I think if animals were as smart as humans, they would follow the same path. The reason we're so hostile and aggressive and "evil" is because we've had to be hostile, aggressive and evil in order to survive. It's in our genes, those that were not hostile were killed by animals or starved to death and they weren't able to pass on their genes. It comes down to evolutions "survival of the fittest" and the fittest are the ones that fight back and are stronger. The baggage that remained for us is still with us and that could be one explanation why we are so aggressive.
But when you think about it, we're actually not that aggressive relative to some animals. We care about empathy and we care about whether things are treated humanly, animals don't care about that stuff (through no fault of their own, it's just there minds haven't evolved enough to care about that stuff (In fact, most animal wouldn't even comprehend the idea of other things with consciousness)). We care about solving situations diplomatically, and most animals wouldn't do that but mostly solve situations through hostility (though there are some exceptions, for example the Bonobo solves social situations and conflict through sexual intercourse). Crime rates in humans has been at an all time low, we are trying to fix the environment, we are trying to improve the past wrongs of society and we [care] about other things, which most animals current do not so much.
However, this fact is mostly overlooked because we kill a lot of animals, we have wars and we've almost destroyed ourselves along with the entire earth. We've become greedy, this is a fact, humans are greedy and we eat a lot of food and we will do a lot of things to get things that we don't need. A comedian brilliantly put it as "We're all about getting stuff, we get stuff and we get stuff to put our stuff in, so we can get more stuff, but then we need more stuff to put our stuff in and so we continually get more and more stuff" (paraphrased). However, if you give a dog a meal, he will eat it, give him another meal, he will eat it until he vomits, dogs are the same in this regard of greediness. The difference is that a dog can't physically get what he wants himself, he needs people to get what he wants for him, but at the end of the day if he had the ability to get as much food, sex and whatever else he wanted, he'd get plenty, probably more-so than a human would get. So yes humans are greedy, but LIFE is greedy, and maybe humans aren't as greedy as some other forms of animals, we're just smart enough to get what we want.
The last thing is the nuclear bomb, doomsday weapons that threaten humanity as a whole. This is a real statistic, but before America dropped the two nuclear bombs on Japan, they were planning to invade Japans mainland. If they had invaded rather than dropped the nuclear bombs, it is generally agreed by most historians that the death-toll would of been considerably higher (as well the tokyo bombing that happened before the nuclear bomb falls killed more people than in both nuclear blasts). That's just an interesting statistic, but the concept of the nuclear bomb is, yes we've created a weapon of incredible destruction. We created it with the intent to stop war though, we created it with the intent to be a deterrent, the creators wanted to enemy to surrender, they did not want to destroy the enemy, even though at the time they probably could. Nuclear bombs are a terrible thing, but it has also given us nuclear energy, which one day will become probably the most efficient energy source we can ever make (as well as the cleanest), the same energy that fuels the sun. So we created these weapons and you won't see animals doing that, but that's because animals don't know how, it's not cause they don't want to. I'm sure given the chance they would, but yes, nuclear bombs are bad but I don't think it separates humanity between the animals.
So what I'm saying isn't that animals are bad, or even that humans are good. I'm more trying to offer a perspective that perhaps humans aren't the worst of all.
Oh and here's an interesting quote from watchmen
"Why do we argue? Life's so fragile, a successful virus clinging to a speck of mud, suspended in endless nothing."