There is no shortage of published psychological profiles of Donald J. Trump that attempt to diagnose him, from a distance, as either a psychopath or a narcissistic sociopath (examples here, here, and here). These profiles, of course, are fatally hindered by the lack of access to Mr. Trump for personal examination and completion of personality inventories. There is a raging debate in the psychology community on the propriety of all of this. (Other kinds of diagnoses and analyses, here and here, and an important essay from Psychology Today.)
However, exploration of the evolutionary features of these very peculiar personality types does not require a personal examination and may provide insight into this important question.
Psychopaths are indeed an evolutionary conundrum because their particular behaviors are not an obvious path toward evolutionary success. For example, the majority of serial killers are childless when they are killed or apprehended. Narcissistic sociopaths, however, invariably have families and children whom they support energetically, and many of the traits specific to this phenotype can fairly be called adaptive. This raises the important issue of the evolutionary niche of a narcissistic sociopath within the societies in which they exist.
[A note on terminology: We employ “narcissistic sociopath” as an umbrella term inclusive of Machiavellianism and narcissistic/antisocial personality disorder but exclusive of sadistic psychopathology, as explained below. Terminology in this area is inconsistent in both the scientific literature and even more so in popular media, in part because these various personality types/disorders exist on a multidimensional spectrum with both common and distinct characteristics. Importantly, our analysis is from the perspective of evolutionary biology, not psychology.]
Narcissistic sociopaths share many features with psychopaths including above average intelligence, considerable social savvy, adaptability, likability, and natural skills in (Machiavellian) manipulation. They are charming, outgoing, feign interest in people and subjects, and can convincingly fake both sympathy and conscience. If they engage in charitable acts at all, they are only in pursuit of ancillary selfish benefits.
They learn from experience and show no dedication to a set of moral values, religious beliefs, truth, or transparency. If they admire anyone, it is other psychopaths and sociopaths that they wish to emulate. Finally, they are effective liars and show a chilling unconcern for the welfare of others.
There is one particular skill that is common to both psychopaths and narcissistic sociopaths and is absolutely essential to their nature: cognitive empathy. This is different from emotional (or affective) empathy, sometimes called emotional contagion, which is regarded as the ability and tendency to closely identify with the emotional experience of others.