Yeah the male gorillas are very violent generally, or, better to say the violent ones become the leaders of a group. But the females don't have to serve the males as an only way to get access to the basic things in life, and all the other fulfilments. And, yes, many male animals are cruel like that, they kill the cubs, just for the sake of it or to get access to the females' attention span etc., but we as humans, have conscience, a sense of justice and humanity. We should not follow the bad instincts!