Category: Darwin

A Pecksniffian anthropologist takes down Darwin for being a man of his time

May 22, 2021 • 11:30 am

It’s the 150th anniversary of the publication of Darwin’s The Descent of Man (people often forget that it’s paired with another book, Selection in Relation to Sex), and the journal Science has celebrated the year in two ways. The first is an article pointing out, tiresomely, erroneously, and not for the first time, that Darwin was a sexist, racist, colonialist, and oppressor whose theories supposedly harmed many people. That is the first note below (click on screenshot), written by Agustín Fuentes, a primatologist and biological anthropologist at Princeton University.

Click on the screenshot to read the piece:

The piece isn’t totally bad, but it’s bad enough that I want to register a few plaints. The main ones are that Fuentes is not saying anything that hasn’t been said before: Darwin indeed had some racist, sexist, colonialist, and white-supremacist views that were expressed in his works, especially in The Descent of Man (Fuentes repeatedly confuses the two books, as some of the views he criticizes appear in Selection in Relation to Sex).

To be fair, Fuentes does credit Darwin with his insight and his durable and correct theory of evolution. But as he gives with one hand, he takes with the other:

 But despite these ideal frames and some innovative inferences, “Descent” is often problematic, prejudiced, and injurious. Darwin thought he was relying on data, objectivity, and scientific thinking in describing human evolutionary outcomes. But for much of the book, he was not. “Descent,” like so many of the scientific tomes of Darwin’s day, offers a racist and sexist view of humanity.

Yes, the tired old Bucephalus of critical theory: “it’s problematic.”

And then we get the usual litany: Darwin believed that whites were superior to blacks and other non-Europeans; he thought women were inferior to men, opined that eventually the white “race” would supplant other groups, and so on. This much we’ve all known for a long time, and many of us, including me, have taught it to our students.

But, despite Fuentes’ admission of Darwin’s strong abolitionism, he seems to forget that Darwin was a man of his time, not of our time. Is it fair to judge Darwin against an enlightened modern liberal? I don’t think so: the proper judgment is to see whether Darwin was palpably morally worse than most other Victorian Englishmen.  And I don’t think he was. I’ll explain a bit more below, but I have a very hard time thinking of someone of Darwin’s stature in Europe who was much better than he on the issue of women, or, for that matter, slavery. (Read Marx and Engels on the Irish if you want real bigotry.) Yes, Darwin saw some South Americans as “savages”, but he also perceived their common humanity with us, and his theory affirmed our common ancestry. And yes, he saw women as the inferior sex; but how many Victorian men were far more enlightened than he?

Frankly, I’m tired of people who say things like “Darwin was bad because he should have known and done better.” Neither he nor his contemporaries did or could have: morality evolves, and in 150 years our own generation may be seen as just as morally deficient as was Darwin. After all, we eat meat, and in the future we may learn more about the suffering of animals in ways that would brand us moderns as horrible barbarians. The judgment of celebrating Darwin should rest on a). “is he being celebrated for the good things he did?” (answer: yes), and b). “did the good he did in his life outweigh the bad?” (answer: also yes).

Now, onto what I see as Fuentes’s missteps. Here’s one about selection and racial differentiation:

Darwin portrayed Indigenous peoples of the Americas and Australia as less than Europeans in capacity and behavior. Peoples of the African continent were consistently referred to as cognitively depauperate, less capable, and of a lower rank than other races. These assertions are confounding because in “Descent” Darwin offered refutation of natural selection as the process differentiating races, noting that traits used to characterize them appeared nonfunctional relative to capacity for success. As a scientist this should have given him pause, yet he still, baselessly, asserted evolutionary differences between races.

. . . His adamant assertions about the centrality of male agency and the passivity of the female in evolutionary processes, for humans and across the animal world, resonate with both Victorian and contemporary misogyny.

The first part of this is fine, but the second, about how “races” and sexes come to differ from one another morphologically, is not. Darwin saw sexual selection (a subset of natural selection, by the way) as the process whereby different ethnic groups come to differ in appearance. He may well have been right about this. And clearly, there are evolutionary differences between the appearance of ethnic groups. These are certainly genetic, and the morphological homogeneity within groups compared to the palpable differences between groups suggest an evolutionary origin.

What kind of evolution was it? As I said, Darwin’s view was that groups of humans (as well as males versus females) are affected by sexual selection based on either male-male competition or “choice”. The choice, according to Darwin, was made by females preferring arbitrary but aesthetically appealing male traits: song, ornaments, plumage, and so on. (For humans, Darwin sometimes intimated that the “choice” was made by males, but by females in other animal species.) This “beauty matters” hypothesis has its biggest exponent in Richard Prum, and though I am not convinced by his arguments, it’s mainly because we lack data, not because Prum is known to be wrong. Here’s Prum in a paper discussing Darwin’s views:

Darwin was explicit, repeated and adamant in maintaining that the evolution of secondary sexual characters by mate choice was an aesthetic mechanism of evolution. For example, he wrote:

With the great majority of animals, however, the taste for the beautiful is confined to the attractions of the opposite sex.* The sweet strains poured forth by many male birds during the season of love, are certainly admired by the females … If female birds had been incapable of appreciating the beautiful colours, the ornaments, and voices of their male partners, all the labour and anxiety by the latter in displaying their charms before the females would have been thrown away; and this is impossible to admit. [, p. 61]; * sentence added in second edition)

On the whole, birds appear to be the most aesthetic of all animals, excepting of course man, and they have nearly the same taste for the beautiful as we have. [, p. 466]

[Male birds] charm the female by vocal and instrumental music of the most varied kinds. [, p. 466]

It is important to establish what Darwin’s language meant in modern terms. Darwin lacked our modern sensitivity to avoiding anthropomorphizing his subjects. Rather, he was actively engaged in reducing the distinctions between humans and animals. But Darwin was not trying to shock his readers. He used these aesthetic terms as ordinary language without any special semantic or cultural implications. Darwin was specifically proposing that animals (mostly females) were making sensory and cognitive evaluations of display traits, and making mate choices based on those evaluations. Darwin used ‘taste for the beautiful’ to refer to differential behavioural response to a secondary sexual sensory stimulus. While this aspect of Darwin’s opinion was highly controversial at the time [], it is mainstream now. If that were the only issue, there would be no need for us to revive Darwin’s use of aesthetic language. Our contemporary terms cover this meaning.

While I doubt Prum’s views as a general explanation of sexual dimorphism (I’m more inclined to see differences between human ethnic groups as a “beauty matters” issue), he may be right in some cases, and at any rate note that the agency here is exercised by females, not males. In what sense, then, are Fuentes’s females “passive” if they are choosing among males competing for their attentions? Darwin makes the females quite active!

Speaking of stuff that Darwin got wrong, his biggest whopper was his erroneous theory of genetics, in which he thought that hereditary “mutations” were invoked by environmental change, a “Lamarckian” view. We know now that Darwin was wrong, but fortunately his theory didn’t depend on a correct mechanism of genetics, but only on the fact that there was genetic variation in populations that could be passed on, and affected survival and reproduction. The fact that Fuentes omits this biggest whopper in favor of moral indictments shows that he has an explicitly ideological aim, which he reveals in the last paragraph of his article (see below).

Here’s a Fuentes whopper about “survival of the fittest,” a term that Darwin didn’t invent and generally avoided, using it only a handful of times in his writings:

[Darwin] went beyond simple racial rankings, offering justification of empire and colonialism, and genocide, through “survival of the fittest.” This too is confounding given Darwin’s robust stance against slavery.

This is wrong on two counts. First, Darwin never justified genocide, though he did think that by virtue of (inherited) superiority, the white race would come to dominate others by higher relative success. But never did he advocate the killing or extirpation of different ethnic groups. Second, the use of “social Darwinism” by others to justify such mistreatment of other groups was always rejected by Darwin. Darwin simply cannot be blamed for the misuse or misconstrual of his theory by others. In fact, I cannot think of what direct harm Darwin really caused to anyone, save his buttressing the views of English men and women of his time. I always maintain that if Darwin lived today, he would likely decry misogyny, racism, and white supremacy, and would be a liberal English guy. It’s unfair, again, to tar him for adhering to the moral standards of his time—indeed, in having higher standards.

Finally, Fuentes neglects that Darwin did do some backsliding about the hegemony of natural selection as an explanation for everything. Here’s a quote from The Descent of Man: (h/t Nick Matzke)

. . . . but I now admit, after reading the essay by Nägeli on plants, and the remarks by various authors with respect to animals, more especially those recently made by Professor Broca, that in the earlier editions of my ‘Origin of Species’ I probably attributed too much to the action of natural selection or the survival of the fittest. I have altered the fifth edition of the Origin so as to confine my remarks to adaptive changes of structure. I had not formerly sufficiently considered the existence of many structures which appear to be, as far as we can judge, neither beneficial nor injurious; and this I believe to be one of the greatest oversights as yet detected in my work. I may be permitted to say as some excuse, that I had two distinct objects in view, firstly, to shew that species had not been separately created, and secondly, that natural selection had been the chief agent of change, though largely aided by the inherited effects of habit, and slightly by the direct action of the surrounding conditions. Nevertheless I was not able to annul the influence of my former belief, then widely prevalent, that each species had been purposely created; and this led to my tacitly assuming that every detail of structure, excepting rudiments, was of some special, though unrecognised, service. Any one with this assumption in his mind would naturally extend the action of natural selection, either during past or present times, too far.

Yes, Darwin went back and altered the fifth edition of The Origin to reflect this change of views.

In Fuentes’s last paragraph, he reveals his aim: to increase inclusion and diversity (presumably racial and gender diversity) among evolutionists in hope that this will it easier to catch Darwin’s moral errors as well as those of other evolutionary biologists.

Fuentes:

Reflecting on “Descent” today one can look to data demonstrating unequivocally that race is not a valid description of human biological variation, that there is no biological coherence to “male” and “female” brains or any simplicity in biological patterns related to gender and sex, and that “survival of the fittest” does not accurately represent the dynamics of evolutionary processes. The scientific community can reject the legacy of bias and harm in the evolutionary sciences by recognizing, and acting on, the need for diverse voices and making inclusive practices central to evolutionary inquiry. In the end, learning from “Descent” illuminates the highest and most interesting problem for human evolutionary studies today: moving toward an evolutionary science of humans instead of “man.”

Re the first part: yes, scientists have long rejected the simplistic view of “races” as easily demarcated groups of people that differ genetically in profound ways, but we still recognize clustered ethnic groupings. As for “no biological coherence to male and female brains”, I believe that this is a matter of debate (see here) and, at any rate, I do believe that evolution has differentiated male and female brains in terms of the tendencies it has given the sexes to behave differently or possess different preferences (there is of course considerable overlap). One example is the male-female difference in sexual behavior, similar to that of many other animals.  This must be coded somehow in the brain. As far as “survival of the fittest” not accurately representing the dynamics of the evolutionary process, well, duhhh. For 30 years I’ve told my classes that “reproduction of the fittER” is a more accurate characterization of how natural selection works, and an even more accurate representation would be that “the genes that become more numerous over evolutionary time are those that leave more copies of themselves.” The latter idea is hard to convey to undergraduates, though!

While I do believe that some of our unrecognized prejudices can be addressed by broadening the types of people we want to attract to evolutionary biology (I think the emphasis on female preference in sexual selection was promoted to some extent by women biologists), I really don’t think that making diversity and inclusion the central focus of “evolutionary inquiry” will lead to profound breakthroughs. This presumes that there are race- or gender-based ways of thinking about evolution, and while this may be true to some extent, I don’t think it’s true to an appreciable or important extent. What we need is to start turning on kids to evolution at a young age; that is, we should “widen the pipeline”, attracting the best thinkers from all groups. It is deeply patronizing to try to hire minorities so they can help us “reject the legacy of of bias and harm in the evolutionary sciences.”

To counterbalance the tut-tutting of Fuentes, though, we have a longer article in the same issue which talks about Darwin’s book, shows its contributions, and steers well clear of morality. Click on screenshot to read the article:

And its summary:

Charles Darwin’s The Descent of Man was published in 1871. Ever since, it has been the foundation stone of human evolutionary studies. Richerson et al. reviewed how modern studies of human biological and cultural evolution reflect the ideas in Darwin’s work. They emphasize how cooperation, social learning, and cumulative culture in the ancestors of modern humans were key to our evolution and were enhanced during the environmental upheavals of the Pleistocene. The evolutionary perspective has come to permeate not just human biology but also the social sciences, vindicating Darwin’s insights.

The ideology and the “I’m better than Darwin was” attitude can be left for classes in the history and philosophy of science.

___________

h/t: Nick Matzke, Andrew Berry, Brian Charlesworth, and Matthew Cobb for discussion.

What I did for Darwin’s Birthday

February 14, 2020 • 9:30 am

by Greg Mayer

As Jerry noted at the time, this past Wednesday was Darwin’s Birthday. My evolutionary biology class met the previous day, Tuesday, and the first slide I showed for the day was the following.

The “click here” in the middle of the slide led to a performance of the Beatles’ song “Birthday”. (For copyright reasons, the video features the Beatles, but the sound is Paul alone in a post-Beatles performance.)

On Darwin Day itself, I watched Creation, a 2009 biopic about Darwin starring Paul Bettany as Charles and Jennifer Connelly as Emma. I did not see it at the time of its release, and it had some difficulty finding a U.S. distributor, ostensibly because Darwin and evolution were too controversial for the American public.

Jerry gathered a few reviews at the time, which were not terribly enthusiastic. I took a look at those reviews, one in the N.Y. Times by A.O. Scott, my favorite film critic, and one by Ryan Jay, another favorite critic. Both were also lukewarm on the film, Jay giving it his middling score of “Rent It”, with Scott being a bit more harsh:

It aims for a liberal-minded balance, at least on the thematic level. But at the same time the film traffics in the pseudo-psychological mumbo-jumbo that is the standard folk religion of the film biography, and undermines its interest in reason by dabbling in emotive pop occultism. Recoiling from the possibility that ideas themselves might impart tension and interest to this tale, Mr. Amiel [the director] and Mr. Collee [the writer] induce a kind of literary brain fever and reduce Darwin’s work to a symptom of his mental and emotional anguish.

I did not look at the reviews before watching the film, so the following comments are not “pre-influenced”. A

ll in all, I was disappointed. The production values are high, and some filming was even done at Down House. The level of production design accuracy was fairly high (e.g., the washroom with curtain in Darwin’s study). Parts of the dialogue I recognized as being taken from Emma’s and, especially, Charles’ letters. Bettany, as made up, does a fair Darwin impersonation, and I was charmed by Benedict Cumberbatch’s unexpected turn as Hooker. (Cumberbatch was largely unknown, at least to American audiences, at the time, and is buried in the credits.) But Connelly is given almost nothing worthwhile to do, wasting her talents; and Huxley (played by Toby Jones) is written as crankily aggressive, rather than as the erudite explicator he seems from his public writings.

And the plot seems quite muddled. The film centers on Darwin’s relationships with Emma and, even more so, on their daughter Annie, who died in 1851. But most of the action takes place several years later, with frequent flashbacks (some to the Beagle voyage), yet Annie is everywhere (except the Beagle). This may be a case of knowing a little being dangerous, as I kept trying to fit the various scenes into a coherent timeline, and only later realized that Annie is a ghost, or better, a symptom of Darwin’s hallucinations, in many, though not all, of the scenes. I don’t know if a naive viewer would be more or less confused than me by this.

Were I someone not versed in the history of evolutionary biology, I would thus give it a mixed review. But knowing some of the actual history, I found some of the themes of the film suffered from being, at best, misplaced in their emphases. The film shows Darwin as losing (most of) his Christian faith as the result of wrenching inner turmoil, leading to open conflict with Emma, with the death of Annie pushing him towards the edge of madness and final loss of faith. Darwin’s well-known ill health is portrayed as essentially psychosomatic, the result of guilt over Annie’s death and his loss of faith. And, his nagging internal torments delayed his work for many years. While there is a grain of truth in each of these elements, the resulting picture is distorted. Darwin did mourn the death of Annie; he did love Emma dearly, and fretted over their differences with regard to faith (see especially this); he knew that consanguineous marriages could lead to “weakness” in children; and he was ill. But he wasn’t nearly mad; his faith more nearly slipped away; he probably didn’t delay terribly long; and the child whose illness was vexing him at the time was not Annie (long dead), but little Charles (who died shortly after Darwin received Wallace’s letter from Ternate).

I searched for, and found two contemporaneous reviews from a more scientific/historical (as opposed to film criticism) perspective. The first was a review by Janet Browne, Darwin’s most authoritative biographer, and professor of the history of science at Harvard. As do the film critics, she takes a lukewarm view

The movie Creation gives . . . a fictionalized perspective. . .  Once one gets over the mismatch between the known historical record and the sentimental version of Victorian family life that is presented here, the film has some rather good sections. . . . [Darwin’s] love for his nine-year-old daughter Anne excessively dominates the plot. There are some delightful scenes, mostly in flashback again, followed by some stupid ones in which Darwin becomes so deranged by her death that he has nightmares (overly tinged with Henry Fuseli) and continuously hallucinates her presence. About ninety minutes into the film, the storyline goes haywire with Darwin vomiting, weeping, and hallucinating. The death of this daughter is presented as the emotional fulcrum of the film, bringing the religious differences of her parents to the fore and serving as a foil for drawing out Darwin’s doubts about publishing. Perhaps.

The other review was by James Williams, senior lecturer in science education at Sussex. His review is scathing. He notes the confusing chronology, details a number of errors and lapses, and laments that the actual events would have made for a better film. Some excerpts.

It promised so much, yet delivered a turkey! . . .

Granted, the film did give some excellent and accurate portrayals of events, but why deliver them out of sequence and why leave out some important details, yet include others? . . .

The film is set in 1858-59, seven years after Annie’s tragic death. Yet the filmgoer is left firmly with the impression that she is alive in 1858 and dies sometime in 1858/9. . . .

At least Alfred Russel Wallace (my personal hero) did get a mention – but only just. It was the receipt of Wallace’s letter by Darwin that prompted Charles Lyell and Joseph Hooker to urge Darwin to write Origin, not a visit by Huxley.

Darwin was distraught by the letter he received from Wallace (accurate in the film), but what put pressure on him was not Annie’s health (she was already dead at this point remember) but the health of his newborn son Charles – who did actually die during the period of his receipt of Wallace’s letter – and the fact that children in the village were sick and dying. Just how Emma could be pregnant with Charles junior, at the same time as worrying about Annie’s health, defies biological understanding.

The film makers were determined to make Annie the focus of Darwin’s angst during the writing of ‘Origin’ and deemed this to be the dramatic ‘device’. When you look at the REAL story of how Darwin was almost forestalled and what was happening in his life during June/July of 1858 and through to the publication of ‘Origin’ in 1859 – there was drama enough without having to destroy historical accuracy.

The film is based (loosely, as Williams insists) on Annie’s Box, by Darwin’s great-great grandson, Randal Keynes. I recalled a paper by John van Wyhe debunking the hypothesis that Annie’s death ended Darwin’s faith.  (We have had a number of occasions here at WEIT to comment favorably on van Wyhe’s work, including his editing of Darwin Online, and Jerry was able to meet him on a visit to Singapore, while I did the same when I invited him to speak as part of our Darwin bicentennial celebrations.) The paper was from 2012; Van Wyhe and his coauthor, Mark Pallen, wrote

That Annie’s death caused great distress to her parents and family is beyond dispute. A week after her death Darwin penned a tender memoir of Annie, which was first published (in part) by his son, Francis, in The life and letters of Charles Darwin (1887) . . .  Darwin closed the memoir with a cry from the heart: ‘We have lost the joy of the Household, and the solace of our old age:—she must have known how we loved her; oh that she could now know how deeply, how tenderly wedo still and shall ever love her dear joyous face. Blessings on her.’ However, it must be stressed that nowhere in the millions of written words by Darwin that survive did he ever indicate, directly or indirectly, that Annie’s death had anything to do with his loss of faith. Of course it would be naïve to restrict the evidence only to explicit statements. But first we must acknowledge that there are none. Furthermore, as we shall see, the balance of all surviving evidence that bears on his loss of faith suggests there was no connection with Annie at all. . . .

The suggestion of a sudden death knell for Darwin’s religious belief built on strong emotion stands in stark contrast to his consistent accounts of his loss of faith, which followed from an assessment of the evidence for Christianity and which took place at a‘rate:::so slow that I felt no distress’ (Barlow, 1958, p. 87). Yet Annie’s death was the most distressing event in Darwin’s life. No explanation for this dramatic contradiction has ever been provided. The time has come to bury the Annie hypothesis.

So, in 2009, it was perhaps defensible, or at least popular, to suppose the truth of the so-called “Annie hypothesis”, but van Wyhe and Pallen seem to have laid it to rest.

Another element of the film, though not quite as prominent, is Darwin’s “delay”. Van Wyhe has also addressed this in his paper “Mind the Gap”

In this essay it is argued that not only is there no evidence that Darwin avoided publishing his theory for many years, but the evidence is overwhelmingly against that interpretation. By re-examining the historical evidence, without presuming that Darwin avoided publication, it can be shown that there is no reason to introduce such a hypothesis in the first place. If we come to the evidence already believing that Darwin put it off, then vague and ambiguous passages will seem consistent with such a view. . . .

A fresh analysis of Darwin’s manuscripts, letters, publications and the writings of those who knew him intimately shows the story to be quite different from one of a lifetime of avoiding publication. It will be demonstrated that Darwin’s delay is a historiographical theme of quite recent date and unknown not only to Darwin and his contemporaries but also to generations of writers after them. Furthermore, this theme is not the product of the greater knowledge of Darwin produced by modern historical scholarship since the 1960s. Modern writers inherited Darwin’s delay from earlier writers who did not have access to the full manuscript corpus.

In fact, Darwin hardly veered from his original plans for working out and publishing his species theory in due course.

If you are a Darwin completist, you’ll want to see the film, but otherwise you can skip it. Its emphases seems wrong, perhaps to the point of no return; but I did enjoy some parts, and the segment conjoining Annie’s death, and the death of a young orangutan at the London Zoo, moved me near to tears. As Janet Browne concluded, “In my view the juvenile orangutan was outstanding.”

Browne, J. 1995. Charles Darwin: a Biography. Volume 1. Voyaging. Princeton University Press, Princeton, New Jersey.

Browne, J. 2002. Charles Darwin: a Biography. Volume 2. The Power of Place. Knopf, New York.

Browne, J. 2010. [Review of ] Darwin’s Darkest Hour [and] Creation. Bulletin of the History of Medicine 84:671-674. gated

Wyhe, J. van. 2007. Mind the gap: did Darwin avoid publishing his theory for many years? Notes and Records of the Royal Society 61:177-205. Darwin Online

Wyhe, J. van, and M.J. Pallen. 2012. The ‘Annie hypothesis’: Did the death of his daughter cause Darwin to ‘give up Christianity’? Centaurus 54:105-123. pdf

Feynman memorabilia for auction, including his Nobel Prize! (Also, Darwiniana and Einstein’s palm print)

November 30, 2018 • 10:00 am

This is sad, and I’m not sure why Richard Feynman’s papers and even his Nobel Prize medal are up for auction rather than going to a museum or an archive (does the family need money?). But if you want some Feynmania, Sotheby’s auction house can accommodate you. You have to have a lot of dosh, of course. The auction site is below, and I’ll put up some selected items with their estimates. (The sale, by the way, started at 10 a.m. eastern time in New York, and you can watch live by going to the site):

There’s a lot more, too.

A cool million for the Prize medal!

Some other cool stuff. You want an Enigma machine?

Anything about Einstein with his signature is worth a ton! Especially his BIBLE!

 

And over here, you can even get Einstein’s handprint! Why isn’t this worth more than his autograph?

Finally, maybe some rich reader would like to give me a Christmas present:

 

h/t: Amy

My letter to Darwin

November 24, 2018 • 10:00 am

Nine years ago, Radio 4 in England invited several of us to write a letter to Charles Darwin, telling the old guy what we think he’d like to know 200 years after his birth in 1809 and 150 years after he published On the Origin of Species.  We read these “Dear Darwin” letters on the air (you can hear them here; the other participants were Craig Venter, Sir Jonathan Miller, Peter Bentley, and Baruch Blumberg). Later, Oxford University Press, the British publisher of Why Evolution is True, published my letter on its website. In honor of the publication of The Origin on this day in 1859, I’ll put that letter below.

My Dear Mr. Darwin,

Happy 200th birthday! I hope you are as well as can expected for someone who has been dead for nearly 130 years. I suppose that your final book, the one about earthworms, has a special significance for you these days. Are the worms of Westminster Abbey superior to the ones you studied so carefully in the grounds of your home at Downe in Kent? They’ve certainly mulched some distinguished people over the years!

But enough of the personal questions: let me introduce myself. I am one of thousands – maybe tens of thousands – of professional biologists who work full time on your scientific legacy. You’ll be happy to know that Britain remains a powerhouse in what we nowadays call evolutionary biology, and your ideas now have wide currency across the entire planet. I work in Chicago, in the United States of America. But even the French have finally reluctantly relinquished their embrace of Jean-Baptiste Lamarck, whose misguided evolutionary ideas you did so much to discredit.

Your Origin of Species turns 150 this year. I just re-read it in your honour and must say that, though you did not always have the snappiest turn of phrase, it really is a wonderfully comprehensive and insightful work. It is remarkable, considering what you did not know when you wrote it, how robust the book has proved over the years. The findings of modern biology, many of them inconceivable to you as you beavered away in your Down House study, have provided ever more evidence in support of your ideas, and none that contradicts them. We have learned a huge amount in the past 150 years, but nearly all of it still fits comfortably into the framework you outlined in The Origin. Take DNA, for example. This is what we call the hereditary material that is passed down from generation to generation. You knew nothing about it – remember how you wished you understood more about how heredity works? Now we have full DNA sequences from dozens of species, each one a string of billions of the four DNA letters—A, T, G and C—each a different chemical compound. What do we find when we compare these sequences, say between a mouse and a human? We see the DNA equivalent of the anatomical similarities – as mammals – that you noted mice and humans share because they are descended from a common ancestor, an early mammal. Strings of As, Gs, Cs, and Ts tell precisely the same evolutionary story as traits like lactation and warm-bloodedness. It is absolutely marvelous that your 150 year old insight on common ancestry should be so relevant to the very latest discoveries of the new field we call molecular biology.

In The Origin, you gave very little evidence for evolution from the fossil record, wringing your hands instead about the incompleteness of the geological record. But since then, the labors of fossil-hunters throughout the world have turned up plenty of evidence of evolutionary change, and many amazing “transitional” forms that connect major groups of animals, proving your idea of common ancestry. You predicted that these forms would exist; we have found them. These include fossils that show transitions between mammals and reptiles, fish and amphibians, and even dinosaurs with feathers—the ancestors of birds! Just in the past few years, paleontologists have unearthed an astonishing fossil, called Tiktaalik, that is intermediate between fish and amphibians. It has the flat head and neck of an amphibian, but a fishy tail and body, while its fins are sturdy, easily able, with slight modification, to give them a leg up when they left the water. The fossil record has given us a direct glimpse of an event of great moment in the history of the planet: the colonization of land by vertebrates. And we have evidence just as convincing for the recolonization of the sea by mammals: the group that gave rise to whales. In The Origin, you were correct in suggesting that whales arose from land animals, but you got it wrong on one point. You thought they may have come from carnivores like bears, but we now know this is not true. Instead, the ancestral whale came from a small hooved animal rather like a deer. And in the last thirty years we have discovered a whole series of intermediate fossils spanning the gap from those ancient deer to modern whales, showing them losing their hind legs, evolving flippers, and moving their breathing hole to the top of their head. Both Tiktaalik and these ancestral whales put paid to the objection, which you yourself encountered, that no transitional form between land and water could possibly have existed.

Perhaps the most remarkable set of intermediate fossils, however, come from an evolutionary transition rather closer to home. In 1871, you more predicted that, since humans seem most related to African great apes, gorillas and chimpanzees, we would find human fossils on that continent. And now we have them—in profusion! It turns out that our lineage separated from that of chimpanzees, our closest living relatives, nearly 7 million years ago, and we have a superb series of fossils documenting our transition from early apelike creatures to more modern human forms. Our own species has become an exemplar of evolution. And we know even more: evidence from our hereditary DNA material has told us that all modern humans came from a relatively recent migration event—about 100,000 years ago—when our ancestors left Africa and spread throughout the world.

The idea you were proudest of was natural selection. That too has had a good 150 years, holding up well as the main cause of evolution and the only known cause of adaptation. Perhaps the most dramatic modern example involves bacteria that are now known to cause disease, including the scarlet fever that was such a plague upon your family. Chemists have developed drugs to cure diseases like this, but now, as you might well predict, the microbes are becoming resistant to those drugs—precisely in accord with the principles of natural selection—for the most drug-resistant microbes are the ones that survive to breed. There are hundreds of other cases. One that will especially please you is the observation of natural selection in the Galápagos finches you collected in the Beagle voyage—now called “Darwin’s finches” in your honor. A few decades ago, zoologists observed a great drought on the islands that reduced the number of small seeds available for the birds to eat. And, just as predicted, natural selection caused the evolution of larger-beaked birds within only a few years. These examples would surely be a centerpiece of The Origin were you to rewrite it today.

All told, the resilience of your ideas is remarkable. But that is not to say that you got everything right. On The Origin of Species was, admit it, a misnomer. You described correctly how a single species changes through time, but you came a cropper trying to explain how one species splits into two. Speciation is a significant problem, because it underpins the branching process that has yielded the tree of life – that extraordinary vision you bequeathed us of the natural world as one vast genealogy. Speciation is the key to understanding how, starting with the very first species on earth, evolution has resulted in the 50 million species that are thought to inhabit our planet today.

You once called speciation the “mystery of mysteries,” but it’s a lot less mysterious these days. We recognize now that species are separated one from another by barriers to reproduction. That is, we recognize different species, like humans and chimpanzees, because they cannot successfully interbreed. To modern evolutionary biologists, studying “the origin of species” means studying how these barriers to reproduction arise. And now that we have a concrete phenomenon to investigate, we are making remarkable progress in understanding the genetic details of how one species splits into two. This is in fact the problem to which I’ve devoted my entire career

I wish I could end this letter by telling you that your theory of evolution has achieved universal acceptance. As you well knew, evolution has proved a bitter pill for religious people to swallow. For example, a large proportion of the American public, despite access to education, clings to a belief in the literal truth of Genesis. You will find this hard to believe, but more Americans believe in the existence of heavenly angels than accept the fact of evolution. Unfortunately, I must often put aside my research to fight the attempts of these “creationists” to have their Biblical views taught in the public schools. Humans have evolved extraordinary intellectual abilities, but sadly these are not always given a free rein by their owners. But this probably won’t surprise you – remember the Bishop of Oxford and his attempt to put your friend Thomas H. Huxley in his place?

You wrote in your introduction to The Origin of Species that

“No one can feel more sensible than I do of the necessity of hereafter publishing in detail all the facts, with references, on which my conclusions have been grounded; and I hope in a future work to do this.”

It seems that, distracted by other projects, you never got around to it, but my own effort along these lines is represented in a book (which I enclose) called Why Evolution is True. It goes further to describe the evidence supporting you than a letter this size ever could, but it’s just one book at just one moment in the history of biology. When I myself am as long gone as you are, somebody else will certainly need to write an update, for the facts supporting your theories continue to roll in, and I wager they will continue to do so.

So, rest in peace, Mr. Darwin, and here’s hoping that the next hundred years will see a steady evolution of rationality in a troubled world.

Your most humble servant,
Jerry Coyne

Teaching Evolution: Darwin: Unity of type and adaptation

March 31, 2018 • 10:30 am

Note from Jerry: Greg plans to run a mini-MOOC here, so if you want some education in evolution, do the readings and answer the questions (to yourself). This is the first installment.

by Greg Mayer

This semester I’m teaching BIOS 314 Evolutionary Biology, an upper level undergraduate course. The students are all or mostly biological sciences majors, and general genetics and biostatistics are prerequisites for taking the course. As a textbook, I use Evolution, by Doug Futuyma and Mark Kirkpatrick, published by Sinauer Associates of Sunderland, Mass., which last year became an imprint of Oxford University Press. This is the 4th edition of the current iteration of this text, which also had 3 editions under an earlier iteration with the title Evolutionary Biology. Doug was my undergraduate evolution teacher, and I took the class with him while he was writing the first edition of Evolutionary Biology.

I hope to say more about the textbook later, but I also have the students read a series of what I regard to be classic papers or extracts– one each week–and these are what I want to share with WEIT readers. Each reading is accompanied by a brief biography and illustration of the author, and a small number of study questions, designed to guide the student in understanding the reading. I sometimes assign these questions as homework essays, or include them on exams. The first week’s reading each time I’ve taught the course this way has been an extract from the Origin. I will, when possible, provide links to the readings. For this Darwin reading, you can use John van Wyhe‘s superb Darwin Online. I’ll be posting a reading every few days. If you want to read along, it will be like taking a guided readings course in evolutionary biology.

Charles Darwin (1809-1882), after studying briefly at Edinburgh to be a physician, went to Cambridge to prepare for the Anglican priesthood. While there, his interest in natural history attracted the attention of his professors, which led to him being invited aboard H.M.S. Beagle as a supernumerary naturalist for that survey vessel’s global circumnavigation (1831-1836). By the time he returned he was already a recognized geologist, and, leaving the ministry behind, he soon established himself as a rising star in all departments of natural history. After study of his Beagle collections convinced him that species were not immutable, he discovered natural selection as a means of modification. Spurred by the later but independent discovery of natural selection by A. R. Wallace, he published his views and evidence in On the Origin of Species in 1859. Within a few years, the whole of the scientific community accepted descent with modification as the key process underlying the phenomena of the organic world, though natural selection as the chief means of modification was not accepted during Darwin’s lifetime. Among his many other works are Zoology of the Beagle (1838-1843, edited by Darwin), Voyage of the Beagle (2nd ed., 1845), Variation Under Domestication (1868) and The Descent of Man (1871). All of Darwin’s published works are available at John van Wyhe’s Darwin Online, http://darwin-online.org.uk/. He is buried in Westminster Abbey, not far from Sir Isaac Newton. The best biography is Janet Browne’s Charles Darwin (vol. 1, 1995; vol. 2, 2002).

 

Reading:
Darwin, Charles. 1859. On the Origin of Species. 1st ed. John Murray, London. Extract from Chap. 13, pp. 434-450, “Morphology” and “Embryology”.

 

Study Questions:

1. Why is the concept of homology crucial for even being able to talk about organic structure? How are homologous organs recognized? What is Darwin’s explanation for homology?

2. How does Darwin’s account of serial homology (the resemblance of parts within an organism, for example, the forelimbs to the hindlimbs, or of a cervical vertebra to a thoracic vertebra) depend on the repetition of parts or segmentation?

3. What is the “law of embryonic resemblance”? How do these resemblance relate to the organisms’ conditions of existence? How does this relation depend on whether the embryo is active and provides for itself?

4. When during development does Darwin suppose most species differentiating characters to become evident? How does this relate to when he supposes the characters to affect the survival and reproduction of their bearers?

The textbook—and misguided—presentation of natural selection

July 17, 2016 • 1:00 pm

I was reading a nice article by Andrew Shtulman* on the most common misconception people have about natural selection (that it involves not differential reproduction among genetically different individuals but the gradual and simultaneous transformation of all individuals in a population), when I came across his presentation of Darwin’s “variational” theory of natural selection. That’s the first view given in parentheses, and the correct one.

This characterization of evolution via natural selection (it’s not really a definition) involves a three- or four-step logical chain. Here’s the way it’s presented in many classes, and the way I used to present it:

  1. Animals and plants produce many more offspring than can survive, ergo there is tremendous mortality in nature.
  2. Animals and plants differ in their traits.
  3. Bearers of some traits leave more offspring, or survive better, than do bearers of others. (For example, those individual moths who match their backgrounds better are less likely to be eaten by birds than are their more conspicuous relatives.)
  4. Some portion of the differences among individuals in these traits will be passed on to the next generation. That is, some of the variation is heritable (“capable of being inherited”).

If these conditions hold, then the population will undergo gradual genetic change, being enriched in the genetic variants that give their bearers greater reproduction and/or survival (“fitness” is the word we use here). This is a variational view of evolution rather than the incorrect transformational view outlined above.  The chain can also be described as “Excess production of individuals + variation in fitness + some heritability of that fitness = evolution via natural selection.”

I hope you’ve followed me so far. If you’ve taken any evolutionary biology, you’re likely to have heard the chain of logic above. It is exactly the chain outlined by Darwin in On the Origin of Species. Darwin, in fact, said that he finally grasped the importance of natural selection when he read Malthus’s “On Population”, which described the overproduction of offspring. For when Darwin realized that the huge excess of young animals and plants must somehow be culled if populations remained at relatively stable sizes, he saw immediately that the culling would probably be based on the traits that individuals had, and if variation in those traits had at least some genetic basis (remember that Darwin was unclear about how genetics worked), it would, over time, produce a predominance of the variants producing those traits.  Curiously, A. R. Wallace also hit on the idea of natural selection after reading Malthus as well.

But there’s one problem with this: one of the points is not necessary for evolution by natural selection. Can you guess which one?

It’s #1—the very point that brought Darwin and Wallace to the brilliant idea of natural selection.

Why isn’t this necessary? While clearly not all offspring survive in any species—otherwise we’d be up to our collective tuchas in rabbits, beetles, or oak trees—natural selection can still cause evolutionary change in a population that is expanding (or decreasing), and in which all offspring survive. Imagine, for instance, that a lizard makes it to a luxuriant island in the ocean, one loaded with food and without predators. Imagine too that every lizard dies only of old age—after it’s already had its offspring. And further imagine that some lizards are better able to digest the local vegetation, and thus are better nourished and leave more offspring than others. Every offspring survives, but more of the next generation will carry those genetic variants that make them better at digestion. Over time, the population will evolve by natural selection, as the carriers of the “good digestion” genes overtake their dyspeptic confrères.  So we have (variational) evolution by natural selection, but every individual that is born survives to reproductive age. And this will work even if individuals are immortal and never die.

Of course the situation I just described is unsustainable: eventually the population of lizards will get big enough that they’ll be competing for food, and might even kill each other. My point, though, was that natural selection can operate independently of a huge mortality—or any mortality—in a population.

Ergo, we can omit #1 above from the characterization of natural selection. When I realized this, I dropped it from teaching.

In fact, the great evolutionary biologist Ronald Fisher made just this point in his famous book The Genetical Theory of Natural Selection (1930). In chapter 2, he objects to the Malthusian point, saying that it not only ignores differential reproduction in favor of differential survival (my example above), but ignores the fact that organisms often overproduce offspring as the very result of natural selection.  The vast overproduction of offspring in some ocean fish, for example, isn’t just a given: it’s likely resulted from the high mortality experienced by tiny fish, due largely to predation. If that’s the case, you have to produce more offspring just so some will survive.

Here’s the quote from Fisher explaining that. Fisher was famous for his dense and often opaque prose, but maybe you can grasp his point:

“. . . it should be remembered that the production of offspring is only excessive in relation to an imaginary world, and the ‘high geometrical rate of increase’ is only attained by abolishing a real death rate, while retaining a real rate of reproduction. There is something like a relic of creationist philosophy in arguing from the observation, let us say, that a cod spawns a million eggs, that therefore its offspring are subject to Natural Selection; and it has the disadvantage of excluding fecundity [offspring production] from the class of characteristics of which we may attempt to appreciate the aptitude. . . [T]he historical fact that both Darwin and Wallace were lead through reading Malthus’s essay on population to appreciate the efficacy of selection, though extremely instructive as to the philosophy of their age, should no longer constrain us to confuse the consequences of that principle with its foundations.”

Fisher was a very smart man. So, if you teach how natural selection causes evolution, you might want to omit point #1 above—or at least qualify it.

Sir_Ronald_Fisher_2
Ronald Fisher (1890-1962)

______________

*Shtulman, A. 2006. Qualitative differences between naïve and scientific theories of evolution. Cognitive Psychology 52:170-194.