"I wonder if that's the difference between fathers and mothers. I'm friends with people who have kids that are like 5 and under, and they're still in that intense mother-bonding phase. It might just be that. Because the dads haven't changed."

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We belong to that order of mammals, the primates, distinguished by its propensity for repeated single litters, intense parental care, long life-spans, late sexual maturity, and a complex and extensive social existence... Our protracted biological and psychological helplessness, which extends well into the third year of life, intensifies the bond between infant and parents, making possible a sense of generational continuity. In contrast to other primates these bonds are not obliterated after sexual maturity.

— Louise J. Kaplan