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Is psychopathy an evolutionary strategy rather than a disorder?

Psychopaths are manipulative, violent, impulsive, and lack empathy — but if psychopathy encourages more frequent reproduction, is it, then, an advantageous strategy?

Photo credit: Isai Ramos on Unsplash
  • It's tempting to think of psychopathy as a kind of aberrant mental condition, but several studies suggest that it may be an evolutionary strategy.
  • A study compared the genetic profiles of psychopaths with individuals who were more likely to have children younger and more frequently and found significant overlap.
  • This suggests that the qualities that bring about psychopathy are also qualities that encourage more frequent reproduction, making psychopathy an advantageous strategy.

From an evolutionary perspective, it seems odd that we would have psychopaths among our numbers at all. A great deal of what's made humanity a successful species is our social cohesiveness, our empathy toward one another, and our understanding of right and wrong. What benefit could there be for individuals to simply lack these socially binding qualities and to feel a tendency toward violence to boot? The evolutionary role of psychopaths becomes even stranger when you consider the fact that psychopaths are at higher risk for becoming disabled or dying early owing to their impulsivity and reckless behavior.

It's tempting to say that psychopathy is simply the result of a short circuit in the complicated wiring that makes up our brains. However, it may be the case that psychopaths are simply employing a different reproductive strategy than the rest of us. At least, that's what Jorim Tielbeek and colleagues argue.

Looking at the genome

While psychopathy is believed to have some environmental causes, much of what brings it about is genetic. We know that there are certain mutations that encourage psychopathic personalities. Tielbeek and colleagues were curious as to whether these mutations also conferred some other kind of benefit. So, they looked at two large databases containing genotypic data on over 31,000 individuals. A prior study had also uncovered the genetic profiles of individuals who were more likely to have children younger and to have more children overall. By looking at the overlap of these two genetic profiles, the research team was able to see whether there was any correlation between the two sets.

They found that there was, indeed, a fairly significant overlap. The genes associated with having children earlier and more often are also associated with the genes that give psychopaths the characteristics that make them psychopathic, like a lack of empathy.

Why psychopathy exists

Photo by Jesús Rocha on Unsplash

It seems counterintuitive, but this finding fits well with what we understand about psychopaths. Previous research has found that psychopaths are often superficially charming, which enables them to attract others in the short term. In the long term, though, this façade crumbles over time. Psychopaths are also prone to greater disinhibition than others, meaning they have problems with impulse control and tend to seek immediate gratification. Combined, these traits would make psychopaths sexually promiscuous, and their disregard for social norms makes them more prone to poaching others' mates or sexual assault, a theory that has been supported by a number of other studies.

But if psychopathy can be a way to have more offspring, why aren't there more psychopaths? After all, Tielbeek and his colleagues' study showed that psychopaths are more likely to have more children, and we know that there is a significant genetic component in psychopathy. Wouldn't the psychopathic gene out-reproduce the non-psychopathic gene?

Why we aren't all psychopaths

One theory is that there's a kind of balancing act going on in the human genome. Highly psychopathic individuals make up about 1 percent of the human population. According to this theory, this number is so low because psychopaths are a kind of social parasite that can only thrive in groups predominantly made up of people who can be taken advantage of; that is, environments made up of moral, empathetic, socially-minded individuals. In groups like these, its easier to take advantage of others' trust to gain resources, like access to sexual partners. If there were too many psychopaths, then this system wouldn't work, and a given social group might become stricter about enforcing group norms. It should be noted that this a difficult theory to test directly.

There's also the idea that the "fast" lifestyles of psychopathic individuals may encourage them to reproduce more frequently, but it doesn't encourage them to invest any of themselves in their offspring's success. Individuals with "slow" lifestyles have fewer children but tend to stick around to make sure their children develop into healthy, competent, and successful adults. The psychopath wouldn't care about that — they demand instant gratification and aren't particularly attracted to the promise of future rewards. In this way, fewer offspring with the psychopathic genome would go on to be in a position to reproduce.

Evolution doesn't have a perspective or an opinion on things. It's a neutral process that selects what works. What these studies show is that, at least when it comes to human evolution, psychopathy is more of a feature than a bug.

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Human brains remember certain words more easily than others

A study of the manner in which memory works turns up a surprising thing.

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  • Researchers have found that some basic words appear to be more memorable than others.
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  • Scientists suggest that these words serve as semantic bridges when the brain is searching for a memory.

Cognitive psychologist Weizhen Xie (Zane) of the NIH's National Institute of Neurological Disorders and Stroke (NINDS) works with people who have intractable epilepsy, a form of the disorder that can't be controlled with medications. During research into the brain activity of patients, he and his colleagues discovered something odd about human memory: It appears that certain basic words are consistently more memorable than other basic words.

The research is published in Nature Human Behaviour.

An odd find

Image source: Tsekhmister/Shutterstock

Xie's team was re-analyzing memory tests of 30 epilepsy patients undertaken by Kareem Zaghloul of NINDS.

"Our goal is to find and eliminate the source of these harmful and debilitating seizures," Zaghloul said. "The monitoring period also provides a rare opportunity to record the neural activity that controls other parts of our lives. With the help of these patient volunteers we have been able to uncover some of the blueprints behind our memories."

Specifically, the participants were shown word pairs, such as "hand" and "apple." To better understand how the brain might remember such pairings, after a brief interval, participants were supplied one of the two words and asked to recall the other. Of the 300 words used in the tests, five of them proved to be five times more likely to be recalled: pig, tank, doll, pond, and door.

The scientists were perplexed that these words were so much more memorable than words like "cat," "street," "stair," "couch," and "cloud."

Intrigued, the researchers looked at a second data source from a word test taken by 2,623 healthy individuals via Amazon's Mechanical Turk and found essentially the same thing.

"We saw that some things — in this case, words — may be inherently easier for our brains to recall than others," Zaghloul said. That the Mechanical Turk results were so similar may "provide the strongest evidence to date that what we discovered about how the brain controls memory in this set of patients may also be true for people outside of the study."

Why understanding memory matters

person holding missing piece from human head puzzle

Image source: Orawan Pattarawimonchai/Shutterstock

"Our memories play a fundamental role in who we are and how our brains work," Xie said. "However, one of the biggest challenges of studying memory is that people often remember the same things in different ways, making it difficult for researchers to compare people's performances on memory tests." He added that the search for some kind of unified theory of memory has been going on for over a century.

If a comprehensive understanding of the way memory works can be developed, the researchers say that "we can predict what people should remember in advance and understand how our brains do this, then we might be able to develop better ways to evaluate someone's overall brain health."

Party chat

Image source: joob_in/Shutterstock

Xie's interest in this was piqued during a conversation with Wilma Bainbridge of University of Chicago at a Christmas party a couple of years ago. Bainbridge was, at the time, wrapping up a study of 1,000 volunteers that suggested certain faces are universally more memorable than others.

Bainbridge recalls, "Our exciting finding is that there are some images of people or places that are inherently memorable for all people, even though we have each seen different things in our lives. And if image memorability is so powerful, this means we can know in advance what people are likely to remember or forget."

spinning 3D model of a brain

Temporal lobes

Image source: Anatomography/Wikimedia

At first, the scientists suspected that the memorable words and faces were simply recalled more frequently and were thus easier to recall. They envisioned them as being akin to "highly trafficked spots connected to smaller spots representing the less memorable words." They developed a modeling program based on word frequencies found in books, new articles, and Wikipedia pages. Unfortunately, the model was unable to predict or duplicate the results they saw in their clinical experiments.

Eventually, the researchers came to suspect that the memorability of certain words was linked to the frequency with which the brain used them as semantic links between other memories, making them often-visited hubs in individuals's memory networks, and therefore places the brain jumped to early and often when retrieving memories. This idea was supported by observed activity in participants' anterior temporal lobe, a language center.

In epilepsy patients, these words were so frequently recalled that subjects often shouted them out even when they were incorrect responses to word-pair inquiries.

Seek, find

Modern search engines no longer simply look for raw words when resolving an inquiry: They also look for semantic — contextual and meaning — connections so that the results they present may better anticipate what it is you're looking for. Xie suggests something similar may be happening in the brain: "You know when you type words into a search engine, and it shows you a list of highly relevant guesses? It feels like the search engine is reading your mind. Well, our results suggest that the brains of the subjects in this study did something similar when they tried to recall a paired word, and we think that this may happen when we remember many of our past experiences."

He also notes that it may one day be possible to leverage individuals' apparently wired-in knowledge of their language as a fixed point against which to assess the health of their memory and brain.

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