I have often stated that Humans are like complex computers: we are, on the one hand, comprised of our Genetic/Biological Hardware, and on the other hand our Cultural/Memetic Software.
As one of my professors would put it we are Biologically Under-determined and Culturally Over-determined. Meaning, we are mostly what we are taught to be.
War, and all the purposes for which humans wage organized conflict, are cultural/memetic ones.
In fact, the rise of organized conflict is a cultural trait that has been shown to have arisen with the development of Agriculture and the resulting sedentary, socially stratified, civilizations that emerged.
Some anthropologists have noted a further developmental characteristic in the rise of organized conflict - that being a move from a primarily Matriarchal Culture to a Patristic one.
James DeMeo, is probably the best example.
Therefore, I think it's safe to say that War is not "Hardwired" into us, but rather "programmed" into us.
It's a cultural trait, and a very powerful Meme, that has managed to cement itself very deeply into our collective memeplex.
That's not to say, however, that it can't be exorcised, and that a new, more peaceful, meme cannot take its place.