All of these are true to varying degrees. Nature is full of complex ecological relationships that have a diverse array of purposes and benefits. There is no one true model for when sadism, mutualism parasitism, commensalism etc is more beneficial than the alternative.
Yes, higher functioning individuals are more crafty and cruel when they decide to be sadistic. Yes, interspecial and intraspecial mutualism ("empathy" between and among species) is extremely common. Yes, intelligence is linked with self-awareness and introspection; so intelligent people can tend to be more moral. But also, the opposite is equally true for all of these statements.
Too many species of bird (like Pigeons and DUCKS) are dicks that seem to enjoy sadism with many finding pleasure from rape, dolphins are sadistic rapists as well. Then there's Orcas, many species of Ape, even Elephants rape and kill their own kind and seem to get something out of it. Otters even rape Baby Seals, and Seals in turn sexually assault baby Penguins for fun, Wolves and some dogs will kill Sheep for fun rather than food, etc.
When they show, not environmental synergy, but needs that require them to study their environment while working within interpersonal politics rather than lone ones? Ruthlessness and Sadism tend to crop up more often.
I tried to avoid the tendency for rape because the animal kingdom is ripe with it. Courtship in a majority of species is forcing an unwilling female to reproduce. Its common among less intelligent species just as much as dolphins, monkeys etc.
Some however enjoy the suffering rather than handling it as something matter of fact, even using it with a gang of others like themselves to abuse other species of animal.
Less intelligent ones rape from not knowing any better, more intelligent ones risk enjoying that part of themselves over how it hits the reward center of their brain.
Even for human comparison look at smart vs dumb expressions of ASPD, both show proclivities for violence for example, both can even enjoy it, but the more intelligent ones can make a poetic ramble out of it that might even draw others into the ideas.
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