Improbable Destinies: Fate, Chance, and the Future of Evolution

Contingency or Determinism? Chance or Necessity? Which is it?On the one hand, Dr. Simon Conway Morris, a Cambridge paleontologist, sides with determinism. He maintains that if we could rewind the clock and start the “Cambrian Explosion” all over again, some intelligent biped very like us would inevitably arise again. Animals will evolve similar solutions to similar challenges, just like sharks, ichthyosaurs, and dolphins in the sea, or pterodactyls, birds, and bats in the air. Thus paleontologist Dale Russell has speculated that if that Chicxulub Asteroid had never wiped out the dinosaurs, the dinosaur Troodon might have evolved into an intelligent humanoid, a vertical biped with that distinctive green lizardly charm.On the other hand, Dr. Stephen J. Gould, a Harvard paleontologist, sides with contingency. He maintains that if we could go back in time to the age of the Burgess Shales of Cambrian times and restart the evolutionary ball rolling from there, the biosphere of our twenty-first century would be unrecognizable. Thus if that nasty asteroid 66 million years ago had whizzed past the earth in a near miss, that intelligent dinosaur would have more likely looked like a Troodon with a long birdlike bill—a horizontal biped with a long tail _a_tergo_ to balance its large brainy head at the other end.This debate is the topic of this book by Dr. Losos. His conclusion? The truth lies somewhere in the middle. To cite but one of his many examples, he discusses the native mammals of Australia. On the side of determinism, many of the marsupial fauna strikingly resemble their placental counterparts elsewhere on the planet. Thus the placental mole, flying squirrel, marmot, cat, and wolf of North America find eerie parallels among the fauna of Australia, such as the extinct Tasmanian wolf. On the side of contingency, however, there are no close placental parallels to the platypus, koala, or kangaroo.Gould’s thought-experiment is infallible—if only it were doable! Admittedly, we cannot restart the Cambrian, but Losos and his colleagues have done the next-best thing by conducting experiments and field studies that have repeated the evolution of species well within a human lifetime. It is impossible to summarize his book at all adequately in an Amazon review, but please consider the following brief examples.Losos earned his Ph.D. with his research on the anole lizards of the four island of the Greater Antilles: viz., Cuba, Hispaniola (i.e., Haiti & Dominican Republic), Puerto Rico, and Jamaica. Lizards of the genus _Anolis_ are armed with toe pads that enable them to climb vertically on trees.Beginning his studies on Jamaica, Losos discovered four distinct species, each suitably camouflaged to blend in with its arboreal environment: the brown bush anole on the ground and low tree trunks, the aquamarine Graham’s anole among the leaves and upper tree trunks, the drab twig anole with unusually short legs ideal for furtively climbing along twigs—and the much larger Garman’s anole lacking any qualms against preying upon its sister species!Losos subsequently discovered that each of the four Puerto Rico species has a counterpart on each of the other three islands of the Greater Antilles. One would suppose that each species would be most closely related to its look-alike counterpart on the other three islands, but DNA studies have demonstrated that each species actually shares a more recent common ancestor with the other species living on its home island.Thus Losos got the idea to reduce Neo-Darwinian evolution to an experimental science. In the Bahamas, he and his colleagues Amy & Tom Schoener experimentally “seeded” one islet after another with a single species of anole, and within a human lifetime, they documented the lizards evolving genetically to function in different environments. When a lizard species was introduced to a particular island, over time its legs would evolve to be shorter if necessary for climbing on slender twigs inaccessible to predators, and its legs would get longer form one generation to the next if necessary for walking, running, or climbing on broader surfaces. Furthermore, when curly-tailed lizards (which prey upon anole lizards) were introduced into some islets but not others, the anoles facing predation evolved short legs to climb on slender twigs high in the trees where the predators could not reach them, unlike their counterparts on the predator-free islets. In his experiments, Losos followed in the footsteps of other biologists: e.g., Rosemary & Peter Grant studying evolutionary change in Darwin’s Finches in the Galápagos Islands; David Reznick and John Endler inducing evolutionary change in guppies by introducing predator pike cichlid fish into their pools (Reznick on site in the mountains of Trinidad, and Endler in laboratory studies); Dolph Schluter replicating the speciation of fresh-water sticklebacks in the lakes of British Columbia in his laboratory experiments--and much more besides.In justice, remember mercy! In particular, two criticisms of Losos’ book are less than fair. First, he has been taken to task for his human-interest fluff—about his run-in with drug-runners when his outboard motor died during his trip in the Bahamas, among other adventures. In reality, publishers will not even touch a book for a general audience unless it is filled with personal anecdotes, as we read in the book by Rabiner & Fortunato,  Thinking Like Your Editor: How to Write Great Serious Nonfiction and Get It Published . Second, he has taken some flak for all the scientific detail that bores his readers to death. On the one hand, I know I am not going to remember all the details of all the experiments that were performed to answer every conceivable objection. However, I am glad that the researchers covered all the bases so that the creationists and intelligent-designists cannot honestly accuse the researchers of sloppy work and dismiss evolution as “just a theory.”Two constructive criticisms of my own! First, when taken out of context, some of Dr. Losos’ statements can be misconstrued as saying that evolution is nothing but a theory of blind chance. Of course, I know what he meant, but in his preface, it would have been wise for him to drive home the point that mutation is random, but selection is the non-random FILTER of mutation. Evolution proceeds a hundred steps forward and ninety-nine steps back, again and again and again. Creationists claim they accept micro-evolution within the “baramin” or created kind, but not macro-evolution from one “kind” to the next. They beg the question by gratuitously asserting that there is a genetic brick wall that blocks evolution beyond the created kind. Creationists assert this premise as if it were the default or null hypothesis, and gratuitously slap the burden of disproof onto scientists to prove the contrary. Actually, there is not a shred of evidence for a barrier to the indefinite accumulation of beneficial mutations. A user-friendly introduction for the intelligent non-expert can be found in (for instance) Richard Dawkins’  Blind Watchmaker Why the Evidence  and  Climbing Mount Improbable .Second, I wish he had included the tale of the Italian wall lizard _Podarcis_sicula_ of southern Europe, including the islet Pod Kopište near the Croatian island of Lastovo. In 1971, scientists introduced ten specimens, divided equally between males and females, from Pod Kopište to the nearby islet of Pod Mrčaru, two miles away, which up to that point had been free of that particular species of lizard. (In case anybody cares, the Croatian letters “č” and “š” with the “hats” on top are pronounced respectively as “ch” and “sh.”) In 2008, scientists from the Universities of Antwerp under the leadership of Anthony Herrel returned to the two islands and found that the lizard population in Pod Mrčaru had evolved some dramatic differences from the parent population. Now Pod Kopište is mostly rocky, whereas Pod Mrčaru is covered with vegetation. The vegetation effectively hides and protects prey from predators, whether the prey be insects hidden from lizards, or lizards hidden from larger predators. Whereas the lizards on the parent island subsist mostly on insects and eat little plant food, the lizards in the colonized island subsist mostly on foliage. Furthermore, food is far more abundant in the colonized island. Whereas the lizards on the parent island stake out and defend territories to maintain their precarious food supply, the lizards in the colonized island obtain enough food in the form of foliage to give up these belligerent ways. The lizards on the colonized island grew bigger heads with a stronger bite to aid them in biting off plant material. Conversely, their legs were shorter and they were bigger and more sluggish than before because they did not have to work so hard chasing insects or hiding from predators. In the intestines of the lizards in the colonized island, caecal valves newly appeared, a novelty absent in the parent population. These valves partially close off a part of the intestine to form a special chamber where cellulose from plant food can be chemically broken down by nematode worms and microbes into simple sugars absorbable in the intestine. (Nematodes, by the way, are not found in the guts of the parent population.) This substantial amount of evolution took place in only thirty-seven years. (For details, see Richard Dawkins’  The Greatest Show on Earth: The Evidence for Evolution , pp. 113-116; Carl Zimmer’s  By Carl Zimmer - The Tangled Bank: An Introduction to Evolution , pp. 102-104; and Wikipedia—Italian wall lizard.)

Many years ago, during a public lecture on the interface of religion and science, I was asked by a belligerent attendee whether I thought religion had been a force for good or evil in the world. I answered "Yes." Many apparent controversies are like that; their public presentation commits the fallacy of the excluded middle ("Either you're part of the solution or you're part of the problem"). This very readable book is about such a controversy in evolutionary biology, pitting the late S.J. Gould against Simon Conway Morris on the issue of chance vs. determinism. Gould famously argued that unique and unpredictable historical events cannot help but shape the future evolution of organisms (the "contingency" argument). Conway Morris points to the near-ubiquity of convergent evolution, in which unrelated organisms "solve" their environmental problems in very similar ways (think cacti and unrelated succulents, or placental vs. marsupial moles), as evidence for a large role of determinism in evolution. Both are "right." As with the immediately antecedent controversy (also involving Gould) over "punctuated equilibrium" vs. "phyletic gradualism," neither side can claim a monopoly on truth, but pursuing the controversy qua controversy can be good for one's career and reputation.The first half of Losos' book surveys the arguments and some of the facts on the ground. That is, it's "gee whiz!" stuff. Parts of it read like the late Victorian evolutionary literature mocked by William Bateson, who wrote in "Materials for the Study of Variation" that the arguments presented therein amount to "if such-and-such happened, well, then, it did!" The second half is much more stimulating. Since the elaboration of the phenomenon of industrial melanism, we have come to realize that adaptive evolution can occur very rapidly even as we speak. Evolution presents a continuing tension between "phylogenetic inertia" or "niche conservatism" on one hand, and "local adaptation" or "rapid evolution" on the other. How can we reconcile, say, cases where naturalized species have evolved rapidly in their new geographic ranges, with the fact that carnivorous and scavenging beetles apparently showed no morphological change at all since the middle Quaternary? At any rate, Losos, who has been very prominent in studies of evolution in Caribbean Anoles (lizards), presents case after case in which real-time evolutionary experiments usually (but not inevitably) argue for determinism. All of these brilliantly-executed studies should be familiar to an educated public, but most are not. Were they better-known, creationists would be much less able to confuse the issues with their spurious arguments. There is thus a real need for books like this, accessible to the intelligent general reader. (There is little in it that is new to professionals, though the presentation alone makes it a good investment of time for us.) How to get the word out?So is evolution contingent or deterministic? Yes.

How did we come to where we are? Are we humans an evolutionary singleton? In the first place, is evolution an incidental result, or inevitable outcome? Is it predictable? Stephen Jay Gould answered this question with “No,” saying ‘ any replay of the history of life altered by an apparently insignificant jot or tittle at the outset, would have yielded an outcome of entirely different form.’ World-famous researchers unfold a fierce competition to demonstrate the evolutionary roles of contingency and determinism. Modern science makes us possible to do experimental approach to these questions, on which ‘gedankenexperiments’ was an only feasible way at the time of Gould. Jonathan B. Losos explains ‘how we know what we know’ and ‘where the ideas come from’ in “Improbable Destinies.” Losos, one of the leading figures in this field, details past results of experimental approaches, conducted out in nature, and in the lab. His writing is easy to understand. Before everything else, he vividly portrays every researchers enjoying their studies. Living in the corona virus era, their laboratory studies excite my interest more. Does evolution follows the same path time and again? Losos says yes at least at the macroscopic level. But, it’s not common. Evolutionary replays can still yield different outcomes. The ubiquity of convergent evolution in general would seem to provide scant support for our evolutionary inevitability. He says someday we routinely will be able to predict which mutations will evolve adaptively, although that day is a long way off. Losos concludes we should make the most of our evolutionary good fortune. Because, history happened as it happened and here we are today.

A obra traz uma importante contribuição à biologia evolutiva de uma forma leve e fácil de ler.Recomendo fortemente a todos, biólogos e não biólogos.

Excellent and readable book. Anoles are clearly loved and understanding their world gives clues to ours.

Excellent book. Finished three chapters till now. Very insightful. Must read for evolutionary biologists.

Ottimo libro sul dibattito contingenza/convergenza, uno dei più vivaci e interessanti della biologia moderna. Prendendo spunto dai suoi esperimenti e dalla storia della disciplina, Losos racconta come si sviluppa la discussione intorno alla domanda: l'evoluzione porta a forme simili in ambienti simili? E quindi, certe caratteristiche sono inevitabili? L'intelligenza e una specie dominante simile all'uomo nascono ovunque e comunque? Non si schiera decisamente da una parte o dall'altra, ma in alcune interviste mi sembra di capire che sia a favore della contingenza, e non inevitabilità della nascita di certe forme. Alleggerito da racconti personali e aneddoti degli esperimenti, il libro è interessante e vivace, e spinge a approfondire la questione. Forse avrei voluto si fermasse di più sull'evoluzione dell'uomo, ma è abbastanza ricco così.

great book, unusual and absorbing