In this presentation we try to understand why people grow-up in such a strange way, taking over twenty years to reach fully productive and reproductive adulthood, but even as adults remain connected and interdependent with so many other people. As part of CARTA I focus on one human-ape paradox – the uniquely human stage of childhood development. Human childhood takes place between the ages of about 3 to 7 years. The evolution of childhood was good for the mother as it freed her from breast-feeding her current infant, allowing her to shift energy and care to another pregnancy and a new infant. In contrast to people, most apes nurse their current infant for 4, 5, even 7 years and this means that those apes reproduce more slowly than do people. A problem with childhood is that the child needs care and feeding from other people. Our ancestors addressed this problem with new biocultural systems to foster and define roles for childcare responsibilities. Eventually these new social systems evolved into the human capacities for language, kinship, and marriage – these are the cultural traits that set us apart from all the other apes.