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

The book seems promising, especially after the first two chapters situate the important debate and findings about convergent evolution. However, the book quickly degenerates into a lengthy series of stories that read like diary entries intermingled with observations on experiments (both the author's and others' experiments). I expected science and I got the Bulwer-Lytton of evolutionary biology: "Another time a walk along a stream above a waterfall turned into a cliff-hanger. Not just because it was suspenseful (which it was), but because he ended up hanging over a cliff, clutching a bush, Indiana Jones-style." (p. 146) Missing? "It was a dark and stormy night." And on and on and on. The book is absolutely nothing like what it claims to be. Popular science writing at its very, very worst. I cannot recommend it.

Nice read so far, but I was surprised to find the author speculating on pp. 40-41 about why Conway Morris 'went from detailing Cmbrian curiosities to cataloging convergence' and offering the following: he may just have been following the crowd, he objected on spiritual grounds to 'Gould's views on the haphazard nature of evolution,' and he was embarrassed that Gould had praised his work, subsequently found to be mistaken. These are completely out of line in a work that claims to be -- and ought to be -- a scientific explanation for why one theory is better than another. The author's job is to explain why Morris is wrong -- either because his claim is incoherent or not well-supported; it is not to disparage the man by querying his motives. His motive may simply be that he thinks the evidence is in his favor. The passages come off as ad hominems.

So...the bottom line is that I now have a question about the author's judgment that I did not have before pp. 40-41 and that puts a damper on the rest of the text.

A must-read for anyone interested in evolution written by a passionate scientist. A magnificent and engaging book, which is highly informative both about how evolution takes place and about how science is done. Losos convincingly shows the importance of contingent events in evolution, despite the existence of larger trends. Highly recommended!

Professor Losos has done an excellent job of trying to elucidate historical and modern convergent evolution studies and experiments in a manner that the layperson can understand. He then delves into the possibilities of further evolution of our species and also gives some excellent insight into the 'what if' of evolution if there had been no mass extinction events. Although many of his examples have been known and available for study for a good p0rtion of the 19th and 20th centuries, he adds additional more recent information on evolutionary studies in microbiology and with insects which have been done in the past twenty years. As a Biologist and educator I found the entire book to be full of the kind of examples that would be extremely helpful to the professional teacher to bring variety and interest into the classroom when elaborating on sections of evolutionary biology at both the high school and college levels of study. Thus it is well worth buying and reading. I do have two criticisms of the author's uses of terminology which I felt were significant enough to warrant not giving a full five star rating to the work. First, I note that Losos does not come out from the get-go to make it clear that his plethora of initial developmental similarities are more likely due to similar plastic materials (read, vertebrate DNA sequences) being similarly shaped or selected for by a common mold (read, similar environmental pressures) to arrive at similar endpoints (read, streamlining of water vertebrates, wing construction of flying vertebrates, camouflaged colors, etc.). Thus the non-biologist reader must be careful not to misinterpret Losos' examples as evidences of Teleology, ie., evidences of some grand planned and directed design in nature. A Theist could go halfway through the book reading his information as evidence of the directional guiding hand of God leading to big brain humans. This was not the author's intention. Secondly, I would criticize Losos' tendency to state some of his examples in the terms of Lamark's theory of acquired characteristics (of dogs evolving longer legs or camouflaged colors to escape a predatory tiger population, rather than a population of dogs being selected naturally over time for longer legs or camouflaged colors due to a predator's actions.). Again this does not destroy the whole nature of an excellent work which pulls together evidence and research for how convergent evolution works and might have worked in different pools of DNA if mass extinctions had not occurred. With these two caveats in mind, I rate this book as an excellent read for both professionals and lay persons desiring to broaden their understanding of mechanisms of evolution.

In 1989, the late Stephen Jay Gould published Wonderful Life, a book intended both for the general public and for professional scientists. In it, Gould presented his thesis that today's lifeforms are the result of a historical process founded on contingency, that is if we were to rewind the biological history of the earth back a half billion years and let the tape play again, there would today be lifeforms but they would not have the shapes we see around us now. The animal kingdom would have no fish or other vertebrates and definitely no human beings.

Gould’s "tape of life" was a thought experiment. He described a fauna from 500 million years ago, a group of fossil animals found in the Burgess Shale quarry of British Columbia, and pointed out that the only chordate animal in it doesn't look nearly as well-adapted as the other Burgess animals. Since all vertebrates are chordates, then the only reason we are alive today is that the chordates of the Burgess shale and their cousins had the good fortune to survive. We are lucky to be here, Gould said, and there's no reason to think that chordates were somehow predestined to take over the earth.

While Gould argued and illustrated his hypothesis convincingly, he was to some extent only speculating. He understood (wrongly as it turns out) that you could not really rewind the tape of life, that you could not go back in time and repeat evolution to see if the same organisms would appear each time you did.

In Improbable Destinies, Harvard professor Jonathan B. Losos gives the story of biologists who have done exactly that. They did this first by observing, in the wild, populations of related species evolving differently in different places.

Losos is a lizard specialist and he describes his own results of how the same species changes in different ways when different populations are let loose on different islands in the Bahamas. This seems to support Gould's hypothesis.

He described another scientist seeding different river streams with one variety of fish and observing how similar changes in conditions result similar changes in the fish, which would seem to go against Gould's hypothesis.

We need to find out what is going on; to do that we need to control the variables and observe them over the long term. We must go to a lab and we have to speed things up. The answer was to create cultures of E. Coli bacteria.

Doctor Rich Lanski in East Lansing Michigan devoted his career to doing that. E. Coli reproduces several times a day, yielding thousands of generations a year. Lanski's team lets the bacteria culture develop in vials full glucose solutions.

Every few weeks, they take a sample of each vial and freeze and label for future reference. They then transfer 1% of each vial into a new one, and discard the rest. They change the conditions in some of the vials to see what happens. Sometimes they add a little glucose, sometimes they add a different substance. The bacteria sometimes adapt to this new environment, and sometimes die out.

I'm oversimplifying here, but the idea is that this allows a replay of Gould's tape of life. When interesting changes occur, the team can retrieve an earlier sample of the culture from the freezer and restart the experiment from that point. If the observed change fails to reappear, then this supports Gould's hypothesis that development depends on luck, but if the change does reappear, then this weakens Gould's thesis.

It turns out life is more complicated than that. Sometimes the same morphological change comes from unrelated genetic differences. Vertebrate flight has evolved several times: pterodactyls and their allies, feathered dinosaurs and their bird descendants, and mammalian bats. The wings are fairly similar but in no case do these groups have a winged common ancestor, so this seems to point to the inevitability of wings. Predestiny, not luck.

But in fact, the same change reappears because there are only so many ways to adapt to a particular environmental pressure. A wing will simply not fly if it is not aerodynamic, and that explains why bat wings look like pterodactyl wings. This is what was also observed in the lab--some of the vials with slighly different organisms converge to the same change when put in similar environments.

A real surprise came one Christmas in Lanski's lab. A new change was observed and it made the career of the lucky graduate student who had drawn the short straw to be at the lab that holiday. (E. Coli never knows it’s Christmas.) That E. Coli strain had evolved to eat something other than glucose and it reproduced wildly in its vial. The team repeated the experiment from earlier generations of that strain, going back from a few hundred generations and also from a few thousand generations. No attempt from much earlier versions resulted in the change they wanted to see again but a very few attempts from the more recent versions of E.Coli yielded similar changes. This allowed the team to isolate the genes responsible for the change. It turns out that the adaptation came from a very unlikely combination of different genetic mutations. The new E. Coli. got lucky,

In the end, all this largely vindicates Gould’s view of evolution. Evolution *is* contingent and there is no hint that any type of life form is predestined. Nevertheless, and as it always does, careful and detailed examination reveals that the story is even weirder, more interesting and wonderful than we ever expected it.

A great book!

Vincent Poirier, Montreal

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, [[ASIN:0393324613 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’ [[ASIN:0393304485 Blind Watchmaker Why the Evidence]] and [[ASIN:0393354083 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’ [[ASIN:1416594795 The Greatest Show on Earth: The Evidence for Evolution]], pp. 113-116; Carl Zimmer’s [[ASIN:B006HB9Z9I 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.

Improbable Destinies brings the highlights of evolutionary biology to nonscientists and scientists alike. The author, Jonathan Losos does an excellent job of explaining complicated results of ecological experiments to people who may or may not have a background in science or experimental design. Many of his statements are cited and a full reference list is provided, as in any peer reviewed publication. The book begins with vivid tales of contemporary evolution experiments on anole lizards on tropical islands, and wild guppies in predator-less or predator-filled streams, and conveys a tone that suggests evolution may have a largely deterministic fate. Losos gives many examples of convergent evolution due to environmental pressure while at the same time effortlessly clarifying complex experimental design. However, as we progress through the chapters Losos elaborates using bacteria for long term evolution experiments (LTEE) which indicate a more unsystematic perspective based on random chance mutation and evolution. Overall, Losos’ perspective is enlightening and lighthearted. Improbable destinies is an enjoyable read for anyone interested in the most profound questions of our existence, how did humans get here, and why.

Thirty years ago, I was reading Stephen J. Gould in the pages of Natural History. The author revisits Gould and a half-dozen other scientists and researchers, discussing primarily convergence and divergence. It illuminated a few of the grey areas in my knowledge of the field. As with dinosaur research, great strides have been made in genetic research in the last fifty years.

This is a fine book. ..Nice light style for a very informative, interesting treatise.