The question of why do we have craving

In Buddhism everything boils down to we as humans and animals crave. Craving is the root cause for suffering and rebirth. So the question becomes why are we hard coded to crave. Is there any reference in Buddhist documents where the Buddha have answered this question? Personally i think every living being is hard wired to crave because of survival. I think at a primal level for every living being the main objective is to survive and to reproduce and i think that is why we have craving and all those akusala karma such as jealously anger etc... please tell me you opinions or any reference in Buddhist scriptures