There doesn't seem anything much in nature to compel the fathers to take care of their offspring. Think of rape here if you don't believe me.
Why should anyone "believe you" when you speak of anthropology? What are your credentials for forming your own, personal explanations, based on your own personal observations?
What experts in the field that know what they are talking about because they have professionally studied the science are saying is that there are several mechanisms to help ensure the father takes responsibility for the child.
1) pheromones are produced by both mother and child that 'attract' the genetically similar male to be protective.
2) the vast majority of babies, when they are born, greatly resemble the father, and less so the mother... this changes as the baby develops, but the evolutionary advantage to that is that, while the mother can be pretty damn sure that she is the mother (lol), the appearance of the child is all the father has to go on in measuring their accountability.
I'm not telling you what you should do, but if I have a thought that starts, "maybe its that...", then I retain the fact that I am just making it up and guessing.