The year is 2579.
The vast majority of the planet earth had turned into an eternal wasteland; pollution, poverty, and war and releases of radio active materials had took it's toll on her.
All major cities were in ruins, with hardly any trees, plants, or anything green for matter- for miles from any place that held humans.
The human race had all but died off...except for the rare packs of mutated mongrels the humans had become; they were pink, clothes less, hunched over creature, on all fours. But the half evolved disgust that it was, had lightly arched backs, as if their backs and forgot to evolve with them, faces very angular, and sharp. Their limbs were awkwardly long, only the back legs evolved really, lowering down so they could run more animal-like, and faster. Add that, and their frail human nature, they were majorly effected with the biohazard waste,
and their brains turned mush. The new evolve, mixed with the biohazards...they turned into monsters.

...They were not as resilient and fast to evolve as us animals.

Now don't get me wrong, it's not like we didn't get effected by the biohazards.
Mutation is the norm now for us animals, and with no habitat to live in we had fled to the human ruins for cover from the acid raid, and for comfort and warmth.
But unlike the humans, we reacted quicker to the danger, evolving earlier and faster, and with the mutation and evolving, most animal species got larger, faster, and smarter. They grew vocal cords, enabling them to learn to talk to one another as well as use body language and 'Animal Speak' using the 'old tongue' to speak in words the twisted humans couldn't understand. They may be stupid, but some words stuck with them. It also can be a secret dialogue between species as well, it still had many uses to them.

Us animals had decided to band together, we're safer in numbers and the humans have been attacking more more. They needed each other.
Of course, there can be the clash of clans from time to time-not all species get along well. But in these desperate times, the only thing you can do is try to survive.