It is called low intelligence and poor impulse control.
That is true and it is the same for dimwit unsocialized white males (a group growing larger with the emergence of the fatherless slacker-stoner generation).
However, there is a feral viciousness among blackamoors that is generally not as marked among whites or even Latino loser males. White people in the Deep South have understood this for a long time and it is a significant component of the real reasons for the Jim Crow regime.