Losos, J. 2017. Improbable Destinies: Fate, Chance, and the Future of Evolution. Riverhead Books; New York.
Right up front, I have to admit that I was very excited for this book. As someone with an academic interest in both herpetology and rapid evolution, I’ve been an admirer of Dr. Losos’s research for a long time.
I ordered my copy as soon as it came out. Unfortunately, it arrived just a little while before my comprehensive exams. Rather than let it sit lonely on my bookshelf while I studied for the next few weeks, I stayed up a couple of consecutive nights and read until my eyes fell shut just before my morning alarm sounded. My intent was to give it a more thorough read again before writing a review, but then Ethan Linck wrote the words right out of my mouth in his review over at The Molecular Ecologist blog, so I’ll just add a few of my non-overlapping thoughts quickly here.
The read:
Improbable Destinies is written by an author with a truly unique perspective at the far forward fringe of eco-evolutionary research. The book is written less as an academic exposition than as a casual conversation between Losos and a new undergraduate researcher. Sometimes, the tone broached into the realm of chummy-awkward conversation, though.
As Linck points out in his review, Losos has a noticeable penchant for dad jokes and puns. At times I also got the feeling that, like a dad misusing slang around his kids in attempt to inflate his hip-factor, Losos tried a too hard to reach for modern references. The references to Chris Pratt in Jurassic Park, Futurama, and Seinfeld were well-placed, but in other cases, like comparing Anole skin patterns to QR-codes, the analogy was dated years before the book was published (I’m a millennial and I’ve never used a QR-code; I can just imagine Gen Z-ers falling back to Wikipedia to understand that reference).
Despite the occasional “dad-vibe” the delivery is inviting and it is written to be accessible for anyone interested in ecology. Although it is an easy read, the book manages to introduce the absolute freshest research while also rooting contemporary studies in the field’s deep history. In some ways, I think of Improbable Destinies as an update and continuation of Weiner’s 2006 book, The Beak of the Finch, which shares the same tone and many of the same characters.
The story:
Without too many spoilers, here’s a quick introduction to the book:
The primary question laid out in the first chapter is borrowed from Stephen J. Gould (who, in turn borrowed it from the movie It’s a Wonderful Life), and boils down to: Is evolution deterministic or contingent? In other words, if we could repeat the Plinko game of evolution, would the puck always end up in the same slot no matter the path (deterministic) or would the puck land in a new slot every round (contingent)?
Just as Gould couched the thesis of his eponymous book (Wonderful Life: The Burgess Shale and the Nature of History) in the movie, Losos uses the same tactic with a different move: Pixar’s The Good Dinosaur. More specifically, Losos wonders, if events had transpired differently many years in the past and the asteroid had not struck the Earth (the plot of The Good Dinosaur)–and thus, if mammals had not inherited the Earth–would some other species have evolved to occupy the same niche as humans? Would a highly intelligent, environment-engineering, abstract-concept-wielding, apex predator have played the part in our absence? And if so, how different would it look alongside a human comparison?
But Losos formulates his question slightly differently in order to answer it with real-world examples. Rather than asking ‘how contingent is evolution?’ he asks ‘how convergent is evolution?’
It’s an interesting question to tee off a long list of empirical examples, including his own research (accompanied by behind-the-scenes anecdotes of the research), that Losos uses to make his case.
He is a great person to answer this question since he’s spent a good portion of his life studying evolutionary convergence in radiations of lizard species (e.g. Losos 1990). He also brings a whole new perspective to the question that Gould never had. In the past few decades, there has been a proliferation of research in rapid and experimental evolution (e.g. Losos, Warheitt & Schoener, 1997). While Gould was stuck playing out his scenarios as thought experiments, Losos draws on new research in rapid evolution that plays out evolutionary scenarios with real populations in contemporary timescales to consider just how deterministic/contingent evolution may be.
I really enjoyed reading the stories behind some of the foundational papers in this relatively new field, like the story John Endler’s first experiments making tinfoil hats for lizard to block light (of that experiment Losos writes “…alas, foiled by equipment malfunction.” [emphasis added for maximum dad-joke power]). Or, David Reznick’s near-death experience in Trinidad. Or, Rowan Barrett’s travails in rattlesnake wrangling. My reading was especially timely since I followed it up with a few solid weeks immersed in evolution literature for my comps. It was fun to read the publications of folks like Dolph Schluter and be able to connect the dots of academic pedigree (Grant and Grant beget Schluter who beget Barrett) and Losos’s stories about them.
The backstory:
One thematic story that the book spends quite a bit of time addressing is that of Simon Conway Morris. The first chapters of the book deal with the origination of the determinist school of evolutionary theory, of which Morris is a major proponent. Although Losos hints at the teleological assumptions adhered to by Morris, Losos avoids pointing out the religious underpinnings that color much of the determinist theory.
Morris believes in a supernatural god. He is also a serious biologist who understands the mechanism of evolution. As such, it seems that his insistence on the inevitable evolutionary outcome of “a creature with intelligence and self-awareness on a level with our own” (cited from this essay) is driven by the realization that there must be a deity-worshiping species if there is to be a deity. Jerry Coyne provides a much more in depth look into Morris’ teleology in his post.
I think Gould charges Morris on this point most clearly in their exchange, published by the Natural History Magazine in 1998 (The article is worth reading in entirety, but if you haven’t the time, I’ve included a few TL;DR excerpts below). Gould writes that Morris’s conclusions, “can arise only from a ‘personal credo’—and I would value his explicit attention to the sources of his own unexamined beliefs.”
I won’t give away Losos’s final conclusion nor where he falls on the Gould vs. Morris debate. However, I will again point out that the strength of his argument lies in the inferential power of the predictive evolution experiments he cites. Both Gould and Morris were limited to retrospective inference (i.e. telling stories about the path of a Plinko puck from nothing but its final resting slot), but predictive experiments are rigorously falsifiable (i.e. testing out stories about the path of a Plinko puck by dropping it down the board in real-time).
One last thing:
I couldn’t help but notice the striking similarity in jacket covers between Improbable Destinies and Dale Peterson’s The Moral Lives of Animals.
I’m sure it wasn’t intentional, but it is hard to miss the lion in the foreground along with the guinea fowl and peacock, the elephant in the background, and the horned ungulate in the middle.
FWIW: Peterson’s cover is a reprint of a Brueghel painting. Losos’s cover is a digital composite of original Mutzel lithographs.
Postface:
Here are my favorite excerpts from the exchange between Stephen Jay Gould and Simon Conway Morris, “Showdown on the Burgess Shale,” Natural History magazine, 107 (10): 48-55.
Morris’s argument:
“Gould sees contingency evolutionary history based on the luck of the draw—as the major lesson of the Burgess Shale. If you rerun the tape of evolution, he says, the results would surely come out differently. Some creature similar to Pikaia, a small eel-like animal with a rudimentary head, may have survived in Cambrian seas to become the ancestor of all vertebrates. If it hadn’t, Gould says, perhaps other—entirely different—major animal groups would have evolved instead from one of the Burgess Shale’s other “weird” body plans. Such a view, with its emphasis on chance and accident, obscures the reality of evolutionary convergence. Given certain environmental forces, life will shape itself to adapt. History is constrained, and not all things are possible.
…
Contingency or no, I believe that a creature with intelligence and self-awareness on a level with our own would surely have evolved—although perhaps not from a tailless, upright ape. Almost any planet with life, in my view, will produce living creatures we would recognize as parallel in form and function to our own biota. But first, life must arise, and we have no idea how rare an event that might be. If we are honest, despite our exciting fancies about extraterrestrials, we must admit the real possibility that life arose but once, and that we are alone and unique in the cosmos—with an awesome and, to many, unanticipated role as stewards of all other living things. But were we to let evolution take another route than it did, why not grant (as, Gould will not) that another kind of being would have evolved to fill our special place in nature?”
Gould’s argument:
“Conway Morris charges that my arguments for contingency arise “not from the evidence of paleontology but from Gould’s personal credo about the nature of the evolutionary process.” This claim, however ungenerously stated, is—and must be—true, for any general view of life must read evidence in the light of a favored theory. I would, however, label my view as a valid reading of paleontological evidence in the context of a theory about life’s evolution and history that I have worked out by considerable thought, practice, and intellectual struggle, and that I always explicitly identify as tentative, undoubtedly wrong in places (but not, I hope, in general approach), and embedded (as all ideas must be) in my own personal and social context.
I am puzzled that Conway Morris apparently, doesn’t grasp the equally strong (and inevitable) personal preferences embedded in his own view of life—especially when he ends his commentary with the highly idiosyncratic argument that life might be unique to Earth in the cosmos, but that intelligence at a human level will predictably follow if life has arisen anywhere else. Most people, including me, would make the opposite argument based on usual interpretations of probability: The origin life seems reasonably predictable on planets of earthlike composition, while any particular pathway, including consciousness at our level, seems highly contingent and chancy.
I don’t know how else to interpret the cardinal fact that life did originate on earth almost as soon as environmental conditions permitted such an event—an indication, although surely not a proof, of reasonable expectation and predictability; whereas consciousness has evolved only once, and in a marginal lineage among so many million that have graced our planet’s history—an indication, although again not a proof, that such a phenomenon is not inevitably meant to be.”
References:
Losos, J. B. (1990). The evolution of form and function: morphology and locomotor performance n West Indian Anolis lizards. Evolution 44, 1189–1203. doi:10.1111/j.1558-5646.1990.tb05225.x.
Losos, J. B., Warheitt, K. I., and Schoener, T. W. (1997). Adaptive differentiation following experimental island colonization in Anolis lizards. Nature 387, 70–73. doi:10.1038/387070a0.
Losos, J. (2017). Improbable Destinies: Fate, Chance, and the Future of Evolution. Riverhead Books; New York.