Katharina Hamann with an international team of researchers from the Max Planck Institute for Evolutionary Anthropology in Leipzig, Germany, Harvard University and the Michigan State University found that sharing in children that young is a pure collaborative phenomenon: when kids received rewards not cooperatively but as a windfall, or worked individually next to one another, they kept the majority of toys for themselves. One of humans' closest living relatives, chimpanzees, did not show this connection between sharing resources and collaborative efforts. …