When we consider the questions of "individualism" and "collectivism", or for less politically charged words, the idea of social animals (including humans). It brings into certain focus the question of the role that natural selection may play in predisposing individuals to be cooperative or not.
In fact, this may well point to a genetic basis for "cooperation" where those animals that benefit from it will tend to foster higher degrees of cooperation in offspring, whereas those where this is minimal or no benefit may tend towards completely "individualistic" tendencies. This also doesn't preclude such values from being taught by parents, but the predisposition to one or the other would be innate.
Cooperation requires that individuals be willing to put group benefits ahead of their own. Not in the slave-like robotic sense that some want to portray, but rather in recognizing that there is a greater benefit to be accrued in getting along than in confrontation. This doesn't negate acting in a self-interested fashion, but it does provide a counter-weight to exclusive self-interest.
Other animals have evolved to be completely individualistic to the point where many male/female relationships don't even exist except for the short duration of reproduction. In those cases, animals tend to behave in a completely isolated fashion with no interest other than their own activities.
I would suggest that psychopaths fit into the latter category and, as such, represent an anomaly of human behavior. It becomes pointless to question why they behave as they do, as it would be pointless to question why a grizzly bear behaves the way it does. It is simply acting in a manner that precludes consideration for anything else, since there is no "social" connection. In other words, the psychopath isn't behaving abnormally if one considers that they are simply asocial (as our grizzly bear example).
It represents the boundary between social and asocial where each animal's behavior must be interpreted within the context of it's society, or lack thereof. Similarly, the psychopath becomes dangerous because they represent the "defector" in game theory that is capable of cheating in a group of "altruists". They simply lack the ability to consider others interests.
The following statement illustrates exactly the type of differentiating one would expect in animals that must operate alone versus those that have social mates they can count on for assistance.
(From the article)
"One brain region less active in psychopaths is the amygdala, which is normally linked with fear."
If this connection between social versus asocial animals is plausible, then instead of studying psychopaths, it may be reasonable to study these animal groups to determine whether there are different brain pathways that are operative to give rise to their respective behaviors.