"How scientists taught monkeys the concept of money. Not long after, the first prostitute monkey appeared"

From ZME Science, July 7, 2011:

You may have thought things like currency or money are concepts known solely by man – something which differentiates humans from animals. Some might have a sense of ownership, besides of course territory, but trading and the likes haven’t been observed in any other species besides homo sapiens. However, in 2005, an economist/psychologist duo from Yale managed to