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Did evolution make us smarter than we think?

ASU Psychologist Douglas Kenrick, co-author of The Rational Animal
September 13, 2013

New book shows that even when we act irrational we might not be stupid, after all

Why do women prefer to date the guy behind the wheel of the flashy Porsche rather than his friend driving the modest Honda? Why do men overconfidently jump to the conclusion, “She wants me,” from the mere glance of an attractive woman who is really just being friendly?

Could Artistotle have been wrong when he referred to man as a rational animal? It’s a debate that’s raged between economists and psychologists alike. Are people like Wall Street economists, eminently self-serving and consistent with their decisions, carefully designed to maximize personal benefits and minimize costs? Or are they quite irrational, making decisions based more on emotion and gut reaction?

Perhaps it’s not a question of either or.

In a new book, "The Rational Animal: How Evolution Made Us Smarter Than We Think," researchers from Arizona State University and the University of Minnesota suggest that both of the prevailing views of decision-making are singularly wrong.

Instead, ASU social psychologist Douglas Kenrick and U of M marketing professor Vladas Griskevicius argue that people’s decisions, even when they appear irrational, are driven by what they call a “deep rationality” – a set of evolved biases that have helped our ancestors survive and reproduce, and that continue to influence our choices in the modern world.

“In this book, we offer a third view, based on emerging scientific evidence that connects human behavior to the rest of the animal kingdom,” Kenrick said. “We need to radically reframe how we think about the human mind. Basically, we have brains designed to maximize evolutionary success – to make decisions in ways consistent with our ancestors’ odds of getting their genes into the next generation.”

As such, the authors assert, many of the decisions people make that appear to be errors or misjudgments might not reflect irrational and arbitrary quirks in the mind. Instead, they are outcomes of intentional features of a generally wise ancestral system of decision-making.

For example, in the same way peacocks flaunt their tails to impress the opposite sex, some men conspicuously flaunt their luxury products to attract women. Does it work? Yes. But women aren’t blindly seduced by the bling; they know what they are getting into.

In another example, research shows that a woman’s monthly cycle affects the type of clothing she buys. While it might seem irrational to overspend on sexy and alluring clothing, she can blame it on ovulation – something that makes sense when you consider she is most fertile and physiologically more likely to get pregnant.

The authors discuss a classic example of what is considered irrational decision-making known as “loss-aversion.” To a classical economist, $100 is worth $100, whether it is coming or going. But people’s psychological pain when they lose $100 is twice the magnitude of the psychological joy they feel when they gain $100.

Biases like loss aversion are also found in monkeys, a sign that it is evolutionary and deeply rational. Kenrick and Griskevicius assert that when you are on the edge of starvation, as our ancestors were through human history, a possible loss is more important than a potential gain.

Their new model also proposes another radical departure from the traditional Rational Man model. Rather than having a single omniscient Wall Street banker inside our heads, we have several different subselves – each one steering us in a different direction when it takes its turn at the controls. Whether we are investing money or finding a job, buying a car or choosing a romantic partner, our choices are driven by competing evolutionary goals.

The evolutionary challenges that trigger our subselves, the authors assert, include 1) evading physical harm, 2) avoiding disease, 3) making friends, 4) gaining status, 5) attracting a mate, 6) keeping that mate, and 7) caring for family.

“Is blowing money on a conspicuous new car a waste or an investment? Is giving my money away a cost or a benefit?” Kenrick said. “The answer depends on whether I am thinking about attracting a mate, or caring for a child, or trying to close a business transaction with a stranger in the marketplace.” 

Back to the guy with the Porsche. While women may want him when they are dating, the luster of the expensive car quickly dissipates when thoughts are on marriage. For long-term commitment, women prefer the less flashy, and likely more reliable, man driving the Honda.

In The Rational Animal, Kenrick and Griskevicius also discuss:

Why people are born to be biased. Behavioral economists have revealed that we have over 100 irrational biases, such as the overconfidence bias, the clustering illusion and many more. But instead of being design flaws, many of our biases are actually design features. Biases like overconfidence may seem irrational on the surface, but on a closer look, it pays to be biased.

Why it’s in our nature to be hypocrites. Because we pursue a set of very different evolutionary goals, our decisions change radically depending on which specific goal is currently on our mind. Although this flip-flopping leads people to appear hypocritical, we are predictably inconsistent.

How decisions can be dramatically altered by our environment. Depending on whether you are at work or at home, your mind is running a very different motivational program. This means your decisions, such as whether to take a risk, will be different if you make them at home, at work or in the marketplace.

How marketers exploit our evolutionary tendencies. Masquerading as helpful individuals, caring politicians or friendly corporations, many manipulators seek to use our ancient biases against us. But by knowing what to look for, we can defend ourselves from these nefarious social parasites.

“Our book presents a new perspective that reveals that to fully understand the present, it is essential to understand the past,” Griskevicius said. “Although we may not be living under the same conditions as our Ice Age ancestors, we did inherit our brains from them.”