The Rational Animal: How evolution made us smarter than we think, by Douglas Kenrick & Vladas Griskevicius

The Rational Animal is a stimulating read for anyone interested in human behavior, linking ideas from evolutionary psychology to work in behavioral economics and motivational research.  It is written in a clear and engaging style focusing on seven ore human motivations and how they shape our thinking and behavior.

They start with a quick and concise summary of why none of us are as rational as we think, and a great quote from Bertrand Russell, “It has been said that man is a rational animal. All my life I have been searching for evidence which could support this.”

They make clear their overall arguments. Firstly, that decision-making serves evolutionary goals (rather than surface short-term ones) and that this can often explain why many decisions that seem superficially irrational may actually be smart and adaptive (at a deeper level). Secondly, humans do not have one overall goal (to be happy and maximize benefits) but rather a number of different evolutionary goals. For example, acquiring a mate is a different goal to self-protection, which is different again to status.


These insights suggest that we don’t just have one ‘self’ making decisions. Instead, our minds contain a number of different ‘sub-selves’ each with different goals. Moreover, our sub-selves are competing for our attention, depending on the current context and the most important current goal. This is a profoundly disruptive and unnerving conclusion: we don’t have a unique self.

The Rational Animal goes on to address how the cognitive biases of behavioral economics fit with this view of decision making by explaining their adaptive value. They discuss the difference between proximate and ultimate reasons for behavior. Proximate reasons are those that we rationalize in the here and now, whereas ultimate explanations show the evolutionary function of behavior (for example, eating chocolate brownies is more about the evolutionary challenge of survival in the pre-modern world than it is about the smell of chocolate). The proximate reasons for many behaviors are that we want to experience pleasure, happiness and satisfaction and avoid pain, sadness and frustration. However, if we dig deeper we realize that ‘economic utility’ (in the rational model of decision making) is not important, while survival, nutrition and reproduction are. The reason that lap dancers can earn twice as much make twice as much money when they’re ovulating, is the ultimate explanation of reproductive success and not one of the proximate explanations that might be given, such as “I’m feeling adventurous today”.

The authors then provide detailed overviews of seven ‘sub-selves’, focusing on those with a social element (rather than more basic ones of survival and reproduction. They cover evading physical harm, avoiding disease, making friends, gaining status, attracting a mate, keeping a mate and caring for family. I was struck by how closely these relate to work in motivational psychology (and archetypal theories) that include different aspects of human behavior.

But how and when do these different sub-selves work? The authors make a clear analogy with a computer. The brain receives input from the outside world through the senses, just as a computer receives a command by pressing a key. The output from the computer depends on the particular button that is pressed.

Computers have different software programs to solve different problems, like calculation, writing or playing a game. In the same way, the brain has different programs to solve different social problems, most of which date back to long before man lived in the modern urban environment. In the same way that inputs shape outputs, the human brain will process information differently depending on which sub-self is running the show. That is, the brain has different programs for achieving different evolutionary goals.

In one revealing experiment, the authors tested different copy for an advertisement for a local café: in one the café was described as ‘a one of a kind place yet to be discovered by others’ and in another as ‘ the most popular café in the area’.  Traditional market research would no doubt segment responses according to the characteristics of people: conforming vs rebellious. However, the idea of different sub-selves suggests that choices might depend on which sub-self is in charge (i.e., what is the context?).

Therefore, the authors primed participants with different contexts in the form of different movies: a romantic comedy or a scary movie. Just as predicted, the situation created by the movie, completely changed the decisions of participants about the choice of restaurant. After seeing a scary movie they they favoured a popular restaurant and also avoided products that were identified as unique. However, after the romantic film participants favoured the out-of-the-way restaurant and were more affected by adverts that talked about the unique properties of products.  If you are primed for romance, you want to stand out, whereas if you are primed for protection you want to fit in.

The remainder of the book walks through the seven sub-selves: self-protection (‘night watchman’) to disease avoidance (‘hypochondriac’), affiliation (‘team player’), status (‘go-getter’), mate acquisition (‘swinging single’), mate retention (‘good spouse’) and kin care (‘nurturing parent’). These sub-selves form a hierarchy, in much the same way as Maslow’s pyramid does, although The Rational Animal argues that caring for others is at the top and not self-actualization.

I really enjoyed this book, although the writing is occasionally too anecdotal and rambling, because it reminds me of the importance of always understanding human goals before interpreting behavior. Behavior is driven by context and motivation, both proximate and ultimate. This book does a good job of placing modern views of human behavior in the broader scheme of evolution and is a good read for any market researcher who wants to dig deeper on why we do the things we do.

Review for Asia Research by Neil Gains, TapestryWorks