evolutionary Psychology, 5, 612-631.

Schmitt, D.P. (2005). Measuring sociosexuality across people and nations: Revisiting the strengths and weaknesses of cross-cultural sex research (Author’s response). Behavioral and Brain Sciences, 28, 297-311.

Wilson, D. S. (2002). Darwin’s Cathedral: Evolution, Religion and the Nature of Society. Chicago: University of Chicago Press.