The exact reasons for gift giving among humans remains a matter of debate, but the most popular theory suggests gift giving evolved as a way to maintain social bonds. This was vital for the nomadic tribes of the paleolithic era, who relied on their cohesion as a group to survive. When you are buying a present for a friend, or unwrapping one you have just received, you are actually participating in a millennia old tradition that stretches back to the very origins of humanity.

Gift giving evolved into different forms across the ancient world, running in parallel with the rise of organized religion. Gift giving is intimately bound up with religious belief—in the Abrahamic religions, gifts are synonymous with charity and thus the act of gift giving is a spiritual practice. Theological debates around gifts appear in Rabbinic literature, in which it is noted that a gift given freely with no expectation of reward is charity, but it creates an inequality between the two parties, contrary to the religious idea of all humans being equal under God.

These sociological concerns in ancient societies were most famously studied in Marcel Mauss’ foundational essay The Gift: Forms and Functions of Exchange in Archaic Societies. Mauss posited that there is a dissonance between our idea of gift giving as a simple kindness with no notion of reciprocity with the reality that gift giving is a complex social exchange. No gift can truly be freely exchanged because gift giving is a kind of social game entailing ritual, manners, and the expectation of reciprocity.

That being said, perhaps it is best not to boil down human behavior to simple evolutionary or sociological functions. Ultimately, when you buy a friend a gift, you do so because it is a nice thing to do, simple as. We are all familiar with the rituals surrounding gift giving: the wrapping paper, the exchange of presents, but gift giving varies considerably between cultures, from the Chinese tradition of sending money in lucky red envelopes on New Year’s, to the Japanese custom of refusing a gift multiple times before accepting. The exact rituals may vary, but the purpose is always the same: to express love or gratitude.

Other cultures vary quite differently from our usual notion of gift giving, like the Maasai people’s tradition of spitting on a gift before handing it over, symbolizing the importance of water in their culture. Mauss’ essay is particularly interested in the Potlatch practice of many indigenous tribes of the Pacific Northwest, in which tribal leaders reaffirmed their power by giving away or even destroying massive amounts of material goods. This practice, still maintained among some tribes, maintains social bonds among the group. One sees that across the world, gift giving traditions have evolved to fit each individual culture’s needs.