My WaPo review of David Quammen’s new book on evolutionary trees (and a comparison with other reviews)

August 24, 2018 • 11:00 am

I’ve just reviewed David Quammen’s new book, The Tangled Tree: A Radical New History of Life, for the Washington Post. Click on the screenshot to see my review. (Note that the original title, which was a bit misleading, has been changed to the new one below.) It will be in the paper version of Sunday’s Post.

Since the topic of the book is evolutionary trees, in particular their reality (or nonreality, according to Quammen), I asked that my piece be illustrated with Darwin’s famous “tree sketch” from one of his pre-Origin notebooks:

Charles Darwin’s sketch of the “Tree of Life” illustrates his theory that species evolved from a common ancestor. (Photo by Mario Tama/Getty Images)

The point of Quammen’s book is largely that the “tree of life” isn’t treelike, and that’s because of endosymbiosis (e.g., the creation of eukaryotic cells that harbored mitochondria and chloroplasts by ingesting and using other microbes), and, mainly, because of “horizontal gene transfer” (HGT): the movement of DNA between rather unrelated organisms.

Besides this point, Quammen’s protagonist is Carl Woese, who discovered that life really comprises three distinct domains: Archaea, Eubacteria, and Eukarya. Because the book consisted of several distinct stories, I chose to concentrate in my review on what seemed to be Quammen’s main point: that the tree of life is simply “wrong” (his words), and can’t really be represented by a tree. The Tangled Tree falls into the “Darwin was wrong” genre of books.

I disagreed about the unreality of trees, especially in the Eukarya, where assumptions of branching trees have worked well in reconstructing the history of species, despite occasional movement of genes between branches. Even in microbes Quammen isn’t completely correct: while HGT is more common among microbes than eukaryotes, it hasn’t, for instance, completely effaced phylogenetic relationships between bacteria, and of course didn’t prevent Woese from discovering, via DNA sequencing and biochemistry, that Archaea is a separate “domain” from the other two. With a limit of 1200 words, I had to largely ignore the stuff about endosymbiosis and Woese’s discovery to concentrate on the main point of the book: the “hook” that was used to sell it.

You can read my review at the link, or, if you’re paywalled, you can get a copy by judicious inquiry.

I’ll also add one correction to my review. Here’s part of what I wrote:

More remarkably, more-complex species can simply incorporate genes from the environment. Microscopic rotifers, for instance, dehydrate in dry conditions; when they rehydrate, the absorbed water can contain bits of DNA from nearby species, so that the rotifer genome can become riddled with “found” DNA segments from groups like fungi and plants.

The rotifer story now appears to be not at all a case of HGT at all, but of contamination by DNA from other species during sequencing. That was revealed in an article published in Current Biology on August 6, and which I didn’t know about until my article was in press (thanks to Matthew Cobb for pointing that out to me). So even that famous example of HGT is wrong. Some biologists think that most evidence of HGT in eukaryotes is due to contamination of this sort, but I remain open-minded. We already know, as I said, that HGT is not sufficiently frequent in multicellular organisms to efface their evolutionary ancestry.

I want to say a few words about three other reviews that have appeared about Quammen’s book. The first two are at the New York Times (click on screenshots to go to articles):

Seghal is a literary critic, and it shows: she criticizes the book as a piece of writing (she likes it) but doesn’t at all tackle the science. In fact, she admits, if not flaunts, ignorance of the science:

In 1977, Woese and his colleagues at the University of Illinois announced their discovery of a “third domain” of life — single-cell microbes they called archaea — genetically distinct from what were thought to be the only two lineages of life: prokaryotes, which include bacteria, and eukaryotes, which include plants and animals. (It’s O.K., I might have missed the memo, too.)

Missed the memo? If you know the least bit about biology, you know about Archaea. And if you don’t, you shouldn’t be reviewing this book. And there’s this:

But this new knowledge — that we are genetically a mosaic — challenges our conception of human identity. What does it mean to be an “individual,” if we are such composite creatures?

Quammen raises and rushes past these existential questions; like the White Rabbit, he spends some sections in a bit of a mad rush. There’s a “Montana blizzard of facts” he wants to shepherd us through; a dizzying array of scientists, past and present, he must introduce. (Please don’t ask me if I can tell my Norton Zinder from my Oswald Avery.)

This is simple parading of the critic’s ignorance to excuse her inability to discuss the science. It is in fact embarrassing. And she doesn’t grasp the science: there’s not a peep about whether the concept of evolutionary trees are, as Quammen claims, pretty useless.  Seghal’s review is a paradigm for why science books should be reviewed either by scientists or by people who know a fair amount about the science at issue.

Erika Hayden, on the other hand, is qualified to review the book: she’s a science journalist and director of the Science Communication Program at the University of California, Santa Cruz. And her review is better than that of Sehgal, although again she doesn’t weigh the evidence for the existence of evolutionary trees; she takes Quammen’s conclusions at face value.

But Hayden has her own beef: she sees the book as antifeminist:

But if Quammen is writing for the ages, his prose at times risks feeling dated. His book spans nearly three centuries and mentions more than 160 scientists by name. Of those, by my count, only 11 are women, and Quammen often dismisses their scientific credentials and achievements or portrays them as appendages to men in the story.

Lynn Margulis, for instance, fundamentally revised our understanding of eukaryote evolution, elucidating how nature’s most complex cells, including our own, arose when simpler cells joined together. She is the only female scientist who is called out and gets significant space in Quammen’s book. But we hear just as much about her pregnancies, motherhood and marriages as we do about her science.

In contrast, Quammen doesn’t really spend equal time exploring the family arrangements of the male scientists in the book. It’s a classic failure of the Finkbeiner test, formulated by the journalist Christie Aschwanden, which posits that a female scientist’s gender is not her most salient characteristic. If scientists’ family lives are important, journalists should write about the families of both male and female scientists. Otherwise, we perpetuate the stereotype that a woman scientist’s primary responsibility is to care for her family, while men should float free from such pedestrian concerns in their pursuit of research.

As for the imbalance between male and female scientists, that simply reflects the gender composition of the field at the time the work was done. In that sense the book is dated, but not unfair.

I reread those sections, and that on Margulis, to see if Hayden had a point, and concluded that she’s wrong. Margulis’s work was discussed in detail, with her science occupying far more space than a few sentences about her family life, including her marriage to Carl Sagan. (The spouses of male scientists aren’t ignored, either, and I don’t think that the women scientists, who are often praised, are given short shrift.) Quammen’s brief mention of Margulis’s family was meant only to show that she accomplished much of her work when she was a single mother of three children and holding down another job, and was meant to laud her accomplishments during a difficult period of her life. (Margulis, of course, was problematic in other ways, being a 9-11 truther, and someone who pushed her theory of endosymbiosis much farther than she should have. She wrote a book on speciation with her son, for instance, that was so bad that it was the only book I’ve ever refused to review for a major venue. It wasn’t even wrong.) In general, then, I don’t agree with Hayden calling out the book for sexism, but you can draw your own conclusions.

Finally, there’s this review from the New Republic (click on screenshot). Gaffney is identified as “a physician and writer with a focus on health care politics, policy, and history. He is an Instructor in Medicine at Harvard Medical School and a pulmonary and critical care physician at the Cambridge Health Alliance.”


Gaffney’s review is good for what it is: a recounting of what the book is about. But it again falls short in evaluating Quammen’s thesis, and says only this (besides a long bit on the transfer of antibiotic resistance among bacteria by HGT):

Ultimately The Tree of Life is merely a metaphor, but I think a pleasant one: It connects us to the lineage of all living things, all the way back to the bag of chemicals—or maybe the single molecule—that one day coalesced in the primordial muck. Yet like all metaphors, the “tree” falls short of reality. For in biology, all boundaries are blurred: between species, sometimes even between individual organisms, and probably between the living and the non-living.

No, not all boundaries are blurred. Homo sapiens doesn’t interbreed with any other species of primate, nor do many, many other species. And really, is the line is blurred between, say, Jerry Coyne and Meryl Streep? How? As for the “unreality” of trees, I disagree. So long as species arise from the transformation of populations, usually geographically isolated ones, the history of life is indeed largely treelike. If it weren’t, we wouldn’t be able to reconstruct the history of life. Yet we can!

Now Quammen’s book has its good points. For one thing, it tells you the nitty-gritty about how science is done, complete with rivalries, jealousies, and backbiting. Quammen did his historical homework. And it’s a well-written story. But as you’ll see from my review, I think his report on the demise of Darwin’s tree is greatly exaggerated.


h/t: Stephen

84 thoughts on “My WaPo review of David Quammen’s new book on evolutionary trees (and a comparison with other reviews)

        1. Yes. That’s largely because of climate change, so if they fuse, they would have once been species isolated by ecological preferences, but then fused back into one species. Speciation need not be permanent.

          1. Depending on how far the two species have differentiated I suppose? There are many examples of congeners that occupy the same geographical ranges and very similar ecological niches but don’t interbreed. I suppose that in these cases a past physical barrier between two populations of a single species generally gave rise to the speciation ‘event’ but once that physical barrier was subsequently broken down, the two new daughter species had differentiated in terms of physiology, morphology, behaviour etc sufficiently for hybridisation to not occur or be possible. In these instances speciation is permanent I presume?

      1. It’s the taxonomic designations that confuse me. Obviously Neanderthals and denisovans (and others yet to be identified)interbred, so insofar as I can understand things, they’re subspecies; but then I see “homo sapiens” and “homo neanderthalensis,” which implies to me that they aren’t sub-species of homo sapiens; yet I see “homo sapiens neanderthalensis,” and “homo sapiens denisova.” And it’s now established that Neanderthals and Denisovans interbred but were the offspring fertile? PCC(E)’s declaration that they’re sub-species makes sense to me.

  1. It is worth noting that cow DNA is 25% from serpent by horizontal gene transfer, yet cows look nothing like snakes. DNA change does not tell us everything there is about “evolution”.

    1. “cow DNA is 25% by horizontal gene transfer from serpent” is plain wrong.
      What is your source of this claim?
      Best to check your source.

  2. Interesting use of the present tense in your WaPo title. I guess it is referring to the virtual Darwin of modern evolutionary science. Or is it the Darwin that still speaks from the pages of his books?

      1. I suspected that was the case. This is so often a problem. I realize that ultimately the publication’s editors must have final say on the title but I get the feeling that they don’t even have a conversation with the author.

          1. Shows why the title conversation needs to happen BEFORE publication. Changing the link now would break all references to it, of course, including the ones from this page. They could publish it again under a link that reflects the new title, while still maintaining it with the old link, but that would create a different set of problems.

          2. Also the TITLE property of the page is:

            “Book review of The Tangled Tree: A Radical New History of Life by David Quammen – The Washington Post”

            This will typically be used by browsers as the window or tab title, as well as the default link text in authoring systems used to write reviews and comments.

  3. There is some hypocrisy in complaining that a biology book should call out more female scientists while, at the same time, maintaining that “a female scientist’s gender is not her most salient characteristic”. I guess one must mention that the scientist is a woman but go no farther. Good to know the rules!

  4. When dealing with works of science (broadly), I find reviews that don’t address the argument or evidence put forward by the author to be useless. What do I care if it is a rolicking, good read? While unreadability detracts from a good argument, readability does not enhance a poor one.

  5. I’ve only read one of Quammen’s books, “The Reluctant Mr. Darwin”, and wasn’t all that impressed. I had trouble understanding why he is so highly regarded as a science writer and popularizer. I thought maybe it was just me, that he didn’t “do it” for me for whatever reason. Anyone else have a similar experience?

    As for Margulis, what is the name of the horrible book she wrote with her son? If it’s that bad, I feel compelled to seek it out.

    1. Quammen is one of my favorite writers, I am sorry he has gone off the rails with this one. I highly recommend The Song of the Dodo, about biogeography.

    2. I’ve long been a fan of Quammen’s but have to agree that “The Reluctant Mr. Darwin” is not impressive (I couldn’t finish it). His earlier books, especially The Flight of the Iguana, and Natural Acts, are excellent, however–perhaps the best popular science books I’ve read. My take is that he is primarily an essayist (both of the books I mentioned are essay collections) and doesn’t do nearly as well with a sustained topic. As for the present book, I haven’t read it and am not either up on or interested enough in the topic to have an opinion.

  6. An interesting example of HGT in an insect. The pigment in reddish aphids is a carotenoid, but animals don’t make carotenoids. Sequencing the aphid’s DNA revealed its genes for carotenoid synthesis to have come from a fungus.

    1. Yes, I think that’s Nancy Moran’s work, or so I recall. And the result is sound, but remember, it’s just one or a few genes being transferred. It doesn’t make aphids look like their closest relatives are fungi!

    2. There is an interesting ‘sprinkling’ of cases of HGT of this sort through the eukaryotes. In other cases, new species can form by hybridization of related species. But these instances fall well short of blurring the overall tree-ness of the tree of life.

    1. You can also avoid the paywall by opening the link in your browser in a ‘private’ or ‘incognito’ window.

        1. It works on sites like the Post or NYT that allow you a set number of free views, like 3 for the Post I think, because your browser doesn’t keep a cookie or any record of the visit. Each time you open a private window, it looks like your first free view to the site. On a normal paywall, with no free views it won’t help.

  7. I think that if you want to sell books about biology, or to generate press in general, you should challenge Darwin or the concept of a the selfish gene. The unfortunate fact is that these challenges regularly fail, often based on the author constructing a straw man or failing to understand the biology.
    Phylogentic trees are clearly not just a metaphor. They have real, predictive value. They help us answer meaningful questions in biology and, even with lateral transfer, represent an underlying, real history. I think the thing that really bothers a lot of people, and makes exaggerations about Darwin’s failure to represent reality profitable, is that Darwin was largely right about the big picture, even though he was sometimes wrong about specifics. Some people simply won’t be happy unless evolution fits their politics (be it compatibility with religion or a “genial” gene).

  8. The review is extraordinarily clear to a lay person such as myself. I wish only that all popular science writing could reach this standard.

    1. PCC(E)’s new side-job? Popular science book reviewer for WaPo, NYTimes, Chicago Tribune, etc. Paid vast sums for concise, erudite and thorough reviews. A new paradigm can be born!

  9. I really don’t like that headline. I’m not adverse to “presentism” in history (particularly history of ideas) in general (since I think it is impossible to avoid), but Darwin really had no theory of inheritance, never mind no knowledge of nucleic acids, so …

  10. It is too bad, really, that a popularizer of science has once again been pursuaded to sell a revolution or paradigm shift instead of the truth.

  11. “Erika Hayden, on the other hand, is qualified to review the book: she’s a science journalist and director of the Science Communication Program at the University of California, Santa Cruz.”

    From the brief reading I’ve just completed, it appears Erika Hayden is very qualified to review books about science (and about genetics and other subjects of biology in particular) and that the program she runs is quite prestigious and widely recognized as such, so what I’m about to write is not a reflection on her.

    It is dangerous to assume that someone who is a science journalist and director of a science journalism program is necessarily suited to those jobs. Unfortunately, we have seen time and again (largely thanks to you, in my case) that science journalists often get such a job not because they are knowledgeable about science, but because of their political positions. Don’t forget that the malicious and incompetent Connie St Louis (she who intentionally lied for months to take down Tim Hunt, and was also shown to have lied on her CV for her position at City College, among other things) was a science journalist and director of City College’s Science Journalism MA program.

    Anyway, this was an excellent post. I’ve found myself very curious and concerned regarding why Darwin’s theories are being repeatedly attacked in the scientific community. This seems to be a trend that has gained a lot of steam in the last few years. Is it because scientists can expect to find lots of coverage — and, often by extension, fame and fortune — when they engage in this? Is there a larger political question behind the trend? I’m interested in your opinion and that of others in the scientific community.

    1. I suspect that a lot of the Darwin attacks are not inspired by religion but reaction to the whole “we’re descended from apes” meme, coupled with the intellectual relativism (truth is culturally determined) that holds much sway these days. It also comes from membership in the red team. While the origin of Republicans’ dislike of evolution may be based in their pandering to the Religious Right, it also affects the non-religious members of their party as part of their “identity”.

      1. I don’t think most of these scientists are doing this because they’re Republicans or generally from the red tribe. I’m looking for other explanations. The overreaching proposals for the role of epigenetics, for example, is unlikely to be the result of red tribe desires and/or biases. There may be no political angle at all, but, if there is…

        1. You misunderstand me. It is not Republican influence on the authors but on the readers, seen by editors and publishers as going to their bottom line.

          There is a general interest in seeing evolution fail, or at least be questioned, by the religious right and, by extension, the party most allied with them. Most of the readers don’t know or care about the details but are only too happy to see evolution attacked. The reference to “epigenetics” is simply to be enable the content to plausibly be portrayed as science. An “Evolution is Wrong” article would just not carry the same weight and would attract much more ridicule.

          1. I don’t know. Many of these articles come from solidly blue tribe publications with blue tribe editors, such at the New York Times or The Guardian. This is too easy and politically convenient an explanation.

          2. My Republican explanation was only one of several contributing factors that I listed. I assume most of the publications we’re talking about are non-partisan, notwithstanding the built-in liberal bias of the press of course.

      2. I think that another factor at play is that sensational claims sell more books. Darwin’s theory of natural history is very solidly established and so a claim that ‘new findings’ have overturned it is by its very nature much more exciting and alluring than to say that new findings have added some extra nuances to an overall correct view of nature. There’s probably a chain of over-reaching too; the scientist making a discovery that ‘challenges’ an established view may over-egg the extent of that challenge, the popularising science journalist exaggerates it a bit further and the publishing blurbs further still until what was once an interesting detail becomes an earth-shattering new paradigm.

    2. I’m guessing that the apparent prevalence of Darwin attacks is largely a selection effect — the media is much more likely to give attention to them.

      1. Sure but doubt about evolution is also very common. Do an informal poll with the typical family and I bet there are a few. I would have said “your family” but with all the scientists on this site, it probably would not be a fair survey.

      2. Good point, but that was part of my point about scientists possibly doing it for fame and/or fortune. Though it does explain why the media itself is so interested in this.

  12. Quammen did a piece on my dissertation research for his column in Outside magazine many years ago. After a couple of very friendly chats on the phone, his article came out trashing my research for no apparent reason. My only chance at rebuttal was a short letter to editor. It was a real d*ck (not duck either) move that mortified me as a young post doc. I use it as an example of why one has to be very careful when talking to the press, even famous authors (PCCe excluded). So, I don’t buy his books and I take everything he writes with a block of salt. Thanks for allowing me to vent.

    1. This is a rather serious accusation. In the absence of any details, it is difficult to see whether it is justified. Maybe I am biased, because “The Song of the Dodo” is one of my favorite books.

  13. I’m about halfway through the book. About the only thing I like about it is that it’s very readable with very short chapters of only a few pages each. It’s very much the ‘Dan Brown’ of science writing.

  14. The review is behind a paywall for me. However on the general topic I would say that trees are useful, while networks can be used to describe phenomena such as horizontal gene transfer or polytomy. So I do not agree with Jerry that non-tree topologies would necessarily efface phylogenetic relationships but rather help detailing them.

    On contamination I do not have much to contribute. But seeing how we have genuine examples of HGT on the one hand and that the rotifer sequencing problem was rare on the other, I would deem it a problem to be aware of rather than a roadblock.

    And of course I will have to note that the three domain tree is a bit dated. Recent trees often place eukaryotes within the TACK archaea to make two domains [ , ].

  15. The Sandwalk blog has an overview of HGT.
    “There are several problems with these claims according to Bill Martin. First, the pattern of LGT doesn’t conform to what we see in bacteria where entire clades have inherited genes transferred from bacteria. Most of the claims of LGT are confined to a single species. Second, there’s no reasonable mechanism for LGT as there is in bacteria.”

  16. I can’t for the life of me imagine why someone would write a book with such a lame thesis as this. It should be embarrassing to play this loose with the facts. If he were simply to read the professional literature, or even consult a biologist about the actual facts involved in the metaphor of a “tree”, he could have saved himself, and others, the trouble. But, then, I suppose if he just presented evolutionary facts and described what the actual role horizontal transfer plays, he couldn’t hook in readers who need a sensational title. $$$maybe???.

  17. I have not yet read the book, since it is not available in Europe until next month. “The Song of the Dodo” shows David Quammen talking to evolutionary biologists and correctly describing their ideas about island biogeography. It is unfortunate if a desire to write a book which will attract attention because of its supposedly iconoclastic message has led Quammen astray. One wonders whom he might have consulted …

    No-one doubts the importance of HGT in allowing bacteria to acquire genes enabling for example resistance to antibiotics or the ability to fix atmospheric nitrogen. But even here there is a “tree of cells” since cells arise in a tree-like pattern by division of existing cells, and I am not aware of any examples of “total genome fusion” between distantly related microbes. The notional tree of cells is approximated by the results from several groups showing the similar trees derived from the sequences of hundreds of conserved genes involved in central cell functions such as replication, transcription and translation, which have credibly accompanied each other during evolution.

  18. Unfortunately, even good writers such as Quammen feel the need for a “hook” to promote sales, and “Darwin was wrong” will certainly get some attention. I’ll still read the book when I have time because I always enjoy reading about the people behind the science. It’s too bad that he didn’t focus on what we’ve learned about the evolution of eukaryotes. That would have been a great book even without the “tree of life” question. As long as we’re on books, I recommend Improbable Destinies: Fate, Chance, and the Future of Evolution, by Jonathan Losos. I don’t agree with everything in it, but it’s a well written account by a researcher.

  19. As an aged retired physician I got nook on Kathryn Schltz’s Glowing tweet. Fascinating to read and thought the tree was a tree, but like many not perfectly adorned. For those of usmlong separated from current science and besieged by short opinions eye opening.
    Difficult to get all reviews even when subscribed but now have printed texts to read.
    Did enjoy the mention of Darwin’s insight from Malthus as we face yet another episode in our history of large numbers of families without food

  20. Endosymbiosis and HGT are superimposed upon the Darwinian Tree of Life. No uprooting or “upending” to quote Sehgal.

    Natural Genetic Engineering doesn’t get a mention. That’s as it should be, at least.

  21. Well, a tangled tree is still a tree. Even if it turns out to be more like a bush or a shrub, it still has branches.
    Craig Venter once offended Dawkins in a conference panel by denying the Tree of Life. But he added: perhaps it’s a bush.
    Doesn’t see too incorrect to me?

    1. Comment from Quammen (Twitter communication): “Yes, I agree. The tree signal is not gone; it is merely complicated now with other signals, convergent, which are little known to the public but very important. Hence my title.”

  22. Thank you for doing the WaPo review and here going over these other ones. Great to have summaries in one spot. I had read 2nd NYT review was disappointed.

    Thanks for other dixcussion in comments.

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