Humans are among the most altruistic species that we’ve studied, due to our alloparental instincts – a trait we evolved into that allows us to care for offspring who are not our own. Across species, the ones who alloparent the most appear to be the most altruistic. Very altruistic people seem to be the opposite of those who are psychopathic in terms of their neural structure, neural function, and characteristic emotional traits. 

Science has been studying psychopathy for decades, but only more recently have we been identifying the basic neurocognitive building blocks of those deficits in psychopathy, says Abigail Marsh, PhD. 

Here, Marsh explains how the psychopathic break is different, early warning signs that may indicate a lack of empathy, and how psychopathy can be treated.

ABIGAIL MARSH: Once upon a time, people thought that there were these people we could call "psychopaths," who were over here, and then everybody else was just normal. And now I think we understand that that's not true, and that psychopathy, like most psychological phenomena, is a variable that ranges continuously throughout the population. So you have some people who are extremely psychopathic, truly heartless, don't care about other people at all, and then you have another end of the continuum as well, people who are anti-psychopathic, who care even more than usual about the average person, because care about other people's welfare is really the variable that is what differs across people at either end. We have a lot of information now about what it is that's different about people who are on the very low end of what I call the 'Caring Continuum.' My fundamental interest is in trying to understand how it is that humans care about each other. Humans are among the most altruistic species that we have studied. One of the reasons that we are such an altruistic species is because we are what's called an 'alloparental species,' which means that we evolved to care for offspring that are not our own. Humans evolutionarily lived in small groups of, you know, 100, 150 people max, who had children that were so needy and resource-dependent that they couldn't possibly be cared for by just one set of parents. And we also know that across species, the ones that alloparent the most also tends to be the most altruistic, but humans do appear to be at the top. In addition, very altruistic people seem to be the opposite of people who are psychopathic in terms of their neural structure and function, and in some characteristic emotional traits. Scientists have been studying psychopathy for decades, and have determined that people who are psychopathic tend to be very antisocial, tend to lack empathy or compassion or remorse. But only more recently have we been identifying the early basic neurocognitive building blocks of those deficits in psychopathy. One of the big ones seems to be So if you don't experience fear yourself when you are under threat, you really struggle to empathize with that same emotion in other people. We can see that from studies of physiology. We don't see the same physiological changes under threat, like their hands sweating or their heart racing when they're threatened. That seems to help us understand why people with psychopathy have so much trouble recognizing when other people are afraid in, for example, an emotion recognition task. Most people, when you show them a series of emotional facial expressions, can recognize other people's fear, you know, maybe 60% or 70% of the time. In people who have psychopathy, it tends to be much less than that, sometimes pretty close to an inability to recognize other people's fear. And again, we think that's because the way that we recognize emotions in other people is by simulating that emotion, and that helps us identify and respond appropriately. People who are at risk for psychopathy show evidence that their amygdala is developing inappropriately from a pretty early age; such that it ends up too small, and it's under-reactive to threats. Decades of research in humans and also non-human species have told us that what the amygdala does is coordinate a lot of the responses that are essential for fear. So it takes in information from the environment about potential threats, and it signals other parts of the brain, regions like the periaqueductal gray in the midbrain that coordinates the startle response or freezing; regions like the hypothalamus that control our autonomic responding, so our hands sweating, our heart racing, our lungs expanding. And then of course our behavioral responses to fear: whether we decide to run away, whether we decide to fight, whether we decide to help others in danger. The amygdala's not doing all of those behaviors, but it is sort of coordinating the whole show. You could sort of think of it as directing the performance. So when there is a threat in the environment, whether you're in danger or whether you see somebody else in danger, the amygdala responds much more weakly than it does in typical people and sometimes doesn't respond at all. The amygdala also sends information to regions of the prefrontal cortex, in particular, a region on the bottom of the prefrontal cortex called the rostral anterior cingulate and ventromedial prefrontal cortex. And these regions use the information the amygdala is sending to guide decision-making. And because the amygdala is responsible for simulating, empathizing with, and recognizing other people's fear, that information is probably not making it to the prefrontal cortex in people with psychopathy. In addition, the amygdala is involved in calculating the value of other people's welfare, so, how bad or good is this thing happening to this person? Based on the choices I make, how bad or good will their outcomes be? That information is also not making its way to the prefrontal cortex, and as a result, people who are psychopathic are much less likely to make decisions based on how they will affect other people, in particular, how they will affect other people who are in danger. And I think that this is probably the fundamental pathway that is broken in people with psychopathy that causes other people harm, because these particular pathways are just not encoding the information correctly. As a result, people who are psychopathic, when they are engaged in moral decision-making and social decision-making tend to rely on a different part of the brain called the lateral prefrontal cortex that's involved in sort of applying rules to decision-making. And so they'll think about decision-making in a much more rational way. You know, am I supposed to do this or am I not supposed to do this, which can be useful, and it can help you get to the same decision, but it isn't going to be as emotional and motivating as a decision that's based in true empathy for other people. The difficulty with treating psychopathy and treating persistent antisocial behavior in adults is that people who are psychopathic tend to be quite narcissistic, and they tend to blame their problems on other people- and that's not a good recipe for seeking therapy. However, some people with psychopathy are insightful enough to figure out eventually that the common thread in all of the problems in their life is them. They're the one who keeps blowing up their relationships and losing their friendships and losing jobs and causing other problems to emerge, right? It's their own decision-making that's the core. If you can get that insight, and if you come across the right information that indeed these problems can be solved, people who are psychopathic can learn to interact with other people differently, they can learn to interact with them in a non-instrumental way, right? To to be honest, to be genuine in their relationships with other people rather than in every interaction, thinking about: How can I get a leg up on this person? How can I put them in my debt? How can I manipulate them? You don't have to interact with other people that way. There are some excellent studies that show that treatments are effective, and people with psychopathy can learn new ways to interact that make their own life better and that certainly make life better for everybody around them.