But in the competitive game of evolution, it’s a losing move for a male to provide resources to a child who is not his own. So active fathers, male-female pair-bonds, male sexual jealousy, and big-headed babies all co-evolved— that is, arose gradually but together. A man who felt some desire to stay with a woman, guard her fidelity, and contribute to the rearing of their children could produce smarter children than could his less paternal competitors.
given the importance of cognitive ability in people and their brain development in the first years of existence, it pays for both parents to support raising the children
