[psychoslave]

That's a rather extreme generalization, isn't it? Not all humans are equally remorseless and prone to carelessly harm others, whatever the entities they interact with and the acculturated categorizations they project on them.

Now we can certainly come with statistics of tendencies, but to my mind they seem to be condemned with cultural biases. Not only the human brain plasticity is molded by the culture where it is immersed, so any data will tell us more about the result of such a culture than about "human inherent tendencies", but even the way we will decide to analyze them and consider/interpret the outcomes will depend on our culture (and our current mood or other more "local" psychological factors).

With that in mind, it's hard to categorically conclude that humans are fundamentally "psychopaths in [their] relation to animals". Dominant cultures, offspring of predatory cultures, surely help to foster such a behavior. That doesn't require it to be an intractable instinctive trait.