How can we explain children's understanding of the unseen world? Young children are generally able to distinguish between real unobservable entities and fantastical ones, but they attribute different characteristics to and show less confidence in their decisions about fantastical entities generally endorsed by adults, such as Santa Claus. One…

From an evolutionary perspective, the normal social play of children involves kids of various ages. Our human and great-ape ancestors most likely lived in small groups with low birth rates, which made play with others of nearly the same age rare. Consequently, the evolutionary functions of children's social play are best understood by examining…