By David Toomey
W W Norton
The best place to start discussing English professor David Toomey’s speculative smorgasbord, Weird Life, is with the book’s cover. That beautiful, evocatively photographed green fellow certainly looks strange. Yet, those of us familiar with nature films might guess that it’s some form of zooplankton–the larval stage many sea creatures experience. Or perhaps it’s even smaller, originating in the microbial realm invisible to the naked eye. What we definitely won’t guess at first glance is that this creature is something that could live in the vast ammonia clouds of Jupiter.
And that is what Toomey means when he suggests searching for “life that is very, very different from our own.” He refers to life that doesn’t use water as a cellular medium, or is built from a different set of amino acids. Ultimately, he searches for life that does not share the ancestry common to everything else living on Earth, including frogs, strawberries, that orange mold in the shower, and you. Toomey, in his conversational prose, puts it this way:
The physical boundaries within which life is possible are unknown and undefined, but most biologists believe that they must exist, for the simple reason that there are temperatures and pressures under which the structures of organisms–cells, DNA, and proteins–will break down, no matter how well protected. In short, life must have ultimate limits.
My fist non-fiction encounter with such limits came from archeologist Charles Pellegrino’s epic and consilient book Ghosts of Vesuvius. In the opening chapter, he dives into a tangent about Jupiter’s moons Ganymede and Europa, and the fact that they’ve got volcanic zones and underground oceans that experience tides: “With so many throws of the hydrothermal dice, the probability of extraterrestrial life in our solar system (including, just maybe, complex creatures resembling fish and crabs and not just bacterial mats) rises so high as to approach a biochemical and statistical certainty.”
The idea that alien life might merely resemble crabs or fish never occurred to me. As a fan of science fiction, I’m trained to think of charismatic beings that may confound us (the liquid planet in Solaris), or simply gestate offspring in our chests (Alien). Yet crabs and fish are beautifully rational as far as what an ocean–of an unknown ammonia and water mix–could shape. The physical laws of our universe, after all, humbly provide evolutionary guidance (the gravitational constant, I know you’re wondering, is G = 6.67 x 10ˉ¹¹). Finding cosmic brethren, however, with whom we can share culturally, amounts to finding a stable world with an environment capable of free and easy molecular exchanges. The technical phrase for this state is thermodynamic disequilibrium–our Moon doesn’t have it, and Mars just barely does. But I’ve raced ahead, as it’s easy to in this subject. If we walk alongside Toomey, he’ll point out some of life’s weirdest, most miraculous possibilities.
His tour begins with extremophiles–microorganisms that thrive where most life can’t. The best known of these are heat-loving bacteria that live near deep ocean chimneys (nicknamed “black smokers”). Remarkably, these thermophiles step outside the normal bounds of life by running their metabolism not with photosynthesis, but with chemosynthesis; they draw energy from chemical reaction. How, and why, might this happen? Like a vegetarian who spares the cow to eat his own leafy greens, try Toomey’s rich explanation for yourself:
Deep within the Earth, naturally radioactive materials produce heat that melts rock into the substance called magma. Magma is pushed up through the seams between the midocean ridges, where it cools and spreads outward to become new oceanic crust. Meanwhile, seawater continually percolates down through the crust, where the sulfate it carries combines with iron in the crust to produce hydrogen sulfide and iron oxides. When the same seawater, now heated, is pushed back up through cracks and fissures in the crust and returned to the deep ocean, it carries hydrogen sulfide that certain bacteria find quite tasty. The same bacteria absorb oxygen dissolved in the water, and some of that oxygen combines with sulfite to become sulfate.
Too crunchy? The data behind this explanation comes from researchers at the Woods Hole Oceanographic Institute, in Massachusetts. Toomey, like pivotal science writers Carl Sagan and Richard Dawkins, bolsters his summary with lovely (if simple) descriptions of nature, compensating for visual non-starters like oxide and sulfide. Here’s the sparkling payoff:
As you may recall from chemistry class, some reactions absorb energy, while others release it. The chemical reaction that yields sulfate releases energy–which the bacteria, in lieu of sunlight and in a model of efficiency–use to drive their metabolism.
All of this takes place at 300ºC (which, to save you a google, is 572°F). And though I love quoting Jurassic Park‘s Ian Malcolm with, “Life finds a way,” Toomey’s observation is a bit defter: “Because no one had thought bacteria could survive at temperatures much higher than 60°C, no one had bothered to look for them.”
Where else had scientists never bothered to look? Toomey goes from extreme heat to below zero cold, performing neat thread-work that stitches together some of the worst challenges life faces. Ice crystals (you may recall from biology class) will shred cell walls. To keep water liquid below 0°C, solvents must mix in. Certain salts will maintain liquid water at -30°C, as will proteins and lipids (soluble organic molecules) modified for the task in the cell membrane. Also, the actions of amino acids (like methionine) and other organic compounds catalyze reactions in the cell, allowing life at -100°C.
Single-celled algae, living in the “slushy channels” of Antarctic ice floes, are capable of such feats. They absorb sunlight filtering through the ice while taking in nutrients from the water. Incredible stuff, enlivened further by Toomey’s gift for serving up perfectly-phrased science nuggets: “The charged poles that pull water molecules together are the very feature that enables them to pull other molecules apart.”
But let’s get back on track and revisit salt. Nowhere on Earth does it hold life hostage more aggressively than in the Dead Sea. There, as graduate student Benjamin Volcani discovered in the 1930s, microbial life (in the form of archaea and bacteria) thrives by balancing the concentration of salt on both sides of the cell membrane. These organisms, called halophiles, harbor large amounts of salt in their own cytoplasm, which prevents the salt outside from stealing their water. They also use “charged amino acids” to hold water in place and defend against salt’s denaturing effects.
Another fascinating body of water, Spain’s Rio Tinto, is as red as wine and more acidic than vinegar. An ancient iron ore deposit at its source gives it color, but why has Toomey mentioned it? Not just for the green algae and white fungus visible without a microscope, but for the bustling community of amoebas, ciliates, euglenoids, and flagellates–the All-Star team of bizarre glass slide specimens found in a freshwater pond. Similar to life adapted to lethal saltiness, these acid-savvy mesophiles have evolved special proteins that maintain a neutral pH inside the cell.
At this point, you’re possibly thinking, “I don’t really thrill to micro-phenomena. Doesn’t life hide any macro-weirdness?” Absolutely, it does–though I’d like to consider Toomey’s discussion of extremophiles a huge rock, looming in the corner of the backyard. Having examined the (relatively) dry surface, he’s now free to flip it over and reveal some staggering oddities hiding below (also, extremophiles keep astrobiologists hopeful that the moons of Jupiter and Saturn–provided our robots someday explore and sample them–will yield proof that life isn’t a fluke of the just right “Goldilocks Zone” that Earth inhabits).
Toomey next explores the ominously-named shadow biosphere, which is far more intriguing than little gray men or their saucers ever could be. He describes this hypothetical concept with–as I imagine it–a measured, sinister voice:
There has been general agreement…that if we could trace the ancestry of all living organisms back far enough, we would find them converging, some 3.5-3.8 billions years ago, at a single genesis. Life of Earth, so most scientists believe, began at one place and one time.
Most scientists, but by no means all. Some suspect otherwise, and their reasoning is quite straightforward. Since, as the vast majority of biologists now believe, life is not a once-in-the- history-of-the-universe event, but a more or less inevitable by-product of physics and chemistry, it follows that life on Earth may well have had more than one beginning. It follows further that if a second beginning had occurred under even slightly different circumstances, a different sort of life would have resulted.
Microbiologist Sheldon Copley coined the phrase shadow biosphere; physicist Paul Davies and NASA astrobiologist Carol Cleland are the idea’s two best proponents. Their support is important because if life on Earth somehow does have a secret alternative lineage–existing alongside ours–scientists could then compare and contrast the two, eventually establishing “universal laws of biology” not unlike Newton’s laws of physics. “The discovery of such life,” Toomey says, “would settle the debate over life’s probability once and for all.”
In this second (and most compelling) chapter, Toomey also shines light on a superb array of esoteric topics: convergent evolution, our possible Martian ancestry, and the bacterial architecture known as stromatolites. Often, his clever wordplay stamps facts directly onto the reader’s mind; for example, mitochondria (the organelles that generate energy within our cells) were once bacteria that achieved survival inside the cell “more by snuggle than struggle.” In other passages, his tone sounds quite like hot gossip to the ears of the biology-minded: “For every species known to science, there is at least one that is unknown, and there may be as many as fifty.”
Midway through Weird Life, Toomey slows a bit before gearing up for his finale. The slim chapters “Defining Life” and “Starting from Scratch” focus on life that we, as beings of carbon and water, might recognize. This touches upon Charles Darwin’s evolutionary insights, and much of what Carl Sagan worked on with NASA scientists during the 1970s. We’re also reminded of British inventor James Lovelock, whose Gaia hypothesis states that the Earth is an organic body writ large, susceptible to fevers (the Greenhouse Effect) and suffocation (deforestation); thermodynamic disequilibrium is another of his creations.
Eventually, Toomey discusses whether or not life might be based on silicon–the element responsible for rock and sand–offering an analogy that’s as seductively lucid as it is charming:
[A living organism’s] biochemistry must be stable enough that its cellular structures hold together, but not so stable that nothing moves–the latter condition being a fair description of death. A working biochemistry is a bit like a juggler. A juggler can’t be too stable… Neither can he be unstable; that is, he can’t drop a bowling pin or let one go flying off in the direction of the audience. To keep his audience interested, he must always seem about to miss a catch, without ever actually missing a catch. He must be continually approaching instability, without ever actually getting there.
Silicon bonds so quickly with oxygen (and other elements) that, in the temperature range comfortable to familiar life, large molecules can’t form. But at the colder temperatures that halt carbon chemistry, silicon is capable of gaining molecular complexity, in the form of rings and cages.
Toomey uses this tantalizing fact to segue into “A Bestiary of Weird Life.” This chapter is–and isn’t quite–as advertised, because so much time is spent contextualizing what else could live on what kind of planet. Long (and mostly interesting) stretches provide solid backgrounds on the history of astronomy, as well as on the environments our space probes have found in the outer reaches of the Milky Way. The best part, naturally, relates to Sagan’s “sinkers, floaters and hunters”–theoretical creatures that could live in the pressurized heat of Venus or the clouds of Jupiter. The best version of this discussion, however, is Sagan’s TV series Cosmos.
The next few chapters are much more like a bestiary than the previous one. They deal with how life could arise on comets, stars, and in the form of giant dust clouds roaming space. If you’ve already read a comprehensive science primer, like Timothy Ferris’s Coming of Age in the Milky Way, these discussions will provide you a marvelous refresher. If Toomey is your first taste of white dwarfs and black holes, please jump in; be aware, however, that here he begins a controlled descent toward the bottom of the speculative barrel. His quick dip into dolphin intelligence fits well enough, but leads to lip-service about studying the thoughts of plants. Most frustrating is his breezy mention of sentient machines (that may decide they don’t like us), which raises an even million questions without addressing them.
The second-to-last chapter deals with weird life in science fiction, and rummages obscurely through some novels just for the hell of it. The last chapter, “Weird Life in the Multiverse”, brings to a rolling boil the boldest (and strangest) concepts found in science. Toomey first traces the history of thought that’s helped establish a flat universe, expanding infinitely. Then he examines the nature of particles making up the universe, introducing us to theoretical physicist Brandon Carter, who in the 1970s wondered, “how the universe might have been different had the laws of physics been other than what they are.”
Change the mass of quarks, in other words, and carbon and oxygen molecules destabilize. Make the electromagnetic force stronger, and atoms wouldn’t share electrons (making chemistry impossible). The cosmic rules that allow life seem “finely tuned” and “for lack of a better word, arbitrary.” If you’ve bounced ahead to that episode of Star Trek or Futurama featuring alternate reality evil twins, congratulations. But a serious conversation had to happen before Parallel Universe could enter pop culture’s lexicon:
Why should the values of the particles and forces be what they are? To this Brandon Carter had an answer. If there are a great number of universes, and laws vary from universe to universe, there may be no reason, and to look for one would be pointless. It is to be expected that we find ourselves in a universe with laws conducive to our existence; obviously it couldn’t be otherwise. If anything explained these laws, Cater said, it was what statisticians call a “selection effect”– something that, on this largest and most fundamental of questions, scientists were failing to take into account.
From this gargantuan weirdness, Toomey moves on to… well, I’d like to leave him with some surprises for you. In his epilogue, he soberly admits that, “At present, no one has discovered an example of weird life, and it’s possible that no one ever will.” But he also bids farewell with a reminder that finding weird life would mean reconnecting, in our fractured age, with the natural world. We’d regain some perspective as we encounter a new one. Acknowledging this today certainly feels like its own accomplishment. In that light, let’s hope the search never ends.
Justin Hickey is a freelance writer, and editor here at Open Letters Monthly.