What DO Sex and Murder Have to Do with the Meaning of Life?

You can see a lot just by looking in the gutter.

Posted Apr 28, 2011

If the nuns who taught me at St. Joseph’s elementary school were still alive, they’d likely say a prayer for me, and wonder where they went wrong. Not only am I still cracking jokes in the classroom, but I’ve spent my adult life mucking around with some pretty sinful topics: I’ve studied one-night stands, incest, homicidal fantasies, and man’s hatred for his fellow man. Goodness, I’ve even published a couple of papers suggesting that going to church may be just another mating strategy (see Li, Cohen, Weeden, & Kenrick, 2010, or my earlier discussion: Religious Piety as a Mating Strategy). 

A number of years back, when I told my friend David Funder that I was doing some research on everyday people’s thoughts about murder, he raised his eyebrow, and observed: “Kenrick, it seems like the M.O. for an evolutionary psychologist is this: Pick a topic that is normally not even whispered about in polite company, and shine a big spotlight on it.” Funder’s assessment was not completely unfair. And if that weren’t bad enough, evolutionary psychologists base their central theoretical models on audacious comparisons between the cultured and sophisticated Homo sapiens, and other decidedly uncouth animal species—howling hyenas, babbling baboons, and even naked mole rats. 

But I would argue that much good has come from: a) a willingness to look carefully at the underside of human nature, and b) a willingness to accept that, however sophisticated our abilities to write sonnets and appreciate a fine Montrachet, we are still members of the animal kingdom, possessed of a multitude of inherited dispositions we share with other members of that kingdom. 

Second is the satisfaction of understanding how it all fits together: Part of why we do scientific research is because we want to understand our place in the universe. Evolutionary psychology is a fusion of Big Ideas from anthropology, evolutionary biology, and social psychology. In recent years, we’ve been combining the insights of evolutionary biology with those from two other revolutionary scientific developments: cognitive science, and the science of complexity. Along the way, we’ve discovered something rather profound: all that research on simple selfish biases is intimately linked to much broader questions about economics, religion, and society.

And the simple biases inside individual’s selfish heads combine to create complex and ordered patterns at the societal life. At the broadest level, probing into all those simple selfish biases has given us some important insights about how to live a more caring and connected life.

And Sister Katherine Mary, if you’re looking down now, there’s something surprisingly uplifting we’ve discovered from all this mucking around in the gutter: It turns out that human beings aren’t designed to spend all day acting on our sexual and aggressive impulses, in fact we feel best when we’re hanging out with our friends and relatives, and we’re designed by nature to get a particularly big psychological boost from doing something for other people. You were right, charity is part of our nature after all, even if those humans were rowdy little delinquents who you had to send down to the principal’s office.


Kenrick, D.T. (2011). Sex, Murder, and the Meaning of Life: A psychologist investigates how evolution, cognition, and complexity are revolutionizing our view of human nature.  New York: Basic Books.

To see a 3 min. video in which I talk about what I believe sex and murder have to with the meaning of life, check out: 

Examples of research on simple, selfish biases, and on their broader connections:

Kenrick, D.T., & Sheets, V. (1994).  Homicidal fantasies.  Ethology and Sociobiology, 14, 231-246.

Kenrick, D.T., Keefe, R.C., Bryan, A., Barr, A., & Brown, S. (1995).  Age preferences and mate choice among homosexuals and heterosexuals: A case for modular psychological mechanisms. Journal of Personality and Social Psychology, 69, 1166-1172.

Li, Y. J., Cohen, A.B., Weeden, J., & Kenrick, D.T. (2010). Mating Competitors Increase Religious Beliefs.  Journal of Experimental Social Psychology. 46, 428-431.

Li, N.P., & Kenrick, D.T. (2006). Sex similarities and differences in preferences for short-term mates: What, whether, and why. Journal of Personality and Social Psychology, 90, 468-489.

Ackerman, J., Kenrick, D.T. & Schaller, M. (2007). Is friendship akin to kinship? Evolution & Human Behavior, 28, 365-374.

Griskevicius, V., Tybur, J.M., Sundie, J.M., Cialdini, R.B., Miller, G.F., & Kenrick, D.T. (2007). Blatant benevolence and conspicuous consumption: When romantic motives elicit strategic costly signals. Journal of Personality and Social Psychology, 93, 85-102.

Sundie, J.M., Kenrick, D.T., Griskevicius, V., Tybur, J., Vohs, K., & Beal, D.J. (2011). Peacocks, Porsches, and Thorsten Veblen: Conspicuous consumption as a sexual signaling system. Journal of Personality & Social Psychology, 100, 664-680.

Kenrick, D.T., Li, N.P., & Butner, J. (2003). Dynamical evolutionary psychology: Individual decision-rules and emergent social norms. Psychological Review, 110, 3-28.