Animal have love too, maybe not expressed exactly like we do but they have it, chimpanzees, monkeys, dogs, doliphins, even moles.
Humans have love but they still kill one another from time to time, if you get them mad enough or belong to another religion or country or steal something from them.
It is just that we have a more developed brains but we ain't all that different from other animals.
We had love way before we beleived in gods or religion, we had love even when we used to eat one another(which some people might still do, or at least did not to long ago). It's just that we don't eat our friends unless were really really really hungry :).