The Eternal Toil of the Motor Protein


A few days ago, I stumbled across this particularly arresting GIF while scrolling through my Facebook feed. The animation shows a stringy figure with huge feet lugging a rippling green sphere along a ribbed beam. “Look at that little guy plodding along,” I thought. “That looks like hard work.”

Here’s the thing: That “little guy” is a motor protein called kinesin. His feet are actually heads. And he isn’t simply plodding. Kinesin is propelled down structures inside the cell called microtubules (that beam in the GIF) as its heads bind and release. Humans plod. Kinesin is driven by chemistry.

Humans can’t help but anthropomorphize. I can’t look at that beanpole of kinesin and not feel sympathy for his struggle. Little guy. Heavy load. Even scientists aren’t immune to this phenomenon. In 1985 luncheon talk, a computer scientist named Edsger Dijkstra told a story about one particular meeting of the Royal Netherlands Academy of Arts and Sciences. The attendees watched a movie of amoebae floating in culture. Dijkstra was bored watching the “aimlessly moving grey blots.” But then one blot constricted and began to divide. Eventually only a thin filament connected the two halves. The connection finally broke, and the two organisms swam away from one another.

“The fascinating and somewhat frightening observation, however, was that at the moment of the rupture one hundred otherwise respectable scientists gave all a sigh of relief,” Dijkstra said. “None of us had been able to resist, as the division process went on, the temptation to discern two individuals with which we could identify and of which we felt … how much they ‘wanted’ to get loose. A whole pattern of human desires had been projected on those blots!”

Dijkstra calls these anthropomorphic thoughts “insidious” and “pernicious.” But I take a softer view. Ascribing intention and emotion to things that have no intention or emotion is one way to make sense of the world.

And it’s especially common in kids. Keith Taber, a researcher at the University of Cambridge interviewed high school students to examine how they thought about the science being taught in school. He found that anthropomorphism was common. For examples, students talked about electricity “trying” to reach the ground, sodium atoms “wanting” to donate electrons, animals eating their young because they didn’t want to make them suffer. (And here is a particularly fun answer one student provided when asked why cheese gets moldy. “If it didn’t the world would be inundated with cheese. The mouldiness is an excuse to get rid of cheese and if cheese didn’t exterminate itself there would be mass chaos world-wide in a desperate attempt to destroy cheese.”)

Taber writes that anthropomorphism “can be a useful way of making technical ideas seem more human, and for getting students to start thinking about abstract ideas in ways they can make sense of.”

Of course, anthropomorphism can also impede understanding. When we view animal behavior through the lens of human emotion, we risk getting things dangerously wrong. Viral videos of giraffes nuzzling ostriches, dogs cuddling owls, and deer frolicking with bunnies provide plenty of warm fuzzies, but what looks like friendship might be something else entirely.

It’s also possible to go overboard. I would argue that the following video—which shows a cartoon, pants-wearing kinesin named John dragging a rock through busy city streets—does just that.

But anthropomorphic metaphors do have value. They can help bridge the no man’s land that exists between ignorance and precise understanding. And they foster engagement. It’s easier to care about kinesin the skinny laborer than it is to care about kinesin the molecular motor driven by chemical reactions. That’s why science writers so often rely on them. Cancer cells invade. Bacteria attack. Kinesin plods. A lion emits a nervous growl. These statements might not be wholly accurate, but they’re undoubtedly evocative.

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2 thoughts on “The Eternal Toil of the Motor Protein

  1. Thank you for this lovely and thoughtful perspective! During my training as a scientist, despite being taught not to anthropomorphize anything (protein, cell, or animal) I kept right on doing it anyway–sure, not in scientific papers, but in casual lab conversations, office hours, even lectures. And I don’t think that’s unusual among scientists, as evidenced by Dijkstra’s story.

    It does seem important to be aware that we’re doing it, so we can question those assumptions of inter-species friendship or whatever other mistakes we might be making, but at the same time I can’t help seeing anthropomorphism as a kind of empathy, and I wonder if squelching anthropomorphism too emphatically would also risk squelching some of our empathic urges.

    Oh hey look, Brooke Borel touched on this topic in 2013, quoting a researcher who says, “Anthropomorphism has implications for morality.”

    Some examples off the top of my head of how anthropomorphic empathy could create moral good: Ascribing intention and emotion to all the animals and plants and microbes we share the planet with must motivate environmental stewardship. Thanking a deer’s spirit for providing us with sustenance probably promotes more humane meat consumption. And even feeling sorry for a piece of trash could exercise our empathy muscles so we’re more primed to help fellow humans. In theory, anyway! I wonder if anyone’s studying connections like these?

    P.S. Just before hitting “post” I remembered Jessa Gamble’s post about the anthropomorphic characters of Rosetta and Philae. There could be a splendid “LWON on Anthropomorphism” series!

  2. Thank you for noticing LWON’s anthropomorphic tendencies, Danna. I wrote a couple of those posts too: and Probably some other people did too and I am too self-centered to remember.
    And the idea that anthropomorphism and empathy are connected is just wonderful in every way. (LWON also has a tendency to write about empathy. It’s interesting, after these years of internet life, to see what we’re adding up to.) So thank you for that too, thank you very much.

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