The following is written by Guest Blogger, Chris Tripoli*

Of all the concepts presented by the field of evolutionary psychology, one of the most intriguing and crucial is that of the mismatch. Evolutionary mismatch is explained as follows: Homo sapiens have existed for approximately five to seven million years. For the overwhelming majority of this time, we lived as hunter-gatherers.  We were never immersed in anything resembling our modern environment until we abandoned the hunter-gatherer lifestyle perhaps a few tens of thousands of years ago and reorganized ourselves into larger agricultural communities. Although the agricultural lifestyle was more sedentary and social dynamics were modernized to an extent, by this point we still had not even begun to imagine anything close to the technologically advanced, fully globalized society of the 21st century. 

During the millions of years in which our ancestors lived in these early environments, the human brain had plenty of time to accumulate beneficial adaptations in response to the recurrent problems of survival and reproduction that came with this relatively unchanging lifestyle. These adaptations were added to numerous pre-existing ones that had evolved during the millions of years before anatomically modern Homo sapiens arrived on the scene, and during the billions of years before the hominids split from other primates. In the grand scheme of deep evolutionary time, the mere thousands of years during which we have found ourselves in a modernized environment have been more or less inconsequential to our development. Evolution is a gradual process that moves very slowly, and it occurs in response to environmental pressures that are recurrent for very significant periods of time. The modern lifestyle has arisen in the blink of an eye and is constantly changing in many respects, and the result is that we still carry brains that are designed to cope with the many adaptive problems of hunter-gatherer life. 

Biological change by natural and sexual selection can’t keep up with man-made change in the environment. Our brains are out of their element, and the consequences of this phenomenon intrigue evolutionary psychologists. Dr. John Montgomery of SUNY New Paltz has used mismatch theory to successfully predict that people living in industrialized societies show a significantly greater frequency of mental health problems than those in modern hunter-gatherer societies. Other unfortunate results of evolutionary mismatch may include obesity, Attention Deficit Disorder, and more subtle phenomena that one might not expect.  Some of these modern mismatches concern the parts of the brain that manage social functioning. 

One prominent feature of the hunter-gatherer lifestyle that permanently affected the human genome was its social organization. Groups typically consisted of few individuals, perhaps 10 or so, many of whom were closely related to one another. Interactions between group members were direct and face-to-face. The human brain evolved the ability to strategize socially in this context.  Today, the communities in which we interact are huge, and this is thought to produce unique mismatch effects with interesting results. According to Dr. Glenn Geher of SUNY New Paltz, one area of human affairs that is strongly affected by the limitations of the stone-age social brain is politics. Modern politics involves the creation of policies that directly affect millions of people. To successfully lead a nation, one must conceptualize population sizes that simply did not exist in the ancestral environment. Small hunter-gather groups had politics too, in a sense, but instead of concerning large-scale policy they concerned the small-scale social dynamics (think petty backstabbing, reputation tarnishing, etc.) characteristic of a group of 10. Dr. Geher’s current research shows that even today our minds are much more adept at understanding these ancient, small-scale politics. His writing analyses have found that when people write about small-group dynamics, language tends to be much more natural and fluid, while language discussing large-scale politics (as measured by the “fog scale”) typically sounds awkward, rehearsed, and pretentious. While we may understand on an abstract, intellectual level the population sizes that we are dealing with in national politics, we lack this understanding in its most intuitive form because our ancestors never required the ability to keep track of such populations. Many other examples illustrate how this particular mismatch affects our lives.

Some social scientists are intrigued by the sincere interest with which we follow the lives of celebrities. We are eager to learn which celebrities are dating, we crave information regarding meltdowns of the famous, and we watch shows like The Bachelor with feeling and strong opinions. We are enthralled by this type of news, but simultaneously we know that it doesn’t concern us in the least. It is a waste of time, and one can assume that this frivolity would not have survived the evolutionary filter; our ancestors would have benefited from spending less time following irrelevant news and re-focusing their attention on that which was relevant and might have mattered directly to their reproductive success. But we also know that this social environment did not exist in the days of our ancestors, and social information was exclusively a product of small, face-to-face groups. It is likely that we care about this distant information because our outdated brains still interpret celebrity gossip as crucial, close-to-home social knowledge. Our ancestors were designed to take interest in all social information because back in the day all social information was relevant. Today, any social knowledge, including that which does not concern us, is good enough to excite the brain’s reward system.

Another consequence of population mismatch concerns perceived threats to survival. There is a good chance that you know of a person who, after hearing of some fatal airplane tragedy, became so frightened of flight that he or she has not ridden on an airplane since. Statistically speaking, this makes no sense; these people probably continue to drive their cars, and the risk of dying behind the wheel is supposedly nineteen times greater than the risk of dying in a plane.  In fact, there are many common activities that pose a higher risk of death than air travel; a quick Google search turns up events like crossing the street and swimming as being significantly riskier.  Surely this fear is not rational, and irrational behaviors always get the attention of evolutionary psychologists.  While the rational mind knows that the odds of dying in a plane crash on any given day are about one in 10,000,000, the brain has not been designed to understand these miniscule odds resulting from a population this massive. It feels like the odds might be one in ten, and prompts the fear response accordingly. Once again, our brain treats national news as it would word-of-mouth news spoken around an ancient campfire. If one person in your small hunter-gatherer group had been killed for a particular reason, you might have decided that as a rule, that thing was best avoided.

You may have already thought of this last example. It is the lottery, which might work like this: the price to play is two dollars. You have a one in 15,000,000 chance of winning. If you do win, you may be awarded 10,000,000 dollars (and this is quite generous). Statistically speaking, it is not a good idea to play the lottery. For every 15,000,000 games you would play under these conditions, your average net loss would be 20,000,000 dollars. It has to be this way; the state wouldn’t willingly continue a program that is costly to run. It is a massive source of income for the state, and it takes advantage of the population mismatch effect.  One person out of every 15,000,000 may win the lottery, but our ancestors never needed to understand such a figure. We can calculate the odds for ourselves, but it will never feel like as bad a decision as it actually is. 

For scientists, philosophers, and anyone who possesses a deep-seated desire to understand the world, irrational tendencies such as these are disturbing. It is an unsettling fact that the human brain did not predominantly evolve to see the world as it is, but rather, as it was useful to during its most major periods of development. Things as fundamental as the perception of space and time are likely subject to evolutionary pressures, and so are the intricacies of our opinions, beliefs, and intellectual capacities. There is no doubt that our cognitive shortcuts have, and will continue to, limit our quest for knowledge to a certain degree. The science of the future may attempt to fix this epistemological dilemma with the help of thinking machine, unbiased artificial intelligence with no evolutionary past to limit its understanding of the world. But in a certain sense, it is neither stupidity nor a lack of understanding that causes modern Homo sapiens to act irrationally. Instead, I believe it is the degree to which our rational knowledge of the world truly has the ability to affect our behavior.

 A central theme of this article has been the human tendency to act on the basis of how we feel, even when we know this is not the advantageous route. Although the lottery player knows intellectually that his chances are miniscule, his reward system tells him that the risk is worth taking. A woman planning her vacation may have heard that the chances of dying in a car crash are greater than those of dying in a plane crash, but news of a distant airplane tragedy feels close to home, and she opts out. Much of the time it is our biological predisposition that directs our behavior in the end. But perhaps I have not given enough credit to the person who uses the rational mind to override the evolved impulse and behaves accordingly. Reason seems to play a role in our actions as well, and I believe the psychology of these situations can’t be fully explained without both elements.

On one hand, we have the emotional brain. It controls our behavior by governing how we feel in response to specific stimuli and acts on the basis that we are programmed to seek pleasure and avoid pain. One decides not to ride the airplane because the news triggers a response of anxiety, and that anxiety prompts a flight reaction (flight as opposed to “fight,” rather than flight as in “air travel.”  Perhaps this is a confusing example).  Meanwhile, the prospective lottery player’s brain sees the ticket as a reward, the same way it has evolved to see food, attractive mates, and certain habitats. These responses are a product of one of the most ancient parts of the brain. We share it with reptiles, birds, and dogs, as well as more immediate family. It motivates organisms to deliberately seek that which has historically contributed to the success of an individual’s genes and avoid that which has been harmful to their replication.

On the other hand, we have the rational mind. To be clear, this is not the antithesis of predisposed tendency; it is itself a product of evolution that arose to help us understand and predict the environment, strategize socially, and cope with evolutionarily novel stimuli.  It is somewhat unique to humans, and arose recently on the scale of deep evolutionary time. Although it is also a product of evolution, it has the power to keep our evolved responses in check to some extent. The pull toward the lottery ticket is met with resistance from the rational brain, which calculates odds and comes to an objective understanding of the situation.

These elements are both strongly present in a decision, but rather than simply acknowledging this, it is interesting to try to figure out exactly how they interact. As neuroscience advances this is becoming an increasingly empirical question, but scientists and philosophers have been offering their ideas on the topic for thousands of years. An extreme genetic determinist would likely believe that it is the instinctual mind that makes the entire decision. Although it feels like reason has a say and possibly even controls the majority of the decision-making process, it may be argued that people generally use reason only to justify their emotional choices. On the other end of the spectrum, we have an argument that was the common sense view before psychology and neuroscience began to uncover more and more truths of the human mind. This opposite perspective idealizes humans as rational agents who usually act not because of evolved tendencies but because of a simple knowledge that an action is good and just. I would describe my beliefs as representing a sort of middle ground that leans slightly toward the deterministic.

 I refute extreme determinism for a couple of reasons. First of all, there is an evolutionary argument. If reason did not have the ability to affect our behavior, the human capacity for it would never have evolved. It requires a huge amount of neurological volume and complexity; this requires large amounts of energy, and in evolutionary terms, that investment is only worth it if the output is significant. To understand a second argument against extreme determinism, we must deconstruct the very idea of reason. The term need not refer exclusively to strong ingenuity or deep philosophizing; reason is simply the logical system we use to discover facts about the world. These truths may be complex and elusive or simple and practical. Facts about the world, however simple, are the products and purpose of the rational mind, and any evolutionary psychologist knows that most evolved psychological mechanisms are useless without some factual input from the environment that is understood by the subject on a conscious level. For example, someone might be able to put two and two together and realize that his significant other has been spending a lot of time with his best friend. Reason brings him to this fact, and knowledge of the fact alone is enough to stir up his evolved jealousy response. Facts are non-sensory inputs that trigger adaptive decision-making and behavioral outputs, and the rational capacity that illuminates them is an absolutely necessary tool.

 I also have good reasons to reject the extreme free will argument. I can use the same evolutionary refutation: if we had not continued to require emotional motivators, we would have lost them over time, as they take up space and energy. Another argument, however, is that the unbounded ability to choose freely and randomly seems to violate some fundamental principles of the universe. Every non-biological entity in the universe is governed by a set of physical rules. The laws of physics give rise to the laws of chemistry, and from chemistry eventually arose biology. Given enough information, any non-biological phenomenon (the motion of a planet, tidal patterns, electromagnetic occurrences) can be predicted on the basis that it follows said rules. Therefore, it makes scientific sense to believe that animal (including human) behavior is as theoretically predictable as the motion of a planet around a star. If we are to avoid the daring assumption that the laws of behavior get to operate separately from the laws of everything else that existed before and continues to exist alongside the animal kingdom, then we must admit that behavior is always (not sometimes, always) the product of some physical stimulus, and “reason” does not seem to qualify. The chemical processes that underlie pleasure-seeking and pain-avoidant behavior, however, do.

The ideal compromise, it seems, is to grant that reason, knowledge of the world, does have an effect on human behavior, but only insofar as it affects the reward system sufficiently. If I know that I require food to live but I lack the natural hunger response, I take no pleasure from eating, and I am not made anxious by the knowledge that I will die, then I won’t eat. If I realize that the well being of an individual should theoretically matter as much as my own but I am unmoved by this fact, I won’t be motivated to act prosocially (hence the evolution of empathy, in which we feel the pain of others as if it were our own). And of course, the rational knowledge that I will not win the lottery will only affect my behavior if the resultant anxiety about paying two dollars overcomes my reward-driven excitement, a response that evolved during a time in which populations were smaller and my chances would have been much greater. 

Pleasure and pain are likely the chief motivators of behavior, human and otherwise. Although we evolved to take pleasure in adaptive pursuits and pain from those which hindered reproduction, modern mismatch effects sometimes mislead us. Some say that the lottery is a tax on stupidity, but maybe it is not a lack of intelligence that causes irrational behavior–it is simply the inability of the rational response to override an evolved tendency that made perfect sense and served us well for the first 5,000,000 years of human history.

*GUEST BLOGGER BIO: Chris Tripoli is a recent graduate of Skidmore College, where he studied psychology and philosophy. He currently conducts research at the Evolutionary Psychology Lab of SUNY New Paltz under Dr. Glenn Geher, and he plans to study evolutionary psychology in graduate school after gaining additional research experience. His interests within the field include social behavior, intelligence, altruism, and the ways in which evolved predispositions influence moral and political beliefs. He is also very interested in the intersection of philosophy and the sciences, particularly evolutionary psychology.


Geher, G. (2014). Evolutionary Psychology 101. New York: Springer.

Montgomery, J. (2010). The Answer Model: A New Path to Healing. TAM Books.

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