The Read: Arik Kershenbaum, The Zoologist's Guide to the Galaxy
Friday's Child Is Loving and Giving
Why did I get this book?
I’m really interested in questions of whether life exists beyond Earth, how we might think about astrobiology in advance of direct observational experience, and how we might identify or think about sapient life elsewhere in the universe. I think it’s the single-best example of a problem that requires interdisciplinary and transdisciplinary conversations to engage intelligently—obviously scholars who identify as astrobiologists, but lots of others too.
So I grabbed this book as soon as I heard about it, and added it to the part of my bookshelf that also includes works like Ward and Brownlee’s Rare Earth, Johnson’s The Sirens of Mars, etc.
Is it what I thought it was?
Yes, very much so. Though not as fully speculative and epistemologically exploratory as I might like (see below).
What continuing uses might I have for it?
Much as I would love to at least be present at the interdisciplinary conversation I can imagine on this topic, any time I mention it to any other professors they tend to shrug and pat me on the head gently and suddenly realize they’re overdue for a meeting. So the main use I can see for this besides taking up room on that section of my bookshelves is in the writing of speculative fiction (hey, you’re not an aging academic if you don’t sometimes think about that novel you want to write).
Quotes
“The evolutionary problems that we observe here are due to pressures and mechanisms that are also very likely to occur elsewhere. Movement, communication, cooperation: these are evolutionary outcomes that are solutions to universal problems.” p. 11
“If we ever make contact with an alien civilization—intelligent beings, rather than just microbes or jellyfish—we can be confident of certain things: they will have a form of technology (or how could we contact them?), and that means they are cooperative and therefore social. But merely knowing that a species is social unleashes an avalanche of additional evolutionary implications. They may be brutal and warlike, like us: but I will argue to to be social they must also be altruistic. An alien spaceship landing in central London would be a sure sign that the passengers ‘spoke’ to each other using some kind of language, but whether this speech might be acoustic, visual or even electrical, we cannot say. Two legs, many legs or none, I believe it is language that will end up being our biggest feature in common with any alien civilization we encounter.” p. 11
“How aliens act is much easier to predict than their appearance.” p. 13
Commentary, asides, loose thoughts, unfair complaints
If I had more extensive formal training in biology and biochemistry, I’d probably be able to articulate my frustrations with Kershenbaum’s analysis more precisely. Don’t get me wrong: I enjoyed reading it and I found it useful and interesting. It’s extremely accessible compared to some of the specialist literature on astrobiology.
I think what frustrates me is that Kershenbaum seems too determined to stress that life on Earth provides a sufficient set of examples to infer both the general principles that life elsewhere must follow and even to speculate about the specifics of life elsewhere. I understand that on some level for the book to move from a general epistemological discussion of whether we can know anything speculatively about life elsewhere to a discussion of the speculatively concrete features of life elsewhere like movement, communication or sapience, you have to eventually say, “What we know already about life on our planet provides sufficient grounds for that concrete speculation”. I suppose my beef is that I wanted a longer and more exploratory working-through of the epistemological problems. I constantly wanted him to push first towards thinking about “what if basic characteristics of life on Earth are unusual? are there conditions or circumstances where life might develop in substantially different ways?” Take the quote above about alien civilizations—for one, it’s tautological though maybe true for all that (that we will only make contact with civilizations that make contact in the same way that we do). I kept having the impulse of the curious child: but why? What if? For a book that’s about speculation in advance of data, it keeps its speculative thinking on a very tight leash.
I think a bit here about what exo-planet research has shown us about solar systems in a more comparative way. On one hand, our basic theories about how planetary systems form still seem valid. On the other hand, there are a lot of variations in the specifics that I think could be said to be surprising in terms of the modelling assumptions made in the 1970s-1980s. Some of those variations might themselves be a bit misleading since we’re still not necessarily detecting all the planets in orbit around various stars due to the techniques in use—the planets we can detect most readily with the two most frequently used methods are in close orbits around their stars. Still, the basic principles governing how solar systems form seem to produce a pretty wide range of planetary sizes, characteristics and orbital relationships.
Kershenbaum assumes that natural selection will shape how life changes over time everywhere that we find life. I’m completely ok with the assumption that there is something about the initial appearance of life in the widest and loosest definition of that term that is likely to happen repeatedly under a wide variety of physical conditions throughout the universe. But past that, I feel like it’s worth spending more time than he does asking, “Are there imaginable physical conditions under which life by some loose definition might not change over time via natural selection?” Say, environments that are far more stable in their basic conditions over much longer time scales than on Earth? For example, if there are microorganisms still alive under the Martian surface, say in a layer of subsurface perchlorated water, they’ve existed under some very similar conditions for a very long time. You could still argue they’re governed by natural selection in the sense that they have to operate within a fitness landscape and that if they are in any sense maladapted to it, they’ll die off. But it’s still a different thing than assuming that life is relentlessly competitive within changing fitness landscapes.
The same goes for assuming that evolution will push life to spread into all available niches, or that life will everywhere demonstrate convergence, that organisms everywhere will find parallel solutions to recurrent environmental challenges. He mentions flight and how it’s evolved multiple times and produced similar morphologies and hence that in any atmosphere that permits flight, flight will evolve. It’s reasonable enough but I kept wanting to push at it. Lots of organisms benefit by moving through air, but some of them aren’t flying the sense of moving in a controlled fashion from point A to point B: dandelion seeds, fungal spores, very small insects that simply get carried by winds. A new volcanic island gets an ecosystem first from life-forms carried on wind that don’t fly. Maybe some features of life on Earth that are highly adaptive are nevertheless accidents that might not repeat; maybe there’s way more ways to skin an environmental cat.
Kershenbaum seems to agree in one way in citing Stephen Jay Gould, but I’m not sure he takes the caution on board. I understand that there are a lot of issues with Gould’s book on the Burgess Shale, but it feels to me, as a complete non-expert, that his underlying thesis is precisely something you can’t really test until there’s some concrete examples of exobiology to test it against. Kershenbaum acknowledges that life on Earth has features and forms that are adaptively neutral—that not everything we see living creatures doing or see in their forms can be explained as an adaptive solution to the challenges of their environments. That just seems to me to offer a chance to think speculatively about the potential vastness of possible morphologies, ecological relationships, behaviors, etc. might be with life elsewhere rather than to immediately pull those speculations as close as possible to life on Earth as it has been. Gould suggests that maybe even on Earth, the tape wouldn’t unfold in the same way if it were rewound—life elsewhere might help us to see whether that’s so and challenge any assumption that what we see is just precisely what life needed to do in a given environment. Maybe some evolutionary accidents don’t or won’t happen in other histories of life even though they materially could happen. Or maybe evolutionary events that we think of as happening only once, and only recently, like sapience, happen far more often for far more reasons in other histories of life.
I sometimes found myself thinking about what we would make of life on Earth if we were gaining information about it for the first time at different moments in its history and we had a wider comparative knowledge of life elsewhere. Would it turn out that environments like Earth in the Mesozoic trend always towards gigantism because of available oxygen in the atmosphere, plentiful water for buoyancy, etc., or would that turn out to involve an endless chain of specific evolutionary precursors back to the Permian-Triassic extinction? Would what we perceive as a tight fit between environmental conditions and the distinctive ecologies of a given period in Earth’s history suddenly become looser? Would there be periods in the history of life on Earth where we as visitors would be at risk of just completely misunderstanding the forces shaping life on Earth and therefore wrong about what kinds of morphologies or adaptations are possible or likely both here and elsewhere?
What I like best in the book is when Kershenbaum does take a step or two into applying what he’s said about movement, communication and so on to extraterrestrial environments that we have some reasonably good data about: Titan and Enceladus, for example. Or thinking about what the material conditions would have to be for systems of animal communication other than the ones we’re familiar with: why, for example, systems involving scents could likely not carry complicated information. Even there, I found myself wondering. He points out real physical constraints involved in using scents to communicate, most notably atmospheric dispersion of chemicals and the difficulty in any windy environment of exchanging information between organisms (only one gets to be upwind). Very small organisms, he notes, might be able to communicate this way. But what if, for example, you had organisms that were relatively or completely sessile in close proximity that could create connected bodily structures (say, a tube) that let them issue chemical signals in rapid sequence, pushed by short blasts of air, and occasionally flushed by liquid to keep residues from forming?
We’ve been surprised by life on Earth so often, after all—that life exists in places we didn’t think, that it behaves in ways we didn’t imagine, that it has had more morphologies and behaviors that we ever dreamed over its whole history, and so on. It just kept feeling to me that for the sake of manageability (the book could bog down every other paragraph with “what if"s like my attempt to think of plausible systems of chemical communication), Kershenbaum has to indulge a winnowing impulse that feels a bit like geocentrism: that we are the likely yardstick that lets us measure life everywhere. Maybe? But I feel more of an impulse to take harder shots at that assumption first before forging on to speculative comparisons.