The Scopes “Monkey trial”, Part 2: Evidence, Confrontation, Resolution, Consequences

This weekend sees the 93rd anniversary of the Scopes Trial, and I am reposting this and its companion piece to celebrate.

I would point out two things. One is that the actual William Jennings Bryan was nothing like the ogre of Inherit the Wind, which was an allegory of McCarthyism. The other is how remarkably well the scientific evidence has stood up to almost a century of examination. There is even a mention, based on serological evidence, of how closely related whales are to hoofed land animals.

Primate's Progress

Darrow: Did you ever discover where Cain got his wife?

Bryan: No, sir; I leave the agnostics to hunt for her.

Both sides, I will argue, were long-term loses in this exchange. But why were such matters being discussed in Tennessee court of law in the first place?

Part 1: the story so far: An extraordinary case indeed, where a school teacher, with the encouragement of his own superintendent, volunteers to go on trial in the State court for the crime of teaching from the State’s approved textbook, and where that same superintendent will be the first witness called against him. And where a mere misdemeanour case, with a maximum penalty of $500, could attract the participation of William Jennings Bryan, former US Secretary of State, and Clarence Darrow, America’s most famous trial lawyer and an agnostic.

Billy Sunday preaching

In the run-up to the case, we even have the…

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The Scopes “Monkey trial”, Part 2: Evidence, Confrontation, Resolution, Consequences

Darrow: Did you ever discover where Cain got his wife?

Bryan: No, sir; I leave the agnostics to hunt for her.

Both sides, I will argue, were long-term loses in this exchange. But why were such matters being discussed in Tennessee court of law in the first place?

Part 1: the story so far: An extraordinary case indeed, where a school teacher, with the encouragement of his own superintendent, volunteers to go on trial in the State court for the crime of teaching from the State’s approved textbook, and where that same superintendent will be the first witness called against him. And where a mere misdemeanour case, with a maximum penalty of $500, could attract the participation of William Jennings Bryan, former US Secretary of State, and Clarence Darrow, America’s most famous trial lawyer and an agnostic.

Billy Sunday preaching

In the run-up to the case, we even have the involvement of Billy Sunday, possibly the greatest of all pre-television evangelists, whose 18 day crusade in Memphis, Tennessee, was attended by some 200,000 people. Billy Sunday told his audiences that Darwin was an infidel: “To hell with the Modernists. Education today is chained to the devil’s throne. Teach evolution? Teaching about pre-historic man? No such thing as prehistoric man.” (Billy Sunday appealed to a broad public. He hosted a “Negro Night”, which 15,000 attended. There was also a Klan Night.)

John Scopes in 1925

The facts were not in dispute. Scopes had of course taught evolution, although the law said he shouldn’t. So it was really the law itself that was on trial. The ACLU was hoping to prove it unconstitutional because unreasonable, ambiguous, and an affront to freedom of conscience. Unreasonable because it opposed established science. Ambiguous because the Bible, to which it referred, was itself open to numerous interpretations. And an affront to freedom of conscience, because it imposed a preference for one religion (Christianity), and indeed one school of thought (the Fundamentalist) within that religion. These arguments were, according to the defence, fatal flaws in the prosecution indictment, which should therefore be quashed. The judge, however, was determined not to issue a ruling of that nature, and ordered the case to proceed. Now read on.

The defence case built on the above arguments. According to their interpretation of the statute, in order to be guilty Scopes would have had to do two separate things; (a) teach that humans were descended from lower animals, and (b) by that teaching, contradict the Bible. But the exact text of the Bible, how it should be understood, and even which books should be included in it were matters of controversy. The Bible was not a science textbook, and

[T]here is no more justification for impos­ing the conflicting views of the Bible on courses of biology than there would be for imposing the views of biologists on courses of com­parative religion. We maintain that science and religion embrace two separate and distinct fields of thought and learning.

Accepting the Bible need not (and for the many Christians who accepted evolution did not) imply accepting the literal truth of the Genesis account. Bryan himself had praised Jefferson’s doctrine that governments had no business regulating religion, but that was exactly what the Tennessee Legislature had done by passing this law. In addition, since Scopes was accused of teaching evolution, it was necessary to establish what evolution science consisted of. The prosecution, more than once, had said that according to evolution man [1] was descended from monkeys. Not so; man and monkey shared a common ancestor, some time in the distant past. The human embryo, at various stages, had gill slits, then a tail, then hair. Evolution played a central role, not only in pure science, but in the applied sciences of medicine and agriculture. All this, and much more, the defence hoped to establish by calling expert witnesses.

None of this was to the liking of the prosecution, who attempted to interrupt even this bare outline, but the judge ruled that he needed to hear what the defence case would be, before deciding whether or not to exclude it. His eventual decision was that while the expert evidence was in his own view inadmissible, and should not be presented to the jury, it should nonetheless be entered into the trial record, for the benefit of the superior courts.

It did not take long for the prosecution to establish its facts. Scopes had reviewed Hunter’s Civic Biology, and in the course of doing so had taught the offending doctrine.

Most (not all) of the defence evidence was submitted in writing, since the judge allowed only part of it to be read out in court, and even that in the absence of the jury. However, I will not differentiate here between spoken and written evidence, and can only give a few samples of the extensive material. Distinguished churchmen testified that one could be flexible in one’s view of the Bible, to the point of accepting evolution, and still be a good Christian. A scholarly Rabbi testified that the King James translation of Genesis was incorrect. In order to counteract rumours to the contrary, former President Woodrow Wilson wrote that

Of course, like every other man of intelligence and education, I do believe in organic evolution. It surprises me that at this late date such questions should be raised.

William Bateson, the evolutionary biologist who coined the term “genetics”, had said at a Toronto conference that

I have put before you very frank­ly the considerations which have made us agnostic as to the actual mode and processes of evolution. When such confessions  are made the enemies of science see their chance. If we cannot declare here and now how species arose, they will oblig­ingly offer us the solutions with which obscurantism is satisfied.

As had indeed happened (see Bryan’s planned closing speech, below), prompting Bateson to submit a letter stating that

We do know that the plants and animals, in­cluding most certainly man, have been evolved from other and very different forms of life. As to the nature of this process of evolution, we have many conjectures, but little positive knowledge. The campaign against the teach­ing of evolution is a terrible example of the way in which truth can be perverted by the ignorant.

One other submission, by Professor Horatio Hackett Newman of Chicago, is noteworthy as a summary of the evidence for evolution that can still serve as a model today. As Prof Newman said, we can observe evolution in the present, which entitles us to invoke it as explanation, over much longer periods of time, in the past. The principle of evolution is “the one great law of life”, and stands in the first rank among natural laws because of the range of observational tests it has undergone, in every conceivable way, for more than half a century (remember that these words were written in 1925; we would now say more than a century and a half). As Newman put it,

The evidences of evolution that we shall investigate are contained with­in the following fields of biology:

First – Comparative anatomy or morphology, the science of structure. Second – Taxonomy, the science of classification. Third – Serology the science of blood tests. Fourth – Embryology the science of development. Fifth – Paleontology, the science of extinct life. Sixth – Geographic distribution, the study of the horizontal distribution of closely similar species upon the earth’s surface.  Seventh – Genetics, the analytlc and experimental study of evolutionary processes going on today.

The only alteration a present-day exponent of evolution would make, is to replace serology (a crude estimate of degree of tissue similarity based on immune responses) with the enormously more refined methods of protein and DNA sequencing. The coming together of this new knowledge, undreamt of at the time of the trial, with the other lines of evidence listed, is as breathtaking as the coming together of lines of masonry in the ceiling of a Gothic cathedral.

Tetrapod forelimbs display homology. Related parts coloured for clarity. Note the arm-like structure, in particular, of the whale’s flipper

The anatomical evidence included the homologous structures of the human arm, the whale’s flipper, the wing of a bird and, less obviously until detailed examination is undertaken, the front leg of a horse. Special creation, on the other hand, “implies a slavish adherence to a preconceived ideal plan together with capricious departures from the plan in various instances.”

Comparative anatomy clearly enables us to distinguish between homologies related to common descent, and the merely analogous independent evolution of similar but unrelated organs. Further anatomical evidence comes from vestigial organs, including transient vestigial organs such as the hind limb buds in a whale embryo. Taxonomy gives us nested classifications; dogs as varieties of the wolf species within the canid genus within the order of Carnivora within mammals within vertebrates within chordates within the Animal kingdom. Taxonomy also places man among the primates, another order within the class of mammals. Man is a species with at least four subspecies (present-day science would blur the boundaries, but that does not affect the argument), evidence of a long evolutionary history incompatible with biblical chronology.

Serology in Newman’s time depended on inducing an immune response in rabbits to one particular species, which would then show a similar immune response to a second, related species, and the greater the biochemical similarity between the species, the stronger that response would be. Remarkably, Newman correctly used this evidence to place whales as most closely related to hoofed animals, and specifically to swine, a conclusion that was not generally accepted until the 1990s.

Human embryo at 6 weeks. Note umbilical cord, yolk sac (a vestigial organ), gill arches, and tail

Embryology recapitulates common ancestry (for an outstanding discussion of this, see Alice Roberts’ prize-winning The Incredible Unlikeliness of Being). Thus the human embryo at an early stage has a two-chamber heart, like a fish, and gill slits, and diverges from the anthropoid apes only in the final stages of development. Palaeontology is closely related to geology, with “a general progression toward more highly specialized forms as one proceeds from lower to higher strata.” The fossil record is patchy (I do not think one would say this now; see for example Prothero’s What the Fossils Say and why it Matters). While reasonably complete for the horse it is [was] patchy for humans, but progress is being made. (Newman, interestingly, explicitly reserves judgement on Piltdown Man. Progress was indeed being made, but the Taung Child, mentioned in Part 1, and referred to in other written evidence, seems to have come just too late for Newman’s deposition.)

Newman’s argument from geographical distribution comes straight out of Darwin, but rings as true today as when it was first minted.[2] Continental islands such as the Galapagos are inhabited by species generally similar to those of the adjacent mainland, whereas those of oceanic islands, such as Hawaii, had until human intervention very different flora and fauna, related to such species as might, from time to time, survive a long ocean journey.

Genetics, in brief, shows evolution in action in the present day. And all these signs of evidence come together in supporting the great evolutionary explanation of resemblance as the result of relationship.

For balance, I should at this point summarise the arguments in the speech that Bryan had planned to make at the end of the trial (see below for how this plan was frustrated), and no doubt formed the basis of the speeches that he did give in the days immediately following. It will not improve our opinion of Bryan’s logic, but will help explain his motivation. And if we are not interested in this, we will not be able to reach out to those we most need to persuade.

The law was not a restriction on Scopes’s freedom as an individual, but merely on his actions as a state employee. Christianity welcomes science, but nothing can be scientific unless it is true, and whatever is true must agree with the Bible. Evolution was a mere hypothesis (here he misquoted Bateson, as Bateson had foreseen; see above). No one had demonstrated the transformation of one species into another, and despite the circumstantial evidence in favour of evolution, this was a fatal flaw. Bryan then brought five specific indictments against evolution. First, it disputes the truth of the Bible. Secondly, it leads, as the horrible example of Charles Darwin himself shows, by way of non-literal reading of the Bible towards agnosticism if not atheism, and the denial of revelation and of eternal life. Half of all academic scientists are atheists, and many students lose their faith while at university. Thirdly, evolution diverts attention from pressing problems of great importance to trivial speculation, and deadens the spiritual life of its students:

Christians desire that their children shall be taught all the sciences, but they do not want them to lose sight of the Rock of Ages while they study the age of rocks; neither do they desire them to become so absorbed in meas­uring the distance between the stars that they will forget Him who holds the stars in His Hand.

Fourthly, evolution deadens the urge for reform, and denies the possibility of individual redemption. “Evolution makes a mockery of the Lord’s Prayer!” Bryan’s fifth indictment is that evolution is based on the survival of the fittest, militates against compassion, and justifies eugenics and the politics of force. It devalues human life, as had been so apparent in the Great War, and is even associated (Bryan never explained the association) with sexual permissiveness. Science had made war more terrible than ever, so that our need for the moral guidance that Christianity offers was greater than ever. But evolution degrades the Saviour’s name,

For, carried to its logical conclusion, it robs Christ of the story of a virgin birth, of the majesty of His deity and mission and of the triumph of His resurrection. It also disputes the doctrine of the atonement.… The case has assumed the proportions of a battle-royal between unbelief that attempts to speak through so-called science and the defenders of the Christian faith, speaking through the legislators of Tennessee. It is again a choice between God and Baal.

Bryan is not attacking a straw man. In his speech he quotes from The New Decalogue of Science, by Alfred Wiggam, typical of the highly influential eugenicist literature of the time, which warns that compassionate social policies would lead to a weakening of the race, and states eugenics as the highest duty of government (for samples of his text see here and here). Wiggam himself was actively campaigning into the 1940s. More than 30 US States passed compulsory sterilisation laws.  Madison Grant’s The Passing of the Great Race, which mingles evolution, racism, and eugenics, was influential in the passage of the 1924 US Immigration Act, just one year before Bryan drafted this speech. This book described the Nordic race as the most advanced, and helped justify a policy that excluded Jews and other Eastern European immigrants.

Bryan is also appealing to religion as the basis for morality. As I have argued elsewhere, the fact that such reasoning is logically unsound does not reduce its psychological appeal, and as Kenan Malik argues in his The Quest for a Moral Compass, we have been struggling with this tension, with doubtful success, for over 2000 years. Finally, Bryan is searching for the comfort of certainty in an uncertain world, and like other creationists he points to the uncertain and provisional nature of scientific knowledge, as if that were a crucial weakness rather than, paradoxically, its greatest strength.

Many of the detailed points raised by Bryan are still being raised today. The claim that evolution is only a theory, that it speculates when jumping over missing links, that plant breeders had only produced varieties within species (“microevolution”), that unnamed great scientists are divided about evolution, that scientific disputes about mechanisms imply doubt about the basic fact of evolution, that if you teach children they are animals they will behave like animals, that evolutionists are intolerant when they demand that their views should be the only one taught, and that schools should teach according to the wishes of the taxpayers who fund them.

Darrow and William Jennings Bryan having a friendly chat in a courtroom during the trial

The enduring interest in the Scopes trial comes mainly from the final afternoon of evidence, when Darrow called Bryan to the witness stand (actually, by this stage, a wooden chair on the courthouse lawn) to testify regarding the contents of the Bible. This testimony also would be  entered into the trial record, but heard in the absence of the jury, who missed one of the most dramatic episodes in legal history. One hardly knows where to begin when discussing this manoeuvre. The strangest thing of all is that Bryan rose to the bait. Judge Raulston made it very clear that he was under no obligation to testify. The cross-examination had nothing directly to do with the point at issue; no possible relevance to what Scopes may or may not have taught in the classroom, and Darrow’s questioning made no reference to the subject under discussion, namely human evolution. Bryan was placing himself at Darrow’s mercy, where Darrow, as one of the world’s best cross-examining lawyers, had total control over what questions would be raised. Indeed, Bryan had on an earlier occasion refused such an asymmetric contest, saying that he would answer Darrow’s questions only if Darrow would agree, turn by turn, to answer his. Bryan did ask whether he would be allowed to call Darrow to the witness stand, but any such idea must have been forgotten long before the afternoon was over.

After some preliminary generalities, Darrow asked whether Bryan believed that Jonah had been swallowed by a whale. A big fish, rather than a whale, otherwise yes. Then a revealing statement of Bryan’s attitude to miracles:

Let me add: One miracle is just as easy to believe as another. When you get beyond what man can do, you get within the realm of miracles; and it is just as easy to believe the miracle of Jonah as any other miracle in the Bible.

Darrow moved on to some deeply searching questions about the biblical passage that describes how Joshua commanded the Sun to stand still, until the Israelite victory was complete. How could this be, when we know that it is not the Sun but the Earth that moves? With great reluctance, Bryan admitted that it must have been the Earth that stood still, and that the Bible was “using language at that time that the people understood.” Yet Bryan denied that this was his interpretation of the passage; to admit that the Bible could be open to different interpretations would undermine the entire Fundamentalist case.

He conceded slowly, under questioning, that actually it must have been the Earth that stood still. At this point, Attorney-General Stewart, the lead prosecutor, interrupted to object that this cross-examination had nothing to do with the trial. Bryan, however, insisted on ploughing on, and did not seem to have even anticipated Darrow’s rather obvious follow-up question:

Q– Now, Mr. Bryan, have you ever pondered what would have happened to the earth if it had stood still?
A–No.
Q–You have not?
A– No; the God I believe in could have taken care of that, Mr. Darrow.
Q– I see. Have you ever pondered what would naturally happen to the earth if it stood still suddenly?
A– No.
Q–Don’t you know it would have been converted into molten mass of matter?

A–I would want to hear expert testimony on that.
Q–You have never investigated that subject?
A–I don’t think I have ever had the question asked.
Q–Or ever thought of it?
A–I have been too busy on things that I thought were of more importance than that.

For what it’s worth, Darrow was mistaken here. The kinetic energy of the Earth’s rotation would be enough to heat it up somewhere between 10 and 20 degrees Celsius, not to melt it. However, the inertia of the oceans would have generated continent-size tsunamis, and making the Earth stand still would have required a temporary suspension of the most basic laws of physics. This is not a problem for Bryan, who thinks that God’s capacity for miracles is boundless.

It gets worse. When asked whether he accepts the date for the Flood [sic] of 4004 BC, Bryan waffles and does not seem to know what that date was based on, although all that is involved is simple arithmetic based on the biblical genealogies. Regarding the age of the Earth, he initially refuses to say whether he accepts Bishop Ussher’s date or not, although he was in fact perfectly ready (as becomes clear later in the cross questioning) to treat each biblical “day” as an age. Here Bryan is fighting on two fronts. He did not want to admit that it is legitimate to impose an interpretation of the Bible, because that would concede too much to the Modernists. On the other hand, he needed to play down the deep division between his own Old Earth creationism, and that of extreme Adventist literalism. He claimed widespread scientific support for his views, but when pressed could only name one; George McCready Price, whom he described as a Professor of Geology at Lodi College near Lincoln, Nebraska. In fact, Price had left Lodi (which was just a boarding school in California) in 1915, was at the time teaching at a Seventh Day Adventist College in England. and had almost no formal training in geology. Pricewas a fierce Young earth creationist, who argued that fossils could not be dated, and that all the sedimentary rocks were deposited during Noah’s Flood.

While Bryan was stumbling over the day-age issue, the judge himself intervened, questioning the relevance of the testimony, but Bryan insisted on continuing, not, as he said, for the benefit of the appellate court, but to show his willingness to defend the Bible against detractors.

Bryan had already affirmed his belief in a literal tower of Babel, at which peoples had first been divided by language, and his lack of interest in the evidence that distinct civilisations with different languages had existed before the time specified in Genesis for this division. When questioned, he also affirmed his belief in a literal Adam and Eve, and in Eve having been made out of Adam’s rib. When asked if he knew where Cain got his wife, he replied “No, sir; I leave the agnostics to hunt for her.” Somewhat belatedly, he defended on purely textual grounds his day-age interpretation of Genesis 1, admitted to believing in a literal serpent that crawls upon its belly as punishment for its role in the Fall, and interrupted shrewd questioning about the origin of the rainbow to say that Darrow was trying to use the court to slur the Bible. With the words “I am exempting you on your fool ideas that no intelligent Christian on Earth believes”, Darrow concluded his cross questioning, and the court adjourned.

I am amazed by how poorly both sides conducted themselves here. Bryan comes over as ill-prepared for questions that any defender of the biblical text should have been well aware of, while Darrow has scored a pyrrhic victory, by ridiculing his opponent and all his supporters. There is nothing unbiblical or subversive in interpreting the story of Jonah as a parable. One can imagine atmospheric lensing that would make the observed Sun, as source of light, stay in place in the heavens (incredible perhaps, but less incredible than Bryan’s alternatives). And had he really not thought about where Cain’s wife came from? (We are told that Adam and Eve had other children, and there was as yet no law against incest.) Bryan would also have done well to explain at the first opportunity, rather than having it wormed out of him, the day-age interpretation of Genesis. He made a few wisecracks that went down well with his own supporters in the crowd but, surprisingly for an experienced politician, he seems to have been quite oblivious of how his performance would appear to the 200 newsmen present at the trial, and refused repeatedly opportunities to bring his ordeal to an end, something that only happened when, eventually, even Darrow had had enough.

Darrow, a highly experienced trial lawyer, I find even more puzzling. Ridicule is a powerful weapon, but not if one wants to win over those who will identify with its victim. Repeatedly, Darrow insults the crowd; “bleachers”, “down here in the hills”, “your fool religion”, “where have you lived all your life? [Answer: Not near you] Nor near anybody of learning?” The only excuse I can offer is that he may have been so afraid of the spread of Fundamentalism that he was willing to play on northern prejudice in order to quarantine it in the deep South.

Bryan still had one powerful shot in his locker; his closing speech on behalf of the prosecution. But he would not be allowed to deliver it. When the court convened the next day, Darrow suggested, and it was agreed, that the judge instruct the jury to find Scopes guilty on the basis of the evidence offered, and then summed up for the defence by saying that he could offer them no reason to do otherwise. This, of course, made any further proceedings unnecessary. Scopes was duly found guilty, and Judge Raulston, after discussion with the jury, imposed a $100 fine, the minimum the law allowed.

The appeal was an anticlimax. The Tennessee Supreme Court ruled that, since the fine had been imposed by the judge, when by law the amount should have been decided by the jury, the penalty should be quashed, and, on the grounds that Scopes had by then left the employ of the State, directed that the case be allowed to lapse.

Bryan, an overweight diabetic, travelled hundreds of miles in the blistering summer heat, and made two major speeches, in the days following the trial. Then, on the following Sunday, he died in his sleep during an afternoon nap. Scopes, who took no pleasure in his brief celebrity status, won a scholarship to the University of Chicago and became a professional geologist. Darrow retired from full time practice shortly after the Scopes Trial, but appeared in a few further high profile cases, and died in 1938.

A whole series of cases (Epperson v Arkansas,    McLean v Arkansas, Edwards v Aguillard, Kitzmiller v Dover) have by now established that under the First Amendment separation between Church and State, evolution should not be suppressed, and creationism (including such variants as Creation Science and Intelligent Design) should not be taught, in US publicly funded schools. In addition, new national standards in the US and in England (but not yet in Scotland) require the teaching of evolution to all schoolchildren. Yet increasingly US school boards and States are finding their way round this, by giving parents vouchers that can be used to pay the fees for nominally independent creationist schools.

Deplorable that they do this; even more deplorable, perhaps, that they even want to. The key here lies in the 2011Science article, “Defeating Creationism in the Courtroom, but not in the Classroom“, which found that only 28% of high school teachers gave lessons on evolution, while 13% refrained because they were themselves creationists. As for the remaining 60%, they wanted to avoid controversy with parents or with children who had been taught creationist arguments, were themselves often unsure about how to handle questions on the subject, and simply avoided teaching it.

Within creationism, Intelligent Design supplies intellectual topdressing, but is increasingly blatant in its tactical alliance with biblical creationism, and within biblical creationism, on the principle that the most uncompromising claim is the most authentic, the dominant school is now Young Earth creationism, reinforced by the Flood Geology of Whitcomb and Morris. This is itself a retreading of the Adventist views of George McCready Price, whom we have already met (see Part 1), and who seems to have been the real long-term beneficiary of the trial.

Price, a Seventh day Adventist, regarded Darwin as having been inspired by Satan. While this post was being revised, his view was echoed by fellow-Adventist Ben Carson, currently running for the Republican nomination for the 2016 US Presidential election. Carson is neither stupid nor ignorant; on the contrary, he is a distinguished neurosurgeon, former Professor at Johns Hopkins University, and led the first team of surgeons to separate twins born joined at the skull. My friend Michael Roberts’ post, which I reblogged yesterday, explores the historical origins of this Adventist creationism. I can only wonder at the power of such a faith.

1] I have not attempted to use gender-free language. Such language would not be appropriate for the time and place of this trial, where all the active participants, including attorneys, witnesses, and jury, were male.

2] Wallace, of course, made major contributions here, and the line separating Asiatic from Australasian fauna is still known as the Wallace Line.

Sources as in Part 1. Billy Sunday portrait by George Bellows, Metropolitan Magazine 1915, via Wikipedia. Scopes photo from Smithsonian (public domain). Darrow and Bryan chatting, author unknown, via Wikipedia. Forelimb homology image from Monroe W. Strickberger, Evolution, Third Edition. Human foetus from babycenter photo gallery. An earlier version of this piece appeared in 3 Quarks Daily.

Reviewed: The Incredible Unlikeliness of Being; Grandmother Fish

In an earlier post, I said that the right way to undermine creationism is to promote appreciation of the science of evolution, by presenting it in ways that are engaging, enjoyable, and above all personal. In this post, I review two more books that succeed in doing this; Alice Roberts‘ The Incredible Unlikeliness of Being and Jonathan Tweet‘s Grandmother Fish.

Grandmother Fish is a book like no other I have seen. It is an introduction to evolution, for adults to read to their pre-school children. It is also much more than that, and comes with well-earned commendations from Stephen Pinker, David Sloan Wilson, and Daniel Dennett.

We start with a delightfully drawn Grandmother Fish, who lived a long, long, long, long, long time ago and could wiggle and swim fast and had jaws to chomp with. At once, this is made personally relevant: “Can you wiggle? … Can you chomp?” We proceed by way of Grandmother Reptile, Grandmother Mammal and Grandmother Ape, to Grandmother Human, who lived a long time ago, could walk on two feet and talk and tell stories, and whose many different grandchildren

could wiggle and chomp and crawl and breathe and squeak and cuddle and grab and hoot and walk and talk, and I see one of them … right here!

Each stage has its own little phylogenetic tree, with the various descendants of each successive “grandmother” shown as each other’s cousins, and there is an overall tree, covering all living things, that anyone (of any age) will find interesting to browse on. Finally, after some 20 pages of simple text and lavish illustration, there are around 4 pages of more detailed information, directed at the adult reading the book, but to which I expect children to return, as they mature, remembering the book with affection, as they surely will, years or even decades later.

So here we have nested families, family resemblance, and the development of more and more specific and complex features. And any adult, or indeed any alert child, will readily extend the discussion. Was there a grandmother cat, whose grandchildren include lions and tigers and pussy-cats, and how was she related to grandmother carnivore? Where do fossils fit in? (The tree shown includes pterodactyls, dinosaurs, and early birds.) And the most common arguments against evolution, from “only a theory” to “where are the intermediate forms?” to “if evolution is true, why are there still monkeys?” will stand immediately revealed as the nonsense they are. Indeed, one of the few statements in the endnotes that I disagree with is that “Evolution by natural selection is very difficult to understand because it doesn’t make intuitive sense.” It will, in my opinion, make perfect sense to a child who has met so clear an exposition early on, and who will therefore find it much easier to understand intuitively than, say, Noah’s Ark.

Back story: this project was crowdfunded on FaceBook, on the basis of some initial sketches and text. The author professes a long-standing interest in evolution, but his career hitherto has been elsewhere, in computer games (he was lead designer on the 3rd edition of Dungeons and Dragons). However, he has had expert advice from many people, including Eric Meikle, Education Director at the [US] National Center for Science Education.

Publication: pending. Initial partial draft available on request here (technical note: the mammalian tree shown there has since been updated). Diagram from book draft website.

Disclosure: I have corresponded with the author who tells me I will be thanked on the book’s website. Review based on initial draft + correspondence with author. I will be buying this book for my grandchildren as soon as it becomes available.

The Incredible Unlikeliness of Being, despite (because of?) coming from an established author and presenter, is as personal as could be. It starts with Alice Roberts’ emotional response to becoming a mother, and the incredibly unlikely being is the reader. The subject matter is (mainly) the development of the human embryo, and that developing embryo is not some third party abstraction, but you. And so evolution is also about you, as example after example throughout the book makes clear:

It’s about your evolutionary heritage, and it is about your own embryological development, when you grew in changed, part of you folding like origami, until you are shaped like a human.… This is the best creation story, because it is true.… This scientific story, pierced together from many different sources of evidence, is more extraordinary, more bizarre, more beautiful, than any creation myth we could have dreamt up.

Alice Roberts is Professor of Public Engagement in Science at the University of Birmingham, and one of the new generation of writers and TV presenters who in the UK fill much the same role as Bill Nye and Neil deGrassie Tyson in the US. She is by training a doctor and anatomist, and much of her own research has involved forensic examination of pre-human hominin skeletons, the coldest of “cold cases”. This background shows up clearly in her detailed descriptions of your developing structures, and she shares with us her emotions about coming face-to-face (in one case literally) with her own anatomy, as when, after x-ray tomography, she was given a replica of her own skull.

Prof Alice Roberts holding a replica of a skull (not, in this case, her own)

The unlikeliness is not just the obvious unlikeliness of your two particular parents meeting, of that one egg becoming fertilised, and of that one sperm out of the enormous number available on being successful. Nor even of the improbability of your parents in turn having come into existence, and so on. Behind all this, and multiplying all those improbabilities, is the meandering history of our evolution:

The more I delve into the structure and workings of the human body, the more I realise what a cobbled-together hodge-podge of bits and pieces this thing we inhabit really is. It is brilliant, but it is also flawed. Our evolutionary history is woven into our embryological development and even adult anatomy in surprising ways; many of our body’s flaws can only understood in an evolutionary context.

We start with a history of ideas, and here it struck me as remarkable how long it took for it to be generally recognised that both parents contribute to the form of their offspring, despite the obvious evidence from physical resemblances. Leeuwenhoek with his microscope first observing sperm, the much later discovery of the mammalian ovum, a comical (in hindsight) controversy between “spermists” and “ovists”, the puzzle, insoluble even in principle until the advent of genetics, of how both parents could contribute to what we now call the information content of their offspring, and the further conundrum, unsolved until DNA was identified as the genetic material, of the material means by which they did so.

Most of the book is concerned with the complex process that leads from first release of the ovum, through fertilisation, implantation, and the many subsequent stages of development, through to birth. This story is inextricably intertwined with the story of your evolution, and I can only pick out a few of the most salient points from a wealth of fascinating detail.

From cell division to implantation, with the cells beginning to form separate layers

There are, of course, vestigial or discarded organs. In your second week of development, when you were not much more than a couple of layers of cells, you generated a yolk sac, homologous with the yolk sac of fish, amphibians, reptiles, and even those mammals (the platypus and the spiny anteater) that lay eggs. The difference is that in these the yolk sac is filled with the nourishment that will sustain the growing animal until its birth, whereas in placental mammals like us, it has been without function for the past 90 million years or so. Nonetheless, the recipe for making it has never been deleted from your assembly instructions.

At an early stage, it is very difficult to distinguish the embryo of a mammal (that includes you, of course) from that of a fish; a little later it is still difficult to distinguish it from a reptile or a bird, and different mammalian embryos continue to resemble each other for even longer. For a while, it was suggested that this is because you were retracing your evolutionary history, but we now know that this idea is based on a mistaken model of evolution. You are not more highly evolved, than, say, a chicken; you have just evolved in a different direction. The earliest stages of development are shared with fish, later stages with reptiles and birds, and later stages yet only with mammals and eventually only with our fellow apes. Thus we do not, strictly speaking, recapitulate our evolution from a fish, nor should we, since the present-day fish is as remote as you are from your last common ancestor with a halibut, but we do recapitulate shared development until the parting of the ways. The new science of “evo-devo” is now beginning to take this story down to the most fundamental level, identifying the molecular basis for the parts of the construction plan that you share with a fish, and the parts, activated later, that you do not.

The cartilage base of human skull resembles that of other mammals.  It is only later, when this is being transformed to bone, that it acquires its specifically human form, with the enlarged dome required to house the brain towering above the rest of the head.

Working down from the head takes us to the larynx, and the unanswered question of the origin of human speech. Here the problem is that the really important working parts – the larynx itself, its associated muscles, and, above all, the tongue – are soft tissues and leave no trace in the fossil record. The position of the larynx lower in the throat, compared with other mammals, may be no more than an accidental consequence of the way our oversized brainboxes sit on top of our spinal column.

The origin of the larynx leads us to the most striking embryological evidence for evolution, namely the direct resemblance between the branchial (gill) bars of fish, and the related structures found, early in development, in terrestrial vertebrates. Then comparative embryology allows us to map our own organs against their fishy counterparts, and to explain some of the more absurd features of our own anatomy.

Our fishy origins are clearest early in development. By week four, the bundle of cells on its way to becoming you has separated into three separate layers, a tube within a tube within a tube. On the outside, ectoderm, which will give rise to your skin; on the inside, endoderm, which will give rise to your digestive tract, from one end to the other, and in between mesoderm, giving rise to a variety of structures. By week five, we can see what will become the backbone, the eye, and the branchial bars in the neck. Each branchial bar has ectoderm on the outside, endoderm inside, and in between a mixture of cells, some from mesoderm and some from neural crest. This in-between layer will develop into a cartilage bar and muscles, and each bar will develop an artery and a nerve.

Land animals and fish have shared much the same developmental instruction manual until this point, but now they begin to diverge. In fish, the branchial arteries accept blood directly from the heart, and the cartilage forms the gill arches. In land animals, development is far more complex. One set of gill muscles becomes larynx muscles, and a nerve that leads to it runs down into the chest, before making its way back up to the top of the throat. Why so? Because the blood vessels that, in fish, run directly between the heart and the gills have become, in land animals, the aorta and main arteries leading from it. And as a consequence, the recurrent laryngeal nerve, as it is called, is trapped beneath the aortic arch when the heart moves downwards, as it does in land animals but not in fishes, and forced to take this convoluted path. Bad design, but an unavoidable consequence of evolutionary history. A creationist with whom I once discussed this suggested that this really was a good design, because it protects the nerve from damage. Tell that to a giraffe.

The first branchial arch gives rise to bones that are part of the jaw joint in reptiles, but in mammals have shifted and shrunk and become two of the bones of the inner ear. And yes, there is an intermediate form, an early mammal with two jaw joints, the outer one thus being made free to move closer to the ear to improve resonance, and, ultimately, to detach itself. Gill flap muscles in the fish end up as face muscles in primates including us, and so on. The cleft between the first and second branchial arch gives rise, in us, to our ears, and to the tubes that connect the middle ear to the throat, thus enabling pressure to equalise.

Descending to the molecular level, these developments are orchestrated by a set of control genes, prominent among them the so-called “homeobox” or Hoxgenes, first discovered in fruit flies, where they regulate the formation of the segments of head, thorax, and abdomen. Similar genes are found in every segmented animal, including us (if you don’t think you’re segmented, think of your backbone and ribs). This arrangement must be very ancient, since your last common ancestor with a fruit fly was some 800,000,000 years ago, but has undergone elaboration. The fruitfly has 8 Hox genes, lined up in a row, that come into play one after the other. In the lancelet, this has been expanded to 14. At some stage between the lancelet and jawed fishes, the entire genome seems to have doubled and redoubled, so that you have four sets of Hox genes, each on a different chromosome.

Some aspects of this regulatory system are much more flexible than others. All land vertebrates have a spine with the same basic sections: neck, chest, lower back, sacrum, and tail. All mammals have just seven neck vertebrae, whereas the number of tail vertebrae is highly variable, being up to 49 in one species of porpoise, which flexes its tail to swim, while our tail, or coccyx, has only 3 to 5 fused together. This tail can be considered as a vestigial organ, since it is a mere relic of that sported by our monkey-like ancestors, but like many so-called vestigial organs it continues to earn its keep, in this case by acting as an anchor for muscles. Our lower backs have one more vertebra then our chimp cousins, and are less securely held in place, developments thought to be related to our habitual walking on two feet

Relevant to Professor Roberts’ own anatomical interests, although less directly so to the question of embryological development, is the detailed history of our limbs. This indicates us to have been truly bipedal as long ago as 3.2 million years ago (Lucy), while long legs at 1.5 million years ago (Narikotome boy) suggest adaptation for running. In popular imagination, we learned to stand upright as we evolved away from knuckle-walking ancestors, but the reverse may be the case. Monkeys, like us, have feet far harder and less flexible than those of modern non-human apes, and Prof Roberts speculates that our ancestors were tree walkers. If so, it is the apes, with their prehensile toes, rather than us, who have diverged from the form of our common ancestor.

But once we started walking on the ground, that change in behaviour, which could occur within a group in a single generation, would have suddenly generated a new set of selection pressures in favour of long distance walking and running. This is an activity for which we are superbly adapted, even though only a few groups, such as the Tarahumara in Mexico, still regularly practice it.

The final Chapter reviews our present understanding, and considers our place in nature.  Development is controlled, more or less, by DNA, including control genes as well as directly expressed genes. It is not, as Haeckel thought, a true recapitulation, but shows clear echoes of earlier stages – segments, gills, fish hearts, the lancelet brain. Our developmental biology is, to use one of Prof Roberts’ many memorable metaphors, a palimpsest.

Similar environmental pressures can give rise to similar adaptations, so that the mammalian ear with its three tiny bones has evolved at least four times in different lineages, while, as hinted above, different ways of moving around including bipedalism may have arisen more than once among our ancestors and their close cousins. But nonetheless, evolution remains unpredictable, if only because changes in the environment are unpredictable. One such change was that triggered by the asteroid that did for the (non-avian) dinosaurs. Selection acts without foresight, and without that asteroid, we would not have had humans (for what it’s worth, my own view is that we would have had the intelligent descendants of the velociraptors instead).

Evolution takes place in context, and that context, for a species capable of learning from each other, includes a technology. An innovation in toolmaking could have spread through a group of our ancestors in a single generation, triggering a new set of selection pressures that moulded their hands and bodies to a new set of tasks. We speak of the survival of the fittest, but fitness here refers to the cultural, as well as the natural, environment. And we are more influenced in our lives, and our evolution, by our own culture and its artefacts than any other species.

The book concludes with reflections on our similarities (profound) and differences (striking, yet perhaps more quantitative than qualitative) from other species, our contingent and transitory nature, and our uniqueness both as species and, returning to the starting point, individuals.

There are numerous drawings (Prof Roberts is an award-winning artist), and an extensive bibliography.

A few detailed comments. Prof Roberts shows, early on, a series of drawings copied from Haeckel. Connoisseurs of creationism will recognise this as a deliberate provocation, since creationist writers repeatedly point to alleged shortcomings in these, as reason to ignore the whole of developmental science. Lancelets are shown as sister group to vertebrates; in fact, we are closer to tunicates (the subphylum that includes sea squirts) than we are to lancelets, although tunicates only acquired their sessile habit after we and they had gone our separate ways (Prof Roberts tells me that this will be corrected in later editions. I occasionally found the layout of diagrams and their explanations rather awkward. This may be an inherent limitation of the e-book format that I was using.

Figures from Prof Roberts’ personal website, and Amazon website.

Disclosure: this review is of the first Kindle edition, personal purchase.

These reviews first appeared here, on 3 Quarks Daily