In a recent op-ed in the Washington Post, an anthropologist asked, "What is the difference between a gift and a bribe?"In contrast to the way the legal profession implicates a gift as a bribe, anthropologists don't focus on whether or not a gift-giver clearly states there is a "quid pro quo" to any gift exchange. For the anthropologist, gift exchange is more nuanced.
The Gift, written in 1925 by French sociologist Marcel Mauss, is the most famous book on gift exchange. Mauss' central point was that regardless of intent, in the act of gift-giving a reciprocal social bond is formed. As such gift-giving can create and reinforce social relationships, including hierarchies.
This is not because one gives a gift expecting it to be reciprocated; in many cases that would spoil the act. Rather it's because gift exchange is one element in how humans forge social bonds and networks. For social ties or friendships to be nurtured and maintained they imply reciprocity, whether it's a gift, favour, hard work, time, loyalty, or something else.