For the male Zeus bug: a monthlong excursion aboard the luxury liner that is the much larger female’s back, with its scooped-out seat tailored to his dimensions and a pair of dorsal glands to supply the passenger with all the proteinaceous wax he can swallow.

For the bonobo you’ve just met: half your food, at least. Just shovel it over. Sharing is fun!

For the bonobos you’ve known your whole life: Eh, maybe nothing this year. It’s not like they’ll stop being your friend if you “forget” to toss them a banana.

We may denounce the hyper-consumerism of the Christmas season until we’re Hanukkah blue in the face, but much of our economy relies on the strength of the gift-giving impulse, and with good reason: The drive to exchange presents is ancient, transcultural and by no means limited to Homo sapiens. Researchers have found striking examples of gift-giving across the phyletic landscape, in insects, spiders, mollusks, birds and mammals.