Norway rats trade different commodities

Researchers have shown for the first time in an experiment that also non-human animals exchange different kind of favors. Humans commonly trade different commodities, which is considered a core competence of our species. However, this capacity is not exclusively human as Norway rats exchange different commodities, too. They strictly follow the principle "tit for tat" -- even when paying with different currencies, such as grooming or food provisioning. https://www.sciencedaily.com/releases/2018/02/180201173109.htm