Dr. Douglas Kenrick, Arizona State University – Evolution and Rational Behavior

Oct 31, 2013

In today’s Academic Minute, Douglas Kenrick of Arizona State University explains why irrational behavior can appear rational when viewed from an evolutionary perspective.

Douglas Kenrick is a professor of psychology at Arizona State University where his work integrates recent developments in evolutionary psychology, cognitive science, and dynamical systems theory. He is the author of more than 190 articles, book chapters, and books and his latest work is <> The Rational Animal: How Evolution Made Us Smarter Than We Think. He earned his Ph.D. at Arizona State University.

About Dr. Kenrick

Dr. Douglas Kenrick – Evolution and Rational Behavior

Cognitive psychologists revolutionized the field of economics by demonstrating that economic decisions are often irrational. One well-known example is “loss aversion.”

To a rational economist, $100 is worth exactly $100, whether it’s coming or going. But numerous studies find that losing $100 has twice the psychological impact as winning that same $100.  

Viewed in an evolutionary light, though, these decision-biases might not be so irrational. For example, loss aversion waxes and wanes in flexible ways, depending on which evolutionary goals is currently on your mind.

In one study, people were asked how happy or unhappy it would make them to gain or lose $100. When they were fearful (after imagining being alone in their house at night as someone breaks in) people were especially loss averse.  From an evolutionary perspective, our ancestors often lived at the margin of survival, and would have wanted to be especially careful when they were feeling threatened.

But the results were very different for people in a mating frame of mind (who’d imagined a romantic encounter with someone highly attractive).  In fact, for men in a mating frame of mind, loss aversion completely disappeared. Again, this makes sense in evolutionary light: male mammals who didn’t take chances in the mating arena didn’t find mates.  For women, though, mating motivation led them to be slightly more loss averse. Females pay a high cost of pregnancy and nursing, so need to be careful about mating decisions.

These kinds of findings contradict both the classic view of humans as eminently rational, and the more recent behavioral economic view of humans as hopelessly irrational and self-defeating. Instead, our biases seem to be rational at a deeper level – designed to maximize evolutionary success.  

Biases our ancestors developed millions of years ago can affect decisions we make today – in ways that influence our finances for years to come.

Production support for the Academic Minute comes from Newman’s Own, giving all profits to charity and pursuing the common good for over 30 years, and from Mount Holyoke College.