14 April 2023

Superheroes and limits: more on Chapter 1 of From Extraterrestrials to Animal Minds

Warning: this post includes spoilers for Black Widow, Avengers: Endgame, and Spider-Man: No Way Home. Seems a small price to pay to understand the biophysical limits of the biosphere, but it's your call.

So, are you sure you want that superpower? Have you noticed that superheroes usually have difficult lives and crushing responsibilities? And have you noticed that even the most potent superheroes and their coveted superpowers come up against explicit limitations?

I haven't yet seen Avengers: Endgame (I know! I'll get to it!) but I know this: Black Widow ends with Natasha riding away to the events that end with her sacrifice, events portrayed in Avengers: Endgame. She has some cool superpowers but she ultimately contributed most to the world's salvation by dying.

For me, the hardest MCU movie to watch was Spider-Man: No Way Home. Peter Parker has superhuman strength and dexterity, and arthropod-like agility et cetera, but couldn't protect the person he loved the most. At the end of the movie he arranges to have himself erased from the memory of his dearest friends. I wept through it, not merely because it's sad but because this impossible burden falls on a teenager. The proverb now forever associated with Spider-Man is "with great power comes great responsibility," and this credo angers me every time I hear it. I don't hear the acknowledgement that no kid should ever have to carry that. And certainly not alone.

Superhero stories are never about life without limitations. Indeed the opposite. They are about what happens inside a world/universe that has different boundaries than our own. It's not the boundaries that matter, whether you're a superhero like Natasha, or a "normal" person like me, or a metaphorical agent like evolution.

Maybe this is why an exhibition developed by the American Museum of Natural History, about life at the extremes, is called "Nature's Superheroes." No one thinks that extremophiles are all-powerful. But we call them superheroes with superpowers.

In my previous post I explain how Simon Conway Morris, in the first chapter of From Extraterrestrials to Animal Minds: Six Myths of Evolution, pulverizes a strawperson who believes that evolution operates "effectively without limits." That cynical move mars a chapter that is really interesting, because it's mostly about the limitations of being an organism on Planet Earth. I already know about the biophysical limits that apply to vision, which Conway Morris explores beautifully in a section that's a tour de force on various kinds of sensation. But my favorite section was about the challenges of being small.

The chapter challenges us to consider an animal (therefore something multicellular) so miniaturized that it has fewer than 50 cells. Such tiny organisms exist and thrive, often in symbiotic relationships. Conway Morris rightly rejects pejoratives like "degenerate" to describe these creatures, and his brief tour of some of the smallest animals ends with one that is effectively a single cell (but with multiple nuclei) and a clear origin in the Cnidaria (the phylum that includes jellyfish, anemones, and corals). The lesson is that extreme miniaturization (starting with a "normal" animal lineage) is common and can be dramatic. Conway Morris chooses to interpret this as evidence that "biology has no further room to maneuver," without explaining why he thinks that. Obviously an animal can't have zero cells, but the success of Myxozoa in their pursuit of extreme miniaturization doesn't cry out "no room to maneuver" to me.

Ant-Man is good at getting very small, but the movies don't trouble us with the barriers faced by a very small organism (or gamete). Here's a big one: once you are less than about a millimeter across, water is a viscous milieu that turns swimming into an exhausting effort. Life in water for very small organisms is utterly different than ours. It's almost impossible. Life in the air is easier, but for very tiny animals the rules of viscosity create big challenges there too. Conway Morris explains this, then tells us about an animal that accepts the challenge: a parasitic wasp that's as little as 150 microns long, barely visible to the human eye. This wasp flies, but its wings don't have blades those would be a hindrance due to the viscosity of the air! Instead the wings look like feather dusters.

The whole chapter is about extraordinary animals (and the occasional plants and bacteria) that flaunt superpowers. Simon Conway Morris suggests that this means that evolution has done almost everything it can possibly do, filling the world with life within a set of boundaries dictated by physics (and time). I think he's probably wrong that there are no (or few) possible new things for evolution to discover, but in the course of trying to convince me, he explored some astonishing new worlds.

Next up is Chapter 2, The Myth of Randomness.

No comments: