What would humans be without the sense of morality? [Not the moral doctrines. The innate sense we possess.]

Theoretically, they should be amoral.

But practically, it seems they turn into psychopaths.

Should amoralism always manifest as psychopathy?

There can be two aspects of a moral sense. One is Positive and the other is Negative. Positive is which leads us to acts which we wouldn't normally do without a moral cause (for example, giving a donation). Negative is what prevents us from doing acts which the moral sense recognizes as immoral (for example, resisting the impulse to steal.)

Now, normal average people seem to have a weak positive morality and a dominant negative morality. Someone we would call a "moral person" would have more positive morality than is average.

When people talk of "amoralism", the picture they usually have in mind is that of an absent positive morality, but an intact negative morality, which they seem to regard as being the natural default condition.

In the absence of negative morality, the natural tendencies of selfishness, aggression, sexual promiscuity and manipulation would dominate.

Strict amoralism should be an absence of both positive and negative morality. Which isn't practically possible... except in psychopaths.

Below is Hare's Psychopathy Checklist of the characteristics of psychopaths. In bold are the features which i think are a consequence of strict amoralism, and in italics are those which i think are not a direct consequence of strict amoralism. Neither in italics nor in bold are those about which i am unsure.