Talk of the Quad: Romancing a biologist
I’m largely indifferent to Valentine’s Day. A little of my indifference is because I’m in a long-distance relationship and our “do something special together” options are constrained, but most of it is just my personality. I may be sentimental, but I’m not romantic. So when Valentine’s Day rolls around, I’m most excited by the prospect of candy that’s cheap in every sense of the word.
Another thing that excites me about Valentine’s Day is that it’s a great opportunity to tell my friends about the other great love of my life: biology. Valentine’s Day is nominally about romantic love, which frequently goes hand-in-hand with sexual activity. Large portions of biology are about sexual reproduction and its consequences. The approach of Valentine’s Day is a fun occasion to babble about bower bird nests, spider mating dances and the way flowers—such a prominent symbol of romance—attract pollinators like bees. It’s sexy stuff.
This year I’ve been thinking a lot about nuptial gifts. Nuptial gifts are sort of like valentines. They’re objects presented to a mate or potential mate as part of courtship. They are given at a specific time of year, i.e., breeding season. They fall into a narrow range of objects, frequently food. They also—forgive me for saying so—are almost always presented to females by males seeking sexual contact. This last part obviously applies more to nuptial gifts than valentines, but I don’t think it’s outrageous to say that a stereotype of human valentines is similar.
Nuptial gifts are fun to talk about because they can be cute, they can be unexpected or they can be weird. For a cute example, consider the Northern Cardinal. (They’re bright red songbirds with a jaunty crest and black masks and are common near Bowdoin.) A male cardinal will bring a seed to his mate and delicately feed it to her. Adorable, and much more socially acceptable between songbirds than high schoolers. If the pair stays together, the male will continue this behavior, which is probably beneficial for both of them because laying and taking care of eggs is hard work and the female needs her strength. Courtship feeding looks very tender to humans, especially if you take into account that fact that male cardinals attack hubcaps when they can see their reflections. I have a soft spot for brash heroes with a heart of gold.
Spiders provide an example of unexpected nuptial gifts. Most people don’t think of spiders as having much social behavior, yet it’s common for male spiders to present potential mates with a carefully wrapped gift. Whereas a human might present a prospective mate with a box of chocolates, the male spider presents the female with her favorite dish: a dead insect! Of course, there are classy dates and those that are much less so. In the spider world, less-than-classy males wrap useless, empty insect husks and present them to females. (Dear male spiders: regifting food is tacky, doubly so when you eat it first.) On the other hand, female spiders seem to place more value on a nice body than a generous spirit. A spider who eats his own present before wrapping it up might be making a smart choice. (Dear humans: this behavior is only advisable if you’re trying to date a spider.)
Finally we come to a nuptial gift we humans would find weird: an edible spermatophore. Katydids (pronunciation help: “who did? Katie did!”) are a kind of insect related to crickets and grasshoppers, and they usually look like leaves. The male katydid produces an object called a spermatophore for the female. As the name implies, the spermatophore contains his sperm in a packet, and the rest of the spermatophore is an edible substance the male produces. If the female accepts the spermatophore, she will fertilize her eggs with the male’s sperm and gain energy by eating the rest. It’s a weird and unromantic present by human standards, but it means a lot to the female katydid. Reproduction is hard work, and the direct cost of reproduction almost always falls more heavily on the female. The male’s contribution to the female’s wellbeing can make a big difference.
I might not be a romantic person, but even I can see that nuptial gifts are distinctly practical. The human stereotype is that practical gifts are unromantic, but one person’s perfect, romantic present is another’s useless gesture. For our anniversary, my boyfriend took me birdwatching, which I considered to be the height of romance. Notably, his gift meant that I woke up at 5 a.m., woke him and ran around getting our birding stuff together while his brain slowly booted up. His real contribution was driving us to the park (which I cannot do) and his company (which is always welcome). If I were less of a morning person, I probably would have hated it.
If he’d gone a more traditional route and opted for jewelry, I’d have thanked him and quietly fretted over the price—which he knows, and it’s probably why I got to go birding in the wee hours. The human concept of romance is a moving target. Maybe the nonhuman animal metric of usefulness is saner. It’s certainly easier to understand than romantic versus unromantic. For humans, a practical gift like a set of kitchen knives is unromantic. I imagine most people would consider nuptial gifts to be unromantic, too. But it’s possible that a person who considered nuptial gifts in terms of self-sacrifice might squeeze a little romantic sentiment from the behavior. A gift of food is significant to these animals, and nuptial gifts can mean the difference between a successful reproductive season or death. The male katydid gives of himself to feed his mate.
Frankly, whether the katydid’s gift is unromantic is not important to me. What matters is that nuptial gifts are very cool. This behavior is found in many kinds of animals, meaning it evolved independently many times. The basic idea seems straightforward, but there are a lot of variations. Some nuptial gifts are in the context of an existing pair, and others are given between relative strangers. Some animals give non-food gifts. As in human gift-giving, there’s a lot of strategy involved. Is it better for a katydid to produce a few large spermatophores or a bunch of little ones? Should a female spider choose a mate who gives her a (possibly empty) gift or a stud with no gift at all? A lot of research has been done studying nuptial gifts, but there’s a lot we still don’t know. That’s what I love about biology and life in general: there’s always more to discover. That’s beautiful. It’s even a bit romantic.
Jenna Watling is a member of the Class of 2016.